journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 81-87 81 doi: 10.17977/um016v3i22019p081 critical solid fraction point analysis: case study on cement mill machine diaphragm mochamad achyarsyah1*, poppy puspitasari2,3 1foundry department, bandung polytechnic of manufacturing, no. 21 kanayakan street, bandung, west java, indonesia 2mechanical engineering department, state university of malang, no.5 semarang street, malang, east java, 65142, indonesia 3center of advanced materials and renewable energy, state university of malang, no. 5 semarang street, malang, east java, 65142, indonesia *corresponding author:achyarsyah@polman-bandung.ac.id abstract during the solidification process, metal liquids turn into solid geometry units including the riser and gating system. the disruption in the liquid flow often causes shrinkage in the object. critical solid fraction point is a critical point where the continuous liquid supply turned solid and unable to pour to some sections. simulation software can predict the critical solid fraction time of an object and the liquid supply behavior. the simulation helps the designer in the casting design. the application of low steel alloys in the cement industry, e.g., the diaphragm, needs development to minimize the shrinkage. this research aimed to analyze the critical solid fraction point in the diaphragm steel casting products. the primary objective of this research was to predict the critical solid fraction point during solidification, started from the longest time in the riser/feeder using solidcast 8.1.1 casting software and provided improvement recommendation to minimize the shrinkage. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: critical fraction solid time, diafragm, shrinkage i. introduction the diaphragm is a component in cement mill machine that functioned as a filter and sorter of the raw material. the component is assembled to a geometrical unit that shaped like a ring into the machine. the component will be rotated and experiences continuous friction with the processed raw material and ball mill component. the component generally made from wearresistant casting steel. the component’s replacement already relies on the domestic supply with a relatively lower service life compared to the foreign supplies. the previous simulation of the diaphragm design predicted that the shrinkage occurred in the riser. however, it was also predicted that the disrupted liquid supply path in some sections of the product. this occurrence indicated that a complex geometrical shape in the diaphragm product also made a relatively complex liquid flow path from the riser [1]. during solidification, liquid from the riser flows through a path that passes the sections up to a section that requires faster supply or faster solidification [2]. the effective duration to 82 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 81-87 supply the liquid correlates with the time the object reaches the critical solid fraction point. when a section reaches the critical solid fraction point, the liquid unable to flow through the section. this research aimed to predict the critical solid fraction time of the diaphragm casting object during solidification, started from the longest time in the riser/feeder using solidcast 8.1.1 casting software and provided improvement recommendation to minimize the shrinkage [3]. ii. method fig. 1. depicts the methods used in this research to obtain the timing prediction of the critical solid fraction point in the diaphragm casting sections [4], [5]. this research only used a computer/laptop with a licensed solidcast 8.1.1 software in each casting simulation. start problem formulation: analyzing the centerline shrinkage research purpose determination: to predict the critical solid fraction point time in some sections of the diaphragm casting finish casting design simulation using solidcast 8.1.1 software conclusions casting design improvent and simulation results analysis iii. results and discussion this research choose the diaphragm casting product as the object since it has a complex geometry. the diaphragm casting product was made from aisi 4041 chrome-molybdenum low steel alloys. table 1 displays the chemical compositions of the object. achyarsyah & puspitasari (critical solid fraction point analysis: a case study) fig. 1. research flow chart issn: 2580-0817 journal of mechanical engineering science and technology 83 vol. 3, no. 2, november 2019, pp. 81-87 achyarsyah & puspitasari (critical solid fraction point analysis: a case study) figure 2 presents the disrupted supply flow from the previous diaphragm casting design [6]. this occurrence indicated that some sections reached the critical solid fraction point first in the middle of the flow during solidification [7]. with some sections reached the critical solid fraction point, the liquid supply from the riser stop flowing through the section. as a result, other sections start from the solid section up to the end need sequent supply and separate from the direct supply [8]. table. 1 aisi 4041 steel chemical compositions aisi 4140 %c 0.36 – 0.43 %mn 0.75 – 1.00 %si 0.15 – 0.30 %p max 0.025 %s max 0.025 %cr 0.80 – 1.10 %mo 0.15 – 0.25 fig. 2. the disrupted supply flow of the diaphragm casting design simulation in the previous research sections without direct supply from the riser take the supply from other sections which contain the remaining disrupted liquid. as a result, the last section to solidify do not receive any 84 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 81-87 supply and causes shrinkage [9]. the critical solid fraction time and solidification modulus are similar where both represent the solidification time. however, both are different in the percentage of the solidification section. solidification modulus represents the solidification time up to 100% solid, whereas the critical solid fraction time represents the solidification time up to x% solid (where x<100%). therefore, there is some residual ((100-x)%) that unable to flow to other sections [10] optimally. due to the above problem, this data collecting and the critical solid fraction time analysis simulation needed an initial simulation of casting only material before the additional riser and chill. the result helped to position the riser or chiller in the casting design [11], [12]. figure 3 shows the predicted critical solid fraction time in each diaphragm casting object from the initial casting only simulation. based on the complex geometrical shape of the diaphragm casting object and the critical solid fraction point in each section, figure 3 also displays the five areas with natural supply flow as circled in blue. fig. 3. the critical solid fraction point differences in the casting object sections from the initial casting only simulation sections circled in blue indicate sections with the fastest critical solid fraction time; in this research it is 3.39 minutes. the color that gradually turned into yellow means that the sections had the slowest critical solid fraction time, and in this research, it is 16.7 minutes. sections with the slowest critical solid fraction point timing were the sections that needed risers. following the consideration, it was ideal for applying five risers so that the five detected areas had their liquid supply. however, the complex geometrical shape became the next obstacle because there were two areas (area 4 and 5) that unable to receive side or top risers. therefore, improving the casting design required four side chillers in area 4 and 5 and three top exothermic risers in area 1, 2, and 3. chillers in the area 4 and 5 made the section reached the critical solid achyarsyah & puspitasari (critical solid fraction point analysis: a case study) issn: 2580-0817 journal of mechanical engineering science and technology 85 vol. 3, no. 2, november 2019, pp. 81-87 achyarsyah & puspitasari (critical solid fraction point analysis: a case study) fraction faster and caused the liquid supply from the top exothermic risers in area 2 and 3 able to reach both areas. figure 4. shows the casting design of the above simulation. figure 5 displays the improved casting design with different critical solid fraction points between the sections. blue sections show the sections with the slowest critical solid fraction time that is 3 minutes. as stated before, the color that gradually turned into yellow meant that the sections reached the slowest critical solid fraction time with the prediction up to 35 minutes in area 2 with the top exothermic riser. fig. 4. casting design with three top exothermic risers and four side chills fig. 5. the differences in the critical solid fraction times between sections from the simulation with top exothermic riser and four side chills 86 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 81-87 achyarsyah & puspitasari (critical solid fraction point analysis: a case study) additionally, it can be observed that there were no sections in the middle of the supply path with faster critical solid fraction point compared to the clamped sections, as observed from the color gradation. in conclusion, the improvement of this simulation was deemed effective to produce the diaphragm casting object without shrinkage [13]. iv. conclusion based on the simulation results of the castings using solidcast 8.1.1, the application of three exothermic top risers and four side chillers made the sections reached the critical solid fraction point in sequential solidification process until the longest time was found in the riser. additionally, the chance of shrinkage in the diaphragm casting product was relatively small due to the improvement in this research. references [1] m. holtzer, “the mold/casting interface phenomena,” in microstructure and properties of ductile iron and compacted graphite iron castings: the effects of mold sand/metal interface phenomena, new york: springer international publishing, pp. 77–108. 2015. [2] t. takahashi, “solidification and casting.,” bull. japan inst. met., vol. 26(7), pp. 687691, 2011. [3] a. a. gaware dan a. k. mahalle, “a review on investigation of casting defects with simulation,” int. j. innov. eng. sci., vol. 2(5), pp. 15-20, 2017. [4] b. ravi, “casting simulation – best practices,” trans. of 58th ifc, 2010. [5] r. w. lewis dan k. ravindran, “finite element simulation of metal casting,” int. j. numer. methods eng., vol. 47(1‐3), pp. 29-59, 2000. [6] j. campbell, complete casting handbook: metal casting processes, metallurgy, techniques and design: second edition. oxford: butterworth-heinemann. 2015. [7] u. a. dabade dan r. c. bhedasgaonkar, “casting defect analysis using design of experiments (doe) and computer aided casting simulation technique,” in procedia cirp, 2013. [8] s. s. m. nazirudeen dan b. chokkalingam, “analysis of casting defect through defect diagnosis study approach,” j. eng. ann. fac. eng. hunedoara, vol. 2, pp. 209–212, 2009. [9] k. d. carlson, s. qu, dan c. beckermann, “feeding of high-nickel alloy castings,” metall. mater. trans. b, vol. 36(6), pp. 843–856, 2005. [10] r. wlodawer. directional solidification of steel castings. new york:pergamon. 2016. issn: 2580-0817 journal of mechanical engineering science and technology 87 vol. 3, no. 2, november 2019, pp. 81-87 achyarsyah & puspitasari (critical solid fraction point analysis: a case study) [11] p. beeley, “casting design,” in foundry technology, oxford: butterworth-heinemann 2007. [12] r. gallo dan d. neff, “asm handbook: vol 15 casting,” asm handbook volume 15 casting. 2008. [13] g. menges, w. michaeli, dan p. mohren, “shrinkage,” in how to make injection molds, 2012. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 37-42 37 doi: 10.17977/um016v4i12020p037 the effect of heat treatment to the erosion rate of brass composite aminnudin aminnudin*, solichin solichin department of mechanical engineering, faculty of engineering, malang state university, jl semarang 6 malang indonesia 65143 *corresponding author: aminnudin.ft@um.ac.id abstract brass composites can be improved their mechanical properties by the heat treatment process. the improvement of the mechanical properties of this technique is expected to increase the resistance of the composite to erosion that occurs in the environment of flow water. brass composites used are composites with fly ash 5, 10, 15, and 20%. the heat treatment process was carried out using electric furnace without protective gas. composite heat up to 350°c and 400°c for 30 min. and quenching with water. before and after the erosion test, the weight of the test specimen was weighed with analytical scales. the treatment process affects the tensile strength of brass composites. the heat treatment process of brass composites with 5% fly ash at 350 °c produces the highest tensile strength. erosion rate testing on brass composites showed the lowest erosion rate occurred on brass composites with 5% fly ash and heat treatment at 350°c. copyright © 2020. journal of mechanical engineering science and technology all rights reserved keywords: brass, composite, erosion rate, fly ash i. introduction water turbine blades work in a water environment require materials that are not only corrosion resistant but must also be resistant to erosion [1]. corrosion at the blade is mainly due to being constantly submerged in water, in a water environment the corrosion can occur faster than in the air environment. the erosion process that occurs on the blade is caused by solid objects carried in the flow of water that enters the turbine. solid particles that are often carried are sand particles [2]. one of the metals suitable for turbine blade material is brass [3][4]. brass has medium strength but has excellent corrosion resistant in water environment. the strength of brass can be increased by adding particles as reinforcement. one of the reinforcement materials used is fly ash [5]. fly ash is the remains of coal combustion in steam power plants. the addition of fly ash by as much as 15% will increase the strength of the brass [6]. the mechanical properties of brass composites can be improved by the heat treatment process [7] [8]. the heat treatment process can increase the hardness of brass composites, while it can also increase the toughness of the composite [9]. the process of treating heat on a brass composite by heating the composite for 30 min. will increase the hardness and ductility of the composite [6]. water turbines work in a water environment (submerged), receiving continuous shock and friction (erosion) loads. the water environment causes the material to become more easily corroded, besides that because it receives shock and erosion loads, the material used 38 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 37-42 aminnudin & solichin (the effect of heat treatment to the erosion rate of brass composite) must have resilient properties and be resistant to erosion. one suitable material is brass which has corrosion resistant properties and is quite resistant to erosion. in this research, erosion resistance testing at brass composite after heat treatment. ii. material and methods the brass composite used in this study uses brass as a matrix and fly ash as a strengthening. brass is an alloy of copper (cu) with zinc (zn) as the main alloying. the composition of fly ash used as strengthening can be seen in table 1, and the brass composition for composites can be shown in table 2. this is brass composition before processed to composite. table 1. fly ash composition materials composition (%) aluminium (al) 9.8 barium (ba) 0.57 calsium (ca) 27.4 chromium (cr) 0.075 cumprum (cu) 0.057 ferro (fe) 30.8 magnesium (mg) 3.0 manganese (mn) 0.32 mercury (hg) 0.2 molibden (mo) 2.1 nickel (ni) 0.04 potassium (k) 1.79 re 0.3 silicone (si) 21.6 sr 0.3 titanium (ti) 1.24 vanadium (v) 0.049 yb 0.05 zink (zn) 0.04 table 2. brass composition materials composition (%) aluminium (al) 0.8 calsium (ca) 0.11 chromium (cr) 0.046 cumprum (cu) 48.73 ferro (fe) 0.707 manganese (mn) 0.045 nickel (ni) 0.61 phospor (p) 0.1 scandium (sc) 0.081 silicone (si) 0.39 zink (zn) 26.0 issn: 2580-0817 journal of mechanical engineering science and technology 39 vol. 4, no. 1, july 2020, pp. 37-42 aminnudin & solichin (the effect of heat treatment to the erosion rate of brass composite) composites are made by melting brass in a gas smelting furnace. fly ash is put into brass liquid according to the specified weight. the mixture of fly ash and molten brass is stirred using an electric stirrer with a rotating speed of 500 rpm. the testing process is carried out on specimens with a size of 20 x 20 mm and a thickness of 5 mm. brass composites tested were are casting composites, composites after heat-treated at 350 and 400 c. the heating process is carried out in an electric furnace without protective gas, with holding time at 30 min. the electric furnace has a maximum temperature of 1100 c with a maximum electricity power 10 kva. the abrasives test was done to determine the durability of the material against abrasives from water and solid particles. in this test equipment, the water from the water tank is pumped with a water pump. the water pump flows towards the nozzle to get high speed. at the nozzle, there is mixing water with sand from the mixing tank. the mixture of water and particles hit the surface of the test specimen at high speed. before and after the erosion test the specimens were weighed using analytical scales fig. 1. abrasive test apparatus the abrasive test carried out in the laboratory of materials at the department of mechanical engineering, state university of malang. the abrasive test apparatus has ¼ hp water pump and water tank capacity is 80 liters. maximum water pressure is 4 atm. tensile testing is carried out using a tensile testing machine with astm e8 standards. the tensile test machine has a maximum load capacity of 30 kn. iii. results and discussions the results of the tensile test of brass composites after the heat treatment process can be seen in figure 2. hardness in brass composites occurs in brass composites and 5% fly ash with heat treatment at 350c. in comparison, the lowest tensile strength occurs in brass composites with 20% fly ash which is heat-treated at 400c. generally, the tensile strength of brass composites which are heat-treated at 350c has a higher tensile strength than those 40 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 37-42 aminnudin & solichin (the effect of heat treatment to the erosion rate of brass composite) treated heat at 400c. this happens because in the heat treatment process at 400c the grain growth [6] and make the tensile strength decreases. fig. 2. tensile strength of brass composite the highest tensile strength of brass composites is 47.21 mpa, i.e. brass composites with 5% fly ash which are heat-treated at 350c. the results of erosion testing on brass composites can be seen in figure 3. lower erosion rates indicate better material resistance to corrosion. the lowest erosion rate occurs in brass composites with 5% fly ash which is heat-treated at 350 c. the increasing tensile strength of brass composites is caused by changes in the composite microstructure [6]. the heat treatment process at 400 c resulted in larger grain size compared than heat treatment at 350 c [6]. increasing in grain size of metals will reduce the hardness and tensile strength of the metals [10][11]. this explains why the tensile strength of brass hail composite heat treatment at 400 c is lower compared to heat treatment at 350 c. the results of erosion testing on brass composites can be seen in figure 3. lower erosion rates indicate better material resistance to corrosion. the lowest erosion rate occurs in brass composites with 5% fly ash which is heat-treated at 350 c. the lowest erosion rate on the brass composites occurs on the brass composites with 5% fly ash and heat-treated at 350 c, the erosion rate is 0.0211 mg/min. the higher erosion rate occurs on the brass composites without heat treatment (as cast) (0.030 mg/min.). generally, the lower erosion rate occurs on the brass composites heat-treated at 350 c. tensile strength greatly influences the erosion rate of brass composites. the higher the tensile strength of the composite, the lower the erosion rate. this rate of erosion is not only influenced by the tensile strength but also by the hardness and ductility. according to aminnudin (2018) [6], the highest hardness and ductility of brass composites are found in brass composites with 5% fly ash. erosion rate on composites with heat treatment 400 c is higher than composites with heat treatment 350 c because of its lower tensile strength and lower ductility. this complies with previous research by aminnudin (2018) [6]. issn: 2580-0817 journal of mechanical engineering science and technology 41 vol. 4, no. 1, july 2020, pp. 37-42 aminnudin & solichin (the effect of heat treatment to the erosion rate of brass composite) fig. 3. effect heat treatment to the erosion rate of brass composite erosion occurs on the material caused by impact energy on the material surface [12] [13]. materials that have high ductility can withstand the impact, but the material is not resistant to scratch due to solid particles, so the erosion rate will increase. erosion that occurs due to friction between the particle and the surface of the material continuously. the continues scratch on the material surface makes material released from the surface, this phenomenon make erosion rate high. hard materials are more resistant to scratches due to friction with solid particles in water, but the hard material cannot withstand the impact [14]. the impact of particle and composite surface will cause deformation on the surface of the material. on brittle materials, the maximum energy can withstand lower than ductile materials [3][10]. therefore, metals with higher hardness are more easily released surface (erosion) than ductile metals. the lowest erosion rate in brass composites occurred in composites that had the highest tensile strength [2]. this shows the composite also has a high ductility [6]. the ductility of brass composites with 5% fly ash content and heat-treated at 350 c is higher compared to other brass fly ash composites [6]. iv. conclusions the treatment process affects the tensile strength of brass composites. the heat treatment process on brass composites with 5% fly ash at 350c produces the highest tensile strength. erosion rate testing on brass composites showed the lowest erosion rate occurred on brass composites with 5% fly ash and heat treatment at 350c. references [1] w. d. callister, materials science and engineering: an introduction, 7th ed. denver: john willey and sons, 2007. [2] t.r.b.b. acharya, c. joshi, r. saini, and o. dahlhaug, “sand erosion of pelton turbine nozzles and buckets: a case study of chilime hydropower plant,” wear, vol. 264(3–4), pp. 177–184, 2007. [3] g.e. dieter, d. bacon, and g.l. wilkes, mechanical metallurgy, si edition. 42 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 37-42 aminnudin & solichin (the effect of heat treatment to the erosion rate of brass composite) singapore: mc graw-hill book co, 1988. [4] s. kalpakjian, s.r.s.r. schmid, and h. musa, manufacturing engineering and technology. singapore: prentice hall, 2009. [5] e. yang, y. yang, and v.c. li, “use of high volumes of fly ash to improve ecc mechanical properties and material greenness,” aci mater. j., vol. 104 (6), pp. 620– 628, 2007. [6] a. aminnudin and m.a. choiron, “heat treatment effect on metal matrix composite with brass matrix and fly ash,” matec web conf., vol. 204, pp. 1–8, 2018, doi: 10.1051/matecconf/201820405020. [7] a. loukus and j. loukus, “heat treatment effects on the mechanical properties and microstructure of preform-based squeeze cast aluminum metal matrix composites,” int. j. met., vol. 5, pp. 57–65, 2015. [8] d.v. hutton, fundamentals of finite element analysis, 1st ed. new york: mc grawhill book co, 2004. [9] s.k.c.h.v. satyanarayanaraju, r. dixit, p. miryalkar, “effect of heat treatment on microstructure and properties of high entropy alloy reinforced titanium metal matrix composites,” mater. today proc., vol. 18, pp. 2409–2414, 2019, doi: https://doi.org/10.1016/j.matpr.2019.07.088. [10] d. hull and d.j. bacon, introduction to dislocations, 5th ed. oxford, 2011. [11] h.s. baghbadorani, a. kermanpur, a. najafizadeh, p. behjati, a. rezaee, and m. moallemi, “an investigation on microstructure and mechanical propertiesof a nbmicroalloyed nano/ultrafine grained 201 austenitic stainless steel,” mater. sci. eng. a, vol. 636, pp. 593–599, 2015, doi: 10.1016/j.msea.2015.04.001. [12] f.y. cheng, erosion-accelerated corrosion in flow systems: the behavior of aluminum alloys in automotive cooling systems. cambridge: woodhead publishing series in metals and surface engineering, 2011. [13] m.y. naz, n.i. ismail, s.a. sulaiman, and s. shukrullah, “electrochemical and dry sand impact erosion studies on carbon steel,” a nat. res. j., vol. 5, pp. 1–9, 2015. [14] p. nova k. and a. macenauer, “erosion-corrosion of passive metals by solid particles,” corros. sci., vol. 35 (1–4), pp. 635–640, 1993. journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.29-34 29 doi: 10.17977/um016v3i12019p029 comparison study of mechanical properties of al-si alloy with and without nanoreinforce iron oxide (fe2o3) cepi yazirin1, poppy puspitasari2*, and muhamad fatikul arif3 1master student, graduate program, engineering faculty, universitas negeri malang, jl. semarang 5, malang, east java indonesia 2mechanical engineering department, engineering faculty, universitas negeri malang, jl. semarang 5, malang, east java, indonesia 2material engineering study program, institut teknologi sumatera, south lampung, 35365, indonesia *corresponding author: poppy@um.ac.id abstract nanoreinforce materials such as zno, eggshell, al2o3, tio2, and zro2 have been shown to improve the mechanical properties of al-si alloy. nanomaterial fe2o3 has many applications as catalysts reaction in electronic devices, for example, semiconductor materials, paint formulations, lithium rechargeable batteries, and is often applied in industrial fields. it is known that fe2o3 can be synthesized through the stirring process on machine and method used will involve several steps that relatively take a long time. in this study, al-si alloy reinforced by using nanomaterial fe2o3 which sintered at a temperature of 600c for 3 hours aimed to improve mechanical and morphological properties of al-si alloy. the method used was stir casting, where this method was known as flexible, simple, and economic. the result of reinforcing al-si alloy by using nanomaterial fe2o3 had affected on the hardness level of al-si alloys as evidenced by the fracture morphology that was brittle and had a light reflection. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: fe2o3, al-si, mechanical properties, morphology. i. introduction fe2o3 is included into iron oxide material which has the same crystal structure as magnetite and also includes spinel ferrite and parts of ferromagnetic. fe2o3 has optical properties that can be understood based on the width of the band gap by using the principle of light absorption. in the industrial sector, fe2o3 has a potential application in catalysts reaction in electronic devices [1][2]. this study will apply fe2o3 that sintered at a temperature of 600c for 3 hours to reinforce al-si alloy. al-si itself is an alloy that has many applications in the industrial field, one of which is used for making piston. the increasing of al-si alloy usage in vehicles should be balanced by the increasing in the quality of these alloys, one of which is reinforced by using fe2o3 which sintered at 600c for 3 hours to improve its mechanical and morphological properties [3]-[5]. the method used is stir casting because this method is known to be economical and maximum during the process of stirring quickly [6][7]. 30 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.29-34 yazirin et al. (comparison study of mechanical properties of al-si alloy with and without nano fe2o3) ii. materials and methods this study used stir casting method with the addition of fe2o3 which sintered at a temperature of 600 c for 3 hours as nano reinforced material with the composition of 0.05% in al-si alloys. the beginning of the process is to melt the al and si alloys in the furnace type t150/120-90 at 950c. then 0.05% of the fe2o3 nanomaterial sintering 600c 3 hours was mixed in the al-si alloy which had melted, and the quick stirring process could be carried out for 30 seconds using a gbm 350 hand drill with a stirrer with a stirring speed of 500 rpm. after that, the mixture of nanomaterial fe2o3 sintering 600c 3 hours and al-si alloy is poured into a permanent mold made of steel, where the pouring process must be done quickly to avoid hardening and minimize the occurrence of porosity defects. after the process is complete, the al-si alloy is removed from the permanent mold, and then the hardness test is done using the mm 0054 micro hardness tool by using a major load of 100 kg, indentor steel ball 1/16, both surfaces of the test material must be flat, and the length of the surface pressing for 5 seconds. the tensile strength test using the tokyo testing machine tool which has a maximum loading of 50 kn and before testing the test material must be measured at the initial length and then mounted on the test equipment by clamping the material in a tight condition so that it is not released when pulled. the measuring needle set on the indicator is shaped like a clockwork consisting of two needles, the first needle is red, and the second needle is black. then the withdrawal is done by giving loading until the test material is cut off. after the material is cut off the needle on the indicator will show the value of the tensile strength of the test material, then calculate the strain that occurs in the test material. microstructure observed with metallurgical microscope olympus type pme3-111b/-312b by placing the material on the preparation table then adjusting the objective lens to fit the target and adjusting the focus of the microscope to clarify the image seen from the eyepiece lens. when the object's shadow has been found, increase the size by replacing the lens according to the desired size and in accordance with the microscope specifications, and macrostructure using a canon eos 1200d dslr camera the material is placed in a flat place and not exposed to vibration, then directs the camera to the object that has been set. iii. results and discussions a. tensile strength analysis figure 1 shows the resulting diagram of tensile test of raw al-si alloy and al-si alloy reinforced nanomaterial fe2o3 sintered at a temperature of 600 c for 3 hours. the tensile test results of al-si raw material showed a tensile strength of 24.76 kg/mm² and al-si alloys reinforced by nanomaterial fe2o3 showed tensile strength of 7.53 kg/mm². the nanomaterial of fe2o3 cannot strengthen the tensile strength of al-si alloys. although the nanomaterial fe2o3 is soluble in al-si alloys, nanomaterial fe2o3 has very little solubility in solids. so that the fe2o3 nanomaterials tend to join with other elements to form intermetallic phase particles of various types of elements, and the phases formed in this case are al8fe2si (α phase) and al5fesi (β phase) [8][9]. the tensile strength can also be influenced by the level of porosity and the small size of the porosity level, which affects the tensile strength of al-si alloys. porosity occurs because the flow of issn: 2580-0817 journal of mechanical engineering science and technology 31 vol. 3, no. 1, july 2019, pp.29-34 yazirin et al. (comparison study of mechanical properties of al-si alloy with and without nano fe2o3) interdendritic fluid is inhibited during the pouring process, so it cannot spread evenly [10]-[12]. fig 1. comparison of the tensile strength of al-si alloy b. hardness analysis figure 2 shows the resulting diagram of hardness test of raw al-si alloy and al-si alloy reinforced nanomaterial fe2o3 sintered at a temperature of 600°c for 3 hours. alsi alloy reinforced by nanomaterial fe2o3 affecting the hardness of al-si alloys. there was an increase in the value of al-si raw hardness 108.83 hv to 118 hv after adding fe2o3 sintering 600 c 3 hours nanomaterials. when the level of fe2o3 increases, the tenacity of the al-si alloy will consistently decrease, and there will be an increase in the hardness. this occurs accompanied by a decrease in tensile strength and general yield strength, which remains unaffected by the fe2o3 sintering 600 c for 3 hours nanomaterial [8][9][13]. fig 2. comparison of the hardness of al-si alloy 24.76 7.53 0 5 10 15 20 25 30 al-si raw al-si reinforced fe₂o₃ sintering 600°c 3 hours t e n si le s tr e n g th (k g /m m ² ) 108.83 118 104 106 108 110 112 114 116 118 120 al-si raw al-si reinforced fe₂o₃ sintering 600°c 3 hours h a rd n e ss v a lu e (h v ) 32 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.29-34 yazirin et al. (comparison study of mechanical properties of al-si alloy with and without nano fe2o3) c. microstructure analysis the following is the result of testing photos of al-si alloys micro alloys, and al-si alloys reinforced fe2o3 sintered at a temperature of 600 c for 3 hours. fig 3. the microstructure of al-si raw material fig 4. the microstructure of fe2o3 sintering 600 c 3 hours figure 3 showed the microstructure of an al-si raw alloy where grain size appears small, grain distribution appears evenly distributed, and dendrites appear small compared to fe2o3. figure 4 showed the microstructure of the al-si alloy reinforced fe2o3 where grain size appears small, grain distribution appears evenly distributed, and dendrites appear larger than al-si raw alloy. other because the cooling and compaction process looks perfect and faster. the intermetallic phase in the process of compaction and cooling is formed before the process of forming dendrites and grows freely in the liquid. al-si dendrite alloy reinforced by fe2o3 appears larger than al-si raw alloy due to compaction rate and cooling of al-si raw alloy faster [9][11][12]. d. analysis of macrostructure the result of a macrostructure observation on raw al-si alloys and al-si alloys reinforced by fe2o3 is shown in figure 5 and figure 6. dendrite aluminium (al) silicon (si) silicon (si) dendrite issn: 2580-0817 journal of mechanical engineering science and technology 33 vol. 3, no. 1, july 2019, pp.29-34 yazirin et al. (comparison study of mechanical properties of al-si alloy with and without nano fe2o3) fig 5. morphology of raw al-si alloy faults fig 6. morphology of al-si alloy reinforced by fe2o3 figure 5 al-si raw alloys seen the fracture appear brittle, fracture surfaces that appear flat, and provide reflective power. figure 6 showed the fracture of al-si alloy reinforced by fe2o3 appear brittle, provide reflected light power, and appear to have considerable porosity. this is due to the presence of a substance trapped at the point of porosity so that the compaction and cooling process seems imperfect [14][15]. iv. conclusions reinforcing al-si alloy by using fe2o3 which sintered at a temperature of 600°c for 3 hours, cannot increase its tensile strength and conversely, its process can increase the hardness of al-si alloys. reinforcing al-si alloy by using fe2o3 increased the hardness of the al-si alloy from 108.83 hv to 118 hv. the microstructure showed that dendrites of al-si raw alloys were smaller than al-si alloys that reinforced by fe2o3. the results of fracture morphology of raw al-si alloys and al-si alloys that reinforced by fe2o3 seemed brittle, and there was a considerable degree of porosity in al-si alloy. references [1] f. wang, x. f. qin, y. f. meng, z. l. guo, l. x. yang, and y. f. ming, “hydrothermal synthesis and characterization of α-fe2o3 nanoparticles,” 34 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.29-34 yazirin et al. (comparison study of mechanical properties of al-si alloy with and without nano fe2o3) materials science in semiconductor processing, vol. 16, no. 3, pp. 802–806, 2013. [2] f. dang, n. enomoto, j. hojo, and k. enpuku, “sonochemical coating of magnetite nanoparticles with silica,” ultrason. sonochem, vol. 17, no. 1, pp.193– 199, 2010. [3] s. nayak, “synthesis of al-si alloys and study of their mechanical properties”. tesis. india: national institute of technology, rourkelapp, 2011. [4] m. t. sijo and k. r. jayadevan, “analysis of stir cast aluminium silicon carbide metal matrix composite: a comprehensive review,” procedia technol., vol. 24, pp. 379–385, 2016. [5] s. soltani, “stir casting process for manufacture of al-sic composites,” rare metals, vol. 36, pp.581–590, 2017. [6] s. naher, d. brabazon, and l. looney, “simulation of the stir casting process,” journal of materials processing technology, vol. 144, pp.567–571, 2003. [7] s. k. pradhan, s. chatterjee, a. b. mallick, and d. das, “a simple stir casting technique for the preparation of in situ fe-aluminides reinforced al-matrix composites,” perspect. sci., vol. 8, pp.529–532, 2016. [8] j. a. taylor, “the effect of iron in al-si casting alloys,” cooperative research centre for cast metals manufacturing (cast), 2016. [9] j. a. taylor, “iron-containing intermetallic phases in al-si based casting alloys,” procedia materials science, vol. 1, pp. 19–33, 2012. [10] i. s. el-mahallawi, a. y. shash, and a. e. amer, “nanoreinforced cast al-si alloys with al2o3, tio2 and zro2 nanoparticles,” metals, vol. 5, pp. 802–821, 2015. [11] m. a. moustafa, “effect of iron content on the formation of -al5fesi and porosity in al-si eutectic alloys,” journal of materials processing technology, vol. 209, pp. 605–610, 2008. [12] z. ma, a. m. samuel, f. h. samuel, h. w. doty, and s. valtierra, “a study of tensile properties in al-si–cu and al-si–mg alloys: effect of -iron intermetallics and porosity,” materials science and engineering a, vol. 490, pp. 36–51, 2008. [13] s. soltani, r. a. khosroshahi, r. t. mousavian, and z. jiang, “stir casting process for manufacture of al – sic composites,” rare met, vol. 36, no. 7, pp.581–590, 2017. [14] h. h. knowl piece, wilbury way, “introduction to tensile testing,” asm int., pp. 1–13, 2004. [15] y. s. irawan, t. oerbandono, d. fitria, and a. aristiyono, “tensile strength and porosity of al-mg-si cylinder resulted from die casting with various pressure,” jurnal rekayasa mesin, vol. 4, no. 1, pp.11–16, 2013. (in indonesian). journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 85-89 85 doi: 10.17977/um016v2i12018p085 the analysis of permeability and mechanical properties of sand moulding using mixed material clamshell (placuna placenta) on sand casting kritchakhris nawettanaprasert1, zakaria bagus aminanta 2,3, and putut murdanto2 1 department of industrial engineering, faculty of industrial engineering, phranakhon rajabhat university, thailand 2 department of mechanical engineering, faculty of engineering, universitas negeri malang 3 bachelor program, mechanical engineering department, universitas negeri malang *zakariabagus20@gmail.com abstract this study objected to determine mechanical properties of sand moulding by conducting tensile test, compressive and shear test, and also permeability test. this study also had the other objective that was analyse clamshell (placuna placenta) as mixture material for bentonite as binder in manufacturing sand moulding in order to reduce the usage of bentonite. the method that used in this study was pre-experimental method with one-shot case study model. the best mechanical properties obtained on sample 3 clamshell 11%, permeability results obtained was 190 ml/min, tensile strength results obtained for the dry sand was 0.015 kg/cm2, compressive strength obtained for the dry sand was 2.91 kg/cm2, and the shear strength of sand moulding in dry condition was 0.92 kg/cm2. copyright © 2018journal of mechanical engineering science and technology all rights reserved keywords: mechanical properties, permeability, sand moulding, clamshell (placuna placenta). i. introduction metal casting is process of processing material to produce various type of metal in various forms depending on the moulding. metal casting is manufacture process by melting metal into liquid form then poured into moulding [1]. thus, the system and casting process cannot be separated from moulding [2]. casting is made of metal melted, poured into moulding then let the metal to be cool and freeze [3]. commonly, the composition of sand moulding that used in casting consists of: silica sand, bentonite, water, carbon, and water-resistant powder [4]. generally, binder which is used in sand moulding is bentonite. the use of bentonite as binder in sand moulding manufacture of sand due to its necessary properties that generate high binding capacity, being clay in wet condition and harden in dry condition, thus, manufacture of sand moulding is easy to be set up [5]. manufacturing sand moulding is not only considering the binder, but also there are several things that need to be understand, that are the permeability and mechanical properties, permeability of sand moulding should be good, the poor permeability will cause defects on the results of the cast product, while permeability is influenced by the percentage of binder [6]. in addition, there are several mechanical properties that should include in standard value of sand moulding. the binder that used in this study is bentonite, but the composition is reduced and added mixture material that is clamshell. nowadays, utilization of clamshell is still to ornaments, cosmetics, mixed fodder. in previous study showed that clamshell can be used for mixture of paving blocks and concrete, so it is possible to be used for a mixture of sand moulding as binder mixture, the content of clamshell was dominated by calcium that up to 98.20% [7]. the use of clamshell as the mixture of paving blocks mentioned that composition of sand and clamshell with a ratio of 100%:0%, 90%:10%, 80%:20%, raw materials mixed with cement binder with a ratio of 1:4 [7]. according to this study showed that the best result of testing water absorption and compressive strength in paving block with composition of 80% sand and 20% clamshell, paving has moisture content of 2.94% and compressive strength of 46.79 mpa that has met the standards. mailto:*zakariabagus20@gmail.com 86 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 85-89 kritchakhris nawettanaprasert et.al (the analysis of permeability and mechanical properties of sand moulding using) the previous study under the title "the effect of limestone and quicklime addition to k-300 concrete mixture" showed that this study using limestone as binder, the calcium content of the limestone has benefit as an adhesive, limestone is selected as binder due to its calcium content which its properties mixed with water can be hardened [8]. ii. methodology the research design that used in this study was pre-experimental and used one-shot case study model. the independent variable in this study using comparison of silica sand with clamshell as a binder of sand moulding. the percentage of silica sand were 88%, 85% and 82% and binder with percentage of 5%, 8% and 11%. the dependent variables were permeability, tensile strength, compressive strength, shear strength. while the control variable of this study was water with the percentage of 5%, clamshell that used had mesh size of 200 or fineness of 0.02 mm, and silica sand with mesh size of 40 or fineness of 0.4 mm. the composition of the sand moulding that used in this study were: 1. 5% clamshell, 2% bentonite, 88% silica sand and 5% water, 2. 8% clamshell, 2% bentonite, 85% silica sand and 5% water, 3. 11% clamshell, 2% bentonite, 82% silica sand and 5% water. iii. results and discussion a. x-ray diffraction analysis the xrd characterization was conducted to clamshell to determine the grain size of clamshell before it used as binder in the metal casting. the xrd result could be seen in table 1 and figure 1. the calculation result of clamshell crystal size obtained was 52.16 nm. the crystal size of clamshell was different with the crystal size of eggshell. xrd result of sintered eggshell nanopowder at temperature of 1100ºc was 59.7912 nm. so the crystal size of clamshell was smaller than the eggshell [9]. table 1. phase identification of clamshell (placuna placenta) material x-ray diffraction (correspond to peak) position (pos) intensity (counts) fwhm (rad) d-spacing (å) crystallite size (nm) clamshell 29.4311 751.66 0.1574 3.03495 52.16 fig. 1. phase identification of clamshell (placuna placenta) issn: 2580-0817 journal of mechanical engineering science and technology 87 vol. 2, no 2, november 2018, pp. 85-89 kritchakhris nawettanaprasert et.al (the analysis of permeability and mechanical properties of sand moulding using) fig. 2. mechanical properties analysis sand moulding in dry conditions fig. 3. mechanical properties analysis of sand moulding in wet condition b. mechanical properties analysis of sand moulding in dry condition according to the figure 2, could be concluded that among samples which had the best mechanical properties such as tensile strength, compressive strength and shear strength was sample 3 with composition of 11% clamshell. in dry condition, the highest tensile strength of sand was 0.15 kg/cm2, the strength was still within the limit that allowed for tensile strength, the standard value of tensile strength for sand moulding was 0.07 to 0.42 kg/cm2. the highest compressive strength value was sample 3 with composition of 11% clamshell with the value of 2.91 kg/cm2, this value included into standard value of compressive strength for sand moulding that was between 1.5 to 17.5 kg/cm2. the highest shear strength also obtained at sample 3 with composition 11 clamshell, with shear strength 0.92 kg/cm2 , this value did not include in standard value of shear strength for sand moulding that was between 0.10 to 0.49 kg/cm2. previous study which conducted by muzayyin (2017) who examined the sand moulding with composition of 10% bentonite, 85% silica sand and 5% water reached the tensile strength of 0.05 kg/cm2, the compressive strength of 1.3 kg/cm2, and the shear strength of 0.3 kg/cm2. compared with the result of clamshell, eggshell and pure bentonite, could be concluded that variation of 11% clasmshell and 2% bentonite had the lower mechanical properties compared with sand moulding which used eggshell as binder. but the value that reached by sample 3 with composition of 11% clamshell was closer to the standard shear testing results, so the results of 11% clamshell was able to be be used for sand moulding manufacture in order to reduce the usage of bentonite. the content of water and binder in dry condition, usually was lower than in wet condition, for the drying process [5], [10]. c. mechanical properties analysis of sand moulding in wet condition figure 3 showed that sample which had the highest mechanical properties was sample 3 with composition of 11% clamshell. in wet condition, this sample had the highest tensile strength value that was 0.06 kg/cm2, but the result was below the standard value of tensile strength, that was 0.07 to 0.42 kg/cm2. the compressive strength value was 0.50 kg/cm2, which included into standard value for compressive strength, which was between of 0.35 to 1.54 kg/cm2, the more percentage of binder the higher compressive strength. this result consistent with the previous study which stated that increasing binder will increase the compressive strength [11], [12]. the highest shear strength value was 0.22 kg/cm2 which included into standard value of shear strength, that was between 0.10 to 0.49 kg/cm2. previous study that examined sand moulding with composition of 10% bentonite, 85% silica sand and 5% water reached the tensile strength of 0.06 kg/cm2, the compressive strength of 0.5 88 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 85-89 kritchakhris nawettanaprasert et.al (the analysis of permeability and mechanical properties of sand moulding using) fig. 4. bar chart sand mould permeability testing results of the variety of shells kg/cm2, and the shear strength of 0.22 kg/cm2. after comparing the result of clamshell mixture and pure bentonite, could be concluded that in mechanical properties testing of sand moulding with 11% clamshell in wet condition was equal to the usage of 10% bentonite. d. permeability testing the permeability test result was showed at figure 4, permeability was influenced by the grain size of sand and its percentage [6]. the characteristic of moulding was highly dependent on the grain size distribution of sand moulding, the percentage of binders and the percentage of water content. figure 4 showed permeability test results, the samples that had the highest permeability result was sample 1 with composition of 5% clamshell with the value of 216 ml/min, then in the second rank was sample 2 with the composition of 8% clamshell with the value of 193.3 ml/min. the third rank was sample 3 with composition of 11% clamshell 11% with the valued of 190 ml/min. the higher binder content in the composition of moulding would create a gap between the sand grains tightly, thus making the air got difficulty in flowing. if the sand mould had low permeability caused trouble in air flow through the sand grains. while the lower binder content in composition of moulding would create a gap between the sand grains loosely, thus air flowing easily. the level of permeability of the moulding was influenced by the binder [13]. according to this explanation, could be concluded about the permeability of dry sand that the sample which had low binder content would resulted high permeability because the binder did not fill the pores between the sand grains, thus the air flowed easily. this was proved in sample 1 with 5% clamshell which had permeability of 216 ml/min while the sample 3 with 11% clamshell had the permeability of 190 ml/min. the lower permeability result due to the high percentage composition of clamshell. the more the amount of binder which added to the sand would fill the pores between the sand grain and the permeability decreased. inversely with mechanical properties result, the higher composition the higher mechanical properties of sand moulding [13]. iv. conclusion recommendation composition sand moulding was sample 3 with 11% clamshell with permeability result of 190 ml/min, tensile strength result of 0.15 kg/cm2, compressive strength result of 2.91 kg/cm2 and shear strength result of 0.92 kg/cm2. v. references [1] c. saikaew dan s. wiengwiset, “applied clay science optimization of molding sand composition for quality improvement of iron castings,” appl. clay sci., vol. 67–68, hal. 26–31, 2012. [2] m. k. joseph, f. banganayi, dan d. oyombo, “moulding sand recycling and reuse in small foundries,” procedia manuf., vol. 7, hal. 86–91, 2017. [3] t. surdia dan s. saito, “pengetahuan bahan teknik,” hal. 372, 1999. [4] f. f. bownes, “sand casting,” in castings, 1971, hal. 63–74. issn: 2580-0817 journal of mechanical engineering science and technology 89 vol. 2, no 2, november 2018, pp. 85-89 kritchakhris nawettanaprasert et.al (the analysis of permeability and mechanical properties of sand moulding using) [5] andoko, p. puspitasari, a. a. permanasari, dan d. z. lubis1, “formula of moulding sand, bentonite and portland cement toimprove the quality of al-si cast alloy,” j. mech. eng. sci. technol., vol. 1, no. 2, hal. 49–52, 2017. [6] m. a. s. i made astika, dnk putra negara, “pengaruh jenis pasir cetak dengan zat pengikat bentonit terhadap sifat permeabilitas dan kekuatan tekan basah cetakan pasir ( sand casting ),” j. ilm. tek. mesin cakram, vol. 4, no. 2, hal. 132–138, 2010. [7] e. w. kusuma, “paving block o l e h : o l e h :,” 2012. [8] j. j. darren, d. gunaran, h. hendy, dan e. k. budirahardjo, “pengaruh penambahan gabungan batu kapur the effect dan batu kapur padam pada campuran beton k-300,” hal. 141–148. [9] m. s. jebeli dan w. kurnianto, “mechanical properties and permeability of sand casting moulds with eggshells binder,” vol. 2, no. 1, hal. 7–12, 2018. [10] s. priyadharsini dan p. karunakaran, “determination of the physical properties of sand moulding bonded with composite of ipomoea batatas and bentonite with casting application,” hal. 2913–2919, 2016. [11] w. yu, h. he, n. cheng, b. gan, dan x. li, “preparation and experiments for a novel kind of foundry core binder made from modified potato starch,” mater. des., vol. 30, no. 1, hal. 210–213, 2009. [12] anon, “sand/binders/sand preparation/mold &amp; coremaking,” foundry manag. technol., vol. 124, no. 1, 1996. [13] n. t. herwido, p. murdanto, dan p. puspitasari, “analisis variasi komposisi fly ash dan bentonit pada,” j. mech. eng. sci. technol., no. 1, hal. 1–11, 2016. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 54-60 54 doi: 10.17977/um016v4i12020p054 hardness evaluation on ss 316l joined with gas tungsten arc welding under constant heat treatment duwi leksono edy*, imam sudjono mechanical engineering department, universitas negeri malang jl. semarang 5, malang, east java, indonesia 65145 *corresponding author: duwi.leksono.ft@um.ac.id abstract the purpose of this study is to show the hardness of the gtaw welding results on ss 316l metal with surface heating during the welding process. observations in this study used ss 316l material with heat temperature regulation on the metal surface of the welding process using heating variations of 100 ℃, 120 ℃ and 140 ℃. the welding process of ss 316l material used a welding joint model uses single v-type welding joint with an angle of 60°, a spacing of 2 mm, a root surface of 1 mm and a thickness of 5 mm. vickers hardness test was conducted to evaluate the hardness of samples. the results indicate that all specimens show a difference in the level of violence comparing with the values of the average level of hardness in each weld specimen. specimens with the welding process heating temperature 100 ℃ have an average hardness value of 115.6 hvn. in contrast, samples with heating 120 ℃ have increased by having an average hardness value of 131.0 hvn. in comparison, heating specimens with heating surfaces of welding 140 ℃ have an increase in hardness values with an average of 171.5 hvn. copyright © 2020. journal of mechanical engineering science and technology all rights reserved keywords: gas tungsten arc welding (gtaw), heat treatment, ss 316l steel i. introduction ss 316l material is stainless steel which has been widely used in the world of oil, gas and manufacturing industries. in the welding process of ss316l material, the welding heat melts the end surface of the welded parent metal which blends with the fused metal fills in the weld area and its surroundings and gives the effect of changing the mechanical and geometrical properties of the weld metal [1]. factors that affect the mechanical properties of welds are affected by the cooling rate that influenced by several factors, namely plate thickness, welding conditions, preheat, heat input and the environment [2]. heat input is one parameter that contributes to distortion and residual stress [4][6]. in previous studies, the process of cooling treatment after welding to obtain the mechanical properties of metals [6]-[10]. the more welding layers increase, the higher the distortion. on thin plates, distortion often occurs, resulting in undesirable dimensions of dimension changes. but on thick plates with a broad cross-section, distortion is not visible, but the formed residual stress is considerable if a measurement is made. changes in the geometry of the welds occur due to local heating with welding heat sources where the temperature distribution is uneven and changing, as well as changes in welding speed [3]. the heating process on the outside of the welding surface also increases welding strength [12]. 55 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 54-60 edy and sujono (mechanical properties evaluation on ss 316l joined with tungsten gas arc welding) different heating processes use plasma for preheating in aluminium alloy welding [13], while other studies conduct the design heating using gas heaters for preheating in carbon steel welding [14][15]. the excessive heating temperature or less heating temperature affects the welding results, and this proof will be evaluated through the heating process during the welding process on ss 316 l metal. the purpose is to show the hardness of the metal after the welding process with tungsten gas arc welding under constant heat treatment. ii. material and methods this study used material of ss 316l, and heat temperature treatment on the metal surface of the welding process applied the heating variations of 100℃, 120℃, and 140℃. the welding process of ss 316 l material with a welding joint model used single v-type welding joint with an angle of 60° (figure 1), root spacing 2 mm, root surface 1 mm at a thickness of 5 mm. the work of making specimens which include cutting material, making the seam is done by cold working. it was intended to change the mechanical properties of ss 316l material due to the influence of heat that arises when the working process occurs. welding was carried out at the welding lab of malang state university using esab asia/pacific low product hydrogen electrodes for small alloy steel types, namely basic ok 74.78. the electrodes used in welding high strength steels and also for low-temperature construction. fig 1. size of the weld seam the chemical composition of ss 316l material in this study is shown in table 1. table 1. chemical composition of 316 stainless steel. elements weight percentage carbon 0.08 manganese 2.00 sulphur 0.030 silicon 0.75 nitrogen 0.10 phosphorus 0.045 chromium 16.0-18.0 nitrogen 0.10 nickel 10.0-14.0 molybdenum 2.0-3.0 the material specifications were 316 austenitic stainless steel with a thickness of 3 mm, length of 100mm and the number of samples were 27. issn: 2580-0817 journal of mechanical engineering science and technology 56 vol. 4, no. 1, july 2020, pp. 54-60 iii. results and discussions the welding area is observed as eleven as the welding process by giving a heating process to the metal surface during the welding process. the welding area is generally divided into three regions that experience differences between base metal, weld metal, heat affected zone (haz) [16]. in detail, the discussion of the hardness of welds through the vickers hardness test in the weld area will be discussed. heating temperature 100 ℃. the final results of the welding process by heating the metal surface reaches a temperature of 100 ℃, macrostructural of welding obtained, as shown in figure 2. fig 2. gtaw welding results with a constant temperature of 100 ℃ the macrostructure shows the results of welding with surface heating has a hardness level with an average value of 115.6 vhn, as shown in table 2. table 2. vickers hardness test results on gtaw welding results with a constant the temperature of 100 ℃. heating temperature test point hardness test (vhn) 100℃ 1 112.5 2 118.6 3 104.6 4 116.8 5 114.4 6 122.3 7 120.8 average 115.6 heating temperature 120 ℃. metal surface heating is carried out by the next gtaw welding process with a heating temperature of 120 ℃ in order to compare and see the maximum results from this test. from the results of surface heating in this treatment, we get a macrostructure image, as shown in figure 3. the results of surface heating with a temperature of 120℃ shows different macrostructure. the vickers hardness test indicates an average value of hardness level of 131.0 vhn (table 3). the level of violence at each point experiences an insignificant difference. edy and sujono (mechanical properties evaluation on ss 316l joined with tungsten gas arc welding) haz base base haz weld 57 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 54-60 fig 3. gtaw welding results with a constant temperature of 120 ℃ table 3. vickers hardness test results on gtaw welding results with a constant temperature of 120 ℃. heating temperature test point hardness test (vhn) 120℃ 1 132.6 2 137.9 3 129.6 4 131.7 5 134.7 6 130.3 7 120.8 average 131.0 heating temperature 140 ℃. consider to the latter to produce the right level of hardness; heating was done by adding a temperature of 140 ℃. the result of the macro welding structure is shown in figure 4. fig 4. gtaw welding results with a constant temperature of 140℃ while comparing the final results to produce a more effective level of violence, the hardness test with a surface heating of 140 ℃ obtained an average value of 171.5 vhn. table 4 shows the level of surface hardness also does not experience a significant difference. this case is due to the amount of the current (ampere), the type of electrode and the same speed edy and sujono (mechanical properties evaluation on ss 316l joined with tungsten gas arc welding) haz base base haz weld haz base base haz weld issn: 2580-0817 journal of mechanical engineering science and technology 58 vol. 4, no. 1, july 2020, pp. 54-60 table 4. vickers hardness test results on gtaw welding results with a constant the temperature of 140 ℃. heating temperature test point hardness test (vhn) 140℃ 1 165.8 2 175.5 3 170.3 4 167.4 5 174.6 6 178.3 7 168.8 average 171.5 hardness test data analysis from the results of the hardness test of the welding process to the three specimens, the anova test will be conducted to see an efficient comparison of results. this step was taken to see the contribution of differences in heating on the ss 316l metal surface by welding gtaw. the results of the vickers hardness test for each specimen described through the anova analysis results are shown in table 5. table 5. homogeneity test of variances hardness test results levene statistic df1 df2 sig. .137 2 18 .873 table 6. anova analysis of hardness test results sum of squares df mean square f sig. between groups 11666.000 2 5833.000 201.690 .000 within groups 520.571 18 28.921 total 12186.571 20 the anova test (table 6) is used to determine the parameters of how much heating effect on the metal surface by gtaw welding. the variations in the hardness level at each point show that the level of hardness of the metal is significant differences. the anova analysis shows that hardness level will have a different peak temperature with different cooling acceleration due to heating of the given metal surface. a right procedure was obtained from the results of this study, which can be applied in the testing process. iv. conclusions it can be concluded that the welding process of ss 316l material with heating temperature 100 ℃, 120 ℃, 140 ℃ results in an average hardness value of 115.6 hvn, 131.0 hvn, and 171.5 hvn, respectively. anova analysis indicates that the variations in the hardness level at specimens are significant differences. by providing heat to the edy and sujono (mechanical properties evaluation on ss 316l joined with tungsten gas arc welding) 59 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 54-60 edy and sujono (mechanical properties evaluation on ss 316l joined with tungsten gas arc welding) metal surface during the welding process will affect the price of cooling on the metal surface. acknowledgement thank’s to all members of this study for their valuable technical support for this research. my special thanks also go to the faculty of engineering, the state university of malang, which provides research opportunities through the 2020 faculty grants program. references [1] h.y. huang, s.w. shyu, tseng, k.h. & c.p. chou, “study of the process parameters on austenitic stainless steel by tig-flux welding”, journal of material science and technology, vol. 22 (8), pp. 367-374, 2008. [2] j.c. lippold, j.k. damian, welding metallurgy and weldability of stainless steel. wiley-interscience publication. 2005. [3] p. burgardt, & c.r. heiple, “interaction between impurities and welding variables in determining gta weld shape”, welding journal, vol. 65 (6), pp. 150-155, 1986. [4] j.c.f. jorge, l.f.g. souza, p.m.c.l. pacheco, r. d. vieira, p.p. kenedi, a.m.f. dos santos filho, o.r. dos santos filho, i.s. bott, l.c.s. da costa, “desenvolvimento de procedimento de reparo por soldagem de amarras de aço para ancoragem de plataformas de petróleo”. in proceedings of the 27th brazilian welding congress xxvii consolda, paper 40. são paulo, brazil, 2001. [5] j.c.f. jorge, l.f.g. souza, o.r. santos filho, a.m.f. santos filho, and i.s. bott “influência da composição química e tratamento térmico pós-soldagem nas propriedades mecânicas e microestruturais de metais de solda de alta resistência”. in proceedings of 33rd brazilian welding congress xxxiii consolda. caxias do sul, brazil, 2007. [6] j.c.f. jorge, l.f.g. souza, p.m.c.l. pacheco, a.m.f.s. filho, o.r. santos filho, j.l.c. diniz and i.s. bott. “evaluation of the mechanical properties of welded links of high strength steel mooring chains after fatigue testing”. in proceedings of the 2 nd latin american welding congress. são paulo, brazil, 2008. [7] j.c.f. jorge, s.m. faragasso, l.f.g. souza and i.s bot. “efeito do tratamento térmico pós-soldagem nas propriedades mecânicas e microestruturais de metal de solda de aço de extra alta resistência para utilização em equipamentos de ancoragem”. soldagem & inspeção, vol. 18 (2), pp. 137-148, 2013. [8] a.j.m. gomes, j.c.f. jorge, l.f.g. souza, i.s bott.“estudo comparativo de metais de solda de aços de extra alta resistência para utilização em componentes de linhas de ancoragem de plataformas de petróleo”. in proceedings of the 67th abm international congress. rio de janeiro, brazil, 2012. [9] a.j.m. gomes, j.c.f. jorge, l.f.g. souza, i.s bott. “influence of chemical composition and post welding heat treatment on the microstructure and mechanical properties of high strength steel weld metals”. materials science forum, vol. 758, pp. 21-32, 2013. [10] p.m.c.l. pacheco, p.p. kenedi, j.c.f. jorge, e.m.d. coelho and g.s. matoso. issn: 2580-0817 journal of mechanical engineering science and technology 60 vol. 4, no. 1, july 2020, pp. 54-60 edy and sujono (mechanical properties evaluation on ss 316l joined with tungsten gas arc welding) “modeling the residual life of recovered schackles”. in proceedings of 20th international conference on offshore mechanics and artic engineering – omae 2001. rio de janeiro, brazil, 2001. [11] j.a. sumam, j.c.f. jorge, l.f.g. souza, and i.s. bott. “efeito de tratamentos térmicos pós-soldagem nas propriedades de aço fundido de elevada resistência para sistemas de ancoragem de plataformas marítimas”. soldagem & inspeção, vol 9 (4), pp. 205-212, 2004. [12] kandasamy, m manzoor hussain, and s. rajesham, “experimental investigation on the influence of external heating on the mechanical and metallurgical properties in friction stir welding of 7075 alloys”, international conference on design and advances in mechanical engineering, pp 266-271, 2011. [13] d.k. yaduwanshi, s. bag, and s. pal, "effect of preheating in hybrid friction stir welding of aluminum alloy," journal of materials engineering and performance, vol.29, 2014. [14] h. lotfi, and s. nourouzi, "predictions of the optimized friction stir welding process parameters for joining aa7075-t6 aluminum alloy using preheating system," international journal of advance manufacturing technology, vol.28, 2014. [15] y.f. sun, j.m. shen, y. morisada, and h. fujii, "spot friction stir welding of low carbon steel plates preheated by high frequency induction," materials and design, vol. 54, pp. 450-457, 2014. [16] n. rajamanickam, and v. blusamy, "effects of process parameters on mechanical properties of friction stir welds using design of experiments," indian journal of engineering & materials sciences, vol.15, pp. 293-299, 2008. journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.35-41 35 doi: 10.17977/um016v3i12019p035 the characteristic of overhang object to material usage on fdm 3d printing technology redyarsa dharma bintara1*, aminnudin1, zumrotul ida2, ferian rizki arbianto1, dani prasetiyo1 1mechanical engineering depatment, state university of malang, jl. semarang 5 malang, malang, 65145, indonesia 2mechanical engineering department, national central university, no. 300, zhongda rd., zhongli district, taoyuan city 32001, taiwan (r.o.c.) *corresponding author:redyarsa.dharma.ft@um.ac.id abstract fuse deposition modeling (fdm) 3d printing is one of additive manufacturing technology which physical 3d model is build up layer by layer. the support structure is almost involved on the process if overhang shape is met on the 3d model. it has main function to prevent the 3d printed model from collapsing. commonly, the single material source of fdm 3d printer machine is to supply building two structure, structure of main 3d object and support structure. hence, our goal optimizes the using of support material for reducing the main material usage. furthermore, the sixteen of variation overhang angle is set to the 3d model. all models are printed into two kind of 3d printed model, printed model with support structure addition and without support addition. the weight of each 3d printed model is measured by weight scale with accuracy of tool is 10-4 g. then the quality and the weight of 3d printed model are compared and analyzed. the result shows that the average overweight of 3d printed model with support structure addition is 40.41% than without support structure addition. furthermore, there are several the 3d printed models without support structure that fail printed on variety model with 0° until 11° of overhang angle. the conclusion of this study is that the support structure can prevent the 3d printed model from collapsing but it does not need be built up if the overhang angle more than 11°. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keyword: 3d printing, overhang, support structure i. introduction the manufacture process is commonly involving several tools to produce a part. additive manufacturing (am) is a technology that can be used to improve quality of manufacturing process. the am is also known as 3d printing technology which can be utilized to build a physical 3d model by depositing material layer by layer. the main application of 3d printing technology is for imitating a 3d model. using imitation model, a user can evaluate and optimize the 3d model for developing a desire physical 3d model, especially for mass production. several 3d printer machines has launched in the market such as selective laser sintering (sls), direct metal laser sintering (dmls), fused deposition modeling (fdm), and stereolithography (sla) [1]. all of it is differenced by type of material used for construct 3d printed model. currently, fdm 3d printing disposes to be used because it has relative small machine and cheap of material price. the 3d printing technology has applied in several fields such training and education [2], pre-operative planning bone surgery [3], automotive [4], and 36 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 35-41 bintara et al. (the characteristic of overhang object on fdm 3d printing technology) industrial application [5]. hence, a user should optimize the material used for reducing cost production [6]. one method to reduce the cost production is optimizing support structure material usage. the support structure is built for prevent the main object from collapsing. it is generated when the overhang shape is met. commonly, the 3d printer machine, especially fdm 3d printer uses single source of material for printing the main 3d model and support structure. hence, the support structure should be optimized for reducing the material usage. furthermore, several researchers have suggested that the minimum selfsupporting angle for dmls printed model is 45 degrees through experimental testing [7]. other researcher also conducts the overhang shape for developing the model of support structure [8]. in this study, the overhang angle is investigated to find out the optimize support structure and get the best 3d printed model setting. ii. methods the support structure is an important shape to be built up when the overhang shape is met. the main task of support structure is to prevent the main 3d object deposit layer from collapsing or falling. in this study, the 3d model is drawn into cad software with sixteen of varied overhang angle (𝜃) is varied 0o up to 15o as depict on the figure 1. furthermore, the 3d model is exported into “.stl” extension file before imported into 3d printer software. in the 3d printer software, the stereolithography (stl) file of 3d model is sliced for simulating the path of deposited material sequence. then the path information of deposit material can be exported into “.gcode” extension file and it is used by 3d printer machine as reference path to deposit the melting material. fig 1. experimental model the fdm 3d printer is utilized for manufacturing the 3d model. furthermore, polylactic acid (pla) is prepared as main source of material to build up the 3d printed model and support structure. it has 1.75 mm of original diameter, whereas the diameter deposit material is set 0.4 mm through to the nozzle. all variation of 3d model is printed into two kind 3d models setting, with support structure addition and without support structure addition. the general setting of 3d printer software for all 3d models follows table 1. 𝜃 3 15 unit: mm 5 issn: 2580-0817 journal of mechanical engineering science and technology 37 vol. 3, no. 1, july 2019, pp.35-41 bintara et al. (the characteristic of overhang object on fdm 3d printing technology) table 1. general 3d model setting in the 3d printer software setting value layer height 0.15 mm wall thickness 1 mm infill density 10 % infill pattern zig-zag printing temperature 200 oc build plate temperature 60 oc printing speed 60 mm/s in the next process, the weight of all 3d printed models is measured using analytic weight scale which has accuracy 10-4 g. the weight and surface quality both of 3d printed models are compared and analyzed. iii. result and discussions the surface quality of 3d printed model is main parameter that should be considered, especially on overhang surface. not only the surface quality of 3d printed model, but also the weight of material usage is considered to find out the support structure addition effect. furthermore, the material usage, overhang angle effect and surface quality of 3d printed model are main focus discussion on this study. a. the supports structure addition effect to weight of 3d printed model the support structure has main function to prevent the main object structure from collapsing. actually, the support usage is depended to orientation of 3d model. the different support orientations will also influence to the final printed mechanical properties [9]. by choosing the optimal part orientation, paul and anand [10] had analyzed the manufacturing of precision parts while additive manufacturing processes with a minimal number of support structures. then das et al. [11] identified a better build direction which can reduce the support material used for a direct metal laser sintering based process. in the general application, the support structure is built from base to the overhang shape (fig. 2a). the 3d printer machine has a single source of material, so that the support structure material is also taken from it. the characteristic of support structure is easy to remove from main 3d printed model. in this study, sixteen of 3d printed models with support structure addition success to be printed for example on the 3d printed model with 0o of overhang angle (fig. 2b). the falling deposit layer does not visible on the overhang shape after removing the support material (fig. 2b). 38 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 35-41 bintara et al. (the characteristic of overhang object on fdm 3d printing technology) (a) (b) fig 2. experimental printed models a) with support structure b) removing support structure fig 3. weight of 3d printed material to build the both type 3d model the support material usage can increase consume material as shows in the fig. 3. the average weight of one 3d printed model with support structure addition is 0.5508 g, otherwise the 3d printed model without support structure addition is 0.3282 g. by using equation (1), where 𝑊𝑃𝑀̅̅ ̅̅ ̅̅ �̅�𝑢𝑝𝑝𝑜𝑟𝑡 is average weight of printed model with support structure addition, whereas 𝑊𝑃𝑀̅̅ ̅̅ ̅̅ ̅𝑛𝑜𝑛 𝑠𝑢𝑝𝑝𝑜𝑟𝑡 is average weight of printed model without support structure addition, the 3d printed model with support structure addition has average overweight around 40.41% than without support structure addition. it indicates that the material usage is a lot and leans to waste the material. the support material should be optimized so as to minimize material usage [12]. however, as a manufacturing process, the producing and removing support material show the significant potential increases in material consumption, energy usage and the several of manual post0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 w e ig h t o f p r in te d m o d e l (g ) overhang angle (o) printed model with support structure printed model without support structure issn: 2580-0817 journal of mechanical engineering science and technology 39 vol. 3, no. 1, july 2019, pp.35-41 bintara et al. (the characteristic of overhang object on fdm 3d printing technology) processing required to produces the final part [12]. as well as, this situation indicates that there is an increase in production costs. 𝑂𝑣𝑒𝑟𝑤𝑒𝑖𝑔ℎ𝑡 (%) = 𝑊𝑃𝑀̅̅ ̅̅ ̅̅ ̅𝑠𝑢𝑝𝑝𝑜𝑟𝑡 − 𝑊𝑃𝑀̅̅ ̅̅ ̅̅ ̅𝑛𝑜𝑛 𝑠𝑢𝑝𝑝𝑜𝑟𝑡 𝑊𝑃𝑀̅̅ ̅̅ ̅̅ ̅𝑠𝑢𝑝𝑝𝑜𝑟𝑡 𝑥 100 (1) b. the overhang angle effect of 3d model to surface quality of 3d printed model the support structure usage has optimized at 45o, 60o and 90o of overhang angle 3d model [13]. in this study, the sixteen kind of overhang angle is set up in this experiment object to find out the minimum angle in term for support structure needed. all 3d printed models with support structure addition were successfully manufactured but it shows different result on 3d printed models without support structure addition. the falling deposit layer depicts on the 3d printed model (fig. 4), especially on 0o until 11o of overhang angle. this phenomenon is caused by there is no support material which prevent the deposit layer. whereas the printed model is successfully to be printed on remain variation model. it can occur when the early deposit structure capable to prevent the next deposit layer. (0o) (1o) (2o) (3o) (4o) (5o) (6o) (7o) (8o) (9o) (10o) (11o) (12o) (13o) (14o) (15o) fig 4. 3d printed model without support structure the quality of printed model is also good enough, that meaning without any defect on the surface of overhang area. its overhang surface quality is better than 3d printed model with support structure addition (fig. 5) because the remaining of support material sometimes makes the overhang surface rough. 40 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 35-41 bintara et al. (the characteristic of overhang object on fdm 3d printing technology) (a) (b) fig 5. quality surface of overhang area a) 3d printed with support structure and b) 3d printed without support structure iv. conclusion the 3d printing technology is one technology to product the physical 3d model layer by layer. the support structure is commonly included on the process for prevent the printed model from collapsing, especially for overhang shape. on this study, the support structure addition can be successfully printed for all 3d models but the material usage is 40.41% overweight than 3d printed model without support structure addition. furthermore, the support structure can be built up but it does not need to generate if the overhang angle more than 11o. acknowledgment i wish to thank for all members on this study for their valuable technical support on this project. my special grateful thanks are also extended to ms. rr. poppy for permitting us to use the measurement device on the nano-material laboratory. references [1] s. bose, s. vahabzadeh, and a. bandyopadhyay, “bone tissue engineering using 3d printing,” mater. today, vol. 16, no.12, pp.496–504, 2013. [2] s. ford and t. minshall, “invited review article: where and how 3d printing is used in teaching and education,” addit. manuf., vol. 25, pp.131–150, 2019. [3] x. chen, l. xu, y. wang, y. hao, and l. wang, “image-guided installation of 3d-printed patient-specific implant and its application in pelvic tumor resection and reconstruction surgery,” comput. methods programs biomed., vol.125, pp.66–78, 2016. [4] ch. v. madhav, r. s. n. h. kesav, y. s. narayan, “importance and utilization of 3d printing in various applications,” pp. 24–29, 2016. [5] y. weng, m. li, m. j. tan, s. qian, “design 3d printing cementitious materials via fuller thompson theory and marson-percy model,” constr. build. mater., 163:600–610, 2018. [6] p. dudek and k. zagórski, “cost, resources, and energy efficiency of additive manufacturing,” e3s web conf., vol. 14, pp. 1-8, 2017. [7] a. t. gaynor and j. k. guest, “topology optimization considering overhang constraints: eliminating sacrificial support material in additive manufacturing through design,” struct. multidiscip. optim., vol. 54, no. 5, pp. 1157–1172, 2016. remain support structure sup https://www.sciencedirect.com/science/article/abs/pii/s0950061817325175#! https://www.sciencedirect.com/science/article/abs/pii/s0950061817325175#! https://www.sciencedirect.com/science/article/abs/pii/s0950061817325175#! https://www.sciencedirect.com/science/article/abs/pii/s0950061817325175#! issn: 2580-0817 journal of mechanical engineering science and technology 41 vol. 3, no. 1, july 2019, pp.35-41 bintara et al. (the characteristic of overhang object on fdm 3d printing technology) [8] thomas. d, “the development of design rules for selective laser melting,” university of wales institute, 2009. [9] j. cantrell, s. rohde, d. damiani, r. gurnani, l. disandro, j. anton, a. young, a. jerez, d. steinbach, c. krsoese, p. ifju, “experimental characterization of the mechanical properties of 3d-printed abs and polycarbonate parts,” rapid prototyp. j., vol. 23, pp. 811–824. 2017 [10] r. paul, s. anand, “optimization of layered manufacturing process for reducing form errors with minimal support structures,” j. manuf. syst., vol. 36, pp. 231– 243, 2015. [11] p. das, r. chandran, r. samant, s. anand, “optimum part build orientation in additive manufacturing for minimizing part errors and support structures,” procedia manuf., vol. 1, pp. 343–354, 2015. [12] j. jiang and x. xu, “support structures for additive manufacturing : a review,” j. manuf. mater. process., vol. 2, pp. 1-23, 2018. [13] a. garaigordobil and r. ansola, “a new overhang constraint for topology optimization of self-supporting structures in additive manufacturing,” structural and multidisciplinary optimization, vol. 58, no. 5, pp. 2003–2017, 2018. journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.42-50 42 doi: 10.17977/um016v3i12019p042 elastic linear analysis of connecting rods for single cylinder four stroke petrol engines using finite element method didin zakariya lubis, andoko* mechanical engineering department, engineering faculty, universitas negeri malang, jl. semarang 5, malang, east java, indonesia *corresponding author: andoko.ft@um.ac.id abstract a connecting rod is one of the most critical parts in engine assembly which transfers energy from the piston to the crankshaft. the connecting rod mainly undergoes tensile and compressive loading under engine cyclic process. the forces acting on the connecting rod are forces due to maximum combustion pressure and forces due to the inertia of the connecting rod. this research aimed to analyze the design of the connecting rod of single-cylinder four-stroke engines. this study used cad software for modeling and structural design. stresses generated across all the locations of the connecting rod were evaluated using fea software. elastic linear analysis of model design was also performed. the simulation results in this study have led to the conclusion that failure occurred due to the incorrect selection of materials. among all materials under study, aa 6061 is considered the most suitable material for use at high rpm. in fact, aluminum is preferable for use at high rpm. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: connecting rod, elastic linear, finite element analysis, internal combustion engine i. introduction according to data released by the central statistics agency (bps) of indonesia 2017, the number of motorcycles grew from 13,563,017 in 2000 to 92,976,240 in 2014, a six-fold increase. this number also shows that motorcycles are the most widely used motor vehicle in indonesia. the increasing number of motorcycles in indonesia leads to a vast number of accidents, particularly due to the failure of the engine components. one of the most frequent failures occurs in the connecting rod because of the static and dynamic forces that work there and heavy loads it withstands [1]. the topography of indonesia, which consists of hills, lowlands and highlands and the poor quality of roads may also contribute to connecting rod failure. in addition, the failure of the connecting rod may also result from other factors, such as poor fabrication and lubrication processes [2]. connecting rod is part of an internal combustion engine that forms a link between the piston and the crankshaft [3], [4]. there are several types of materials and various production processes to create connecting rods. the two most common materials are steel and aluminum, while the manufacturing process generally used is casting [5]. casting is the preferable method of the production of connecting rods for motor vehicles. this method involves a series of process, including pouring molten steel into a mould and machining the finished product. the cast connecting rod can be used for lower horsepower-producing engines and is economical to manufacture. 43 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) connecting rods must be lightweight and have high stiffness. to achieve such properties, a lot of research has been conducted on various aspects of connecting rods such as materials, production technology, performance simulation, and fatigue. this study aimed to investigate the difference in stiffness between steel and aluminum alloy by using finite element modeling and comparison technique on the motorcycle engine of honda supra x 125. ii. materials and methods a. materials in this research, a static stress analysis was conducted on connecting rods made of commonly used materials, i.e., aisi 4340 (honda standard) and 1045 steel and proposed materials, i.e., aa 6061 and 7075. the chemical composition of the materials used is presented in table 1. table 1. chemical composition of connecting rods (%wt) [9] honda original part common uses aluminum alloy aisi 4340 aisi 1045 aa 6061 aa 7075 al 95.80 – 98.60 87.10 91.40 fe 95.19 96.33 98.51 98.98 0.70 0.50 cu 0.15 0.40 1.20 2.00 mg 0.80 1.20 2.10 2.90 cr 0.04 0.35 0.18 0.28 zn 0.25 5.10 6.10 si 0.15 0.30 0.10 0.35 0.60 0.40 c 0.37 0.43 0.43 0.50 mn 0.60 0.80 0.60 0.90 0.15 p 0.03 0.04 s 0.04 0.05 b. numerical evaluation of maximum loading condition of connecting rod it is assumed that the forces acting on the connecting rod are forces on the piston due to combustion pressure and tensile forces due to inertia and pressure of the bearing. the mechanical properties of the materials are shown in table 2 [6]. table 2. mechanical properties of different materials used for connecting rods [9] aisi 4340 aisi 1045 aa 6061 aa 7075 young’s modulus 190 x 109 pa 200 x 109 pa 68.9 x 109 pa 71.7 x 109 pa poisson’s ratio 0.27 0.29 0.33 0.33 density of material 7850 kg/m3 7870 kg/m3 2700 kg/m3 2810 kg/m3 ultimate tensile strength 745 x 106 pa 565 x 106 pa 290 x 106 pa 572 x 106 pa yield strength 470 x 106 pa 310 x 106 pa 276 x 106 pa 503 x 106 pa issn: 2580-0817 journal of mechanical engineering science and technology 44 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) table 3 shows the overall engine specification based on the data from honda [8]. table 3. design specifications of connecting rod no. properties nominal 1. torque (𝝉) 9.58 nm/6308 rpm 2. connecting rod length (𝒍) 0.1 m 3. cylinder diameter (𝒅) 52.4 ⅹ 10-3 m 4. stroke (𝒔) 57.9 ⅹ 10-3 m 5. stroke volume 124,89 cc 6. compression ratio 9.3 : 1 a) forces due to gas pressure the volume of the combustion chamber was measured by the compression ratio. where: density of petrol at 15oc (288.85ok) (ρ) = 770 x 10-3 kg/m3 molecular weight (m) = 114.228 g/mol ideal gas constant (r) = 8.3143 j/mol.k calculating the mass: m = 𝜌 . ʋ (1) m = 770 x 10−3 . [3.14 ( 52.4 ⅹ 10 −3 2 ) 2. 57.9 ⅹ 10−3] m = 0.007335 kg defining the rspecific: 𝑅𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 = 𝑅 𝑀 (2) 𝑅𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 = 8.3143 0.114228 = 72.78 j/kg.k ideal gas equation, p = 𝑚.𝑅𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 .𝑇 𝑉 (3) p = 0.007335 . 72.78 . 288.85 9526.6−6 p = 16186.3 pa b) inertia force due to reciprocating mass mass of the aisi 4340 material: m = mass of (piston rings and piston pin + 1 3 𝑟𝑑 𝑜𝑓 𝑐𝑜𝑛𝑛𝑒𝑐𝑡𝑖𝑛𝑔 𝑟𝑜𝑑) (4) m = 0.5 + ( 1 3 . 0.9) m = 0.8 n ꙍ = 2 .π .n 60 (5) ꙍ = 2 . 3.14 .6308 60 = 660.2 𝑟𝑎𝑑/𝑠 r = stroke of piston 2 (6) 45 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) r = 57.9 𝑥 10−3 2 = 28.95 𝑥 10−3 𝑚 θ = 0 (considering that connecting rod is at the tdc position) inertia force of aisi 4340 material: 𝐹𝑖 = m ꙍ 2r (cosθ + rcosθ l ) (7) 𝐹𝑖 = 0.8 . 660.2 2 . 28.95 𝑥 10−3(1 + 28.95 𝑥 10−3. 1 0.1 ) 𝐹𝑖 = 13018.6 n the results of a calculation using the same equation showed the inertia forces of aisi 1045, aa 6061, and aa 7075. table 4. inertia force of each material under study material mass (n) inertia force (n) aisi 1045 0.83 13506.6 aa 6061 0.61 9926.7 aa 7075 0.62 10089.4 c. modeling of connecting rod the connecting rod was designed following the dimensions of the regular connecting rods used in motorcycle engines from honda. the specification of the connecting rod by solid modeling is presented in fig 1. a finite element analysis under the influence of compressive and tensile stress due to combustion and inertia was performed using fea software. a linear elastic stress analysis was also conducted on the connecting rod model. the connecting rod should not experience buckling and fatigue under the working loads. fig 2 shows the loading conditions for the connecting rod. fig 1. connecting rod model; a) 100 mm; b) 30 mm; c) 13 mm c rod small end connecting rod rod big end b) a issn: 2580-0817 journal of mechanical engineering science and technology 46 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) fig 2. loading conditions for connecting rod iii. result and discussion a. mesh sensitivity study a mesh sensitivity study or convergence test is an analysis to determine the number of elements by showing appropriate values acceptable in a finite element analysis [7]. the mesh sensitivity study showed an insignificant difference in von mises values. the element mesh used in this study was the adjustment of the number of elements in the model, starting from a small number of elements (very coarse) to a large number of elements (very fine). fig 3. mesh sensitivity study of connecting rod for aisi 4340 fig 3 suggests that the more the number of elements, the greater the value of von mises stress. the maximum von mises stress on the aisi 4340 connecting rod as a convergent sample was at the fourth iteration with several elements 31406. furthermore, this number of elements then used in the modeling of the connecting rods. b. results of the elastic linear analysis on connecting rod the results of the finite element analysis using fea software are presented in table 5. the materials used were in safe condition based on the maximum working stress for 47 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) each material. the aisi 4340 material had maximum stress of 118.7 mpa, less than the allowable yield strength of the material, i.e. 310 mpa (see fig 4). fig 4. the elastic stress comparison results of finite element analysis on the materials a) aisi 4340; b) aisi 1045; c) aa 6061; d) aa 7075 the design of the connecting rod model was considered safe, if only under static loading conditions. the lowest stress of 186.5 mpa occurred in the proposed material (aa 6061) with an allowable yield strength of 276 mpa. this result suggested a material with a lighter material mass. when subjected to an inertia load, the mass was one of the multiplier factors comparable to the inertia force. fig 5 shows the comparison of the maximum stress in the connecting rod model. table 5. characteristics of connecting rods simulated using element analysis with tetrahedral shaped elements connecting rod material no. of element von mises stress (mpa) aisi 4340 31406 195.4 aisi 1045 31303 187.6 aa 6061 31303 186.5 aa 7075 30815 190.4 a) b) c) d ) issn: 2580-0817 journal of mechanical engineering science and technology 48 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) fig 5. von mises stress maximum comparison on the material study a) aisi 4340; b) aisi 1045; c) aa 6061; d) aa 7075 fig 6. von mises stress of each material as put forward by [1], the greatest stress occurs at the small end of the connecting rod. therefore, connecting rod failure is more likely to happen at the oil hole and the fillet section of the big end of connecting rod. also, even though the maximum stress is a) c) b) d) 49 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) less than the allowable material stress, fatigue failure can occur under dynamic loads due to high-stress concentrations and material defects. some of the major factors determining the damage to the connecting rod include connecting rod hardness, connecting rod design, clearance between the bearing and crank pink that exceeds its limit, and poor engine lubrication. fig. 6 shows the maximum stress of each material. iv. conclusion the simulation results in this study have led to the conclusion that failure occurred due to the incorrect selection of materials. among all materials under study, aa 6061 is considered the most suitable material for use at high rpm. in fact, aluminum is preferable for use at high rpm. aluminum is a material of choice for connecting rods due to its lightweight. besides good throttle response, its lighter weight can minimize vibration and stress on the connecting rod. however, steel is recommended for use in high-performance engines because aluminum will stretch more than steel under the same load. nomenclature 𝐹 engine force (n) 𝑣 volume (m3) 𝑠 engine stroke (m) 𝑎 cylinder area (m2) 𝑃 pressure (pa) 𝑚 mass (n) ꙍ angular speed (rad/s) 𝑟 crank radius (m) 𝛳 crank cycle 𝑙 length of connecting rod 𝐹𝑖 inertia force due to reciprocating mass (n) t temperature references [1] d. gopinath and c. v sushma, “design and optimization of four wheeler connecting rod using finite element analysis,” mater. today proc., vol. 2, no. 4–5, pp. 2291–2299, 2015. [2] c. juarez, f. rumiche, a. rozas, j. cuisano, and p. lean, “case studies in engineering failure analysis failure analysis of a diesel generator connecting rod,” biochem. pharmacol., vol. 7, pp. 24–31, 2016. [3] s. rakic, u. bugaric, i. radisavljevic, and z. bulatovic, “failure analysis of a special vehicle engine connecting rod,” eng. fail. anal., vol. 79, no. august 2016, pp. 98–109, 2017. issn: 2580-0817 journal of mechanical engineering science and technology 50 vol. 3, no. 1, july 2019, pp.42-50 andoko & lubis (elastic linear analysis of connecting rods for single cylinder four stroke) [4] m. n. ilman and r. a. barizy, “failure analysis and fatigue performance evaluation of failed connecting rod of reciprocating air compressor,” eng. fail. anal., vol. 56, no. april, pp. 142–149, 2015. [5] d. visser, “a comparison of manufacturing technologies in the connecting rod industry,” department of metallurgical and materials engineering, 2008. [6] j. r. davis, aluminum and aluminum alloys. asm international, 2001. [7] d. v. hutton, fundamentals of finite element analysis. mcgraw-hill companies, 2004. [8] ahm. (https://www.astra-honda.com/product/supra-x-125-fi). pt. astra honda motor. [9] asm international, volume 2: properties and selection: nonferrous alloys and special-purpose materials (https://www.asminternational.org/). 1993. journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 79-84 79 doi: 10.17977/um016v2i12018p079 analysis of mechanical properties and permeability of sand moulding by using eggshell in sand casting wahyu kurnianto 1,3, poppy puspitasari 1,2, and wahono1 1 department of mechanical engineering, faculty of engineering, universitas negeri malang 2 center of nano research and advanced materials, universitas negeri malang 3 bachelor program, mechanical engineering department, universitas negeri malang *poppy@um.ac.id abstract this study aimed to analyse the usage of eggshell as mixture material of bentonite in metal casting process which used dried sand moulding. eggshell variations in this study were 4%, 7%, 10% eggshell, and additional 3% of bentonite on each sample. this study used pre-experimental method and included to oneshot case study model. the highest strength was found on the sample 3 es 10%. tensile strength of dried sand moulding reach up to 0.09 kg/cm2, the compressive strength of dried sand moulding reached up to 3.11 kg/cm2, and the shear strength of dried sand moulding reached up to 1.13 kg/cm2. based on the test result indicated that permeability of sand moulding by heat treatment at 110ºc for 60 minutes at sample of 3 es 10% was at 178.3 ml / min. copyright © 2018journal of mechanical engineering science and technology all rights reserved keywords: mechanical properties, permeability, sand moulding, eggshell. i. introduction metal casting is process of formation of work piece that conducted by melting or heating metal, then poured into moulding to form the desired work piece. nowadays, casting process by using sand moulding is widely used due to its relatively low cost of raw materials, various size and composition, and also it is possible to reuse the sand moulding [1] material which commonly used in metal casting is aluminium. based on the world economic outlook, imf, submitted in october 2015, aluminium was in third ranked as the main base metal, with the value of global sales of usd 90 billion per year (ministry of industry of republic indonesia, 2016). while the medias which used in sand casting practice are composed of several compositions, such as silica sand, bentonite, water, carbon, and water-resistant powder. generally, the binder used in sand casting is single binder bentonite. bentonite is used as a binder in manufacture of sand moulding due to its necessary properties that generate high binding capacity, being clay when wet, so it will facilitate the making process of moulding, it’s being hard after drying [2]. in this study, the binder material that used in sand moulding was bentonite mixed eggshell. utilization of eggshell was dominated in cosmetics and fertilizer for the plant due to its high calcium content. the usage eggshell in casting had not been interesting. while the chemical content of eggshell represented 11% of total weight of the egg and composed of calcium carbonate (94%), calcium phosphate (1%), organic material (4%), and magnesium carbonate (1%) [3]. previous study under the title "the effect of combined limestone and quicklime addition to k300 concrete mixture,” the limestone was used as one of binder in this study, the calcium content had superiority as an adhesive, materials with calcium content was selected due to their properties which was able to be hardened after mixed with water [4]. mailto:*poppy@um.ac.id 80 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 79-84 wahyu kurnianto et.al (analysis of mechanical properties and permeability of sand moulding) ii. methodology this study used pre-experimental research design with one-shot case study model, in which sample group was given a treatment then the results was observed. the independent variable in this study was comparison of silica sand with eggshell as mixture of sand moulding with the percentage of silica sand 88%, 85% and 82% and binder eggshell with a percentage of 4%, 7% and 10%. the dependent variables in this study were the permeability, tensile strength, compressive strength, and shear strength. the control variable in this study was water with percentage of 5% in all of samples, eggshell with a mesh size of 200 or fineness of 0.02 mm, bentonite with percentage of 3% and silica sand with a mesh size of 40 or fineness of 0.4 mm. the composition of sand moulding which were used in this study were divided into several variations, they were:  4% eggshell, 3% bentonite, 88% silica sand, and 5% water (sample 1 es 4%).  7% eggshell, 3% bentonite, 85% silica sand, and 5% water (sample 2 es 7%).  10% eggshell, 3% bentonite, 82% silica sand, and 5% water (sample 3 es 4%). iii. results and discussion a. x-ray diffraction analysis before conducting sand moulding test, material which was used as mixed binder in casting process should be tested using xrd test to determine the elements contained in eggshell. the xrd results had been showed in figure 1 and table 1. according to calculation of eggshell crystal based on xrd result, the crystal size of sintered eggshell nanopowder at temperature of 1100ºc was 59.7912 nm, it was consistent with hall petch’s law that stated the smaller the crystal size, the harder the material hardness [5], as showed in table 2. b. mechanical properties testing mechanical properties testing of sand moulding in this study was divided into two states conditions. they were in wet and dry conditions of sand moulding. 1) mechanical properties analysis of sand moulding in wet condition. according to figure 2, obtained research result which stated that each moulding had the different of strength value. the sand moulding strength in wet conditions increased along with the increasing of bentonite content and showed the optimum value with the particular bentonite content [6]. this showed that the adding of binder in different percentage yielded different strengths. the different percentage of binder mixture in a wet sand moulding caused differences in strength [7] fig. 1. phase identification of sintered eggshells nanopowder treatment at temperature of 1100ºc table 1. phase identification of sintered eggshells nanopowder at temperature of 1100ºc post. [º2θ] height [cts] fwhm [º2θ] d-spacing [å] rel.int. [%] 29.4265 1606.40 .1378 3.03541 100.00 issn: 2580-0817 journal of mechanical engineering science and technology 81 vol. 2, no 2, november 2018, pp. 79-84 wahyu kurnianto et.al (analysis of mechanical properties and permeability of sand moulding) the highest mechanical properties which consisted of tensile strength, compressive strength and shear strength of sand moulding in wet conditions was sampling 3 es 10%. the highest tensile strength of sand moulding was 0.068 kg/cm2, this showed that this sand moulding in wet condition was worth to be used due to its value included into standard value, that was 0.07 to 0.42 kg/cm2, the highest compressive strength was 0.74 kg/cm2, in this case the compressive strength of sand moulding was also worth to be used due to its value was included into standard value, that was 0.35 to 1.54 kg/cm2. while, the highest shear strength was 0.28 kg/cm2 also was included into standard value that was 0.10 to 0.49 kg/cm2. compared to the previous study, the result of this study showed the better result. the previous study (muzayyin, 2017) used sand moulding that consisted of 85% silica sand, 10% bentonite and 5% water and yielded tensile strength was 0.06 kg/cm2, compressive strength was 0.54 kg/cm2, and shear strength was 0.022 kg/cm2. based on the explanation, the mixture of 10% eggshell and 3% bentonite could be used as binder in casting to reduce the usage of bentonite. fig. 2. bar chart mechanical properties analysis of sand moulding in wet condition fig. 3. bar chart mechanical properties analysis of sand mouldibg in dry condition 82 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 79-84 wahyu kurnianto et.al (analysis of mechanical properties and permeability of sand moulding) 2) mechanical properties analysis of sand moulding in dry condition. according to figure 3 could be understood that sand moulding which had the highest mechanical properties in dry condition was sample 3 es 10%. this sample had the highest tensile strength of 0.09 kg/cm2, this value included into standard value of sand moulding that was 0.07 to 0.42 kg/cm2. while the highest value of compressive strength was 3.1 kg/cm2 and this value included into standard value that was 1.5 to 17.5 kg/cm2, the addition of limestone (caco3) into lapindo mud affected the compressive strength of concrete which made of lapindo mud [8]. the higher calcium that used would yield a high compressive strength, and the highest shear strength of 1.13 kg/cm2, but this shear strength value was not included into standard, that was 0.10 to 0.49 kg/cm2. this result consistent with the result entitled analysis of binding material variation in sand moulding malang against the strength and permeability with composition of 10% bentonite, 82% sand, 8% water had tensile strength value of 0.07 kg/cm2, compressive strength of 1.2 kg/cm2, and shear strength of 0.5 kg/cm2 [9], [10]. sand moulding with a natural binder was able to obtain better mechanical properties at the casting of aluminium alloy [11]. c. permeability testing permeability test was a test which conducted to determine the ability of sand moulding to be able to transport gas/air and water vapour which contained in sand moulding. casting defects occurred due to the condition was not optimal during the casting process [12]. therefore, needed space between the sand grains for place where gas escaped during casting process. the amount of air/gas through the sand moulding should be indicated on the permeability meter [13]. permeability value should not be low or high, usually the value was ranged between 50-170 ml/min. all samples used 5% of the water which was the optimum value for binding. low permeability of sand moulding caused the air difficulty in flowing through the sand grain [2]. as the result when the molten metal poured, the air/gas couldn’t flow properly and caused defects on the casting product. conversely, if the permeability was too high, the cast metal could sink in between the sand grain and the result was the rough surface on the casting. according to explanation above, the content of binder in moulding composition was excessive would create a gap between the sand grain tightly, thus making the air got difficulty in flow. while the content of binder in moulding was less would create a gap between the sand grain loosely so air flowing easily. related to this study, the lack of binder in sample 1 es 4% would make the gap between the grain getting loose so that the air easily flowed and while the binder content in sample 3 es 10% was excess that made a gap between the sand grain getting narrower so the air got difficulty in flowing. the sample 2 es 7% had the highest value for the percentage of binder content. sample 1 es 4% and sample 3 es 10% with the percentage of sand was 85%. the result of this study was better compared with the other study entitled analysis binder material variations in sand moulding malang against strength and permeability with composition of 10% starch, 82% sand, 8% water with the permeability value of 180ml/min. fig. 4. bar chart sand moulding permeability issn: 2580-0817 journal of mechanical engineering science and technology 83 vol. 2, no 2, november 2018, pp. 79-84 wahyu kurnianto et.al (analysis of mechanical properties and permeability of sand moulding) combination of 5% bentonite and 5% of portland cement generated permeability up to 176 ml/min [2]. previous study entitled analysis of variations in composition of fly ash and bentonite as binder of sand moulding against permeability, compressive strength and fluidity of green sand moulding with the composition of 7% bentonite and 2% fly ash, this molten had permeability of 231.67 ml/min. as the highlight, mechanical properties value of sample 3 es 10% on sand moulding in dry condition had the highest value and the permeability of sample 3 es 10% had the lowest score. but, the value was slightly higher than the standard that had been determined ie. 50-170 ml/min. according to study result, the recommended composition for casting process was sampling 3 es 10% in dry conditions. sand moulding in dry conditions was more improved the mechanical strength due to water which absorbed on the surface of sand grain had been removed. sand with binder of dried clay had the best permeability and strength which increased compared to the wet one, as water was absorbed on the surface of clay grain had been removed. besides having a high value on mechanical properties, the sample 3 es 10% had permeability value that approached standard that had been determined in casting, thus the samples 3 es 10% was suitable for the composition of sand moulding in casting. iv. conclusion based on the discussions that had been presented, could be concluded that sand moulding in dry condition with a proper permeability value which was suitable for use in metal casting according to standard was the composition of sample 3 es 10% with permeability value of 178.3 ml/min. the highest tensile strength value and included into standard that was in sample 3 es 10% with tensile strength value of 0.09 kg/cm2, compressive strength of 3.11 kg/cm2, and shear strength of 1.13 kg/cm2. v. references [1] c. saikaew dan s. wiengwiset, “applied clay science optimization of molding sand composition for quality improvement of iron castings,” appl. clay sci., vol. 67–68, hal. 26–31, 2012. [2] andoko, p. puspitasari, a. a. permanasari, dan d. z. lubis1, “formula of moulding sand, bentonite and portland cement toimprove the quality of al-si cast alloy,” j. mech. eng. sci. technol., vol. 1, no. 2, hal. 49–52, 2017. [3] f. s. murakami, p. o. rodrigues, c. maria, t. de campos, m. antônio, dan s. silva, “physicochemical study of caco 3 from egg shells,” vol. 27, no. 3, hal. 658–662, 2007. [4] j. j. darren, d. gunaran, h. hendy, dan e. k. budirahardjo, “pengaruh penambahan gabungan batu kapur the effect dan batu kapur padam pada campuran beton k-300,” hal. 141–148. [5] m. multigner, e. frutos, j. l. gonzález-carrasco, j. a. jiménez, p. marín, dan j. ibáñez, “influence of the sandblasting on the subsurface microstructure of 316lvm stainless steel: implications on the magnetic and mechanical properties,” mater. sci. eng. c, vol. 29, no. 4, hal. 1357–1360, 2009. [6] w. yu, h. he, n. cheng, b. gan, dan x. li, “preparation and experiments for a novel kind of foundry core binder made from modified potato starch,” mater. des., vol. 30, no. 1, hal. 210–213, 2009. [7] n. t. herwido, p. murdanto, dan p. puspitasari, “analisis variasi komposisi fly ash dan bentonit pada,” j. mech. eng. sci. technol., no. 1, hal. 1–11, 2016. [8] a. pujianto, a. na, m. dc, dan hendra, “kuat tekan beton geopolimer dengan bahan utama bubuk lumpur lapindo dan kapur,” konf. nas. tek. sipil, vol. 7, no. konteks 7, hal. 129–136, 2013. [9] anon, “sand/binders/sand preparation/mold &amp; coremaking,” foundry manag. technol., vol. 124, no. 1, 1996. [10] m. holtzer, “the mold/casting interface phenomena,” in microstructure and properties of ductile iron and compacted graphite iron castings: the effects of mold sand/metal interface phenomena, 2015, hal. 77–108. [11] w. a. ayoola, s. o. adeosun, o. s. sanni, dan a. oyetunji, “effect of casting mould on mechanical properties of 6063 aluminum alloy,” j. eng. sci. technol., vol. 7, no. 1, hal. 89–96, 2012. [12] m. v. mohiuddin, a. krishnaiah, dan s. f. hussainy, “effect of composition of sand mold on mechanical properties and density of al-alloy casting using taguchi design approach,” int. j. eng. res. appl., vol. 5, no. 3, hal. 37–41, 2015. 84 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 2, november 2018, pp. 79-84 wahyu kurnianto et.al (analysis of mechanical properties and permeability of sand moulding) [13] s. priyadharsini dan p. karunakaran, “determination of the physical properties of sand moulding bonded with composite of ipomoea batatas and bentonite with casting application,” hal. 2913–2919, 2016. journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 88-95 88 doi: 10.17977/um016v3i22019p088 failure analysis on titen proto-xx car chassis gaguk jatisukamto*, rika dwi hidayatul qoryah, santoso mulyadi department of mechanical engineering, university of jember, indonesia jl kalimantan 37, jember, 68121 *corresponding author:gaguk.ft@unej.ac.id abstract the car chassis as a skeleton supports all loads and is the most important component. car chassis requirements must be rigid, twisting resistant, vibration resistant and resistant to fatigue. this study aims to find the cause of the failure of the titen proto-xx car chassis connection. the research methodology was conducted by testing the composition of materials and structural analysis using ansys workbench release 15.0 software. the conclusion of the research is that the skeletal structure material uses aluminum aa series 1xxx with al content greater than 99.5%, the welding ability is low, causing a failure in the welded joint. the rivet connection failure is caused by the stress concentration in the rivet holes in the plates so that the connection crack propagation occurs. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: alumunium, chassis, rivet connection, titen proto, welding connection 1. introduction the electric car was first developed by thomas davenport and robert anderson around 1830. the first electric vehicle using a non-rechargeable battery. its development is relatively slow when compared to oil-fueled vehicles. the reduced availability of fuel oil, encourages research on lightweight and strong chassis material, thereby saving battery energy [1]. the choice of lightweight chassis material is highly expected on condition that it has good mechanical properties and is expected to match or even exceed steel so the duration of battery charging can be extended. the titen proto-xx is one of the electric cars that use battery power as a source of energy and aluminium as a chassis material. automotive chassis requirements must be able to withstand the weight of the vehicle, hold dynamic loads, resist twisting, resist vibration and rigid [2]. elastic deformation is still possible as long as it still meets the allowable tolerance. aluminium and steel structures are generally used as automotive chassis materials because they have good mechanical properties, although the strength of aluminium is still below steel. the use of aluminium as an automotive component material for steel substitutes continues to be developed, due to various advantages in terms of corrosion resistance and relatively lightweight. the ratio of mechanical properties of aluminium to good weight can reduce co2 emissions and improve engine efficiency [3]. chassis weight affects the rolling resistance value of a vehicle. reducing the weight of a vehicle will improve acceleration and improve braking characteristics [4]. the use of aluminium as a chassis must be careful analysis because the deformation and elastic strength of aluminium are still below the steel structure. critical points that must get mailto:author:emailname@place.ac.id issn: 2580-0817 journal of mechanical engineering science and technology 89 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) the main attention lies in the connection [5]. alloy elements such as cu, zn, mn, mg, si and li greatly influence the grain boundary strengthening, precipitation hardening, and aluminium hardening work. the cu element will reduce corrosion resistance and improve weldability, but increase the weight of aluminium [6]. the weldability of aluminium causes difficulties in the connection between elements of the chassis structure. in this case, the rivet connection is also an alternative choice. the rivet cross-section is able to withstand shear stresses, but plastic deformation and material failures often occur on plates which are joined with rivets, due to the stress concentration in the geometry discontinuity of the hole aperture [7]. this research was conducted to determine the causes of damage to the structure of the electric car titen proto-xx. in general, structural failures at electric car titen proto-xx often occur at structure joint that receives dynamic loads. this research is focused on structural materials, welded joints, rivet joints which receive critical loads ii. methods materials and tools the material used is aa 1xxx series aluminium based on x-ray fluorescence (xrf) analysis. the composition of the chemical elements from xrf observations is listed in table 1. the cross-section of a rectangular-shaped chassis with dimensions of 50 x 25 mm and a plate thickness of 1 mm. the design of the titen proto-xx car chassis has been using welded joints, but due to its low weldability, some connections use rivets, as shown in figure 1. some connections between truss use weld and rivet connections. some connection frames among the trunk fail when welded. it can be avoide by using the rivets as the joint. table 1. chemical composition of aluminum aa 1xxx elements fe cr ti al % 0,264 0,165 0,014 balance fig. 1. welding and rivet connections on the proto-xx titen car rivet weld fracture on weld joint 90 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) procedure the research methodology is carried out through the stages that have been determined, as follows: a. determination of location and type of support figure 2 shows the type of fixed hinge on the titen proto -xx electric car. fig. 2. fixed pedestal position at 4 pedestal points b. determination of the loading position. c. loads are centered on the mainframe (driver load = 500 n) and compressive loads imposed on the roll bar (700 n). d. centralized loading of frame = 500 n, roll bar load load = 700 n, battery centralized load = 200 n) as shown in figure 3. fig. 3. loading on mainframe and rollbar issn: 2580-0817 journal of mechanical engineering science and technology 91 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) e. input data i. chassis design on the titen proto-xx car using the inventor software using in figure 4. fig. 4. 2d chassis of a titen proto-xx car i i . titen proto car chassis material specifications. the specifications of the titen proto-xx car chassis use aluminum material as listed in table 2. table 2. specification of aluminium aa 1xxx properties value unit mass density () 2.710 g/cm 3 yield strength (y) 275.000 mpa ultimate tensile strength (t) 310.000 mpa young's modulus (e) 68.900 gpa poisson's ratio () 0.330 software analysis of the loading and deformation of the titen protto-xx car chassis was carried out with the help of the 2015 autodesk inventor professional software and ansys workbench release 15.0, each of which has functions according to table 3. table 3. software for the analysis of the structure of a titans proto car structure software useful autodesk inventor profesional 2015 ansys workbench release 15.0 software for technical drawing design software for analysis of material strength, deflection and stress concentration in the chassis 92 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) iii. results and discussion figure 5 shows the simulation results of loading and deformation on the titen protoxx car chassis. chassis loads include roll bar weights, passenger weights and battery weights. the red color is in the middle, indicating that the deformation is the largest. real uneven road conditions cause dynamic loads in the form of impact, vibration and fatigue loads on the structure. rigid structural design and improper material selection endanger the safety of passengers. fig. 5. simulation of loading and deformation on titen proto-xx car chassis; a). structural joints are assumed to be weld joints. b). the deformation plot structure of the chassis. analysis of titen proto-xx car chassis failure analysis is based on the material used and analysis of simulation results with the help of ansys software. a detailed discussion of the causes of failure of the titen proto-xx car can be described as follows: a. failure due to material selection factors the results of the chemical composition test with the xrf method obtained the conclusion that the material of the titen proto-xx car chassis is aluminium series one, namely aa 1xxx. the most dominant main element is al, whose number is greater than 99.5% (% weight), while the rest is an impurity, which is shown in table 1. the weldability of aluminium aa 1xxx is very low. aluminium has good weldability if the al content is less than 94%, where the best weldability is at the al content of about 50% [8]. the use of aluminium aa 1xxx is the cause of cracks in the welded joint. the failure of the welding joint is due to improper preparation of the workpiece before it is welded. dirt such as dust, oil, grease, and aluminium oxide must be removed before welding. aluminium oxide should be removed first by brushing, scraping or blasting. for large-scale welding work, the removal of oxides should be done with chemicals, but it is constrained by the relatively expensive costs of the environmental impact produced. chemicals for removing the oxide layer are naoh and hno3 [9]. b. rivet connection failure connections between truss in some places also use rivets, as shown in figure 6. inaccurate cutting elements of the trunk element cause clearance between trunks when connected, causing greater deformation when the vehicle glides on the road. chassis deformation will be even greater when the vehicle glides on the road, due to the influence of vibrations, impact loads, and uneven road contours. a) b) issn: 2580-0817 journal of mechanical engineering science and technology 93 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) fig. 6. rivet connection on the titen proto-xx car chassis figure 7 shows the distance between rivet (rivet pitch) and the distance of rivet from the edge of the plate (edge distance) [3]. the position of the rivet hole greatly influences the fatigue life of the plate joints. a rivet hole is a form of plate geometry discontinuity, where the hole also apparently has an impact as a crack initiation. the movement of the car on the road will provide an external dynamic load that initiate the crack propagation. the end of the failure at the connection between the two plates is the material fail (fracture). figure 8 shows a macro photo of a two-plate fatigue failure in figure 7. the fatigue test results show that the closer the rivet is to the edge, the greater the fatigue failure will be (figure 8a). the greater edge distance gives smaller fatigue damage, as shown in figure 8 (b, c and d). the smaller the distance of the rivet from the edge of the plate will cause a greater distribution of stresses in the plate hole. the plate tears in figure 8a show that the area experiences critical stress due to stress concentrations. fig. 7. specimen geometry for lap shear tests [3] fig. 8. lap shear fatigue fracture interfaces of specimens tested at low load amplitudes, 1.35 kn or 1.575 kn, for specimen with different edge distances: (a) 6 mm, (b) 8mm, (c) 11.5 mm and (d) 14.5 mm [3] rivet 94 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) the discontinuity at the plate joints causes stress concentrations in the holes that initiate cracks, as shown in the bolt connection in figure 9 [10]. the von mises yield stress distribution of single and double bolt joints that accept tensile loads shows different von mises voltage contours. a connection of two parallel bolt holes results in a greater von mises stress distribution when compared to a connection with one hole. the increasing number of holes will not necessarily improve the strength of the structure but can be the opposite. figure 9b illustrates that the red contour shows a greater critical load than just one connection hole. fig. 9. tensile test of von mises stress distribution bolt connection; a). single bolt connection; b) double bolt connection [10]. 4. conclusions the causes of the failure of the titen proto-xx electric car can be described as follows: (1) the use of aluminum aa 1xxx, which has no weldability. the oxide layer on the surface causes aluminium aa 1xxx does not have good weldability; (2) the cause of failure in the electric vehicle structure titen proto-xx lies in the rivet connection. the layout and number of rivet holes have not been studied in terms of crack propagation that will occur. the gap between the plates connected to the rivet needs to be studied further because the gap has a very large stress concentration so that it becomes a crack initiation; (3) deflection of the electric car titen proto-xx is relatively large, so it is necessary to improve the truss design; (4) analysis of fatigue life needs to be studied further because there are many extreme changes in geometric shapes. issn: 2580-0817 journal of mechanical engineering science and technology 95 vol. 3, no. 2, november 2019, pp. 88-95 jatisukamto et al. (failure analysis on titen proto-xx car chassis) acknowledgment i wish to extend my full appreciation to all the people who helped me throughout this research. i would also like to thank prof. ir. achmad subagio, m.agr., ph.d and ir. khairul anam, s.t., m.t., ph.d for the support of the research funding provided through lp2m unej. i would also like to thank the electric car research group for their discussion and support in providing research topics. references [1] todd, j., chen, j., clogston, f., “analysis of the electric vehicle industry”, creating the clean energy economy, international economic development council, 2013. [2] sigh, a., soni, v., singh, a., “structural analysis of ladder chassis for higher strength”, international journal of engineering technology and advanced engineering/ijetae, vol. 4(2), pp. 253-259, 2014. [3] li, d., han, l., thornton, m., shergold, m., “influenced of rivet to sheet edge distance on fatigue strength of self-piercing riveted alumnium joints”, materials science & engineering a, 2012. [4] denny, j., veale, k., adali, s., leverone, f., “conceptual design and numerical validation of a composite monocoque solar passenger vehicle chassis”, engineering science and technology, an international journal, pp. 1067-1077. 2018. [5] ramesh kumar, s., dhandapani, n. v., parthiban, s., kamalraj, d., meganathan, s., muthuraja, s., “design and analysis of authomotive chassis frame using finite element method”, international journal of pure and applied mathematics, vol. 20, pp. 961-972, 2018, [6] mukhopadhay, p., “alloy designation, processing and use of aa6xxx series aluminium alloys”, review article, international scholarly research network, isrn metalurgy, 2012. [7] sire, s., mayorga, l. g., plu, b., “observation of failure scenarios in riveted assemblies: an innovative experimental strategy”, procedia engineering, pp. 430436, 2015. [8] alabode, m., “weldability of high strength aluminium alloys”, lappeeranta university of technology, 2015, lappeeranta, finland [9] deekhunthod, r., “weld quality in aluminium alloys”, uppsala universiteit, 2014 [10] fallahnezhad, k., steele, a., oskouei, r, h., “failure mode analysis of aluminium alloy 2024-t3 in double-lap bolted joints with single and double fasteners; a numerical and experimental study”, materials, vol 8, pp. 3195-3209, 2015 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no 1, july 2017, pp. 9-14 9 doi: 10.17977/um016v1i12017p009 factors affecting the surface roughness in sinking edm process ahmad atif fikri1, a *, maftuchin romlie1, aminnudin1 1department of mechanical engineering, faculty of engineering, universitas negeri malang, semarang street no. 5, malang, east java, indonesia corresponding author : * atif.fikri.ft@um.ac.id abstract the purpose of this study is to gain insights into the surface quality (smoothness) of sinking edm machining products. among other non-conventional machining processes, electrical discharge machining (edm) is the most commonly used process. edm is a machining process that uses electric sparks created between a workpiece and a tool (electrode). as a manufacturing process, edm is used for workpieces which have intricate contours and precise dimensions, and works by using electric discharges (sparks) applied in a rapid series of repetitive electrical discharges between the two electrodes, separated by a dielectric fluid, and subject to an electric voltage. since the tool tends to wear easily and the mould material is very hard and tough, it is necessary to keep within appropriate edm machining parameters, so that the smoothness of the mould lives up to expectations. therefore, the parameters of sinking edm process should be well established to produce the expected results, i.e. the smoothest surface quality and the maximum removal rate. regarding the electrode materials used, conducting a further experiment is required to achieve the appropriate settings of pulse current, on-time, off-time, servo voltage, and gap width. this experimental study involved several factors: (a) electrode material, (b) magnitude of current, (c) on-time, and (d) quality of surface (smoothness). in this study, the gap between the electrode and the workpiece was controlled at a distance of 40 μm, and with an off-time of 5 seconds, the same dielectric fluid, the same flow speed and the same dielectric immersion, and using the workpiece (aisi p20m steel). quantitative approaches (t test, one-way, and anova) were applied to analyse the results of comparison test and to determine the best parameter in sinking edm process. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: edm process, electrode, surface roughness i. introduction the development of manufacturing technology is growing rapidly along with the need to improve human welfare. means of transportation such as motorcycles, home appliances, and communications devices such as cellular telephone, both made of metal or other materials (plastic and composite), are advancing. the development speed has been greatly influenced by the availability of supported technology, such as machining, formation, and moulding technology. the oldest machining process is the one performed by removing material in the form of chips. in metallic materials machining, the most used tools are lathes, freis, saws, grinders, etc, whereas in non-metal machining, the process is done by casting, forming, and moulding. therefore, in mass manufacturing industry (casting, forming and moulding), the process of producing moulds, particularly the ones made of metal (both ferrous and non-ferrous), should be faster and efficient. the durability of mould is strongly influenced by the mechanical properties of metal as the moulding material. materials that have a high resistance to a wide range of requirements are typically made of hard materials but with low machining capabilities. in other words, the production capability of the machine is very low, because it is beyond the machine’s capacity to work with much stronger cutting tools. furthermore, workpieces with difficult and intricate contours are no longer able to be processed with any conventional machine, or even with the most advanced cnc milling machine. non-conventional machines such as chemical machining, electrochemical machining, electrical discharge machining, and high energy beam machining, are intended to manufacture products with intricate and complex contours. one of the four types of non-conventional machines owned by the department of mechanical engineering, universitas negeri malang, is the electrical discharge machining (edm), namely sinking edm. according to schey (2009) [1], the surface quality of mailto:atif.fikri.ft@um.ac.id 10 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 9-14 ahmad atif fikri et.al (factors affecting the surface roughness in sinking edm process) edm products is determined by many factors; the surface becomes rougher if the current density is higher, the viscosity of the dielectric material is higher, and the frequency is lower. these parameters highly depend on the enabled settings in the machine's features. there are various metals with different mechanical properties which can be used as a workpiece for intended purposes. edm is capable of handling the mechanical properties of metals, in terms of hardness, tensile strength, and toughness under static and dynamic loads. edm process is used in mould-making, thus surface smoothness is prioritised. in conventional machining process, the roughness level is determined by the established parameters in the machine’s system and the type of cutting tool used, thus the desired degree of smoothness is more achievable. while in edm process, the factors affecting results are very complex, because the metal etching process involves heat generated by electric sparks, frequency of current discharge (on-current), level of cathode electrical conductivity (cutting tool), dielectric material, and mechanical properties of the workpiece (melting point). dewangan (2010) [2], through his study on the steel aisi p20, concluded that the forming tool (cathode) wear was affected by the amount and frequency of current discharge, and the diameter of the forming tool. the fact that forming tool wear occurred showed how the factors affecting the surface smoothness of the mould were becoming more complex. the forming tool materials that can be used in edm are copper, brass, and graphite. these materials are more easily formed using a machine with a simple cutting tool (hss material), thus the desired shape or dimension can be very easily achieved. a research conducted by kumar et al. (2012) [3] found that silver electrode provided a better performance in certain characteristics, but was relatively costly. thus, graphite electrode was preferable in terms of metal removal rate (mrr) since its cost was comparatively lower than copper. the edm machining parameters examined were fixed distance control variable between the electrode and the workpiece, positive polarisation (electrode connected to the positive pole), and the use of dielectric available in the market. the research only focused on volume8 reduction speed, not on surface quality (smoothness). a mould is (usually) made of hard solid steel which has an intricate contour and thus very difficult to process with a conventional machine. consequently, the use of non-conventional machines, one of which is edm, is more suitable for mould-making. the value of material removal rate and level of surface roughness of sinking edm products depend on several parameters, such as pulse current, onand off-time, servo voltage, and gap width. the bigger the value of pulse and gap width and the smaller the value of off-time and servo voltage, the higher the material removal will rate. if the value of pulse and width gap is big, and the value of off-time and servo voltage is too small, then the surface of the products will be rough [4]. the fact that cutting tool wear occurs and mould material is very hard and tough, denotes that it is necessary to utilise appropriate edm machining parameters so that the surface quality of mould lives up to expectations [5]. therefore, the parameters of sinking edm process should be well established to produce the expected results, i.e. the smoothest surface quality and the maximum removal rate. regarding the electrode materials used, conducting a further experiment is required to achieve the appropriate settings of the pulse current, on-time, off-time, servo voltage, and gap width. a. determining factors in the ease of edm process the machining factors affecting the edm machines differ from the conventional ones. conventional machines rely on the hardness of tools and workpieces, whereas edm machines depend on λ (thermal conductivity) θ (melting point) and ρ (electrical resistivity) [6]. the machining time cannot be considered as a parameter for the ease of edm process because there are many other relatively complex factors affecting it, such as adhesion, cavitation, and short-circuiting [6]. ii. method this experimental study was done to investigate the quality of surface roughness of sinking edm machining products. the variables involved in this study were (a) magnitude of current, (b) forming tool materials, (c) length of the current release time and (d) level of roughness. a. tool, workpiece, and data analysis technique electrode materials used were: (a) copper, (b) brass, and (c) graphite. the workpiece materials used were the ones for manufacturing plastic moulds, namely assab steel 618 supreme, aisi issn: 2580-0817 journal of mechanical engineering science and technology 11 vol. 1, no. 1, july 2017, pp. 9-14 ahmad atif fikri et.al (factors affecting the surface roughness in sinking edm process) p20m steel (chemical composition: c 12:37%, cr 2:00%, mo 12:20%, mn 1.4%, si 0.3%, ni 1.0%, and s <a 0.01%). these materials were utilised for injection moulding, extrusion dies, and forming tools. the forming tool specimen was prepared in the workshop at the department of mechanical engineering, universitas negeri malang. the apparatus utilised were an edm machine (c-tek znc-320-50a), a vertical freis machine for manufacturing forming tools (cathode), a surface grinding machine to smooth the workpiece surface, and a roughness measuring tool (mitutoyo portable surface roughness tester sj-301p). the analysis techniques consisted of (a) descriptive analysis and (b) 4x3x3 anova statistical analysis integrated with the assumption tests: (1) the normality of distribution and (2) homogeneity of variance. the analysis was performed using a relevant computer programme. iii. findings and discussion the data obtained from the experiments in this study are presented in table 1. the results of the descriptive analysis are shown in table 2, and the ones of 4x3x3 anova statistical analysis are shown in table 3. table 1. results of roughness testing (µm) no electrode current (a) time on (second) average 0.5 1 1.5 2 1 copper 5 3.3 3.6 3.6 3.7 3.3 10 2.9 3.1 3.2 3.4 2.9 15 2.1 2.3 2.7 2.9 2.1 2 brass 5 4.3 4.6 4.7 4.9 4.3 10 3.9 4.2 4.2 4.4 3.9 15 3.1 3.4 3.7 4.9 3.1 3 graphite 5 8.3 8.6 8.7 8.9 8.3 10 8.9 8.2 8.2 8.4 8.9 15 8.1 8.4 7.7 8.9 8.1 average 4.54 4.74 4.82 5.24 table 2. results of data analysis no electrode current (a) average median mode standard deviation 1 copper 5 3.3 3.6 3.6 0.15 10 2.9 3.15 #n/a 0.180277564 15 2.1 2.5 #n/a 0.316227766 2 brass 5 4.3 4.65 #n/a 0.216506351 10 3.9 4.2 4.2 0.178535711 15 3.1 3.55 #n/a 0.683282518 3 graphite 5 8.3 8.65 #n/a 0.216506351 10 8.9 8.3 8.2 0.286138079 15 8.1 8.25 #n/a 0.438035387 12 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 9-14 ahmad atif fikri et.al (factors affecting the surface roughness in sinking edm process) table 3. results of anova anova: single factor summary groups count sum average variance copper with a current of 5 a 4 14.2 3.55 0.03 copper with a current of 10 a 4 12.6 3.15 0.043333 copper with a current of 15 a 4 10 2.5 0.133333 brass with a current of 5 a 4 18.5 4.625 0.0625 brass with a current of 10 a 4 16.7 4.175 0.0425 brass with a current of 15 a 4 15.1 3.775 0.6225 graphite with a current of 5 a 4 34.5 8.625 0.0625 graphite with a current of 10 a 4 33.7 8.425 0.109167 graphite with a current of 15 a 4 33.1 8.275 0.255833 anova source of variation ss df ms f p-value f crit between groups 196.815 8 24.60188 162.6073 8.45e-21 2.305313 within groups 4.085 27 0.151296 total 200.9 35 fig. 1. the average roughness level of workpieces with different electrode materials the anova test yielded a p-value of 8.45e-21. this value indicates that this research result was not obtained by chance but as a result of significantly tested variables. figure 1 illustrates the results of surface roughness testing on workpieces with three different materials. the electrode made of graphite had the highest surface roughness value while copper had the lowest value. this result appears to be supported by previous research by mahardika (2007) [6], which suggested that there were at least three important factors affecting the edm machining process, i.e. λ (thermal conductivity), θ (melting point), and ρ (electrical resistivity). the detail of electrode properties used in this study is presented in table 4. table 4. properties of electrodes used in the experiment issn: 2580-0817 journal of mechanical engineering science and technology 13 vol. 1, no. 1, july 2017, pp. 9-14 ahmad atif fikri et.al (factors affecting the surface roughness in sinking edm process) no material λ (w/mk) θ (k) ρ (ω cm) 1 copper 401 1356 0.0000017 2 brass 109 1173 0.000007 3 graphite 120 3565 0.0007837 fig. 2. workpiece surface roughness based on current discharge rate graphite has the highest value of electrical conductivity, thus it requires a greater energy to cause a spark. as a result, this type of electron will hit the workpiece so strongly that it causes a deeper electron penetration, which eventually leads to an increase in roughness of the workpiece. meanwhile, this aforementioned circumstance will not happen in electrodes made of copper and brass. when it comes to the brass electrode, the energy needed for the electron to jump to the workpiece is relatively low because the electrical resistivity of brass is higher than graphite. as a result, the electron will hit the workpiece relatively weakly, hence the lower value of roughness. figure 2 shows that in addition to the types of electrodes used, the current discharge rate affects the roughness of the workpiece. the higher the current discharge rate is, the higher the discharge energy is released [7]. thus, the beam of electrons will hit the workpiece harder so that the value of its surface roughness is higher. iv. conclusions our work has led us to conclude that the types of electrode, the magnitude of current/the amount of pulse current, and material removal rate affect the surface roughness of the workpiece. electrodes with properties λ (thermal conductivity), θ (melting point) and ρ (electrical resistivity) would affect the level of surface roughness of workpieces. the mechanism of the mechanical properties needs to be studied further to obtain information about electron behaviour related to its determining factors. references [1] j. a. schey, introduction to manufacturing processes, yogyakarta: andi, 2009 [2] s. k. dewangan, "experimental investigation of machining parameters for edm using u shaped electrode of aisi p20 tool steel," thesis. department of mechanical engineering national institute of technology rourkela, rourkela, 2010. [3] n. kumar, l. kumar, h. tewatia and r. yadav, "comparative study for mrr an die-sinking edm using electode of copper & graphite," international journal of advanced technology & engineering research (ijater), vol. 2, 2012. [4] suhardjono, "pengaruh arc on dan arc off time terhadap kekasaran permukaan dan laju pembuangan geram hasil pemesinan sinking edm," jurnal teknik mesin, vol. 6, no. 1, p. 14—19, 2004. 14 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 9-14 ahmad atif fikri et.al (factors affecting the surface roughness in sinking edm process) [5] f. han, c. li, y. dingwen and z. xiaoguang, "basic study on pulse generator for micro-edm," the international journal of advanced manufacturing technology, vol. 33, pp. 474-479, 2007. [6] m. mahardika, t. tsujimoto and k. mit, "a new approach on the determination of ease of machining by edm processes," international journal of machine tools & manufacture, no. 48, p. 746–760, 2008. [7] m. mahardika and k. mitsui, "a new method for monitoring micro-electric discharge," international journal of machine tools & manufacture, no. 48, p. 446–458, 2008 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no 1, july 2017, pp. 44-48 44 doi: 10.17977/um016v1i12017p044 effect of magnetic field on diesel engine power fuelled with jatropha-diesel oil sukarni sukarni1,*, partono partono1, deni krisdianto1, and retno wulandari1 1center for renewable and sustainable energy engineering, department of mechanical engineering, faculty of engineering, state university of malang, indonesia corresponding author: *sukarni.ft@um.ac.id abstract jatropha oil has characteristics very close to the diesel fuel, so it has good prospects as a substitute or as a mixture of diesel fuel. previous research showed that jatropha oil usage in diesel engines caused power to decrease. it was probably owing to the higher viscosity of the jatropha oil compared to that of diesel oil. installing the magnetic field in the fuel line of a diesel engine fueled with jatropha-diesel oil is expected to reduce the viscosity of jatropha-diesel oil mixture, hence improve the combustion reaction process. this research aims to know the influence of the magnetic field strength in the fuel lines to the power of diesel engines fueled with a mixture of jatropha-diesel oil. the composition of jatropha oil-diesel was 20% jatropha oil and 80% diesel oil. magnetic field variations were 0.122, 0.245 and 0.368 tesla. the results showed that the higher the strength of the magnetic field was, the higher the average diesel engine’s power would be. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: diesel engine power, jatropha oil, magnetic field i. introduction. the depletion of world oil reserves and the environmental pollution due to an increase in exhaust emissions have become major issues which call for prompt and apt actions, one of which is finding a suitable alternative fuel for diesel engines. vegetable oil is a promising alternative fuel due to its renewable, environmentally friendly, and easy to produce in rural areas [1]. in addition, its chemical and physical properties are similar to diesel oil [2]. one source of non-food vegetable oil potential for diesel fuel is jatropha oil. even so, the use of jatropha oil as diesel engine fuel is encountered several drawbacks. jatropha oil has a higher viscosity than diesel oil, making it difficult to atomize in the combustion chamber. the high viscosity of jatropha oil is due to the presence of glycerol in the backbone of its chemical structure [3]. moreover, its high viscosity is caused by its large molecular mass and chemical structures, which can cause problems in the pumping system, combustion and atomization in the diesel injection system [1]. therefore, it is necessary to decrease the viscosity of jatropha oil so that it can be used as a viable alternative fuel for diesel engines. the problem owing to the high viscosity of vegetable oil has been addressed in several ways, such as preheating, mixing or diluting with other fuels, transesterification, and thermal cracking or pyrolysis [1]. in fact, it is common to mix vegetable oil with diesel fuel. previous research has revealed that the greater the amount of jatropha oil in the mixture affected to the lower of engine power. the power generated from diesel engine fuelled with jatropha biodiesel oil is slightly smaller than the one with the use of diesel fuel; it is due to the lower calorific value of biodiesel [4]. the decrease in engine thermal efficiency with an increase in the proportion of jatropha oil is related to the incomplete combustion of jatropha oil because of high viscosity and low volatility [1, 5]. it is critical to improving combustion process of jatropha oil in term of decreasing its viscosity. giving magnetic field on jatropha fuel before entering the combustion chamber is one of the solutions to reduce the viscosity. the use of magnet established throughout the fuel flow pipe facilitates the binding of oxygen atoms by fuel during the combustion process [6]. there have been a number of researches on the influence of magnet on the characteristics of the fuel. research conducted by chalid, et al. [7] examined the effect of magnetic dipole system on the mailto:*sukarni.ft@um.ac.id issn: 2580-0817 journal of mechanical engineering science and technology 45 vol. 1, no. 1, july 2017, pp. 44-48 sukarni et.al (effect of magnetic field on diesel engine power) characteristics of kerosene. the results showed that the addition of a magnetic field of 4330 gauss with 60 minutes magnetization increased the refractive index (from 1.447 to 1.449) and decreased the viscosity level from 1.278 to 1.256. in other words, it raises the possibility of de-clustering reaction between molecules as well as an increase in the polarity of the molecules of kerosene. tung et al. [8] investigated the relationship between magnetization and viscosity of crude oil containing a big amount of paraffin. the results showed that there was a decrease in viscosity due to magnetization. there is a considerable amount of literature on the use of magnetic field on the fuel line of diesel engines. sudrajat and hendratna [9], for instance, have conducted research on the effect of a portable magnet on the fuel line to the temperature of exhaust gas and fuel consumption of a direct injection diesel engine fuelled with marine diesel. it is found that fuel consumption decreased by 1314% under normal load conditions. a previous study by siregar [10] has investigated the influence of coil wire diameter of energy-saving electromagnetic devices to the performance of diesel engines. the results showed that the use of wire with 0.35 mm diameter and 4000 windings offered fuel savings of approximately 30.79%. furthermore, wahyudi [11] utilized an inducer in the form of the magnetic field from solenoids with 1000 and 2000 windings. as a result, there was an increase in power and decrease in fuel consumption. the present research was conducted to determine the effect of variations in magnetic field strength on the fuel line to the engine power fuelled with jatropha-diesel oil. ii. method in the initial stage, a coil from copper wire with 1 mm diameter and 400 windings was made. then, it was electrified at 0.5, 1.0 and 1.5a subsequently. magnetic field strength generated was measured using teslameter. the measurement was performed by placing the tip of the probe teslameter at the center of the coil. according to chalid, et al. [7], the type of magnet used for fuel should be about 2000 to 4000 gauss (0.2-0.4 tesla), while some others recommended only up to 500 gauss (0.05 tesla) [6]. furthermore, the magnetic field coil was mounted in the fuel line before entering the injection pump. the next stage was mixing jatropha oil with diesel oil—4 liters jatropha oil were mixed with 16 liters diesel oil in a container. an empty diesel fuel tank was then filled with the mixture. the diesel engine was turned on until it reached the operating temperature. the power measurement was performed using the dynamometer test, measuring the braking torque. from the torque and engine speed recorded on the tachometer, power measurement can be done. it was performed 8 times at each variation in magnetic field strength and machine rotation. power measurements were carried out at various machine rotations, i.e. 1300, 1600, 1900, 2200 and 2500 rpm. the results of engine power measurements of variations in magnetic field strength and machine rotation were analyzed using two-way anova. the specifications of the diesel engine are the type of dwe -47 -50 –hs –av, 4 strokes, 4 cylinders, 2164 cc, 83 mm of cylinder diameter, 47 bhp of maximum shaft power at 3200 rpm, 22:1 of compression ratio. iii. results and discussion. results of measuring magnetic field strength of coil carrying a current of 0.5, 1.0 and 1.5a subsequently are presented in table 1. based on the literature [6,7], the resultant magnetic field strength generated by the current-carrying coil was adequate to produce an effect on fuel. table 1. measurement results of magnetic field strength current (ampere) magnetic field strength (tesla) 0,5 0,122 1,0 0,245 1,5 0,368 46 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 44-48 sukarni et.al (effect of magnetic field on diesel engine power) table 2. analysis of variations on effective power source of variation sum squares degree of freedom mean squares f calculate f table sig. magnetic field strength 13.878 3 4.626 51.439 3.924617 0.000 machine rotation 5459.067 4 1364.767 15175.371 3.456075 0.000 magnetic field strength* machine rotation 111.604 12 9.300 103.414 2.314158 0.000 error 12.591 140 0.090 total 5597.140 159 fig. 1. effective powers of variations on magnetic field strength and machine rotation table 2 presents the results of two-way anova test to determine the effect of variations in magnetic field strength and machine rotation, as well as to identify the effect of the interaction between magnetic field strength and the machine rotation on the effective power of diesel engine. table 2 shows how magnetic field strength affected effective power, the rotation affected effective power, and interaction between magnetic field strength and rotation affected effective power. sudrajat dan hendratna [9] pointed out that the use of magnet facilitated the process of ionization of engine fuel. ionization is highly beneficial to facilitate the fuel in binding oxygen during the combustion process. the size of molecular structures of the fuel will transform into smaller bonds after the fuel is subjected to magnetization [12]. these smaller molecules result in the easier combustion process in the combustion chamber. in other words, the process of fuel magnetization will make a complete combustion. the more complete the combustion is, the greater the engine power will be. the magnetic field generated the repulsive forces among hydrocarbon molecules so that the optimal distance between the hydrocarbon molecules will be formed; it will lower the hydrocarbon bond strength. as a consequence, the hydrocarbon molecules will be more reactive with oxygen and be more combustible, hence resulted in a complete combustion process. better combustion resulted in better diesel engine performance [11]. the power generated from diesel engines in variations on magnetic field strength and rotation is shown in figure 1. the effect of magnetic field strength on the average power of the overall engine rotation is presented in figure 2. issn: 2580-0817 journal of mechanical engineering science and technology 47 vol. 1, no. 1, july 2017, pp. 44-48 sukarni et.al (effect of magnetic field on diesel engine power) fig. 2. average powers of variations on magnetic field strength figure 1 and figure 2 suggested that the higher the magnetic field strength, the greater the engine power. this phenomenon was because of by the fact that an increase in magnetic field strength affected stronger repulsion among the molecules in the fuel, making the viscosity of the fuel at low rates. the decrease in viscosity led to a better fuel atomization in the injector, hence promoting a more completed combustion. the phenomenon in which the viscosity level of the fuel dropped due to the influence of magnetic field strength has been explained by chalid, et al. [7]. hydrocarbon molecules tend to attract one another to form molecular clusters. as a result, they will not part ways when reacting with oxygen. a relatively strong magnetic field in hydrocarbon molecules results in the repulsion reaction between hydrocarbon molecules (de-clustering), so that optimal distance between the hydrocarbon molecules and oxygen are formed. increasing the strength of magnetic field had a significant influence on improving the de-clustering effect. the strength of the magnetic field caused a change in electron density on atomic or molecular bonding region and increased the dipole moment thereby increased the polarity of molecules. increasing the polarity had a strong relationship with the phenomenon of de-clustering due to an increase in the dipole moment on the bond among the molecules. increasing the repulsion between the molecules led to a decrease in viscosity of the fuel, creating maximum distance between molecules of hydrocarbon and oxygen. as a result, fuel undergone magnetization reacts more easily during combustion, hence led to a higher engine power. the effect of the magnetic field was significant at low rpm but tended to decrease as the rotation speed increased, and then disappeared at 2200 rpm (as shown in figure 1). it happened because a fuel flow tended to slow down at the low-speed rotation, meaning that it took longer time for fuel being exposed to the magnetic field. the higher the engine rotation, the shorter the impact of magnetic fields on fuel. it is in agreement with previous research conducted by chalid, et al. [7], which revealed that the longer the fuel exposed to a magnetic field, the higher refractive index of the fuel. in other words, the longer the fuel affected to the magnetic field, the lower the viscosity level would be. as illustrated in figure 1, the faster the engine rotation, the higher the overall power. theoretically, engine power is the function of engine rotation. nonetheless, it was found that the highest power was reached at 2200 rpm and subsequently the power decreased over 2200 rpm. the decreasing of power after reaching a peak at high speed (2200 rpm) was owing to the higher friction losses [13]. at rotation rates above 2200 rpm, magnetic field adversely influenced the power, which made the engine power decreased. this was probably caused by fuel that was exposed to a magnetic field, making its viscosity value dropped and resulting in greater friction losses, e.g. dilute fuel can raise the friction between the piston and the cylinder wall. 48 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 44-48 sukarni et.al (effect of magnetic field on diesel engine power) the maximum power generated in the test was far different from the standard specifications of the machine, where the maximum power is 47 bhp occurring at 3200 rpm. the most likely explanation is that the machine was worn out; so that the friction losses increased significantly resulting in power generated was low, only up to 28 hp at 2200 rpm rotation. iv. conclusion. the results of this research have led to the conclusion that the magnetic field strength affects the power of diesel engine fuelled with a mixture of jatropha-diesel oil. the stronger the magnetic field, the higher the engine power. the maximum power increase of 12.76% occurred at 1300 rpm with the magnetic field strength of 0.245 tesla. references [1] pramanik, k., “properties and use of jatropha curcas oil and diesel fuel blends in compression ignition engine”, renewable energy, vol. 28, iss 2, 2003, pp. 239-248. [2] muniyappa, p. r., brammer, s. c., and noureddini, h., “improved conversion of plant oils and animal fats into biodiesel and co-product”, bioresource technol., 56, 1996, pp. 19-24. [3] wardana, i.n.g., “combustion characteristics of jatropha oil droplet at various oil temperatures”, fuel, volume 89, issue 3, march 2010, pp. 659-664. [4] chakrabarti, m.h. and ali, m., “performance of compression ignition engine with indigenous castor oil bio diesel in pakistan”, ned university journal of research, vol 10 vi, no. 1, 2009, pp. 10-19. [5] rao, t.v., rao, g.b., and reddy, k.h.c., “experimental investigation of pongamia, jatropha and neem methyl esters as biodiesel on c.i. engine”, jordan journal of mechanical and industrial engineering, volume 2, number 2, jun. 2008, pp. 117 – 122. [6] magnetizer and hydrocarbon fuel, http:// www.magnetizer.com [7] chalid, m., saksono, n., adiwar dan darsono, n., “studi pengaruh magnetisasi sistem dipol terhadap karakteristik kerosin”, makara, teknologi, vol. 8, no. 1, april 2005, hal. 36-42. [8] tung, n.p., vinh, n.q., phong, n.t.p., long, b.q.k. and hung, p.v., “perspective for using nd-fe-b magnets as tool for the improvement of the production and transportation of vietnamese crude oil with high paraffin content”, institute of material science hcm city branch ncst, vietnam, 2004. [9] sudrajat, a. dan hendratna, k.k., “menghemat bahan bakar dengan magnet portabel”. inovasi online, edisi vol.6/xviii/maret 2006. (online) (http://io.ppi-jepang.org/article. php?id=145). diakses 10 juni 2009. [10] siregar, h. p., “pengaruh diameter kawat kumparan alat penghemat energi yang berbasis elektromagnetik terhadap kinerja motor diesel”, jurnal teknik mesin, vol. 9, no. 1, april 2007, hal. 1-8. [11] wahyudi, lilik, “studi karakteristik pengaruh alat penginduksi elektromagnetik dari solenoida untuk menambah sifat reaktif bahan bakar solar terhadap unjuk kerja mesin diesel”, (online) (www.etd.library.ums.ac.id/go.php?id=jtptums-gdl-s1-2006). diakses 10 juni 2009. [12] zarutskaya, t. and shapiro, m., “capture of nanoparticles by magnetic filters”, journal of aerosol science, volume 31, issue 8, 2000, 907. [13] pulkrabek, w. w., engineering fundamentals of the internal combustion engine, 2nd edition, upper saddle river, new jersey: prentice hall, 2003. http:// http://www.magnetizer.com http://io.ppi-jepang.org/article. http://www.etd.library.ums.ac.id/go.php?id=jtptums-gdl-s1-2006). journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 1-7 1 doi: 10.17977/um016v3i12019p001 preparation of chitosan-polyethylene oxide-colocasia esculenta flour nanofibers using electrospinning method riesca ayu kusuma wardhani1*, lia asri2, muhamad nasir3, bambang sunendar purwasasmita1,4 1advanced materials processing research group, engineering physics study program, institut teknologi bandung, jl. ganesha 10, bandung, 40132, indonesia 2materials engineering study program, institut teknologi bandung, jl. ganesha 10, bandung, 40132, indonesia 3research center for chemistry, indonesian institute of sciences, jl. sangkuriang komplek lipi, bandung, 40135, indonesia 4research center for nanosciences and nanotechnology, institut teknologi bandung, jl. ganesha 10, bandung, 40132, indonesia *corresponding author: riesca.wardhani@gmail.com abstract nanofibers have been prepared from the mixture of chitosan, polyethylene oxide (peo) and colocasia esculenta flour (ce flour) by using the electrospinning method. two different nanofibers were formulated, containing chitosan-peo and chitosan-peo-ce flour. the higher concentration of peo (3%chitosan-6%peo) (w/v) resulted in more uniform chitosan-peo electrospun nanofibers without beads. chitosan-peo-ce flour was prepared by addition of colloidal ce flour into the solution containing 3%chitosan-6%peo with variation of the ce flour concentration of 5, 15 and 25% (w/v). scanning electron microscopy demonstrated that the average diameter of chitosan-peo nanofibers was 128±41 nm, whereas the diameter of chitosan-peo-ce flour nanofibers was 159±45 nm. the diameters of nanofibers increased with the increase of ce flour content. fourier transform infrared spectra demonstrate the presence characteristic peaks of chitosan, peo and ce flour. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: chitosan, colocasia esculenta, electrospinning, nanofibers, polyethylene oxide. i. introduction the use of biopolymers such as protein (collagen and fibrin) and polysaccharides (cellulose, chitosan, and hyaluronic acid) as biomaterials for wound healing has attracted many attentions in the biomedical field. these biopolymers provide many instructive cues required by the cells attachment and proliferation [1]. colocasia esculenta flour (ce flour) is known as botanical collagen due to its some essential amino acid contents (protein). it has been reported that c. esculenta can be used in medicine, skin wounds healing [2][3] and as poison antidote [4][5]. carbohydrates and some essential amino acids contents in c. esculenta make this material is not toxic and compatible with the body. wound dressing has to be antibacterial, the addition of antibacterial agent then becomes important. chitosan is one of biopolymer that has antibacterial properties, biocompatible, and biodegradable. chitosan is obtained from n-deacetylation of chitin, the second-most abundant natural polysaccharide, which is embedded in a protein matrix of a crustacean shell [6]. ce flour and chitosan are good candidates to be used as a wound dressing. 2 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 1-7 wardhani et al. (preparation of chitosan-peo-colocasia esculenta flour nanofibers) electrospinning has been regarded as the most promising approach to generate continuous nanofibers on a large scale, and the fiber diameter can be adjusted from nanometers to micrometers. electrospun nanofiber is a good wound dressing candidate because of its unique properties: the highly porous structure and well-interconnected pores are particularly important for exuding fluid from the wound. the small pores and very high specific surface area not only prevent the microorganism invasions but also assist the control of fluid drainage [7]-[9]. electrospun chitosan-peo nanofiber containing ce flour has not been reported. in the present study, we describe how we have adapted the electrospinning process to fabricate nanofibers of chitosan and peo with containing ce flour. polyethylene oxide (peo), a stable polymer, easily soluble in water, non-toxic and non-irritating, was also added to decrease the conductivity of the polysaccharide content and to regulate the polymer chain entanglement in the solution [10]. combination of peo and biopolymers is expected to result in nanofibers that are easily fabricated and has excellent properties for wound dressing. ii. materials and methods a. materials chitosan with low molecular weight (mw = 20000 da, deacetylation degree = 7585%) and polyethylene oxide (peo, mw = 600000 da) were purchased from sigma. acetic acid glacial was obtained from merck. ce flour was kindly provided by pt. sentra biogen bandung, indonesia. ce flour contains protein of 12.92% consisting of 17 different amino acids, carbohydrate of 71.05%, and fat of 0.91%. b. methods various concentrations of polymers solutions were prepared using different solvents. peo solutions were prepared with concentrations of 4% – 6% (w/v) in deionized water, while chitosan solutions were made with concentrations of 3% – 4% (w/v) in 80% (v/v) acetic acid. ce flour colloidal solutions were prepared with concentrations of 5, 15, and 25% (w/v) in deionized water. afterward, chitosan and peo solutions were mixed with volume ratio 40:60 under stirring for 24 hours at room temperature. chitosan-peo-ce flour solution was prepared by adding 1 ml ce flour colloidal solution into 20 ml solution containing 3% chitosan – 6% peo with a volume ratio of chitosan: peo of 40:60. the mixture was stirred for 24 hours at room temperature until the solution was homogeneous. the chitosan-peo and chitosan-peoce flour solutions were processed by electrospinning (built-up electrospinning apparatus vf-s11, research center for chemistry, indonesian institute of sciences, indonesia). electrospuns were collected on a plate drum by connecting a high voltage power supply. a syringe pump was used for delivering the polymer solution at a rate from 0.005 ml/min with a voltage from 15 to 20 kv and a needle to collector distance of 12 cm. c. characterizations the morphologies of the nanofibers were examined using a scanning electron microscope (sem) jeol-jsm-6360la. the nanofibers samples were sputter-coated with gold. the average diameter of nanofibers was determined by selecting 100 fibers issn: 2580-0817 journal of mechanical engineering science and technology 3 vol. 3, no. 1, july 2019, pp. 1-7 wardhani et al. (preparation of chitosan-peo-colocasia esculenta flour nanofibers) at random from sem images with 1000x magnification. ftir spectra of nanofibers were measured using attenuated total reflectance fourier transform infrared (atr-ftir) spectroscopy, recorded on bruker alpha ftir spectrometer with a wave number of 4000 – 750 cm-1. iii. results and discussions figure 1 shows sem images of chitosan-peo electrospuns, confirming that nanofibers structure have been successfully formed in all solution compositions. the best condition used in electrospinning parameters was obtained at a voltage of 20 kv, polymer solution flow rate of 0.005 ml/min, and the distance between the nozzle – collector of 12 cm. fig. 1. sem morphologies of chitosan-peo electrospuns nanofibers were collected from solutions containing (a) 3% chitosan – 5% peo; (b) 4% chitosan – 4% peo; (c) 4% chitosan–5% peo; (d) 3% chitosan – 6% peo. the bar denotes 2 µm. the diameter of the fibers chitosan-peo ranged from 41 to 262 nm, with the average fiber diameter of 128±41 nm. it is found that some of nanofibers still contain beads (figure 1a-c), showing that the concentration of polymer solutions was not high enough to tie chitosan and peo chains. nanofibers from 4% chitosan – 5% peo (figure 1c) showed fewer beads than 3% chitosan – 5% peo (figure 1a) and 4% chitosan – 4% peo (figure 1b), whereas beads were not observed in nanofibers obtained from 3% chitosan – 6% peo solution (figure 1d). from the sem images, it can be concluded that the best concentration of the solution used in electrospinning was found at 3% chitosan and 6% peo. the higher concentration of peo (6%) resulted in more uniform electrospun nanofibers as the long peo molecular chains can make other molecular 4 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 1-7 wardhani et al. (preparation of chitosan-peo-colocasia esculenta flour nanofibers) chains fully stretch and effectively entangle with each other in solution [11][12]. a number of peo molecules at this concentration was sufficient to balance the amount of molecular chains of chitosan, so that interlacing fibers were able to form the uniform nanofibers without beads. the 3% chitosan and 6% peo concentration was then used in the formation of chitosan-peo-ce flour nanofibers. the best condition used in electrospinning process of chitosan-peo-ce flour solution was set at a voltage of 15 kv, polymer solution flow rate of 0.005 ml/min., and the distance between the nozzle – collector of 12 cm. formation of chitosan-peo-ce flour nanofibers required lower voltage than chitosan-peo nanofibers (20 kv). addition of ce flour into chitosan solution could strongly increase the conductivity of the solution that makes the solution is difficult to be processed by electrospinning. chen et al. reported the influence of polymer on solution conductivity following this order: collagen (protein) > chitosan > peo [13]. the ce flour consists of carbohydrate as major component, protein (17 amino acids), and fat. protein (12.92%) contents seem responsible in increasing the solution conductivity. the presence of peo in the solution plays a role not only in promoting chain entanglement of polymers but also decreasing the conductivity of polymer solution [10]. fig. 2. sem morphologies of chitosan-peo-ce flour nanofibers. electrospuns were collected from solutions of 3% chitosan – 6% peo and various concentrations of ce flour (a) 5% ce flour; (b) 15% ce flour; (c) 25% ce flour. the bar denotes 2 µm. sem images confirm the formation of nanofibers for all concentration of ce flour (figure 2). the smooth nanofibers were observed at a concentration of 25% ce flour (figure 2c), whereas a small number of beads were still found in nanofibers with ce flour content of 5 and 15% (figure 2a-b). it can be concluded that solution containing 3% chitosan – 6% peo – 25% ce flour was the best composition among other formulations. the diameter size of resulting chitosan-peo-ce flour nanofibers range from 50 to 292 nm with an average fiber diameter of 159±45 nm, indicating slightly bigger than the diameter of chitosan-peo nanofibers. in this works, the electrospinning parameters indicated that the increase of higher power supply voltage caused a faster rate as the process of spinning mass rate of the polymer out of the nozzle also increased so that the diameter of the fibers were smaller [9]. nanofiber diameters increased with the increase of ce flour content as solution became more conductive. when the solution subjected to an electric field, the fiber jet was easier to be withdrawn. higher voltages were applied during electrospinning (16-18 kv) in order to decrease the diameter of the fiber, but it resulted in discontinuous structure of nanofibers. issn: 2580-0817 journal of mechanical engineering science and technology 5 vol. 3, no. 1, july 2019, pp. 1-7 wardhani et al. (preparation of chitosan-peo-colocasia esculenta flour nanofibers) to confirm the chemical composition of the electrospun nanofiber, atr-ftir was employed. afterward, the ft-ir spectrum of chitosan-peo-ce flour nanofiber was compared to the electrospun chitosan-peo, and electrospun peo nanofibers (figure 3). fig. 3. atr-ftir spectra of peo, chitosan-peo, and chitosan-peo-ce flour nanofibers. electrospun peo displays absorption peaks at 2885 cm-1 originating from –ch2– stretching vibrations, 1465 cm-1, at 1363 cm-1, 1340 cm-1, 1279 cm-1, 1241 cm-1, and 845 cm-1 indicates the presence of ch bending, peaks of the c-o-c stretching vibrations at 1149 cm-1, 1101 cm-1, 1062 cm-1 and 959 cm-1 [12]. the characteristic absorption peaks of chitosan appear in the area of 3600 cm-1 – 3000 cm-1 indicating the presence of o-h and n-h stretch, peak at 1655 cm-1 originating from –c=o stretch and at 1570 cm-1 from the amide bond –nh2. the two absorption peaks –ch2– at 2885 cm -1 and c-o-c at 1101 cm-1 were observed for peo. for electrospun chitosan-peo-ce flour, each absorption peaks of chitosan and peo are identified, while the typical absorption bands of chitosan and peo represent –ch2– stretching and –nh2 did not change. the absorption peaks of amide i (1650 cm-1) and amide ii (1550 cm-1) indicate characteristic of structure protein and chitosan. iv. conclusions nanofibers have been successfully prepared from solutions containing chitosanpeo and chitosan-peo-ce flour using the electrospinning method. sem analysis of the resulting electrospuns confirms the formation of nanofibers. it shows that the optimum concentration on nanofibers formation with braided fibers are uniform without any beads in concentrations of 3% chitosan, 6% peo, and 25% ce flour. ftir analysis shows the existence of ce flour, chitosan, and peo on the surface of the nanofiber membrane as indicated by some characteristic peaks in ftir spectra. 6 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 1-7 wardhani et al. (preparation of chitosan-peo-colocasia esculenta flour nanofibers) acknowledgment this work was supported by lembaga pengelola dana pendidikan (lpdp), ministry of finance republic indonesia. references [1] agarwal, s., wendorff, j.h., and greiner, a, “use of electrospinning technique for biomedical applications”, polymers, vol. 49, pp. 5603-5621, 2008. [2] agyare, c., asase, a., lechtenberg, m., niehues, m., deters, a., and hensel, a, “an ethnopharmacological survey and in vitro confirmation of ethnopharmacological use of medicinal plants used for wound healing in bosomtwi-atwima-kwanwoma area, ghana”, journal of ethnopharmacology, vol. 125, pp. 393-403, 2009. [3] goncalves, r.f., silva, a.m.s., silva, a.m., valentao, p., ferreres, f., izquierdo, a.g., silva, j.b., santos, d., and andrade, p.b, “influence of taro (colocasia esculenta l. shott) growth conditions on the phenolic composition and biological properties”, food chemistry, vol. 141, pp. 3480-3485, 2013. [4] nwauzom,a a.b., and dappa, m.s, “ethnobotanical studies of port harcourt metropolis, nigeria”, isrn botany, article id 829424, 2013. [5] prajapati, r., kalariya, m., umbarkar, r., parmar, s., and sheth, n, “colocasia esculenta: a potent indigenous plant”, international journal of nutrition, pharmacology, neurological diseases, vol. 1, no. 2, pp. 90-96, 2011. [6] geng, x., kwon, o.h., and jang, j, “electrospinning of chitosan dissolved in concentrated acetic acid solution”, biomaterials, vol. 26, pp. 5427-5432, 2005. [7] zahedi, p., rezaeian, i., siadat, s., jafari, s.h., and supaphol, p, “a review on wound dressings with an emphasis on electrospun nanofibrous polymeric bandages”, wiley intersciences, vol. 21, pp. 77-95, 2010. [8] huang, z.m., zhang, y.z., kotaki, m., and ramakrishna. s., “a review on polymer nanofibers by electrospinning and their applications in nanocomposites”, composite science and technol., vol. 63, pp. 2223-2253, 2003. [9] sill, t.j., and von. r.h.a, “electrospinning: application in drug delivery and tissue engineering”, biomaterials, vol. 29, pp. 1989-2006, 2008. [10] jeong, s.i, krebs., melissa, d., khan, s.a., bonino., christopher, a., samorezov., julia, e., and alsberg, “electrospun chitosan–alginate nanofibers with in situ polyelectrolyte complexation for use as tissue engineering scaffolds”, tissue engineering. part a, vol. 17, no. 1-2, pp. 59-70, 2011. [11] sun, k., and li, z.h, “preparations, properties and applications of chitosan based nanofibers fabricated by electrospinning”, express polymer letters, vol. 5, pp. 342–361, 2010. [12] chen, l., zhu, c., fan, d., liu, b., ma, x., duan, z., and zhou, y, “a human-like collagen/chitosan electrospun nanofibrous scaffold from aqueous solution: https://scholar.google.es/javascript:void(0) https://scholar.google.es/javascript:void(0) https://scholar.google.es/javascript:void(0) issn: 2580-0817 journal of mechanical engineering science and technology 7 vol. 3, no. 1, july 2019, pp. 1-7 wardhani et al. (preparation of chitosan-peo-colocasia esculenta flour nanofibers) electrospun mechanism and biocompatibility”, biomedical material, vol. 99a, pp. 395-409, 2011. [13] chen, j.p., chang, g.y., and chen, j.k, “electrospun collagen/chitosan nanofibrous membrane as wound dressing”, colloids and surfaces, vol. 313, pp. 183-188, 2008. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 135-143 135 doi: 10.17977/um016v4i22020p135 new design of aluminum 6061 welding joining using friction stir welding method widia setiawan*, nugroho santoso, surojo departement of mechanical engineering sekolah vokasi university of gadjah mada, yogyakarta, indonesia *corresponding author: widia_s@ugm.ac.id abstract parallel, lap, corner, and t joints are commonly used in fusion welding and solid welding. other joints made are lap and butt joint. this study aims to evaluate a new design of fitting model single u and double u for friction stirr welding of aluminum. aluminum sheet 6061with a thickness of 10 mm, will be cut to a length of 150 mm and a width of 100 mm, then a locking groove will be made with an inner size of 5 mm and a length of 150 mm the flow is used to be paired in the fsw process. this experiment results show the high tensile strength that occurs in the double joint u, is 13.4 kn while the average is 12 kn. single connection experiment u the highest tensile strength is 12.89 kn, while the average value is 10.37 kn. the hardness is higher in double u joints compared to single u joints. copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: aluminum welding, double u, friction stir welding, lap butt joint, single u i. introduction friction stir welding (fsw) is a solid-phase joining technique on fabrication industry. good quality single-sided and double-sided butt, “t”, and lap joints. it was invented in 1991 and was originally used to produce butt joints of aluminum alloys [1]. fsw is a method of welding solid metals, capable of connecting two different metals (dissimilar metal) in plastic conditions. the probe is a solid welding aid to produce heat and make the material plastic. this connection occurs because the plastic material is continuously stirring along the joint line. this method was discovered and patented by the welding institute (twi) [1]. fsw combine two ferrous or non-ferrous metals without the metal transfer, under pressure or without pressure. it have applied to metals and does not change its basic characteristics. the fsw is often applied to aluminum and not post weld heat treatment (pwht). pwht is heat-treatment of metal after welding with the aim of reducing residual stresses [2]. fsw has several advantages including, metals low carbons with good weldability, low heat energy, no electrodes, no residual stress, low distortion, good appearance welds at relatively and low cost. the relative motion between the rotating tool and the substrate generates frictional heat that creates a plasticized region around the immersed portion of the tool [3]. the success of the fsw process depends on the design, diameter, and probe material that will be used. the probe consists of a shoulder, arm, and pin, each part of which functions as follows: a heat-producing shoulder, a chuck grip arm on the engine, and a pin as a plastic 136 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) material stirrer. pressure of 18.7 kn apply to the materials, then the pressure will be reduced by a certain speed [4]. the base materials for welding were aa6063 (al–0.7%mg–0.4%si) aluminum alloy and aa5052 (al–2.5%mg) aluminum alloy. the thicknesses of the aa6063 plate and the aa5052 plate were 4 mm and 2 mm, respectively. the plates were friction stir welded vertical to their rolling directions. the so-called lap–butt joint of dissimilar to aa6063/aa5052 aluminum alloys consisting of three plates [5]. the material structure during fsw is shown at figure 1. during the welding process, the heat is generated from the friction by the probe that spins on the work-piece which eventually creates plastic state compound. this state can be observed in the thermomechanically affected zone (tmaz) [6]. fig. 1. fsw process in metal: a) parent metal, b) haz on fsw, c) tmaz on fsw, d) plastic on fsw [6] the fsw has become an efficient option of welding method for the same or dissimilar aluminum alloys, especially those which are difficult or impossible to be welded by the conventional fusion welding without any hot crackings, blow holes or distortions [7]. lap connection is a connection process by overlapping or stacked, then the probe is rotated on a pile material (figure 2). the length of the pin penetrates the two materials, then the connection process is carried out with the probe rotated and shifted on the workpiece surface [8]. key features on tjoint fsw optimization are 1000 rpm rotation speed, 15 mm shoulder diameter, 3.9 mm, and 2.5 mm in aluminum thickness [9]. fig. 2. a) fsw lap joint process, b) tensile fracture test [8] fsw is a current technique in joining aluminum without feeder electrode required. the heat is generated from the rotation of welding tool which results in deformation in the welding area. this joining process is called solid welding [10]. the heat is generated from the spindle rotation and the joining occurs because of the radial force toward the axial (a) (b) issn: 2580-0817 journal of mechanical engineering science and technology 137 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) direction. the higher the pressure, the more heat is generated. such condition will greatly influence the result of the welding and affect the material’s mechanic state [11]. fsw is a welding method for two ferro or non-ferro metals without liquefication and can be done with or without pressure. fsw does not alter the basic characteristics of the metals and is often performed to aluminum that does not endure post weld heat treatment (pwht) pwht is heat-treatment of metal after welding with the aim of reducing residual stresses [12]. the heat in fsw technique is influenced by the probe’s diameter. its size will affect the formation of microstructure, macrostructure, and the tensile strength on the welding of the dissimilar metals between al 6061 dan az 31 magnesium [13]. the micro hardness value above 52 hvn was formed by all joint variations on 30 mm/min feedrate speed because the temperature distribution with such speed was low, therefore the magnesium loss was just minimum. the highest tensile test score was 163.7 mpa by c-b 45 joint on 10 mm/min feedrate speed. the temperature distribution reached 420°c, consequently forming plastic state on the work-piece [14]. this study aims to evaluate a new design of fitting model single u and double u for fsw in aluminum welding. ii. material and methods the aluminum 6061 as the object of this research contain chemical substance as described in table 1. table 1. chemical composition of 6061 aluminum alloy (wt.%) compositions mg si cu mn fe cr ti zn al content 0.9 0.6 0.25 0.086 0.18 0.1 0.192 0.01 bal the probe was made from low carbon steel with hardened ems 45, simple design and with size is shown in figure 1, then hardened to 62 hrc fig. 3. simple design of probe with ems 45 materials table 2. chemical composition of 6061 aluminum alloy (wt.%) compositions mn c si fe contens 0.486 0.450 0.156 bal before welding 6061 aluminum sheets were made in pairs of single u and double u grooves using a cnc machine as shown in figure 2 and figure 3. it is used 2000 rpm motor 138 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) speed and 10 mm/min. feed rate. this study measured the temperature manually using a simple thermocouple measuring instrument that has been calibrated (portable temperature). fig. 4. new design single u joint of the aluminum 6061 for fsw fig. 5. new design double u joint of the aluminum 6061 for fsw this research emphasizes on the new joint design, namely single u and double u, then the strength is compared. the welded joint is used only as a lock, while the tensile strength lies in the design. fig. 6. preparation of fsw samples. single u and double joint design after cnc processing (a and b), designs that are paired before the fsw process (c and d) up up issn: 2580-0817 journal of mechanical engineering science and technology 139 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) iii. results and discussions a. macrostructure visually, the material produced by the friction stir welding process with the design single u and double u, as shown by figure 5 and figure 6. fig. 7. a) fsw aluminum 6061 setting process, b) the fsw process is ongoing, c) result of fsw the process in single u design the texture of the nuggets looks rough. this is due to the low heat energy of the probe below 0.8 tm (temperature melting) (figure 7a); it also affects the hardness of the heat generated. the resulting texture is smooth due to high heat energy or reaches 0.8 tm (figure 7b). this will affect the hardness value and tensile test. the design of this welded joint does not affect the tensile strength that occurs; it only functions as a lock. fig. 8. a) fsw aluminum 6061 double u process, b) the process is good c) the process is not good the double u joint design in figure 8a and figure 8b is a pairing of the fsw process with good texture results. this will increase the locking strength of the joint. in figure 8c, the texture of the image looks very rough. the chips appear on the advancing and retreating side due to the high probe pressure and high heat. double u joint design fits well for fsw processing. the double u tensile strength is better than the u single due to the two protrusions as anchors. the fsw welding itself only functions as a lock so that it does not get separated from the welding pair. b. temperature measurement temperature measurement is done manually, using a thermocouple which is attached to the workpiece. recorded manually in several sections on a single u or double u connection and graphed. results of temperature evolution is shown in figure 9. 140 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) fig. 9. the measurement temperature figure 9 show a low temperature below 200° on both single u and double u joints. at this temperature, a coarse microstructure will be produced, which will result in high vickers hardness, but the resulting shear strength is high, also has not reached perfect plastic. as a result the mechanical properties that occur are not as expected, so as a result the microstructure contains little oxide and low hardness. c. microstructure figure 10 shows a lot of black spots are oxides trapped in the nugget area due to the position of the probe pin directly stirring the plastic material. the heat that occurs is high and the cold quickly due to the heat loose that results in an oxide layer on aluminum 6061. this oxide will reduce the mechanical properties of aluminum 6061. fig. 10. (a) haz microstructure, (b) nuggets, and (c) tmaz single u joining 200 x magnification fig. 11. (a) haz microstructure, (b) nuggets and (c) tmaz double u joining 200 x magnification issn: 2580-0817 journal of mechanical engineering science and technology 141 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) the microstructure shown in the double u joint is slightly different. the microstructure in the nuggets is mostly formed by oxides, this is due to the low temperature achieved or a very rapid decrease in temperature resulting in decreased mechanical properties. in tmaz the microstructure that occurs is dominated by small oxides that are evenly distributed, this is due to the low process temperature. d. micro hardness vickers tests hardness tested against aluminum 6061 with single u and double u designs using the vickers method with a loading of 300 gf or 0.3 kgf. it can be seen that the double u design has a higher hardness than single u. this is because the heat energy at low fsw does not change the basic structure of 6061 aluminum, especially the magnesium (mg) content. the trapped oxide in the nugget will slightly increase the mechanical properties, especially hardness (figure 11). silica (si) alloys have no effect on improving mechanical properties. silica in aluminum alloy 6061 will increase the flowability of the casting material. the blue color is the hardness on the upper side is 52 69 vhn. red color decreased vickers microhardness, namely 45 50 vhn. this is because the high heat energy (0.8 tm) will cause a decrease in the hardness value, also the oxide trapped in the nugget will reduce its mechanical properties, especially hardness (figure 12). fig. 12. vickers hardness (a) single u joint, (b) double u joint at 300 gf load e. tensile force tests figure 13 shows tensile test results. the highest tensile strength at the double u joint is 13.5 kn, the lowest is 10 kn, while the average tensile strength is 12 kn. fig. 13. tensile force of single u joint and double u joint after fsw 142 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) fsw welded joint only functions as a lock, while the tensile strength is focused on the joint design. the double u joint design has a major influence on the tensile strength of the test. single u joint design, the highest tensile strength is 12.9 kn, the lowest is 7.35 kn, while the average tensile strength is 10.37 kn. this tensile test is high; this is due to the joint design as a strength enhancer. nugget, tmaz, and haz on the weld have functioned as fastening only. iv. conclusions fsw for 6061 aluminum using single u and double u joint was evaluated. the joint design studied has good tensile strength and will provide information about the newly designed joints in the fsw welding method. the nugget, tmaz, and haz only function as locks, while their shear strength lies in the joint design. acknowledgement the authors full thank to head of lipi laboratory. references [1] thomas, w.m., friction stir butt welding, international patent application no pctrgb92 patent application no.9125978.8, 1991. [2] vaughn g., a., microstructural study of friction stir welded joints of carbon steels, exxon mobil upstream research company, houston, texas, usa, 2004. [3] thomas w. m. and nicholas e. d., friction stir welding for the transportation industries, twi, abington hall, abington, cambridge cb1 6al, 1997. [4] lienert, t. j., stellwag, w. l. jr., grimmett, b. b., and warke, r. w., “friction stir welding studies on mild steel”, supplement to welding journal, pp. 1-9, january 2003. [5] li b., shen y, a., “feasibility research on friction stir welding of a new-typed lap– butt joint of dissimilar al alloys”, materials & design, vol. 34, pp. 725-731, pebruary 2012. [6] nandan, r., debroy, t., bhadeshia, h.k.d.h., “recent advances in friction-stir welding – process, weldment structure and properties”, progress in materials science, vol. 53, pp. 980–1023, 2008. [7] nelley, mc. t.r., swaminathan, s., su, j.q., “recrystallization mechanisms during friction stir welding/processing of aluminum alloys”, scripta mater, vol 58(5), pp. 349-345, 2008 [8] gao, y., nakata, k., nagatsuka, k., liu f.c., liao j., “interface microstructural control by probe length adjustment in friction, stir welding of titanium and steel lap join”, materials & design, vol. 65, pp. 17-23, 2014. [9] silva, a. c. f., braga, d. f. o., de figueiredo, m. a. v. and moreira, p. m. g. p., “friction stir welded t-joints optimization”, materials & design, vol. 55, pp. 120-127, 2014. issn: 2580-0817 journal of mechanical engineering science and technology 143 vol. 4, no. 2, november 2020, pp. 135-143 setiawan et al. (new design of aluminum 6061 welding joining using friction stir welding method) [10] padgett, p.n., paglia, c., and buchheit, r.g., “characterization of corrosion behaviour in friction stir weld al–li–cu af/c458 alloy”, friction stir welding and processing ii. usa: warrendale, 2003. [11] mortensen, k. s., jensen, c.g., conrad, l.c. and losee, f., mechanical properties and microstructures of inertia-friction-welded 416 stainlessteel, utah: departement of mechanical, brigham young university, 2011. [12] ozekcin, a., jin, h.w., koo, y.j., bangaru, n.v., ayer, r., vaughn, g.a, “microstructural study of friction stir welded joints of carbon steels”, the international society of offshore and polar engineers, 2004. [13] malarvizhi, s. and balasubramanian, v., “influences of tool shoulder diameter to plate thickness ratio (d/t) on stir zone formation and tensile properties of friction stir welded dissimilar joints of aa6061 aluminum–az31b magnesium alloys”, materials & design, vol. 40, pp. 453–460, 2003 [14] setiawan, w., darmadi d.b., suprapto w., soenoko, r., “the position of the joints with angle of 90° at friction stir welding (fsw)”, mm science journal, vol. 2017, pp. 2128-2135, 2018. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 125-134 125 doi: 10.17977/um016v4i22020p125 design of savonius vertical axis wind turbine for vehicle filian arbiyani*, fernando pranata lasut department of mechanical engineering, atma jaya catholic university of indonesia, jl. jend. sudirman no.51, jakarta, 12930, indonesia *corresponding author: f.arbiyani@atmajaya.ac.id abstract the use of cellular phones is increasing in society, but due to the limited battery capacity of cell phones, it is necessary to charge the battery when travelling in the long distances. the savonius type wind turbine has a potential as an energy source harvesting the wind energy flowing around the car. however, due to the available space on the car, careful design of savonius vertical axis wind turbine for vehicle is necessary. the research is conducted numerically using matlab software. the wind speed, reynolds number, and electric power output are numerically simulated to obtain the swept area design. innovative pla material in the design is also investigated by simulating the effect of mass inertia moment to the design. this design of savonius vertical axis wind turbine for vehicle is expected to charge maximum four cell phone batteries with the total electrical output of 60 w. the optimum swept area design of savonius vertical axis wind turbine for vehicle is 0.150 m2 using 3 fins, pla filament material, with an overlap of 5.3 cm, and a diameter for each blade 22 cm according to the overlap ratio used of 0.242. this savonius vertical axis wind turbine design is feasible as an energy source for vehicle owing to its compact design, innovative material used in the design, and providing the electric power demand in the vehicle. copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: matlab, savonius, vehicle mounted wind turbine, vertical axis wind turbine, wind turbine. i. introduction in the digital era, electronics devices are highly used, including a cell phone or smart phone as a basic need for distance communication. cell phones use battery as an energy source and it always must be recharged. cell phones or smart phones becomes a basic need, and everyone always bring their smartphones while travelling, including while travelling by vehicle, such as a car. travelling in the long journey sometimes need the smartphones to be recharged. there are numerous kinds of renewable energy. one of them is a wind energy. travelling by vehicle, such as a car, has an enormous potency of a wind energy. therefore, by implementing a savonius vertical axis wind turbine on a vehicle, one can harvest this energy resources. a savonius vertical axis wind turbine operates using the drag force, and the highest drag force can be attained by placing the wind turbine on top of the car cabin [1]. a savonius vertical axis wind turbine takes advantage from the car velocity to gain the maximum wind force, which then connected to the power generator. in general, to obtain the maximum electric power output, the swept area of wind turbine has to be designed as big as possible. however, there is a limit space of the car cabin rooftop 126 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) while implementing the savonius vertical axis wind turbine on a vehicle. the maximum swept area is 0.25 m2 with the ratio of height (h) and diameter (d) is 1:1. the maximum swept area is determined based on the shortest length of the common vehicle, while the height and diameter are determined based on the regulation from ministry of transportation republic of indonesia. the length is 0.922 m from the size of rooftop pick-up vehicle daihatsu granmax [2], and the height and diameter size are 0.98 m [3]. further safety consideration is also applied by implementing half size from the maximum available space in the design, i.e. 0.5 m for the height and diameter, thus the design for maximum swept area is 0.25 m2. based on the available maximum swept area, careful design of a savonius vertical axis wind turbine is conducted numerically using matlab software. the wind speed, reynolds number, and electric power output are numerically simulated to obtain the optimum swept area design. innovative pla material in the design is also investigated by simulating the effect of mass inertia moment to the design. ii. material and methods there are four parameters used to determine the design of savonius vertical axis wind turbine for vehicle, i.e. car velocity which also represents the wind speed, reynolds number, electric power output, and mass inertia moment. the study was conducted numerically using matlab software. a. car/vehicle velocity (u) the car velocity values were range from 40 km/hour to 80 km/hour. these values are allowable car speed in a highway or express way. in aerodynamic, a car velocity would be assumed as a representative of a wind speed. therefore, this parameter would determine the swept area design according to eq. (1). 𝑃𝑤 = 1 2 ×𝜌×𝐴×𝑈3 (w) ..............................…………………………………........... (1) where: 𝑃𝑤 : wind power (w) ρ : density (kg/m3) a : swept area (m2) u : wind speed (m/s) with the air density of 1.293 kg/m3 at air standard condition [4]. the swept area design can be seen in figure 1, and its calculation using eq. (2). 𝐴 = 𝐻×𝐷 ......................................………………………………………………… (2) where: a : swept area (m2) h : height wind turbine (m) d : diameter (m) issn: 2580-0817 journal of mechanical engineering science and technology 127 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) fig. 1. swept area design of savonius vertical axis wind turbine b. reynolds number (re) the air flow at the surface of the wind turbine blade is assumed as an external flow at flat plate. at this phenomenon, reynolds number of 5 × 105 and higher will result in turbulence flow. reynolds number is simulated using eq. (3). 𝑅𝑒 = 𝑈×𝐷 𝑣 ................…………………………………………………………...…. (3) where: u : wind speed (m/s) d : diameter (m) v : kinematic viscosity (m2/s) with the kinematic viscosity of 1.56 × 10-5 m2/s at air standard condition [4]. c. electric power output (pe) the electric power output of savonius vertical axis wind turbine (pe) is a results process as can be seen in figure 2. fig. 2. main component of a wind turbine the electric power output (pe) is obtained using eq. (4). the generator efficiency (ηg), swept area (a), transmission efficiency (ηm), and the wind speed (u) are determined based on the various vehicle velocity with the performance coefficient (cp) of 0.2 [6]. 𝑃𝑒 = 𝐶𝑝×𝜂𝑚×𝜂𝑔× 1 2 ×𝜌×𝐴×𝑈3 (w) ……………….……………..........…………. (4) the generator efficiency (ηg) was calculated using eq. (5)... 𝜂𝑔 = 𝑋−(0.5)𝑌(1−𝑌)(𝑋2+1) 𝑋 …………………………………….…………………… (5) with x and y variable were calculated using eq. (6) and eq. (7), respectively. 128 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) 𝑌 = 0.05 ( 106 𝑃𝑒𝑅 ) 0.215 ………………………………….……....…………………….. (6) in this design, the output power of the generator used is 100 w. this generator specification was set as the maximum electric power output (per). 𝑋 = 𝑃𝑡 𝑃𝑡𝑅 ……………………………………………………………………………... (7) where: per : maximum generator electric power (w) pt : transmission power (w) ptr : maximum transmission power (w) since the wind speed affects the mechanical (transmission) power, thus the ratio of pt/ptr can be assumed as in eq. (8). 𝑃𝑡 𝑃𝑡𝑅 = 𝑈 𝑈𝑅 ……………………………………………...…………………………... (8) where: u : wind speed (m/s) ur : wind speed at the maximum power (m/s) the transmission power and the generator efficiency affect the electric power output as can be seen in eq. (9). 𝑃𝑒 = 𝜂𝑔×𝑃𝑡 (w) …....……………………………………………………………… (9) in the transmission section, the transmission efficiency (ηm) can be calculated using eq. (10). 𝜂𝑚 = 𝑃𝑚−(0.02)𝑞×𝑃𝑚𝑅 𝑃𝑚 = 1 − (0.02)𝑞× 𝑃𝑚𝑅 𝑃𝑚 …………………...………………… (10) where: pm : mechanical power (w) pmr : maximum mechanical power (w) q : stage number this transmission efficiency (ηm) and the mechanical power (pm) affect the transmission power (pt) as can be seen in eq. (11). 𝑃𝑡 = 𝜂𝑚×𝑃𝑚 (w) ……………...………………………………………………...… (11) with the mechanical power (pm) is calculated using eq. (12). 𝑃𝑚 = 𝐶𝑝×𝑃𝑤 (w) ………………………......………………………………...……. (12) with performance coefficient (cp) of 0.2 [6] and wind power (𝑃𝑤) from eq. (1). the expected electric power output in this design is 60 w to recharge the four cell phone batteries [4]. in the power plant, it is wise to provide the electric power output (pepf) higher than the expected (pe), thus a power factor (pf) is applied in this simulation using eq. (13). 𝑃𝑓 = 𝑃𝑒 𝑃𝑒𝑝𝑓 ………………………………………………………………………….. (13) power factor (pf) of 0.9 is widely used in the electrical distributor company. d. mass inertia moment the mass inertia moment is calculated using eq. (14). issn: 2580-0817 journal of mechanical engineering science and technology 129 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) 𝐼 = 𝐽×𝜌𝑎 (kg.m2) ……………………………………………………………….. (14) where: j : area inertia moment (m4) ρa : : density of the area (kg/m2) the area inertia moment (j) can be calculated using eq. (15). 𝐽 = 𝜋×𝑟4 2 (m4) …………………………………………………………………….. (15) where: r : radius (m) density of the area (ρa) is determined using eq. (16). 𝜌𝑎 = 𝑙×𝜌 (kg/m2) ………………………………………………………………. (16) where: l : length (m) ρ : material density (kg/m2) in this savonius vertical axis wind turbine for vehicle design, there are three (3) materials for the options, including an innovative pla filament material produced by advanced technology of 3d printer. the material density is shown in table 1. table 1. material density material density (kg/m3) aluminum 6061 [8] 2700 low carbon steel aisi 1018 [9] 7870 pla filament [10] 1240 this mass inertia moment would affect the blades movement of a wind turbine, therefore the proper material chosen is necessary in the design. besides the four parameters above, there are another parameter that are also important in designing a savonius vertical axis wind turbine for vehicle. these parameters are the overlap (e) and diameter size for each blade (d) as can be seen in figure 3. the optimum overlap ratio (e/d) for savonius wind turbine is 0.242 [11], and the diameter for each blade can be calculated using eq. (17). fig. 3. schematic drawing of savonius wind turbine [11] 130 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) 𝐷 = 𝑒 + (2 [𝑑 − 𝑒]) (m) ………………………………………………………… (17) where: d : total diameter (m) d : diameter for each blade (m) iii. results and discussions a. effect of wind speed to swept area design the effect of wind speed to the swept area design of savonius vertical axis wind turbine for vehicle can be seen in figure 4. fig. 4. effect of wind speed to swept area as we can see from figure 4 that the higher wind speed would need smaller swept area. the available maximum swept area on vehicle is 0.25 m2. at this area, the required wind speed is 52 km/hour which would result in 0.236 m2 of swept area. this wind speed is acceptable as smaller than the available maximum swept area and feasible as a car velocity. another feasible wind speed which represents the car velocity is 55 km/hour which resulted in 0.197 m2 swept area and 60 km/hour with 0.15 m2 swept area. these three feasible wind speeds and its swept area would then be used as variables to simulate other parameters. b. effect of wind speed to reynolds number based on previous simulation, the three feasible wind speeds of 52 km/hour, 55 km/hour and 60 km/hour would result in 0.236 m2, 0.197 m2, and 0.15 m2 swept area design. these three swept areas would then be used to determine diameter using eq. (2). using these diameters at various wind speed would affect the reynolds number as seen in figure 5. issn: 2580-0817 journal of mechanical engineering science and technology 131 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) fig. 5. effect of wind speed to reynolds number larger swept area design would rapidly increase the reynolds number until it reaches the turbulence at reynolds number of 5 × 105. higher reynolds number would affect to higher performance coefficient (cp), thus increasing the electric power output [12]. however, this turbulence might cause the chaotic flow which then would change the wind direction and might break the wind blades for single wind direction. therefore, the optimum swept area design to prevent this turbulence is 0.15 m2. c. effect of wind speed to electric power output the swept area design from the feasible three wind speed simulation would be used as variables to simulate the electric power output. the results of wind speed effect to electric power output can be seen in figure 6. fig. 6. effect of wind speed to electric power output 132 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) higher wind speed with larger swept area design would result in higher electric power output. at the same wind speed, swept area of 0.236 m2 would reach the expected electric power output faster. d. effect of swept area design to mass inertia moment using the density of each material in this design and the radius of the wind blade, the mass inertia moment was obtained as seen in figure 7. fig. 7 effect of swept area design to mass inertia moment the larger blade radius would result in higher mass inertia moment. this would obstruct the blades movement. therefore, smaller mass inertia moment would be recommended as a wind turbine material. pla filament with 0.150 m2 swept area has smallest mass inertia moment. based on the four parameters investigated, it was found that the suitable swept area design is 0.236 m2 and 0.150 m2, as seen in table 2. table 2. parameters matrix of design savonius vertical axis wind turbine for vehicle swept area (m2) wind speed reynolds number electric power output mass inertia moment 0.236 √ √ 0.197 0.150 √ √ both swept areas have fulfilled the most required parameters. finally, swept area design of 0.150 m2 was selected considering the safety application on vehicle and the capability of 3d printer while using pla filament as the material. furthermore, using eq. (17), the diameter size for each blade is 22 cm and 5.3 cm for the overlap. additional features of 3 fin were also recommended in the design [13]. the final design of savonius vertical axis wind turbine on a vehicle was summarized in table 3 with its implementation on truck model vehicle as shown in figure 8. issn: 2580-0817 journal of mechanical engineering science and technology 133 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) table 3. design of savonius vertical axis wind turbine on a vehicle design size swept area (m2) rasio h:d total height (cm) total diameter (cm) material and mass inertia moment (kg/m2) fin overlap ratio overlap (cm) diameter for each blade (cm) 0.150 1:1 38.81 38.81 filament pla; 0.959 3 [13] 0.242 [11] 5.3 22 fig. 8 design of savonius vertical axis wind turbine for vehicle iv. conclusions the optimum swept area design of savonius vertical axis wind turbine for vehicle is 0.150 m2 using 3 fins, pla filament material, with an overlap of 5.3 cm, and a diameter for each blade 22 cm according to the overlap ratio used of 0.242. this savonius vertical axis wind turbine design is feasible as an energy source for vehicle owing to its compact design, innovative material used in the design, and providing the electric power demand in the vehicle. 134 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 125-134 arbiyani & lasut (design of savonius vertical axis wind turbine for vehicle) references [1] sofian, m., nurhayati, r., and rexca, j., “an evaluation of drag coefficient of wind turbine system installed on moving car,” applied mechanics and materials, vol. 660, pp. 692–693, 2014. [2] “granmax pu,” daihatshu indonesia. [online]. available: https://daihatsu.co.id/product/granmax-pu. [accessed nov 21, 2019]. [3] biro komunikasi dan informasi publik, “direktorat jenderal perhubungan darat,” kementrian perhubungan republik indonesia, 2018. [online]. available: http://www.dephub.go.id/post/read/pastikan-keselamatan-jalan,-kemenhub-aturketentuan-bak-kendaraan-barang. [accessed nov 21, 2019]. [4] g. l. johnson, wind energy systems : electronic edition. manhattan: kansas state university, 2006. [5] f. m. white, fluid mechanics, seventh. new york: mcgraw-hill, 2011. [6] m. sathyajith, wind energy : fundamentals, resource analysis, and economics. berlin: springer, 2006. [7] ware, j., “power factor correction (pfc),” wiring matters, pp. 23, 2006, doi: 10.1109/t-aiee.1925.5061090. [8] b. toulas, “6061-t6 aluminium – the ultimate guide,” engineering clicks, 2017. [online]. available: https://www.engineeringclicks.com/6061-t6-aluminum/. [accessed jan 10, 2020]. [9] azom, “aisi 1018 mild/low carbon steel,” azo materials, 2012. [online]. available: https://www.azom.com/article.aspx?articleid=6115. [accessed jan 10, 2020]. [10] “filament properties table,” simplify3d. [online]. available: https://www.simplify3d.com/support/materials-guide/properties-table/. [accessed jan 10, 2020]. [11] menet, j.-l. j., bourabaa, n., “increase in the savonius rotors efficiency via a parametric investigation,” in ewea 2004 european wind energy conference, april, 2004. [12] bachant, p., wosnik, m., “effects of reynolds number on the energy conversion and near-wake dynamics of a high solidity vertical-axis cross-flow turbine,” energies, vol. 9 (2), pp. 2, 2016. [13] utomo, i. s., tjahjana, d. d. d. p., and hadi, s., “experimental studies of savonius wind turbines with variations sizes and fin numbers towards performance,” aip conference proceedings, vol. 1931, february, 2018. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 28-36 28 doi: 10.17977/um016v4i12020p028 the influence of the reference area of aileron on the n2xx aircraft using computational fluid dynamics siti nur rahmah1*, gaguk jatisukamto2, hary sutjahjono2 1bachelor program of mechanical engineering department, jember university, jl. kalimantan 37, 68121, jember, indonesia 2mechanical engineering department, jember university, jl. kalimantan 37, 68121, jember, indonesia *corresponding author: snrahmah.id@gmail.com abstract aileron is a control surface that functions as a regulator of roll motion. the movements of the ailerons are opposite to the left and right sides. previous studies have shown that graphs of hinge moment coefficient (chm) values increases with increasing angle of attack. this study is to determine the aerodynamic characteristics of aileron by combining the surface area of the vane into the aileron by varying the aileron’s deflection. the calculation is performed using a numerical method in two dimensions (2d) commercial cfd simulation software. the results of the study concluded that the hinge moment coefficient for modified airfoil at δa = -20°, 0°, and 20° was -0.071, 0.078, and 0.177, respectively. these values are smaller when compared to chm value in basic aileron that was -0.094, 0.095, and 0.201, respectively. copyright © 2020. journal of mechanical engineering science and technology all rights reserved keywords: aileron, computational fluid dynamics, hinge moment coefficient. i. introduction indonesia is an archipelago with 16.056 islands [1]. the geographical location of indonesia, which is separated by seas and mountains, has led to uneven development in indonesia. modes of air transportation are a good choice for connecting between islands and remote areas. airplanes have good time effectiveness compared to land and sea transportation modes [2]. these considerations encourage pt. dirgantara indonesia and lapan worked together to make a pioneering aircraft named the n2xx aircraft. n2xx aircraft has a control surface that regulates the basic movements of the aircraft, including ailerons (roll), elevators (pitch), and rudder (yaw). the pilot regulates the movement of the control surface through the aircraft cockpit [3]. an aircraft control system is a system that functions to control an aircraft using an aerodynamic control surface. aileron is a control surface for the movement of roll on the longitudinal axis. aileron mounted on the left and right wings of the aircraft with deflection movements that are opposite each other in direction. increased aileron deflection will affect the coefficient of drag, lift, and hinge moment [4]. zhang et al. [5] investigated the hinge moment characteristics generated by the oneram6 wing with aileron. the method used was a three-dimensional (3d) simulation. the research parameters are variations in the gap, angle of attack (aoa) and aileron deflection 29 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) angle (δa) angle. the results showed that a greater gap and δa angle could produce hinge moment curves that bend upward at high aoa. makarov and pavlenko [6] examined the effectiveness of ailerons on high lift wing airfoils. the method used is a simulation with a two-dimensional (2d) cfd method by varying the nose contour on the aileron. the results showed that the parabolic nose contour has a lower hinge moment value and higher efficiency than the nose circular arc. herdiana et al. [7] studied the hinge moment aileron on national transport aircraft. the method used is a 2d cfd simulation using fluent software with aoa and δa angle variations. the results showed that the graph of chm is linear, so with a certain increase in aoa the hinge moment value is absolute and will be enlarged depending on the orientation δa angle. wijiatmoko et al. [8] investigated aileron effectiveness on the puna alap-alap aircraft. the method used was experimental using a wind tunnel test with a variation of the δa angle = 0° to -25°. the results of the study concluded that the δa angle was still quite effective up to -25°. the decrease in effectiveness occurs when the angle of attack approaches the stall angle for all δa angles. n2xx aircraft development is being carried out related to the effectiveness of aircraft ailerons in order to get a good chm value which is close to 0. the smaller chm value of aileron will make the use of wheel force lighter by pilots to run the aileron when they want to roll. the results of a literature review search show that research on the influence of aoa and δa has been carried out. research on the influence of the aileron surface area is still being developed. the purpose of this study was to determine the effect of aileron area and aileron deflection using the two-dimensional computational fluid dynamics (cfd) simulation method so that it can determine the aerodynamic characteristics of the aileron. ii. material and methods the study was conducted at pt. dirgantara indonesia, especially in the aerodynamics division. this study uses a 2d simulation method using commercial cfd software. environmental parameters for aileron based on wind tunnel test conditions at pt. dirgantara indonesia. the airfoil used in this study was ls (01)-0417 mod. airfoil for validation is a whole airfoil that has not been split into vane, aileron, and trim tabs. airfoil ls (01)-0417 mod used for validation can be seen in figure 1. validation is done by comparing the lift coefficient (cl) of the wtt result with the simulation result. validation is using grid independency mesh to determine the meshing that will be used in this aileron study. fig. 1. the airfoil of ls (01)-0417 mod [9] the research airfoil used was the n2xx aircraft wing which consisted of several parts. airfoil research uses two variations of aileron, namely basic and modification. the airfoil of issn: 2580-0817 journal of mechanical engineering science and technology 30 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) basic aileron consists of four parts, namely the main wing, vane, aileron, and trim tab. while the modified aileron only consists of wing, aileron, and trim tab. the design of basic and modified aileron can be seen in figure 2 and figure 3. this research conducted aileron deflection variation (δa) of -20°, 0°, and 20°. fig. 2. basic aileron [10] fig. 3. modified aileron [10] this simulation uses boundary condition input adjusted to the wind tunnel test data from pt. dirgantara indonesia (persero). the boundary condition can be seen in figure 4. table 1. fluid domain name distance ad=be=cf 20 x chord ab=bc 12.5 x chord fig. 4. fluid domain main wing vane aileron trim tab aileron trim tab main wing 31 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) the parameters set in this study is shown in table 2. table 2. input parameters parameters value type solver density-based input pressure far-field mach number 0.2 mach operating pressure 101325 pa turbulence model viscous k-ω sst temperature 300 k chord length 1.7102 m iii. results and discussions the simulation results from this research are coefficient value and velocity contour analysis. a. validation validation of the ls (01)-0417 mod airfoil uses variations in the value of y+ as an independence mesh. this study uses the k-ω sst turbulence model. validation results can be seen in table 3. table 3. validation result element y+ cl of simulation cl of wtt error mesh 1 69,724 0.944 0.37757 0.41 7.91% mesh 2 91,574 0.75 0.37761 0.41 7.9% mesh 3 363,724 0.64 0.39458 0.41 3.76% the result of this method at angle of attack α = 0°, lift coefficient (cl) was calculated for wall y+ value and compared with experimental data of wind tunnel test from nasa [9]. mcghee and beasley [9] contained experimental data of cl for ls (01)-0417 mod. the error of this simulation and experimental data is not allowed bigger than 10%. the validation results show that mesh 3 has the smallest cl error of 3.76%. the small error is caused by mesh 3 has a better mesh density so that it produces a better mesh in the layers around the airfoil wall. mesh 3 is chosen as meshing, which will be applied to the aileron simulation. b. simulation results data table 4 shows the drag coefficient (cd) of the basic aileron when δa = -20° and 20° are 0.072 and 0.089, respectively. this value is smaller than the cd of the modified aileron of 0.075 and 0.100, respectively. the lift coefficient (cl) of the modified aileron when δa = -20° and 0° are -0.114 and 0.452, respectively. this value is higher than cl of basic aileron of -0.125 and 0.446, respectively. herdiana et al. [7] studied the aileron hinge moment coefficient of national transport aircraft basic. figure 5 shows the curves of chm for various aileron deflected angle, compared issn: 2580-0817 journal of mechanical engineering science and technology 32 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) with herdiana’s report at an angle of attack α = 0°. the value of chm from the two aileron shapes is not very close to simulation data by herdiana et al. herdiana’s report shows that chm at δa = -20° is bigger than the two aileron shapes at the same deflection. the hinge moment coefficient (chm) of the modified aileron when δa = -20°, 0°, and 20° is -0.071, 0.078, and 0.177, respectively. this value is smaller than the chm of aileron basic, each of which is -0.094, 0.095, and 0.201, respectively. the cause of chm produced by a modified aileron is lower than the basic aileron is the increase in the area of the modified aileron. the surface area in front of the hinge line will be able to produce a higher counter moment so that it will reduce the moment behind the hinge line. table 4. data of simulation geometry δa cd cl chm basic -20° 0.072 -0.125 -0.094 0° 0.047 0.446 0.095 20° 0.089 1.334 0.201 modified -20° 0.075 -0.114 -0.071 0° 0.045 0.452 0.078 20° 0.100 1.207 0.177 fig. 5. comparison between simulation data for aileron design from herdiana et al. [7] and two different aileron shape result of the hinge moment coefficient curve for n2xx aircraft aileron. c. analysis of velocity contour aileron analysis is performed using velocity contours. in the velocity contour display (figure 6), we can see the range of velocity values at a point or area of the colormap on the left. the red color indicates a high-velocity value, while the blue value indicates a lowvelocity value. 33 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) (a) (b) fig. 6. velocity contour at deflection of -20°. (a) basic aileron; (b) modified aileron. caption: a = direction of flow; b = stagnation point; c = laminar separation bubble (lsb); d = bubble; e = separation figure 6 shows the velocity contour at δa = -20°. stagnation occurs at the leading edge, causing local velocity of the fluid to decrease to zero, as shown in figure 6 [11]. flow flowing on the upper surface will experience a laminar separation bubble (lsb) which can be seen at point c. lsb is formed in the upper surface area in the second airfoil. lsb is formed in the boundary layer, which causes the transition from laminar to turbulent [12]. lsb on the wing modification looks bigger than on the basic wing. the resulting coefficient of drag (cd) will be greater if the lbs that is formed is getting bigger. flow visualization also shows that shortly after reattachment of the two wings, separation occurs and creates bubble separation on the upper surface of the aileron which can be seen at point d. bubble separation occur as a result of weak momentum flowing through the underside of the wing to meet the flow with large momentum so give rise to flow blockage [13]. figure 6(b). shows the bubble separation that occurs over a modified sloping aileron because there is a change in the geometric contour on the trailing edge wing. the pressure that occurs on the upper surface of the modified aileron becomes smaller so that it will increase the coefficient of lift (cl). the separation was seen at the lower surface of the two ailerons at point e. the modified aileron appeared to undergo turbulized separation first. the advanced separation of the modified aileron is due to the increased deflected surface at the leading edge of the aileron. this separation can cause the value of the drag coefficient on the modified aileron to be higher [6]. the area that deflects the modified aileron has a wider reference area than the basic aileron. the addition of the cross-sectional area to the aileron will have an impact on the value of the hinge moment coefficient. the counter moment which serves to reduce the moment to the area behind the hinge line becomes higher [14]. this counter moment will cause the hinge moment coefficient (chm) value to be smaller. e a b c d e issn: 2580-0817 journal of mechanical engineering science and technology 34 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) (a) (b) fig. 7. velocity contour at deflection of 0°; (a) basic aileron; (b) modified aileron figure 7. shows the velocity contour at δa = 0°. the velocity contour at δa = 0° on the leading edge of the wing does not show a significant difference, as seen in figure 7. the difference is clearly seen in the gap between the wing and aileron. basic airfoil has a wider gap due to the presence of vane. a wide gap will cause low-velocity flow to accumulate in the gap [14]. the gap on basic aileron has a larger area so that the resulting drag coefficient becomes larger, as shown in figure 7(a). the separation that occurs in the lower surface of the two wings looks no different. the decrease in velocity occurs after separation, which is marked by the presence of green contours on the lower surface wing to trim tabs on both ailerons. the green velocity contour indicates a lower flow velocity compared to the yellow contour below. declining velocity indicates that the pressure that occurs in the area becomes greater. the area of the modified aileron that is reached by a large pressure is wider than the basic aileron depicted in figure 7(b), so that the resulting lift coefficient becomes larger. the area that deflects the modified aileron has a wider reference area than the basic aileron. the addition of the cross-sectional area to the aileron will have an impact on the value of the hinge moment coefficient. the counter moment which serves to reduce the moment to the area behind the hinge line becomes higher [14]. this counter moment will cause the hinge moment coefficient (chm) value to be smaller. figure 8. shows the velocity contour at δa = 20°. lsb at the speed contour is formed in the upper side region on both airfoils. figure 8(b). shows the lsb on the modified wing having a redder color contour than the basic wing. this indicates that more low-pressure flow accumulates in the wing modification area, so that drag will increase [12]. gap direction of flow 35 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) (a) (b) fig. 8. velocity contour at deflection of 20°. (a) basic aileron; (b) modified aileron the aileron that deflects at 20° makes the modified aileron nose protrude. separation occurs after the bubble on the upper surface of the two ailerons. separation of the modified aileron occurs first so that the free flow produces a greater weak [6]. this separation makes the cl value in the modified aileron lower than the basic aileron, as shown in figure 8(b). iv. conclusions this paper showed the behavior of the aileron of n2xx aircraft at various aileron deflected angle. the validation was conducted to comparing the simulation and experimental data. the validation meshing for y+ value is obtained that y+ = 0.64. has the smallest lift coefficient error ε = 3.760%. by this method, the computational results agreed well with corresponding experimental data. the simulation is continued by using the validation meshing results of y+ value. basic aileron on n2xx aircraft has a greater hinge moment coefficient compared to modified aileron of author version. this is due to changes in surface area in the aileron area. changes in the area in front of the hinge line will increase the value of the counter moment, so the resulting hinge moment coefficient will be smaller. however, it is necessary to make improvements to the modified nose aileron design so that it will be able to reduce the cd value and increase the value of cl. acknowledgment the authors would like to thank pt. dirgantara indonesia, for providing research support facilities. direction of flow separation gap issn: 2580-0817 journal of mechanical engineering science and technology 36 vol. 4, no. 1, july 2020, pp. 28-36 rahmah et al. (the influence of the reference area of aileron on the n2xx aircraft) references [1] badan pusat statistik, statistik indonesia, badan pusat statistik, jakarta. 2019. [2] kementrian perhubungan, kriteria penyelenggaraan angkutan udara perintis di indonesia, available from: hubud.dephub.go.id/?id/news/detail/2833, 2016. [3] r. h. barnard, and d. r. philpott, aircraft flight 4th ed, pearson education limited, harlow, 2010. [4] federal aviation administration (faa), pilot's handbook of aeronautical knowledge, u.s. department of transportation, 2016. [5] g. q. zhang, s. c. m. yu, and a. chien, “investigation of the three-dimensional hinge moment characteristics generated by the onera-m6 wing with an aileron”, advanced in mechanical engineering, vol. 5, pp. 1-11. 2013. [6] k. a. makarov and a. a. pavlenko, “numerical investigation of an aileron hinge moments and effectiveness on a high lift wing airfoil”, in 29th congress of the international council of the aeronautical sciences, curran associates inc. 1-10. [7] d. herdiana, s. t. pinindriya, and r. triwulandari, “investigation of aileron hinge moment of national transport aircraft basic to numeric method”, in international seminar on aerospace science and technology iii, institute of physics publishing (iop), 45-51. [8] g. wijiatmoko, “analisa efektivitas sudut defleksi aileron pada pesawat udara nir awak (puna) alap-alap”, in seminar nasional inovasi dan aplikasi teknologi di industri 2017, itn malang, 1-6. [9] r. j. mcghee and w. d. beasley, wind-tunnel results for a modified 17-percentthick low-speed airfoil section, nasa tp-1919, 1981. [10] pt. dirgantara indonesia, report data pt. dirgantara indonesia, pt. dirgantara indonesia, bandung, 2016. [11] d. c. eleni, t. l. athanasios, and m. p. dionissios, “evaluation of the turbulence models for the simulation of the flow over a national advisory committee for aeronautics (naca) 0012 airfoil”, journal of mechanical engineering research, portico, vol. 4(3), pp.100-111, 2012. [12] r. ma and p. liu, “numerical simulation of low-reynolds-number and high-lift airfoil s1223”, in proceedings of the world congress on engineering 2009, international association of engineers, 1-6. [13] a. w. e. sadewo and h. sasongko, “studi eksperimen dan numerik pengaruh slat clearance serta slat angle untuk mengeliminasi stall pada airfoil "studi kasus pada airfoil naca 2412”, jurnal teknik its, 4(1), pp.108-113. 2015. [14] m. h. amir, and sarwono, “analisa nilai hinge moment coefficient pada pengaruh bentuk rudder pesawat n-2xx dengan variasi defleksi rudder 0°, 10°, dan 25° berbasis computational fluid dynamics”, jurnal teknik its, 7(2), pp.140-145, 2018. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 72-81 72 doi: 10.17977/um016v4i22020p072 the effect of guide vane opening variations and total blades on cross flow turbine performance using computational fluid dynamic muhamad akbar navis, heru suryanto*, putut murdanto department of mechanical engineering, universitas negeri malang, jl. semarang 5 malang, east java, indonesia *corresponding author: heru.suryanto.ft@um.ac.id abstract indonesia is an agrarian country that continuously produces water, so it has the potential to develop a hydroelectric power plant. computational fluid dynamic (cfd) application could be used to be an economical, quick, and efficient approach to improve the engineering design and turbine performance. this research aimed to find the effect of guide vane opening variations and total blades on cross-flow turbine performance using cfd simulation. this research used experimental modelling method with ansys program for turbine design with 22, 24, and 26 turbine blades and guide vane opening variations of 12°, 16°, 20°, 24°, and 36°. the data were collected by reviewing the simulation results after the numerical calculation process. the results showed that the cross-flow turbine performance was improving along with the increasing guide vane opening. the optimum turbine performance (power and efficiency) was obtained at 24° opening of guide vane and 26 total blades, producing 868.53 w power with 75.16% efficiency. copyright ©2020. journal of mechanical engineering science and technology. all rights reserved. keywords: cfd, cross-flow turbine, guide vane opening, performance, total blades i. introduction currently, the overuse of fossil energy decreases the energy availability level. the situation is made aware by researchers who try to find various alternative energy. hydroelectric power plant (hpp) exists and already used for more than one century as a source of energy and technology until now all over the world [1]. the electrical energy supply in indonesia that is sourced from renewable energy is enormous due to the abundant water source and can be used as the source for micro hydro power plant (mhpp). mhpp is a small-scaled power plant (less than 200 kw) that uses water flow as the energy source. water turbine utilizes the energy in the flow to create power in the form of electricity in the generator. natural water, before streamed into the turbine, is put into a container then goes through a penstock or water channel and streamed into the turbine. during the flow process in the pipe, the potential energy of water gradually changes into kinetic energy [2]. in the turbine, water pounded or gave energy into the turbine blade that rotates the turbine shaft. in this condition, water kinetic energy transforms into mechanical energy in the form of turbine shaft rotation. next, the turbine shaft was connected with the generator using a mechanical transmission. cross-flow impulse type turbine is one of the most used turbines for the microhydropower plant in indonesia because it covers all locations with high water flow rate and low, medium, and high headwater. cross-flow type turbine, also called the banki turbine, 73 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) has more advantages compared with the usage of the water wheel or other types of microhydro turbines [3]. the components that influence the performance of the cross-flow turbine, among others, are the total of blades and guide vanes, water flow rate, and head. the performance of the cross-flow turbine is known from the simulation analysis of runner and guide vane when the water flow hits the runner blade. the cfd methodology emerged as an efficient approach to compile the information to improve the turbine engineering design because the cfd has a complex geometry, complex current, and more efficient duration [4]. the flow system and the power in the turbine were taken and drawn in the computer software to compare the power and efficiency results between the simulation and real results [5]. thus, this research was conducted to find the effect of each guide vane opening variations and the variation of total blades on the torque, output, and efficiency as the performance characteristics of cross-flow turbine performance using the ansys computer software. ii. material and methods this research used an experimental modelling method to analyse the effect of guide vane openings and total blades on the cross-flow turbine performance. the turbine model used referred to the cross-flow turbine. it was produced by cv. hydro cipta mandiri type c4-24 (lumajang, east java) with a design flow rate of 0.3 m3/s. it was performed variations on the independent variables of 12°, 16°, 20°, 24°, and 36° guide vane openings with 22, 24, and 26 total blades on the dependent variable of cross-flow turbine performance. fig. 1. cross-flow turbine design sudu runner α guide vane runner issn: 2580-0817 journal of mechanical engineering science and technology 74 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) the turbine runner had 240 mm diameter, 250 mm width, and 12° angle emitting pipe. this research used the 2016 autodesk inventor professional software. after the design was finished, the simulation and analysis were done using ansys workbench 14.5 with the fluent method to obtain the performance value (power and efficiency) from the cross-flow turbine. figure 1 presents the cross-flow turbine design. figure 1 is the geometrical design of the cross-flow turbine with the guide vane opening (α) that can be controlled/varied following the electricity need in the society. the research object here was the cross-flow turbine performance (power and efficiency), of which the data was expected to be used in managing the power value on the electricity need in the society. the obtained data through reviewing the results were the outcome of numerical cfd and was processed using ms excel 2016 to create the total value of cross-flow turbine performance on the simulation results. the performance value of cross-flow turbine was calculated using the formulation below: u = (π . d . n)/60 ............................................................................................. (1) pt = (t .2 .π .n )/60 ............................................................................................. (2) ph = ρ .q .(v^2/2) ............................................................................................. (3) η = pt/ph x 100% ............................................................................................. (4) where, u = tangential speed (m/s) d = runner diameter (0.24 m) n = runner rotation speed (rpm) pt = turbine power (watt) ph = hydraulic power (watt) t = torque (nm) ρ = fluid density (998.2 kg/m3) q = volumetric flow rate (0.3 m3/s) v = water velocity (2.778 m/s) η = turbine efficiency (%) the data analysis in this research used comparative descriptive method by describing the simulation results from the comparison of guide vane opening variations and total blades on the cross-flow turbine performance using the cfd simulation. iii. results and discussions the data from cfd simulation were torque, tangential speed, water flow velocity, streamline, and pressure contour. variables that were obtained from the numerical simulation using the cfd method was used in the calculation to get the cross-flow turbine performance values. the pressure moment data were obtained by reviewing the numerical simulation results that were used to calculate the performance values (power and efficiency) of the cross-flow turbine. the pressure moment value was assumed as the torque that was obtained from the simulation results. the chart below helps identify the simulation results. 75 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) figure 2 shows the torque values as a result of the numerical simulation using the fluent method that tends to increase along with the increasing guide vane openings and total blades. the lowest torque is obtained at the guide vane opening of 12° and total blades amount of 22 with the value of 13.76 nm whereas the highest is obtained at the guide vane opening of 36° and total blades amount of 26 with the value of 17.5 nm. the guide vane openings in a range of 16° to 20°, the torque has a significant improvement that greatly influenced the cross-flow turbine performance. a guide vane opening of 16° with total blades amount of 26, the torque value is 14.15 nm, jumps up for 2.54 nm at guide vane opening of 20°. fig. 2. guide vane openings influence on the torque of cross-flow turbine fig. 3. streamline simulation results figure 3 is the streamline simulation results at guide vane opening of 24°and total blades amount of 24. it shows the turbine tangential velocity (u) of 6.333 m/s by reviewing the issn: 2580-0817 journal of mechanical engineering science and technology 76 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) value of the maximum tangential speed. based on the formulation (1), figure 4 shows the runner rotation speed value. fig. 4. calculation results of cross-flow turbine runner rotation figure 4 shows the rotation chart that was produced by the turbine runner after simulation process at guide vane openings of 12°, 16°, 20°, 24°, and 36° and total blades amount of 22, 24, and 26. it presents the decreasing runner rotation along with the increased torque in the simulation process because of the continuously decreasing loads. at guide vane opening of 16° with 26 blades, the runner rotation is 525 rpm, then decreases up to 31 rpm at 20° due to the increases torque value at the same guide vane opening. this result is in line with other findings that show the influence of the variations of total blades on the cross-flow turbine performance, the efficiency test of cross-flow turbine runner with blades variations of 18, 20, and 22 resulted in the highest efficiency at 20 blades [5]. turbine design variations for the optimum performance can be done by testing several parameters such as blade shape, guide vane opening, and total blades, of which those parameters affecting the power created by turbine generator, efficiency of the turbine, and performance. by conducting the cfd simulation, pressure contour in each blade that hit by the water is known and can be used to identify which blade greatly influences the power through the flow rate calculation in each blade. in figure 5, the yellow runner contour is a part with immense pressure and is assumed as the blade that influences the turbine power. for observing the effect of each blade, the water flow rate calculation in each runner blade was conducted. with total blades of 22 and 24, the yellow contour appears in 6 blades. however, with 26 blades, the pressure that affects the turbine power is found in 7 runner blades. this situation occurred because, in 26 blades, the gap among the blades was narrower compared to the turbine with 22 and 24 blades. 77 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) fig 5. turbine runner contour at 24° guide vane opening with total blades amount of (a) 22, (b) 24, and (c) 26 fig. 6. water flow rate input in each blade at 22 blades water turbine issn: 2580-0817 journal of mechanical engineering science and technology 78 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) the flow rate calculation chart in the blade that influenced the runner power was shown in figure 6. the highest flow rate and the largest influence is found in the blade 2. on blade 1 with guide vane opening of 36° obtained the flow rate value of 0 m3/s because the lower nozzle of the guide vane was closed off entirely, so the water only passed the upper nozzle and hit the second blade. fig. 7. water flow rate input in each blade in 24 blades water turbine figure 7 shows that the highest flow rate and the largest influence is found in blades 2. at blade 1 with guide vane opening of 36°obtained the flow rate value of 0 m3/s because the lower nozzle of the guide vane was closed off entirely so that water only passed the upper nozzle and hit the second blade. fig. 8. water flow rate input at each blade in 26 blades water turbine 79 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) figure 8 shows that the turbine with blade 2 and guide vane opening of 12° generated the largest water flow rate of 0.054 m3/s. there is a decrease of 0.007 m3/s at blade 3. meanwhile, the lowest flow rate occurred at blade 7, with a value of 0.0278 m3/s. at 16° guide vane opening, blade 1 turbine created in 0.0429 m3/s flow rate, and there was an increase of 0.0082 m3/s of flow rate in blade 2. at 20° guide vane opening, the largest flow rate occurs with blade 2 with the value of 0.0504 m3/s, whereas at 24° opening, the largest flow rate occurs with blade 2 for 0.0478 m3/s. in correlation with the guide vane opening variations on the cross-flow turbine performance, the turbine power and efficiency could be varied according to the water flow rate and not the guide vane opening. the maximum efficiency of 89% was obtained at the middle position and 30.5° guide vane angle [6]. guide vane opening with the angle between guide vane and turbine runner and produced the highest power and efficiency of 75.16% at 24° guide vane opening [7]. turbine shaft power is a power that was created by the turbine to drive the generator in its application. turbine power can be calculated using formulation (2) with the results presented in figure 9. fig. 9. guide vane opening influence on cross-flow turbine performance figure 9 shows the variations of guide vane opening of 12°, 16°, 20°, 24°, and 36° with total blades of 22, 24, and 26. the turbine power tends to increase along with the additional opening. however, at the maximum opening of 36°, turbine power experiences a decrease due to stream turbulence in the guide vane area caused by a closed lower nozzle from the guide vane so that the tangential flow speed also decreased. the sharp increase occurred at 16° to 20° guide vane opening. this phenomenon can be utilized to control the desired power following electricity consumption by society in its application. at noon, the electricity consumption tends to be low so that the guide vane can be managed at 12° to 16°. at night, the consumption is high and requires larger power; hence, the guide opening is adjusted at 20° to 24°. the lowest turbine power is obtained at guide vane opening of 12° with 22 total blades with a value of 770.51 watts. meanwhile, the largest turbine power was obtained at 24° guide vane opening with 26 total blades and resulted in 868.53 watts. issn: 2580-0817 journal of mechanical engineering science and technology 80 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) hydraulic power is the power that enters the turbine in the form of water potential power. the total value of hydraulic in this research was calculated using equation (3) and was obtained 1155.509 w value. meanwhile, turbine efficiency was found from the comparison between turbine power (pt) with hydraulic power (ph) times 100%. the turbine value (pt) and hydraulic power (ph) were known from the previous calculation. figure 10 presents the results of the efficiency calculation. figure 10 displays the turbine efficiency at 12°, 16°, 20°, 24°, and 36° openings with 22, 24, and 26 blades. turbine efficiency increases along with the additional guide vane openings and total blades. however, at 36° opening, the efficiency experiences a reduction. the efficiency decrease occurs because of the closed-off lower nozzle that made current turbulence in the guide vane and caused a decrease in the absolute speed that also caused a decrease in the turbine runner rotation; hence, turbine power and efficiency also decreased. fig. 10. the effect of guide vane opening on cross-flow turbine efficiency at 16° to 20° guide vane opening, the efficiency sharply increases with the value of 67.25% at 16° opening and increases for 7.50% at 20° opening. the improvement can be used to control the guide vane opening by adjusting the high and low electricity consumption in society at certain times. the lowest efficiency is found at 12° opening and 24 blades with a value of 66.59%. meanwhile, the highest efficiency was found at 24° opening and 26 blades with a value of 75.16%. the high turbine efficiency occurred because, during the 24° guide vane opening, the flow rate that flew in the upper nozzle of guide vane was larger so that the power that arose from the water to runner blade impact was more extensive. the torque was also larger because the length blade was constant and the efficiency at 26° occurred because, at that opening, the gap between the blades was shorter and narrower and made the water flow rate that entered the gap larger; thus reducing the chance of air to fill the gap between the blades. besides, the larger contraction value between water impact on the blade created higher torque, power, and efficiency values. the efficiency that was obtained from this research was lower than the efficiency from khosrowpanah research [8], where he used the cfd simulation to achieve efficiency of 80%. performed analysis by simplifying the screw of guide vane in a cross-flow turbine and achieved 79% efficiency [9]. 81 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 72-81 navis et al. (the effect of guide vane opening variations and total blades on turbine performance) iv. conclusions the cfd analysis to guide vane opening variations and total blades had been conducted. it can be concluded that guide vane opening variations and total blades affecting the crossflow turbine performance (power and efficiency). turbine performance increased following the additional guide vane opening. the optimum value for turbine performance was obtained in 26 blades and 24° opening with a value of 868.53 watts and 75.16% efficiency. based on the characteristics of turbine power and efficiency that were generated, technically, 12° to 16° guide vane opening had a significant impact on the increase of turbine power. thus, this range can be used as the technical reference setting in adjusting the fluctuating electricity consumption. references [1] zimny, j., michalak, p., bielik, s., and szczotka, k., “direction in development of hydropower in the world, in europe and poland in the period 1995-2011”, renewable and sustainable energy reviews, vol. 21, pp. 117-130, 2013. [2] munandar, a.w., penggerak mula turbin, itb bandung, bandung, 1982, pp.10-14 [3] larasakti, a.a., himran, s., and arifin, a.s., “pembuatan dan pengujian pembangkit listrik tenaga mikrohidro turbin banki daya 200 watt”, jurnal mekanikal, vol. 3(1), pp. 2-4, 2012. [4] gohil, p., and saini, r. p., “numerical study of cavitation in francis turbine of a small hydro power plant”, journal of applied fluid mechanics, vol. 9(1), pp.357-365, 2016. [5] chiyembekezo, s.k., cuthbert, z.k., and torbjorn, k.n., “experimental study on a simplified crossflow turbine”, international journal of energy and environment, vol. 5(2), pp. 2-12, 2014. [5] sugiri, a., burhanudin, h., and trinando, e., “studi kelayakan pembangkit listrik tenaga mikrohidro (pltmh) pada sungai arter desa hurun kecamatan padang cermin kabupaten pesawaran lampung”, jurnal mechanical, vol. 4(2), pp. 2-5, 2015. [6] salman, a., shoukat, a., naif a., tahir, m.h., shahid, m., razzaq, s., sabri, m.a., asghar, m.a., saeed, m.w., waqas, m., “experimental evaluation on performance of novel cross-flow impulse turbine for water stream in hilly areas of pakistan”, international journal of renewable energy research, vol. 9(4), pp.1782-1789, 2019. [7] haurissa, j., wahyudi, s., irawan, y.s., and soenoko, r., “the cross flow turbine behavior towards the turbine rotation quality, efficiency, and generated power”, journal of applied sciences research, vol. 8(1), pp. 448-453, 2012. [8] khosrowpanah, s., fiuzat, a.a., albertson, m.l., “experimental study of cross flow turbine”, journal hydraulic engineering, vol.114, pp. 299-314, 1988. [9] chiyembekezo, s.k, cuthbert, z.k., and torbjorn, k.n., “a numerical investigation of flow profile and performance of a low cost crossflow turbine”, international journal of energy and environment, vol. 5(3), pp. 23-25, 2014. journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp. 8-17 8 doi: 10.17977/um016v3i12019p008 the effect of chemical pretreatment process on mechanical properties and porosity of bacterial cellulose film tito arif sutrisno1, heru suryanto2,*, retno wulandari2, m. muhajir1, shikh mohd shahrul nizan shikh zahari3 1master student of mechanical engineering program, graduate school, universitas negeri malang, jl. semarang 5, malang, east java, indonesia 2mechanical engineering department, engineering faculty, universitas negeri malang, jl. semarang 5, malang, east java, indonesia 3industrial chemical technology program, faculty of science and technology, universiti sains islam malaysia, bandar baru nilai 71800, negeri sembilan, malaysia *corresponding author: heru.suryanto.ft@um.ac.id abstract bacterial cellulose (bc) is a natural polymer which have superior properties, like high porosity, high purity, and high permeability. the study objective is to determine the influence of chemical pretreatment on tensile strength and the porosity of bc. the method was to make bc films from pineapple peel extract through fermentation process for 14 days. the pretreatment was conducted by immersion of bc in bmimcl, h2o2, and naoh solution with a concentration of 2.5%; 5%; and 7.5 %, heated at 80 °c then dried in the oven, and the samples were then tested by a tensile test using astm-d636-v standard, morphology analysis using scanning electron microscope, and porosity analysis. the results indicate that the tensile strength of control sample was 123 mpa, whereas after chemical pretreatment, the tensile strength was decreased with the greater reduction occurred using naoh pretreatment compared than the other solutions that having a lower tensile strength of 8.54 mpa at 7.5 % of naoh. the results of porosity show that the value increased after being treated chemically. the bc film porosity was 87.13% after naoh treatment of 7.5% while bc film untreated had porosity of 19.15%. this phenomenon was occurred due to the increasing pore, so the absorption of water increased. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: bacterial cellulose, bmimcl, h2o2, naoh, porosity, tensile strength i. introduction at present, natural materials, like fiber, has been applied as materials for various biodegradable technology equipment. cellulose produced by bacteria had a specific character and more purer than plant cellulose [1]. plant cellulose is impure because of containing a complex carbohydrates like cellulose (35-50%), hemicellulose (20-35%) and lignin (10-25%)[2][3]. nata, known as bacterial cellulose (bc), able to be produced using fruit extracts [4][5]. bc pellicle is produced from the glucose fermentation by acetobacter xylinum bacteria for resulting the cellulose. bc films have advantages as paper, food, biomedicine, and filtration 9 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 1, july 2019, pp. 8-17 sutrisno et al. (the effect of chemical pretreatment process on bacterial cellulose film) membranes [6]-[8]. bc is a natural polymer which have superior properties, like high degree of porosity, high purity, high permeability relative to gases and liquids, strength and ultrafine tissue, and high water absorption [8]. bc has a high surface activity because of its fibril; its tensile modulus can reach 16-30 gpa. viewed from its structure, bc has a very fine band-shaped fiber network with a fiber diameter of 20-100 nm [9]. the bc contents are glucose, fructose, sucrose, and mannitol [10]. bc, with its hydrophilic properties, can absorb a high level of water content [11]. bc forms a thin and transparent layer on the surface, and its thickness can be increased over time, forming thick white sheets after 1015 days [5]. cellulose films can be modified using several methods, including mechanical, enzymatic, and chemical treatment. the chemical pretreatment method applied to reduce amorphous constituents and increasing its thermal stability [12]. the benefits of chemical treatment are to clean and modify the surface chemically, increase the surface roughness and to stop the moisture absorption process [13][14]. the four main classes of solvents are naoh solution, ionic liquids, and hydrogen peroxide (h2o2). naoh is dissolving, which causes the breaking of hydrogen bonds in the structure of bc pellicle network so that it can increase the surface roughness [15]. the hydrogen peroxide ussualy used as bleaching agent [16]. the ionic liquid is an organic solvent that is harmless and environmentally friendly [17]. the study objectived for describing influence of pretreatment of naoh, h2o2, bmimcl on the strength, porosity and morphology of bc surface synthesized by fermentation of pineapple peel waste. ii. methods a. materials the study used pineapple peel extract and a. xylinum for fermentation process for 14 days, aquades, and chemical solution (naoh, h2o2, bmimcl). b. bacterial cellulose synthesis the synthesis methods of bc pellicle was addapted from suryanto (2017) [18]. bc production used fermentation media containing 2000 ml extract of pineapple peel, ammonium sulphate of 0.5%, acetic acid of 5% (v/v) sugar of 10%, and the fermentation medium with ph 4.5. medium was added by a. xylinum of 10% (v/v) for fermenting process conducted for 14 days at 30°c. the pellicle was collected then washed by fresh water to remove the dirt. c. bacterial cellulose pretreatment bc pellicles were boiled to remove bacteria and acid content, afterward, they were rinsed using water then took bc pellicles to be and treated in all chemical solutions (naoh, h2o2, and bmimcl). after that, bc was put into 250 mm 3 beaker glass with four variations of a chemical solution (control, naoh, h2o2, and bmimcl) each with different chemical solution concentration of 2.5; 5; and 7.5 % into solution with a total volume of 100 mm3, issn: 2580-0817 journal of mechanical engineering science and technology 10 vol. 3, no. 1, july 2019, pp. 8-17 sutrisno et al. (the effect of chemical pretreatment process on bacterial cellulose film) thus, the bc pellicles can be fully immersed and took the glass on a hot plate (sp13132033 type, thermo scientific) then heated until 80°c and stirred by 100 rpm. bc pellicles were rinshed using water until netral and then drying process conducted in an oven for four hours at 80°c. before putting them to the oven, bc pellicles were clamped to get smooth sheets. d. tensile test the strength of the bc film were observed by tensile test in techno lab. indonesia based on astm d638-v standard. the samples having a length of 26.35 mm were attached at the clamping system of the tensile test machine and tested with a pulling speed of 0.025 mm/s. each sample was tested for five repetitions. tensile strength was calculated by formula [19]: o a f  (1) where: f is force (n), σ is tensile strength (mpa), a is cross-sectional area (mm2). e. bc porosity test the porosity of samples was tested before and after chemical treatment. the samples were immersed for 4 hours at a temperature of 250c. wd is defined as sample weight measured at dry condition (weighed in the air) while ww is defined as sample weight measured by submerging them in the water. the porosity was calculated using equation [20]: %100 )( )( )( x dxaxd wdww pporosity o   (2) where: ww and wd is the wet film weight (g) and dry film weight (g), respectively, d is the pure water density at ambient temperature (1 g/cm3), d is the film thickness, and a surface area (4 cm2). iii. results and discussion a. morphological analysis the surface morphology of bc film formed after chemical pretreatment using the concentration of 2.5; 5; and 7.5 % were analyzed using scanning electron microscopy (sem) with 50000 times of magnification. the sem analysis was utilized to compare the morphology of all chemically-treated sample and untreated sample (control). the sem images of bc film are presented in figure 1. chemical pretreatment of cellulose aimed to clean the surface, modify the surface chemically, increase the surface roughness, and reduce the moisture absorption [13],[14]. bc films were formed from fiber networks arranged irregularly or randomly in three dimensions during the fermentation process produced by bacteria [18]. morphological 11 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 1, july 2019, pp. 8-17 sutrisno et al. (the effect of chemical pretreatment process on bacterial cellulose film) changes after the chemical pretreatment caused expansion of cavity size and decrease in fiber size. based on research that has been carried out, the morphology of bc fibers formed by interconnected fibril tissue containing bonds. if bc films were observed, there were fibrils appearance having three-way branching points. this type of branching caused the bc film to have a unique nature. naoh is in the form of white crystals and is dissolving, causing the rupture of hydrogen bonds in the structure of bc pellicle networks. therefore, it can increase the surface roughness [15]. pretreatment using naoh can be harmful to the bc fiber because of its extremely high degradation [21]. alkali pretreatment of cellulose affects the fiber structure, pore size, and particle size of cellulose, the cellulose of excess naoh concentration causes damage to the cellulose surface [22]. hydrogen peroxide also has several advantages such as fiber treatment which has a high resistance and a tiny decrease in fiber strength [23]. cellulose fiber can be dissolved by using an ionic liquid of 2% at a temperature of 110-150 °c. because the nature of bmimcl is a solvent, it can cause cellulose fibers to break down from hydrogen bonds to produce particles and fibers that look irregular and fragile. (a) (b) (c) (d) fig 1. the surface of the bc film (a) control (b) 7.5% naoh (c) 7.5% h2o2 (d) 7.5% bmimcl issn: 2580-0817 journal of mechanical engineering science and technology 12 vol. 3, no. 1, july 2019, pp. 8-17 sutrisno et al. (the effect of chemical pretreatment process on bacterial cellulose film) b. mechanical properties figure 2 shows a bar chart of tensile strength, as mechanical properties indication, before and after pretreatment using bmimcl, h2o2, and naoh. the value of the tensile strength of bc with aquades (control) is 123 mpa. in general, the tensile test value decreased after being treated chemically. at 2.5% naoh concentration showed a tensile strength value of 33.02 mpa. the 2.5% h2o2 treatment was 44.62 mpa, and 2.5% bmimcl treatment was 83.37 mpa. at 5% concentration naoh treatment tensile test value of 11.8 mpa, with h2o2 treatment tensile test value of 29.9 mpa, and bmimcl treatment tensile test value of 42.25 mpa. at a concentration of 7.5% bc with naoh treatment tensile test value was 8.54 mpa, with h2o2 treatment equal to the tensile test value of 16.84 mpa, and with bmimcl treatment tensile test value was 22.36 mpa. fig. 2. the tensile strength of bc before and after chemical treatments after the chemical treatment, a reduction in tensile strength was caused by the dissolution or exfoliation occurred on bc fiber, so the binding capacity between fibers becomes brittle. the improvement and reduction of tensile strength were influenced by fiber network structure interaction between hydrogen bonds [24]. the results of tensile strength in the control sample showed the highest tensile test value because bc pellicles remained intact, or the solubility does not occur. therefore, the fibers in bc had stronger surface bonds. cellulose consists of a large number of hydrogen bonding networks with intraand inter-molecular h bonding networks insoluble in water [24][25]. 13 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 1, july 2019, pp. 8-17 sutrisno et al. (the effect of chemical pretreatment process on bacterial cellulose film) high chemical and mechanical stability of cellulose and its hydrophobic properties were caused by strong glycoside bonds and very high levels of hydrogen bonds [26]. in this study, it shown that the chemical treatment of bc causes the tensile strength to decrease. treating cellulose using naoh caused transformation of cellulose i to cellulose ii, which caused a reduction of the modulus [27]. the use of hydrogen peroxide in bc treatment caused tensile strength to drop because of the nature of hydrogen peroxide could cause the dissolution of bc pellicles. the treatment of h2o2 against cellulose caused oxidation [28]. the ionic liquid is considered a harmless organic solvent because it can be recycled and is environmentally friendly [17]. the application of ionic liquids on chemical treatment of bc led its tensile strength to decrease because bmimcl is a type of organic solvent. c. porosity analysis analysis of film porosity as shown in figure 3 that show the results of porosity testing from bc before and after chemical pretreatment using bmimcl, h2o2, and naoh at a concentration of (a) 2.5%; (b) 5%; and (c) 7.5%. (a) (b) (c) fig 3. the porosity of bc film before and after treatment at the concentration of (a) 2.5; (b) 5; and (c) 7.5% issn: 2580-0817 journal of mechanical engineering science and technology 14 vol. 3, no. 1, july 2019, pp. 8-17 sutrisno et al. (the effect of chemical pretreatment process on bacterial cellulose film) the porosity of the control was 19.15%. in general, after the chemical pretreatment, the amount of porosity increased. the pretreatment of bmimcl, h2o2, and naoh with concentration of 2.5% resulted porosity by 21.88%, 28.99%, and 50.94%, respectively. the pretreatment of bmimcl, h2o2, and naoh with concentration of 5% resulted 25.08%,38.18 %, and 61.90%, respectively. the pretreatment of bmimcl, h2o2, and naoh with concentration of 7.5% resulted porosity by 30.06%, 63.32%, and 87.13%, respectively. porosity was influenced by the transport of oxygen and water diffused into bc [29]. the chemical treatment of bc caused the particles in bc to be chipped and more damaged, causing water to be easily diffused. narrowing the inter-cavity could reduce water vapor transmission, so the water vapor transmission rate affected the ability of the film to hold the water vapor [30]. the chemical pretreatment of bc film was able to increase porosity because bc tissue was broken down, causing an increasing number of pores and water could be absorbed into the film. after the pretreatment, the porosity produced was higher because bc had a network of nano and microfiber with a porous structure, so it provided space for diffusing water. thus, the more pores formed made, the easier absorbability on water. iv. conclusions morphological analysis, porosity, and mechanical properties with variations of chemical solutions were carried out. on the whole, the chemical pretreatment affected the character of bc. the results of the tensile test showed that the chemical pretreatment of the bc film could reduce tensile strength. the addition of chemical solutions (naoh, h2o2, bmimcl) caused the dissolution on bc pellicles. the fiber of bc film dissolved and peeled. therefore the binding capacity between fibers becomes brittle. the chemical pretreatment of bc film was able to increase porosity because the bc film was broken down, causing an increase of pore amount and water absorbability into the film. acknowledgments great appreciate for lp2m um through pnbp research grant 2019. references [1] i. reiniati, a. n. hrymak, and a. margaritis, “recent developments in the production and applications of bacterial cellulose fibers and nanocrystals,” crit. rev. biotechnol., vol. 37, no. 4, pp. 510–524, 2017. 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(the effect of chemical pretreatment process on bacterial cellulose film) [30] r. r. amaliya, w. dwi, and r. putri, “characterization of edible films from corn doves by adding white turmeric filtrate as antibacterial,” jurnal pangan dan agroindustri.vol. 2, no. 3, pp. 43–53, 2014.(in indonesian). journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 61-71 61 doi: 10.17977/um016v4i12020p061 the effect of solution treatment temperature and quenching media variation in heat treatment process cu-zn-al shape memory alloys on shape memory effect and microstructures wikan jatimurti1*, monica gayatri k1, mavindra ramadhani1, rochman rochiem1 1department of materials and metallurgical engineering, institut teknologi sepuluh nopember, jalan kampus its, surabaya, 60111, indonesia *wikan@material.its.ac.id abstract shape memory alloys (smas) are metal alloys with a reversible ability to recover their shape at a certain temperature after being deformed. this ability referred to as shape memory effect (sme). the application of smas such as ni-ti and cu-zn-al alloys usually used on automotive, biomedical, etc. the commonly used sma is ni-ti because of its superior sme properties than cu-zn-al, even though the price is quite higher. the sme of cu-zn-al might be improved by increasing the presence of the martensite phase in its microstructure by heat treatment. the heat treatment process given to cu-21zn-5al alloy is a homogenizing, annealing, solution treatment process and quenched with brine solution and dry ice. the heat-treated alloys then undergo several examination trough hardness tests, x-ray diffraction, metallography, sme test, and differential scanning calorimetry to determine the sme and microstructure of cu-21zn-5al. from the test results, the specimen with temperature treatment solution of 850oc and quenched by brine solution had the highest sme value by 36.67%. all of the microstructure contained α, β, (martensite) and γ phases. copyright © 2020. journal of mechanical engineering science and technology all rights reserved. keywords: cu-zn-al alloy, heat treatment, shape memory alloy i. introduction shape memory alloys (smas) are smart material with ability to remember or to reverse the former shapes in response to heat, magnetic fields or electromagnetic waves after being deformed. this ability called by shape memory effect (sme). these unique properties allowed smas to utilized in various fields such as actuators in automotive field and blood clotting filter devices in medical field. both of these tools utilized sme ability to remember or reverse shape back to former shape in response to the shift of temperature by surrounding environment. the sme ability is closely related to the microstructure of the alloy in the presence of a martensite phase. the martensitic phase at room temperature is twinned martensite and easily deformed then, the martensitic phase of deformed smas is detwinned martensite. if detwinned martensite phase provided by a shift of temperature, a transformation would occur such as reserve transformation to austenite phase through a heating process then the austenite phase undergoes forward transformation to austenite phase through a cooling process and the smas restore its former shape. the transformation involves changes in the alloy's crystal structure [1]. in general, smas often used are ni-ti. ni-ti alloys have a superior sme (above 8%) but a fairly expensive price. an alternative to substitute ni-ti alloys as smas is cu-based 62 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 61-71 alloys, especially cu-zn-al alloys with a lower price and sme ability than ni-ti alloys. the sme ability in cu-zn-al alloys is 4-5%. the sme of cu-zn-al might be improved by increasing the presence of the martensite phase in its microstructure by heat treatment. the heat treatment is based on the cu-zn-al ternary phase diagram and the intended heat treatment objectives such as homogenization, annealing, and solution treatment. for this reason, this study was conducted to determine the effect of variations temperature solution treatment and quenching media on sme and microstructure of shape memory alloys cu-znal [2]. ii. material and methods the method includes research chronological, including research design, research procedure (in the form of algorithms, pseudocode or other), instruments, and analysis techniques used in solving problems. experimental procedures should be given in sufficient detail to allow these to be replicated by other researchers. the source of the various reagents and materials used in the study should be given, where possible. a. material the specimen is x-ray fluorescence (xrf) tested by panalytical minipal4 xrf. table 1 shows the composition of cu-21 zn-5 al shape memory alloys based on the asm standards and as cast. table 1. composition cu-21 zn-5 al shape memory alloys annotation composition cu (%) zn (%) al (%) asm handbook volume 2 chapter: shape memory alloy balance 10-35 4-10 as cast balance 21 5 fig. 1. cu-21zn-5al alloys (a) as cast; (b) after the machining process figure 1(a) shows as cast of cu-21zn-5al alloy with dimension length, width and height of 32.2, 2.36 and 2.5 cm. the cu-21zn-5al alloy is yellow colored-like brass in general. then the machining process is carried out on the alloy using a cnc wire cutting tool. jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) issn: 2580-0817 journal of mechanical engineering science and technology 63 vol. 4, no. 1, july 2020, pp. 61-71 figure 1(b) shows cu-21zn-5al alloy after the machining process as the form of a wire with a diameter and length of 1 mm and 10 cm. the wire is test specimens for the effect of memory shape test in accordance with astm f2082 standards. b. material preparation a homogenization treatment performed at 850°c for 2 hours followed with air cooling, was undertaken to improve the chemical and microstructural homogeneity in cu-21zn-5al alloys. the alloys with dimension length, width and height of 1, 2.36, and 2.5 cm. the machined cu-21zn-5al alloys annealed at 550°c for 4 hours with air cooling and thereafter, solution treatment with temperature variation at 750, 850, dan 900°c followed by variations quenching media such as brine solution and dry ice. the samples for the research are 7, which consist of ac, 750-bc, 750-dc, 850-bc, 850-dc, 900-bc, and 900-dc. the number on sample stands for solution treatment’s temperature variation, bc means brine solution cooling, dc mean dry ice-cooling, and ac means as-cast alloy. c. vickers hardness test the vickers hardness tests were undertaken to determine the hardness value of cu21zn-5al alloy for identifying the material's resistance to localized plastic deformation induced by indentation. the vickers hardness tests were performed by universal hardness tester hbrv 187.5 a with a diamond pyramid indenter with a square base and an angle of 136o between opposite faces. the samples and method for the vickers hardness test were prepared following standard procedures of astm e92-17. the test involves delivering 30 kgf load for 10 seconds trough the indenter at 3 different points on each sample. the samples are as cast and after solution treatment process of cu-21zn-5al alloy. d. x-ray diffraction (xrd) x-ray diffraction (xrd) analysis was undertaken for the phase characterization of the cu-21zn-5al alloys produced. the samples for the analysis were prepared following standard procedures dimension with length, width, and height of 2.5, 1, and 0.4 cm. the analysis was performed by pan analytical xrd test equipment with diffraction 2θ angle spectral range of 10o to 90o. the xrd analysis was determined by pan analytical high score plus-marven software to compare the peaks formed with international center for diffraction data (icdd) standard data according to the phase characterization. the samples are as cast and after solution treatment process of cu-21zn-5al alloy. e. metallographic examination the observation of the microstructure of the cu-21zn-5al alloy was studied using olympus bx51m-rf optical microscope. the samples for the observation were prepared following standard procedures of astm e-407. the samples were etched by immerse method with fecl3+hcl+h2o solution for 10 seconds to reveal the microstructure. the metallographic observation was undertaken on as cast and after solution treatment of cu21zn-5al alloy. the samples are as cast and after solution treatment process of cu-21zn5al alloy. f. different scanning calorimetry (dsc) the shape memory effect (sme) test was undertaken to determine the percentage of recovery in deformed cu-21zn-5al alloys. the samples for the analysis were prepared following standard procedures of astm f2082 with dimension of a wire with a diameter and length of 1 mm and 10 cm. the sample is cu-21zn-5al wire after the solution treatment jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) 64 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 61-71 process. the sme test involves cooling a test sample to its nominally fully martensitic phase, bending the sample at 20°, and heating the sample to its fully austenitic phase. after heating, the angle of the sample is measured and calculated by equation (1), as in: 𝑆𝑀𝐸 = 𝜃𝑜−𝜃𝑡 𝜃𝑜 ×100% ............................................................................................... (1) where: θ0: initial angle θt : final angle iii. results and discussions the results of vickers hardness test for all sample is given in figure 2. the highest value of hardness vickers (hv) is sample 750-bc, and the smallest value of hv is sample ac. cu-21zn-5al alloys have α, β, and martensite phase as the main microstructures. fig. 2. hardness of investigated cu-21zn-5al alloy the characteristic of α phase is more lenient than β phase [3]. he hardness of cu-zn-al shape memory alloys comes from β phase, because its properties as hard and brittle. aluminum can increase the existance of β phase and hardness value [4]. as in martensite in steel, martensitic properties are hard and brittle. however, in shape memory alloys, the nature of martensite is soft and resilient [5]. the microstructure with more amount of α and martensite phase will make the hv value smaller. in addition to the types of phases, the grain shape can affected the value of hv. the value of hv in microstructures with finer grains are higher than the one with coarser grains [6]. the xrd pattern of cu-21 zn-5 al alloys quenched by dry ice and solution treatment is shown in figure 3 and figure 4. the diffraction pattern represents the crystal lattice of the α-brass, β-brass, and γ-brass phases. according to the chemical composition of investigated alloy, it can be expected that alloy consists of 3 phases (α, β, and γ), which is confirmed by the xrd pattern. according to the cu-zn-al ternary diagram, the presence of α and β phases jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) 0 20 40 60 80 100 120 140 160 180 200 0 750 850 900 h a rd n e ss ( h v ) temperature (oc) ac brine cooling dry ice cooling issn: 2580-0817 journal of mechanical engineering science and technology 65 vol. 4, no. 1, july 2020, pp. 61-71 jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) indicated the potential ability of sme and the martensitic phase formed. the pattern of sample ac and cu-21 zn-5 al alloys quenched by dry ice shown a more dominant presence of the α-brass phase than the β phase. on the contrary, the sample of cu-21 zn-5 al alloys quenched by dry ice shown a more dominant presence of the β-brass phase than the α-brass phase. fig. 3. xrd pattern of cu-21 zn-5 al alloys quenched by dry ice. fig. 4. xrd pattern of cu-21 zn-5 al alloys quenched by brine solution. 66 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 61-71 jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) the microstructure observation of cu-21zn-5al alloy analyzed by comparing the percentage of phases using fiji app in figure 5. the result shown a formation of 4 phases namely α, β, β' (martensite) and γ. the results of metallography analysis using optical microscopy for sample ac is given in figure 6 the optical microscopy reveals that the microstructure of sample ac consist of α phase the irregularly light colored shaped grains, β phase the dark colored grains due to corrosion from etching process, and γ phase the black dot shaped grain [7]. the formed phases are similar with the xrd pattern from the same sample. fig. 5 the percentage of phases in cu-21zn-5al fig. 6 the microstructure of sample ac with 100x magnitude 0 10 20 30 40 50 60 70 80 ac 750-bc 750-dc 850-bc 850-dc 900-bc 900-dc p e rc e n t (% ) α β γ β' issn: 2580-0817 journal of mechanical engineering science and technology 67 vol. 4, no. 1, july 2020, pp. 61-71 the results of metallography analysis using optical microscopy for sample 750-bc, 850-bc, and 900-bc is given in figure 7. the optical microscopy reveals sample 750-bc, 850-bc, and 900-bc have the same microstructure as sample ac which is consist of the same 3 phases (α, β, and γ) but with additions martensite (β') phases. the martensite phase formed by a dissolved α phase in β phase as the consequence of quenching a single phase form at such a high rate that the atoms do not have time to diffuse out of the crystal structure in large enough quantities [8]. in cu-21zn-5al alloy's case the appeared martensite phase caused by a solution treatment at high temperature until the full β phase then quenched at high rate by brine solution [9]. fig. 7 the microstructure of sample (a) 750-bc; (b) 850-bc; and (c) 900-bc with 100x magnitude the results of metallography analysis using optical microscopy for sample 750-dc, 850-dc, and 900-dc is given in figure 8. the optical microscopy reveals sample cu-21zn5al alloy quenched by dry ice have the same microstructure as sample cu-21zn-5al alloy quenched by brine solution which is consist of the same 4 phases (α, β, γ, and martensite). it's also shown from figure 4 and figure 5, the effect of the higher variation temperature solution treatment is a larger or coarser the grains formed. the effect of different quenching media is the amount of martensite phase in each sample. the sample with brine solution as quenching media have larger amount than the other sample [10]. jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) (b) (c) (a) 68 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 61-71 jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) fig. 8. the microstructure of sample (a) 750-dc; (b) 850-dc; and (c) 900-dc with 100x magnitude the pattern differential scanning calorimetry (dsc) of cu-21zn-5al shown in figure 9. the pattern shown 2 peaks with the first peak on the left caused by an exothermic reaction and the second peak on the right caused by an endothermic reaction. the formation of these two peaks is in accordance with the principle of dsc based on astm e2253 to analyze the exothermic reaction [11]. exothermic and endothermic reactions occur due to reactions that absorb energy and release energy at certain range temperature [12]. in cu-21zn-5al alloy, the reaction takes the form of a phase change from martensite to austenite and vice versa with temperature range shown in table 2. the temperature range of the dsc pattern in figure 8 in accordance with astm f2005-00 for standard graph of smas having two temperature transformation peaks. the two temperature transformation peaks referred as the martensitic transformation temperature (ms and mf) and the austenitic transformation temperature (as and af). table 2. the temperature transformation of cu-21zn-5al alloy sample temperature (°c) as ap af ms mp mf cu-21 zn-5 al 275 282 289 197 152 94.8 ( a ) ( b ) (a) (b) (c) issn: 2580-0817 journal of mechanical engineering science and technology 69 vol. 4, no. 1, july 2020, pp. 61-71 jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) fig. 9. the dsc pattern of cu-21zn-5al alloy the sme value of cu-21zn-5al alloy shown in table 3. the sequent of highest to smallest recovery shape value from cu-21zn-5al alloy with brine solution are the variation temperature of solution treatment at 850oc (36.67%), 900 oc (21.67%), and 750 oc (13.33%). on cu-21zn-5al alloy with brine solution, 850 oc (16.67%), 900 oc (13.33%), and 750 oc (10%). table 3. the recovery shape of cu-21zn-5al alloy sample no. initial angle final angle deviation angle recovery shape (%) 750-bc 1 20o 16 o 4 o 13.33 2 20 o 18 o 2 o 3 20 o 18 o 2 o 750-dc 1 20 o 18 o 2 o 10 2 20 o 18 o 2 o 3 20 o 18 o 2 o 850-bc 1 20 o 10 o 10 o 36.67 2 20 o 13o 7o 3 20 o 15 o 5 o 850-dc 1 20 o 15 o 5o 16.67 2 20 o 18 o 2 o 3 20 o 17 o 3 o 900-bc 1 20 o 16 o 4 o 21.67 2 20 o 15 o 5 o 3 20 o 16 o 4 o 900-dc 1 20 o 17 o 3 o 13.33 2 20 o 17 o 3 o 3 20 o 18 o 2 o 70 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 61-71 jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) the sme mechanism of shape memory alloy occured because reversible phase transformations between the austenite and martensite phases [13]. therefore, the more martensite phase formed in smas, the greater the recovery shape and its sme [14]. sample 850-bc have the highest recovery shape because the dominant of martensite phase which is confirmed by the microstructure sample in figure 7. iv. conclusions the effect of temperature variation of the treatment solution and the quenching media on the sme of cu-21zn-5al alloy is the value of recovery shape depended on the amount of martensite phase formed. the more presence of martensite phase, the greater the value of recovery shape. the highest value of recovery shape is sample 850-bc with 36.67%. the effects of temperature variation of the treatment solution and the quenching media on the microstructure of cu-21zn-5al alloy are 3 phases formed in all variations, namely α, β, and γ phases. in addition to the three phases, martensite or β’ phases is formed due to the influence of a rapid quenching media. the microstructure with the most dominant area of martensite phase is sample 850-bc. references [1] w. huang, shape memory alloys and their application to actuators for deployable structures, britania raya: university of cambridge, 1998. [2] v. asanovic, and k. delijic, “the mechanical behavior and shape memory recovery of cu-zn-al alloys”, metalurgija: journal of metallurgy, vol. 13, pp. 57-65, 2007. [3] p.s. lobo, j. almeida, l. guerreiro. “shape memory alloys behaviour: a review”, procedia engineering, vol. 114, pp.776-783, 2015. [4] m. sadayappan, grain refinement of permanent mold cast copper base alloys. usa: materials technology laboratory, 2004. [5] asm international, asm handbook volume 9: alloy phase diagrams. asm international handbook committee, 2004. [6] c. newey, and g. weaver, materials principles and practice. butterworthheinemann: britania raya, 1990. [7] asm international. asm handbook volume 9: alloy phase diagrams. asm international handbook committee, 2004. [8] a. molinari, m. pellizzari, s. gialanella, g. straffellini, k.h. stiasny, “effect of deep cryogenic treatment on the mechanical properties of tool steels”, j. mater process technol. vol. 118, pp. 350–355, 2001 [9] asm international, asm handbook volume 3: metallography and microstructures, asm international handbook committee, 1992. [10] l. babouri, k. belmokre, a. kabir, a. abdelouas, r. khettabi, y. el mendili, “microstructure and crystallographic properties of cu77zn21 alloy under the effect of heat treatment”, materials at high temperatures, vol. 36 (2), pp.165-172, 2018. issn: 2580-0817 journal of mechanical engineering science and technology 71 vol. 4, no. 1, july 2020, pp. 61-71 jatimurti et al. (the effect of solution treatment and quenching media in cu-zn-al shape memory alloys) [11] o.e. martinez, y. cesa, n. mingolo, r. romero, “photoacoustic detection of phase transitions with a resonant piezoelectric scheme with extreme sensitivity to small volume changes”, applied physics b: lasers and optics, vol. 80, pp. 365-371, 2005. [12] a. balfas, analisis termal bionanokomposit filler serat kulit rotan. bogor: institut pertanian bogor, 2012. [13] p.k. kumar, dan d.c. lagoudas. shape memory alloys: modeling and engineering applications, us: springer, 2008. [14] e. panjaitan, g.s. sulistioso, sumaryo, “temperatur transformasi fasa shape memory alloy tini hasil pemaduan teknik arc-melting”, urania jurnal ilmiah daur bahan bakar nuklir, [s.l.], vol 14, pp. 77-83, 2016. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 43-53 43 doi: 10.17977/um016v4i12020p043 performance enhancement of shell and tube heat exchanger on parallel flow with single segmental baffle avita ayu permanasari*, poppy puspitasari, sukarni sukarni, retno wulandari department of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang 5, malang 65145, indonesia *corresponding author: avita.ayu.ft@um.a.c.id abstract the shell and tube heat exchanger was a tool to exchange the heat energy between fluids with different temperatures that occurred through direct or indirect contact. the energy exchange in fluids could be occurred with the same phase (liquid to liquid or gas to gas) or two fluids with different phase. to date, the process of heat transfer in the industrial field was crucial in machine work. therefore, there were studies directed to optimize and develop the function and thermal performance of a heat exchanger by adding baffles to the side of the shell. vortex flow that occurs with the addition of baffles will make the area of fluid contact in the shell with the tube wall larger, so the heat transfer between the two fluids will increase. this study aimed to obtain the efficiency of the heat exchanger and its effectiveness when put on parallel flow. the heat exchanger had the dimensions of 54.6 x 10-3 m in outer diameter and 22.4 x 10-3 m in inner diameter with a tube thickness of 3 mm. the variations on water flow from both fluids were 0.5, 1, 1.5, 2 l/min for hot water and 1, 2, 3, 4 l/min for cold water to obtain the effectiveness of heat exchanger on parallel flow. this research heated the hot fluid in electric heating and used water as the cold fluid. the results showed that heat exchanger with single segmental baffle was more efficient in reducing heat in hot water than heat exchanger without bafe. the flow of fluid affected the average temperature difference; the higher the flow of fluid created a more significant temperature difference. the use of single segmental baffle affected the average temperature difference that was higher than without the baffle. the use of single segmental baffle also influenced the heat transfer greater than without baffle because of the longer distance travelled by the fluid on single segmental baffle with the same flow. thus, the heat transfer process that occurred was more significant by using a single segmental baffle. copyright © 2020. journal of mechanical engineering science and technology all rights reserved. keywords: baffle, heat exchanger, parallel flow, shell and tube i. introduction heat transfer is a heat transformation or transfer process from a high-temperature object to a low-temperature object and has critical applications in daily life. the heat exchanger is the device to transform energy. it has a wide range of use, particularly in food and beverage processing industries and other industries [1]–[9]. in usage, there are many types and kinds of heat exchanger. the widely used model, compared to others, is shell and tube type. li and kottke [5] suggested that the shell and tube type is customary because of its benefits, such as sturdy construction, easy maintenance, and easy to split apart (not in a single entity) that ease the maintenance. the main components of shell and tube heat exchanger are a tube, baffle, shell, front head, rear head, and nozzle. 44 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) there are researches to optimize the function and performance of the heat exchanger, considering the vital usage. several previous types of study such as lei et al. [6] stated that close-installed baffles increase the heat transfer between two fluids; however, it created a significant obstacle to the flow that went through the gap between baffles, and in turn, mainly decrease the pressure. meanwhile, if the baffles installations were too far in spacing, the pressure drop was small, but the heat transfer was low and could damage the pipes due to bending or vibration. this occurrence shows that the distance between baffles cannot be too close or too far, and that there is a certain optimal distance for a particular heat exchanger. shrikant et al. [10] observed the effect of baffle type and in-between range on the flow performance and characteristics of sthx in an experiment using computational fluid dynamics (cfd) numerical method to obtain a 3d simulation. finding the flow condition inside sthx, and correlating it with the experimental results using a single and triple segmental baffle. the results showed that the 5 cm baffle spacing created a higher total heat transfer coefficient compared to the 10 cm baffle spacing. akbar et al. [11] experimented the turbulent flow using various reynolds numbers and different baffle heights. the results indicated that the pressure increased along with the baffle heights on a particular flow. kumaresan et al. [12] performed an experience to reduce the pressure drop and increase the heat transfer rate from various (25%, 30%, and 35%) shell diameters, then compared the results with the 0˚ segmental baffle. the results exhibited that the 35˚ angle and 30% baffle cut from the inside diameter produced a higher heat transfer and a minimum pressure drop. eiamsa-ard et al. [13] also carried a similar experiment using cfd from single-pass parallel flow in sthx to design the sthx with segmental and helical baffles and to investigate its characteristics. the best sthx from the research was sthx with 0˚ helical baffle in a segmental partition with 10˚ of baffle angle. du et al. [14] held an inquiry to observe the effect of various baffle slope angles on the fluid flow in shell and tube with 0˚, 10˚, and 20˚ angles. the conclusion was that the 20˚ corner created a better performance than the 0˚ and 10˚ corners. this research conducted a numerical comparison study between with and without baffle to find the temperature distribution to generate optimal performance. generally, this research aimed to analyze the effectivity of shell and tube heat exchanger with the baffle. ii. research methodology a. experimental apparatus this research used the shell and tube heat exchanger, with the outer material of stainless steel in 54.6 mm diameter and 900 mm length. the inside pipe material (tube) was copper with 25.4 mm diameter on the outlet and 22.4 mm diameter on the inlet tube as depicted in figure 1. this research used water as the fluid in the outside and inside pipes. the flow directions in the baffle and without baffle sthxs were parallel flow, disregarding the pipe loss and heat loss, or considered to be steady. the flowmeter for hot water was at maximum 4 l/min, and cold water was at maximum 8 l/min. the inlet and outlet thermometer measurement was 0–100℃. this research used an electrical immersion heater as the water heater with 600 watt power. the hot water flowed through the tube while the cold water flowed through the shell. this research used the shell with and without baffle. this research used the open and closed system in the valve from the pump that headed to the cold and hot water channels to control the flow. table 1 displays the flow in this research. the measurement taken during the process was hot water inlet temperature (t1), hot water outlet temperature (t2), cold water issn: 2580-0817 journal of mechanical engineering science and technology 45 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) inlet temperature (t1), cold water outlet temperature (t2), hot water mass flow rate (w), and cold water mass flow rate (w). the output parameters were the heat released by hot water (qw), the heat received by cold water (qw), the difference in average temperature (δtm), the overall heat transfer coefficient (u), and efficiency. figure 2 shows the used section from shell and tube heat exchanger for this test. the blue pipe represents the cold water flow, and the red pipe represents the hot water flow. figure 3(a) presents the shell and tube dimensions with baffle, where the red line represents hot water through the tube, and the blue line represents cold water through the baffled shell. whereas figure 3(b) illustrates the dimensions and flow direction in the shell without baffle. table 1. hot and cold water fluid flow code flow (litre/minute) hot water cold water e 0.5 1 f 1 2 g 1.5 3 h 2 4 fig. 1. heat exchanger area fig. 2. shell and tube heat exchanger (a) cold water pump, (b) hot water pump, (c) cold water tank, (d) hot water tank, (e) switch, (f) flow meter, (g) thermometer digital, (h) cold water line, (i) hot water line, (j) heat exchanger pipe baffle and no baffle 46 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) (a) (b) fig. 3. dimensions and water flow direction (a) heat exchanger with baffle, (b) heat exchanger pipe without baffle b. mathematic model equation (1) formulates the average temperature difference from the parallel flow with and without baffle in cold water channel [15]. ∆𝑡𝑚 = (𝑇1−𝑡1)−(𝑇2−𝑡2) 𝑙𝑛 𝑇1−𝑡1 𝑇2−𝑡2 (1) δtm is the logarithmic average of temperature difference, t1 is the hot water input temperature, t2 is the hot water output temperature, t1 is the cold water input temperature, and t2 is the cold water output temperature. equation (2) devises the overall heat transfer coefficient (u) [16]. 𝑈 = 1 1 ℎ𝑖𝐴𝑖 + ln ( 𝐷𝑜 𝐷𝑖 ⁄ ) 2𝜋𝑘𝐿 + 1 ℎ𝑜𝐴𝑜 (2) where a0 is the total surface area of the outer tube in heat transfer, and ai is the surface area of the inner tube. equation (3) and (4) formulate the above factors [16]. 𝐴𝑜 = 𝜋 𝐷𝑜 𝐿 (3) 𝐴𝑖 = 𝜋 𝐷𝑖 𝐿 (4) equation (5) and (6) calculates the heat balance value, of which qw is the released heat, qw is the received heat, t is the high-temperature fluid, t is the low-temperature fluid, and w is the flow rate of high-temperature fluid [15]. 𝑄𝑤 ≅ 𝑞𝑤 (5) 𝑊𝐶𝑝(𝑇1 − 𝑇2) ≅ 𝑤𝐶𝑝(𝑡2 − 𝑡1) (6) equation (7) devises the heat transfer convection coefficient. kin,out is the fluid’s thermal conductivity, dh is the hydraulic diameter, and nu is the nusselt number [16]. issn: 2580-0817 journal of mechanical engineering science and technology 47 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) ℎ𝑖𝑛.𝑜𝑢𝑡 = 𝑘𝑖𝑛.𝑜𝑢𝑡 𝐷ℎ 𝑁𝑢𝑖𝑛.𝑜𝑢𝑡 (7) equation dittus-boilter, displayed as equation (8) and (9), formulates the nusselt numbers from the outer and inner pipes of the shell and tube heat exchanger [16]. 𝑁𝑢𝑜 = ℎ𝑜.𝐷ℎ 𝑘 = 0.023𝑅𝑒𝑜 0.8𝑃𝑟𝑜 0.33 (8) 𝑁𝑢𝑖 = ℎ𝑖.𝐷ℎ 𝑘 = 0.023𝑅𝑒𝑖 0.8𝑃𝑟𝑖 0.4 (9) where dh = do – di is the hydraulic diameter influenced by fluid area inside the pipe – heat exchanger pipe. equation (10) formulates the reynolds numbers and equation (11) calculates the heat transfer rate between the fluids in the pipe and on the pipe’s surface [15]. 𝑅𝑒𝑖𝑛.𝑜𝑢𝑡 = 𝑢.𝐷 𝑣 = 𝜌𝑖𝑛.𝑜𝑢𝑡.𝑢𝑖𝑛.𝑜𝑢𝑡.𝐷𝑖𝑛.𝑜𝑢𝑡 𝜇𝑖𝑛.𝑜𝑢𝑡 (10) 𝑄 = 𝑈 𝐴𝑠 ∆𝑇𝐿𝑀𝑇𝐷 (11) equation (12) formulates the efficiency of the heat exchanger by comparing the actual quantity of heat transfer and the ideal quantity of heat transfer [16]. 𝜂𝐻 = 𝑎𝑐𝑡𝑢𝑎𝑙 𝑞𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 ℎ𝑒𝑎𝑡 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟 𝑖𝑑𝑒𝑎𝑙 𝑞𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 ℎ𝑒𝑎𝑡 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟 = 𝑊.𝐶𝑝(𝑇1−𝑇2) 𝑊.𝐶𝑝(𝑇1−𝑡1) (12) iii. results and discussions data comparison of two test results are with baffle and without baffle. a. the average temperature difference the average temperature difference in the heat exchanger with baffle increased because the cold water fluid was still cold. it eventually decreased due to continuous usage of cold water without cooling, and thus, the temperature between cold and hot water was almost balanced without the occurrence of heat transfer. meanwhile, the test in heat exchanger without baffle underwent increasing average temperature difference because the heat absorption by cold fluid was not maximum due to the cooling process in a short time [7]. the reynolds number affected the average temperature difference, meaning the higher reynolds number increased the average temperature difference. this condition was due to the change in the flow type that affecting the temperature, a result of the flow variants. figure 4 and table 2 displays that the average temperature in the heat exchanger with baffle had a better performance compared to heat exchanger without baffle; therefore, it absorbed higher heat [5]. 48 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) fig. 4. correlation graphs between the average temperature difference and the reynolds number in two tests: with and without baffle table 2. correlation between flow type in parallel flow and the average temperature with and without baffle parallel flow (baffle) variation flow direction ∆tm (˚c) e h: laminar, c: laminar 12.15 f h: laminar, c: laminar 14.19 g h: transitional, c: laminar 14.57 h h: transitional, c: laminar 11.29 parallel flow (no baffle) e h: laminar, c: laminar 9.47 f h: laminar, c: laminar 10.92 g h: transitional, c: laminar 12.14 h h: transitional, c: laminar 11.94 b. heat transfer the heat transfer process from hot water increased along with the increased fluid flow and the average temperatures in inlet and outlet. the received heat in cold water also improved along with the fluid flow and the average temperatures in inlet and outlet. the small gap in the fluid flow affected the heat rate balance closer to the balance rate [4]. meanwhile, the significant difference in the fluid flow changed the heat rate balance farther from the balance value. the reynolds number affected the heat transfer, meaning the higher reynolds number increased the heat transfer rate. this condition was due to the change in the flow type that affecting the temperature, a result of the flow variants. the laminar flow had a lower heat transfer rate compared to the turbulent flow [1]. moreover, baffle usage in heat exchanger also affected the heat balance. figure 5 and table 3 shows that by using baffle, there was greater heat absorption compared to without baffle with the evidence found in the gap between the released-heat (qw) of hot water and the received-heat (qw) of cold water. issn: 2580-0817 journal of mechanical engineering science and technology 49 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) fig. 5. correlation graphs between hot and cold water heat transfer and the reynolds number in two tests: baffle and no baffle table 3. correlation between flow type in parallel flow and heat transfer with baffle and without baffle parallel flow (baffle) variation flow direction ∆tm (˚c) e h: laminar, c: laminar 12.15 f h: laminar, c: laminar 14.19 g h: transitional, c: laminar 14.57 h h: transitional, c: laminar 11.29 parallel flow (no baffle) e h: laminar, c: laminar 9.47 f h: laminar, c: laminar 10.92 g h: transitional, c: laminar 12.14 h h: transitional, c: laminar 11.94 c. efficiency heat exchanger efficiency depended on the comparison of the actual heat transfer rate with the ideal heat transfer rate. the real heat was the result of the temperature difference between the hot water inlet and outlet channels. the ideal heat was the result of the temperature difference of the cold water inlet and outlet channels. there was a high efficiency in the initial test and eventually declined in the next test because there was no cooling process for the cold water. it continued to circulate and made it hot (close to the hot water temperature). the reynolds number affected the heat exchanger efficiency, meaning the lower reynolds number resulted in the high efficiency. this condition was due to the change in the flow type that affecting the temperature, a result of the flow variants. the laminar flow had a higher efficiency rate compared to the turbulent flow. figure 6 and table 4 shows that the efficiency of the heat exchanger with baffle was higher than heat exchanger without baffle because the cold water ability in absorbing heat was higher using the blocked heat 50 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) exchanger [11]. besides, the average temperature difference in the heat exchanger with baffle was larger than without baffle. fig. 6. correlation graphs between heat exchanger efficiency and the reynolds number in two tests: with baffle and without table 4. correlation between flow type in parallel flow and efficiency with and without baffle parallel flow (baffle) variation flow direction ƞ (%) e h: laminar, c: laminar 70 f h: laminar, c: laminar 67 g h: transitional, c: laminar 61 h h: transitional, c: laminar 58 parallel flow (no baffle) e h: laminar, c: laminar 56 f h: laminar, c: laminar 50 g h: transitional, c: laminar 46 h h: transitional, c: laminar 47 d. overall heat transfer coefficient the average temperature influenced the overall heat transfer coefficient, where the fluid flow was also affecting the average temperature differences supported by the test duration. the small fluid flow had a lower ability to transfer the heat, and the high fluid flow had a higher capacity to transfer the heat. the reynolds number affected the overall heat transfer coefficient, meaning a higher reynolds number increased the overall heat transfer coefficient. this situation was due to the change in the flow type that affecting the temperature, a result of the various flows. the laminar flow type had a lower heat transfer coefficient compared to the turbulent flow [9]. overall heat transfer coefficient was the combination of the convection coefficient and the thermal resistance in the pipe’s wall of the heat exchanger. figure 7 and table 5 presents that the overall heat transfer coefficient in a issn: 2580-0817 journal of mechanical engineering science and technology 51 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) heat exchanger with baffle was greater than without baffle because the overall heat transfer coefficient was directly proportionated with the heat transfer value. fig. 7. correlation graphs between overall heat transfer coefficient and the reynolds number in two tests: with baffle and without baffle table 5. correlation between flow type in parallel flow and efficiency with and without baffle parallel flow (baffle) variation flow direction u (kkal/m2.h.˚c) e h: laminar, c: laminar 131.13 f h: laminar, c: laminar 231.05 g h: transitional, c: laminar 297.71 h h: transitional, c: laminar 429.82 parallel flow (no baffle) e h: laminar, c: laminar 107.13 f h: laminar, c: laminar 221.11 g h: transitional, c: laminar 262.35 h h: transitional, c: laminar 322.93 iv. conclusions heat exchanger with baffle was more efficient in reducing heat in hot water compared to heat exchanger without baffle. the more significant difference in heat transfer in exchangers with and without baffle was because of the longer distance travelled by the fluid on single segmental baffle with the same flow. thus, the heat transfer process that occurred was greater by using a single segmental baffle. • the efficiency value of a heat exchanger with baffles is 64%, where the efficiency value is greater than the heat exchanger without baffles is 49.75%. • the overall heat transfer coefficient value of a heat exchanger with baffles is 272.42 kcal/m2.h.0c, where the overall heat transfer coefficient value is greater than the heat exchanger without baffles is 228.38 kcal/m2.h.0c. 52 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) • the average temperature difference of a heat exchanger with baffles is 13.05 0c, where the average temperature difference value is greater than the heat exchanger without baffles is 11.12 0c. • the heat released value of a heat exchanger with baffles is 975.76 kcal/h, where the heat released value is greater than the heat exchanger without baffles is 604.7 kcal/h. • the heat received value of a heat exchanger with baffles is 104.41 kcal/h, where the heat received value is lower than the heat exchanger without baffles is 201.46 kcal/h. references [1] f. n. taher, s. z. movassag, k. razmi, and r. t. azar, “baffle space impact on the performance of helical baffle shell and tube heat exchangers”, applied thermal engineering, vol. 44, pp. 143–149, 2012. [2] y. qiu, m. li, w. wang, b. du, and k. wang, “an experimental study on the heat transfer performance of a prototype molten-salt rod baffle heat exchanger for concentrated solar power”, energy, 2018. [3] b. sciences and t. nadu, “shell side numerical analysis of a shell and tube heat exchanger considering the effects of baffle inclination angle on fluid flow”, thermal science, vol. 16, no. 4, pp. 1165–1174, 2012. [4] j. wen, h. yang, s. wang, y. xue, and x. tong, “international journal of heat and mass transfer experimental investigation on performance comparison for shell-and-tube heat exchangers with different baffles”, heat mass transf., vol. 84, pp. 990–997, 2015. [5] h. li and v. kottke, “effect of baffle spacing on pressure drop and local heat transfer in shelland-tube heat exchangers for staggered tube arrangement”, int. j. heat mass transf, vol. 41, no. 10, pp. 1303-1311, 1998. [6] y. lei, y. li, s. jing, c. song, and y. lyu, “design and performance analysis of the novel shell-and-tube heat”, appl. therm. eng., 2017. [7] b. gao, q. bi, z. nie, and j. wu, “experimental study of effects of baffle helix angle on shellside performance of shell-and-tube heat exchangers with discontinuous helical baffles”, exp. therm. fluid sci., vol. 68, pp. 48–57, 2015. [8] t. v. s. siva and p. sai chaitanya, “optimization of shell and tube heat exchanger used in a rankine cycle of exhaust gas waste heat recovery system using cfd”, int. j. chem. sci., vol. 14, no. 4, pp. 2247–2258, 2016. [9] m. bahiraei, m. hangi, and m. saeedan, “a novel application for energy efficiency improvement using nano fluid in shell and tube heat exchanger equipped with helical baffles”, energy, vol. 93, pp. 2229-2240, 2015. [10] a. a. shrikant, r. sivakumar, n. anantharaman, and m. vivekenandan, “cfd simulation study of shell and tube heat exchangers with different baffle segment configurations”, appl. therm. eng., 2016. [11] a. akbar, a. arani, and r. moradi, “shell and tube heat exchanger optimization using new baffle and tube configuration”, appl. therm. eng., vol. 157, 2019. [12] g. kumaresan, r. santosh, and p. duraisamy, "numerical analysis of baffle cut on shell side heat exchanger performance with inclined baffles", heat transfer engineering, vol. 7632, 2017. [13] s. eiamsa-ard, k. ruengpayungsak, c. thianpong, m. pimsarn, and v. chuwattanakul, “international journal of thermal sciences parametric study on thermal enhancement and flow characteristics in a heat exchanger tube installed with protruded baffle bundles”, int. j. therm. sci., vol. 145, 2019. issn: 2580-0817 journal of mechanical engineering science and technology 53 vol. 4, no. 1, july 2020, pp. 43-53 permanasari et al. (performance enhancement of shell and tube heat exchanger on parallel flow) [14] b. du, y. he, k. wang, and h. zhu, “convective heat transfer of molten salt in the shelland-tube heat exchanger with segmental baffles”, int. j. heat mass transf., vol. 113, pp. 456– 465, 2017. [15] d.a. firlianda, a.a. permanasari, and p. puspitasari, “heat transfer enhancement using nanofluids ( mnfe2o4-ethylene glycol ) in mini heat exchanger shell and tube heat transfer enhancement using nanofluids ( mnfe 2 o 4 ethylene glycol ) in mini heat exchanger shell and tube”, aip conf. proc., vol. 2120, 2019. [16] a.a. permanasari, b.s. kuncara, and p. puspitasari, “convective heat transfer characteristics of tio2-eg nanofluid as coolant fluid in heat exchanger convective heat transfer characteristics of tio 2 -eg nanofluid as coolant fluid in heat exchanger,” aip conf. proc., vol. 2120, 2019. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no.2, november 2020, pp. 115-124 115 doi: 10.17977/um016v4i22020p115 surface properties and adsorption capacities of rice bran-activated carbon dewa ngakan ketut putra negara1,2*, tjokorda gde tirta nindhia1, wayan nata septiadi1 1mechanical engineering department, udayana university, jl. raya kampus unud, bukit jimbaran, south kuta, badung bali, 80361, indonesia 2master program of mechanical engineering, udayana university, jalan p.b. sudirman, denpasar bali, 80232, indonesia *corresponding author:devputranegara@unud.ac.id abstract the growing need for activated carbon requires alternative raw materials to replace non-renewable raw materials whose existence is decreasing. biomass is a very promising precursor, one of which is from rice bran. this research concerns the development of activated carbon derived from rice bran. carbonization was carried out at 600 oc and physically activated with nitrogen flow rates of 150 ml/min for 40, 80, and 120 minutes. the activated carbons produced (ac-d40, ac-d80, and ac-d120) were characterized to determine the surface properties, surface morphology, and adsorption capacity for nitrogen and blue methylene adsorptions. the results showed that activated carbon that activated for 80 minutes (ac-d80) had the best characteristics. with a pore surface area of 109.389 m2/g, a pore volume of 0.083 cm3/g, and pores that mostly distributed in the micropore area, this activated carbon has the highest adsorption for nitrogen (53.874 cm3/g) and methylene blue (87.560 mg/g) adsorptions compared to activated carbon with activation times of 40 minutes (ac-d40) and 120 minutes (ac-d120). copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: activated carbon, activation, adsorption, characteristic, rice bran, surface i. introduction activated carbon is an adsorbent that has unique characteristics. it has a high pore volume and surface area that causes activated carbon to have high adsorption. because of its high adsorption capacity, activated carbon widely applied in various fields of life such as for the purification of water from industrial waste pollutants [1] [2], removal of methylene blue [3]-[5], a cathode battery material in electrochemical devices [6], co2 adsorption [7] [8], biogas purification [9] [10], and supercapacitor [11]. to be applied optimally, the properties or characteristics of activated carbon and the type of adsorbate to be adsorbed must be well known. for instance, for gas storage and purification, the surface characteristics of activated carbon such as pore-volume, surface area, and distribution of pore size play an important role. in the gas storage process, an adsorption process occurs, which is the accumulation of gas molecules on the surface of the activated carbon due to the van der walls forces. the pore volume, surface area, and pore distribution of activated carbon determine the number of gas molecules that can be adsorbed. the behavior of porous media such as movement and fluid flow are largely influenced by these characteristics. the pore size distribution of activated carbon is the relative pore 116 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. (surface properties and adsorption capacities of rice bran-activated carbon) volume associated with different pore sizes [12], and in gas storage and separation application strongly associated with adsorption capacity [13]. the high use of activated carbon demands high availability of activated carbon as well. unfortunately, the raw material for activated carbon generally comes from coal or petroleum residue, whose availability is decreasing. some researchers have started to develop activated carbon using raw materials from biomass such as palm-shell [14], rice straw [15], agricultural solid wastes [16], chips from spruce and birch [17], and bamboo [18][19]. but it is still very minim literature associated with activated carbon made from rice bran. rice bran is a waste from rice milling with a proportion of 10% of the weight of rice harvested [20]. the chemical composition and physical element content of rice bran strongly determined by rice varieties and environmental factors. the characteristics and quality of activated carbon depend on the chemical and physical properties of the precursor [21], the activator, the temperature, and the method of activation [22]. the process of making activated carbon consists of dehydration of raw materials, carbonization, and activation processes. dehydration is done to reduce the moisture content of raw materials. carbonization is carried out by heating the raw material at a temperature of 400-850oc [23] in order to form an initial porosity. activation is a process to form new porosity, widen the porosity that has been formed during the carbonization process and can be done without involving agents (physical activation) and by involving agents (chemical activation). the purpose of this study was to determine the characteristics and adsorption ability of activated carbon derived from rice bran that is physically activated with different activation times. ii. material and methods a. production of activated carbons the raw material used as activated carbon is rice bran obtained from the home industry of the rice mill in banjar pengaji, payangan, gianyar bali indonesia, as shown in figure 1 (a). thermo gravimetric analyzer (tga) test results showed that rice bran contained 15.04% moisture, 62.05% volatile, 13.21% ash, and 9.7% fixed carbon. rice bran is dried under the sunlight for seven days for 5 hours from 10.00 am to 03.00 pm and meshed with 60 mesh. the meshed powder was dried in an electric furnace at 105oc for 2 hours. a 20 gram of dried powder rice bran was loaded into a stainless cylindrical reactor, and the reactor was then entered into an electric furnace for furthermore heated to a temperature of 600oc. the heating was held at that temperature for 40 minutes, at the same time, an activation process was carried out by flowing nitrogen with a flow rate of 150 ml/min. the activated carbon cooled in the electric furnace for 12 hours. the same steps were carried out for activation times of 80 and 120 minutes. the produced activated carbons were then coded as ac-d40, ac-d80, and ac-d120 for the activation period of 40, 80, and 120 minutes, respectively. the sample of activated carbon produced is shown in figure 1(b). b. characterization of activated carbons characterization carried out included sem, adsorption isotherm, and methylene blue tests. sem test equipment (jsm-651ola) was used to observe the activated carbon surface morphology. adsorption isotherm test equipment (the micromeritics® tristar ii plus) was applied to determine the surface structure of the activated carbon, including pore surface area (sbet), pore-volume, and adsorption of nitrogen. methylene blue test was undertaken to determine the adsorption of activated carbon against methylene blue using an ultra violetissn: 2580-0817 journal of mechanical engineering science and technology 117 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. (surface characteristics and adsorption capacities of rice bran-activated carbon) visible (uv-vis) spectroscopy. determination of the adsorption of methylene blue by measuring the maximum wavelength of the 5 mg/l methylene blue solution in the range 664 nm. (a) rice bran (b) activated carbon fig.1. precursor and sample of activated carbon produced iii. results and discussions a. adsorption isotherm of activated carbons the adsorption isotherm of activated carbon, as shown in figure 2, is the relationship of the amount of nitrogen absorbed by activated carbon at different relative pressure levels. the three activated carbons produced have almost the same pattern, only differing in the rate of nitrogen adsorption. the activated carbon ac-dp40 has the lowest adsorption rate, whereas the relative pressure increases the amount of nitrogen adsorbed is relatively constant until the relative pressure of 0.9. then it increases significantly and reaches a peak at a relative pressure of 1. the low absorption of activated carbon ac-d40 is due to its short activation time resulting in less opportunity for the formation of new pores and widening of the pores formed during the carbonization process. as a result, this activated carbon has a low surface area and pore volume as shown in figure. 4 and 5. fig. 2. adsorption isotherm of activated carbons 118 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. (surface properties and adsorption capacities of rice bran-activated carbon) whereas ac-d80 and ac-d120, nitrogen adsorption began to increase until the relative pressure of 0.1, then remain constant until the relative pressure was 0.9. from a relative pressure of 0.9, it increases dramatically and reaches a peak at relative pressure 1. both activated carbons have a type ii of adsorption isotherm classification related to iupac1985 [24]. in this type, there is a single and double layers adsorption mechanism that is characterized by a convex shape at a relative pressure (p/po) less than 0.2 followed by a linear form over a long-range. the point of transition from convex to linear is the condition for the completion of single layer adsorption and when entering the linear portion indicates the start of double-layer adsorption [24]. activated carbon ac-d80 and ac-d120 have higher adsorption at all relative pressure levels compared to ac-d40. at the end of the adsorption process, ac-d80 has a higher nitrogen adsorption capacity than ac-d120. b. pore size distribution of activated carbons the pore size distribution is a graph that shows the relationship between the amount of nitrogen absorbed per gram of activated carbon at different pore sizes. as shown in figure. 3, the three activated carbons have almost the same pore distribution pattern. most of them are distributed in the micropore area (less than 2 nm) in the 0.4 nm to 1.75 nm range, but with different adsorption rates. ac-d80 has a pore size distribution with a peak adsorption rate of 0.0089 cm3/g at a pore diameter of 0.652 nm, followed by ac-d120 and ac-d40 with the highest adsorption rates of 0.00837 cm3/g and 0.00227 cm3/g, at pore diameter of 0.652 nm and 0.591 nm, respectively. even though they are in almost the same distribution range (micropore area), activated carbon ac-d40 has the lowest adsorption capacity. the 40-minutes activation duration of activated carbon ac-d40 provided less opportunity for the formation of new pores or widening of existing pores during the activation process. as a result, the number of pores formed is also less compared to activated carbons ac-d80 and ac-d120. fig. 3. pore size distribution of samples issn: 2580-0817 journal of mechanical engineering science and technology 119 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. (surface characteristics and adsorption capacities of rice bran-activated carbon) c. surface pore structure of activated carbons the surface pore structure of the activated carbons, as shown in figure. 4 and 5, show that produced activated carbons have a pore surface varying from 26.613-109.389 m2/g, and pore volume from 0.028-0.083 cm3/g. activated carbon ac-d80 has the highest surface area and pore volume followed by ac-dp120 and ac-dp40. in this case (figure. 4 and 5), the pore surface area of activated carbon is proportional to the pore volume, where the higher the pore surface area higher the pore volume of activated carbon. the existence of pores in the surface of activated carbons is shown in the sem image of the surface morphology of activated carbon in figure. 6, where there is a difference between the morphology of precursors and activated carbon. the formation of pores occurs when the precursor was heated in the carbonization process [25] [26] and then continued in the activation process [21]. fig. 4. surface area (sbet) of activated carbons fig. 5. pore volumes of activated carbons 120 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. (surface properties and adsorption capacities of rice bran-activated carbon) d. adsorption of nitrogen and methylene blue through activated carbons the adsorption capacity of activated carbons for nitrogen and methylene blue is presented in table 1. activated carbon ac-d80 has the highest adsorption capacity of nitrogen and methylene blue. in this case, there is a linear relationship between the pore surface area, pore-volume, and the adsorption capacity of nitrogen and methylene blue. the higher the surface area and pore volume of activated carbon, the higher the adsorption capacity. activated carbon ac-d80 that has the highest pore area (109.389 m2/g) and the highest pore volume (0.083 cm3/g), also has the highest adsorption of nitrogen (53.874 cm3/g) and methylene blue 87.56 (mg/g). the comparison of methylene blue adsorption of the activated carbons produced in this study and other adsorbents is shown in table 1. rice bran ac-d40 ac-d80 ac-d120 fig. 6. surface morphology of activated carbon issn: 2580-0817 journal of mechanical engineering science and technology 121 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. (surface characteristics and adsorption capacities of rice bran-activated carbon) fig. 7. adsorption capacity of activated carbon table 1. methylene blue adsorption capacity of some adsorbents adsorbens/activated carbons methylene blue adsorbed [mg/g] references rice bran 82.84-87.56 this study modified activated carbon by surfactants 64.4-195.7 [27] periwinkle shells activated carbon 89.8-431.1 [28] parthenium hysterophorus activated carbon with h2so4 treated 39.7 [29] bagasse activated carbon with h2so4 treatment 49.8-56.5 [30] ficus carica activated carbon with h2so4 treatment 47.6 [31] delonix regia pods activated carbon with h2so4 treatment 23.3 [32] coconut leaves activate carbon 127-149 [33] iv. conclusions the rice bran precursor has been manufactured to become activated carbon with promising characteristics. activated carbon that produced with an activation duration of 80 minutes (ac-d80) has the most optimal properties and adsorption capacity. with increasing surface area and pore volume, the adsorption capacity of activated carbon to nitrogen and methylene blue also increases. activated carbon ac-d80 has the greatest surface area, porevolume, and ability for adsorption of nitrogen and methylene blue. with its characteristics, activated carbon ac-d80 has the potential to be used for the purification of biogas from co2 and h2s impurities or for adsorption of motor vehicle exhaust emissions. 122 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 115-124 negara et al. 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[33] jawada, a.h., rashida, r.a., mohd ishaka, m.a., and lee, d. w., “adsorption of methylene blue onto activated carbon developed from biomass waste by h2so4 activation: kinetic, equilibrium and thermodynamic studies”, desalination and water treatment, vol. 57, pp. 25194–25206, 2016. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 144-152 144 doi: 10.17977/um016v4i22020p144 tool life prediction of ti [c,n] mixed alumina ceramic cutting tool using gradient descent algorithm on machining martensitic stainless steel joseph daniel s1 and senthil kumar a2 1department of mechanical engineering, mepco schlenk engineering college, sivakasi, india. 2department of mechanical engineering, sethu institute of technology, kariapatti, india. *corresponding author:asenthil123@gmail.com abstract in automated manufacturing systems, most of the manufacturing processes, including machining, are automated. automatic tool change is one of the important parameters for reducing manufacturing lead time. machining studies on martensitic stainless steel was conducted using ti[c,n] mixed alumina ceramic cutting tool. tool life was evaluated using flank wear criterion. the tool life obtained from experimental machining process was taken as training dataset and test dataset for machine learning. tool life model was developed using gradient descent algorithm. the accuracy of the machine learning model was tested using the test data, and 99.83% accuracy was obtained. copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: gradient descent algorithm, machine learning, machining, prediction, tool life model. i. introduction alumina based ceramic cutting tools have unique chemical, and mechanical properties and these tools can offer increased metal removal rates, extended tool life and the ability to machine hard workpiece materials like hardened steel and stainless steel. the ceramic cutting tools can reduce the cost of machining and increase productivity because of their high material removal rates [1]. alumina based ceramic cutting tools are capable of machining various types of hard materials due to the improved cutting tool properties such as fracture toughness, thermal shock resistance, hardness and wear resistance. the advantages of using ceramic cutting tools are that, the hard materials like hardened steels, stainless steels and hard powder metal materials with complex shapes can be machined in their hardened conditions. the grinding quality surface finish can be obtained by turning the hard work materials using ceramic cutting tools. the properties of aluminium oxide are enhanced by the addition of titanium carbide (tic) in the alumina matrix, which increases the transverse rupture strength and thermal shock resistance of the composite tool. the titanium nitride (tin) is also used as a secondary ceramic phase because of its superior thermal conductivity. by adding these non-oxide particles like tic and tin in the alumina matrix, the thermal conductivity, the thermal shock resistance and the hardness are increased. these composite ceramic cutting tools retain their hardness even at elevated temperature. in the ti[c, n] mixed alumina composite ceramic cutting tool, the tic, tin grains pin the crack initiated in the matrix [2]. the toughening mechanism for this type of mixed ceramic cutting tools is known as precipitate or dispersion strengthening. mixed alumina based ceramic tools are fabricated by hot pressing, which 145 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) involve mixing of fine grained alumina with 20 –30 % volume of tic and tin powders. these ceramic cutting tools are generally used for machining of hardened steels because of their increased hardness. martensitic stainless steels are iron alloys with a minimum of 11.5% chromium. in addition to iron, carbon, and chromium, stainless steel may also contain other elements, such as nickel, niobium, molybdenum, and titanium. the chromium content in stainless steel enhances the corrosion resistance. martensitic stainless steels are magnetic, contains higher carbon content than the ferritic types. they are hardenable by quenching and tempering like plain carbon steels and find their main application in cutlery, surgical tools, aerospace and general engineering. ronald klueh and donald harries (2001) have reported that advanced ferritic/martensitic stainless steel is used in thermal power plants, nuclear power plants and in other demanding environments for its high temperature properties, and high creep rupture strength [3]. grade astm a276 is the basic martensitic stainless steel, and like most nonstainless steels it can be hardened by a "quench-and-temper" heat treatment. in the annealed or highly tempered conditions grade astm a276 machined without much difficulty, but if hardened to above 30 hrc machining becomes very difficult. stainless steel grade astm a276 is used for parts requiring a combination of good strength, toughness and reasonable corrosion resistance and typical applications include bolts, nuts, screws, bushings, pump and valve parts, shafts, steam turbine parts, gas turbine parts, petrochemical equipment, mine equipment etc. in this present work, the tool life of ti [c,n] mixed alumina based ceramic cutting tools is evaluated on machining hardened martensitic stainless steel – grade astm a276. tool life and tool wear prediction have been attempted by many researchers using various tools and machine learning algorithms. artificial neural network has been widely used to predict tool wear and tool life. mikołajczyka et al. used artificial neural network (ann) and trained them using the data subset obtained from actual machining and a predicted data subset obtained from image recognition. the trained ann is used to evaluate the tool life in turning operations of a third test set [4]. gouarir et al. used sensors to continuously monitor and measure the flank wear and adaptive control (ac) along with convolutional neural networks (cnn)was used to predict tool wear [5]. xuefeng wu et al. used ann to monitor the tool wear from the tool wear data obtained through cameras. a convolutional automatic encoder (cae) is used to train the neural network with data obtained from the camera. backpropagation and stochastic gradient descent are performed to obtain average recognition precision rate of 96.20% [6]. apart from ann, the researchers used support vector machines, logistic regression, random forest algorithms to predict tool wear and tool life. jaydeep karandikar et al. used support vector machines and logistic regression methods to predict the tool wear characteristics of a given tool and to model the tool life [7]. schwenzer et al. used support vector machine (svm) and random forest algorithms on datasets obtained from orthogonal cutting in milling. they are used to classify the tool as ‘sharp’ or ‘dull’ with the help of force and current signals obtained from sensors [8]. yang hui et al. used support vector machine (svm) algorithm to extract the features from the vibration signals are sensed from a milling tool. the stacked generalization (sg) ensemble model based on svm, decision tree (dt), naive bayes (nb) algorithms are used to recognize the tool wear state of the milling tool [9]. benjamin neef et al. used svm .and random forest ensemble (rse) algorithms to analyse the high frequency current samples of a cnc turning machine terminal to estimate of the tool wear. experimental studies are conducted and the accuracy of the machine learning model is noted. an online continuous tool wear monitoring system is proposed for easy tool wear monitoring [10]. dazhong wu issn: 2580-0817 journal of mechanical engineering science and technology 146 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) used cloud computing, industrial internet of things (iiot) and machine learning to estimate the tool wear characteristics of a cutting tool. random forests (rf) algorithm was used alongside ‘mapreduce’ data processing scheme and the training time is reduced by 14.7 times along with a high prediction accuracy [11]. in addition to machine learning algorithms, signal and image processing were also used to predict tool wear. giovanna mart ́ınez et al. used signal imaging to encode the images of the tool at specified time steps and fed to a premade deep learning package for classifying the tool wear as break-in wear, steady wear, severe wear and failure region [12]. bovic kilundua et al. measured vibration signals on the tool holder and pseudo-local singular spectrum analysis was done to extract the features that are essential for the quality of the tool and is monitored continuously [13]. even though the researchers attempted various machine learning algorithms, few has attempted linear algorithms. most of them used classification for predicting the status of the tool. linear algorithms are simple, but powerful tools for modelling. gradient descent algorithm (gda) is one of the linear algorithms widely used in various types of modelling. an attempt has been made to predict tool life using gda by training them using the data obtained from machining hardened and tempered martensitic stainless steel – grade astm a276 by ti [c,n] mixed alumina based ceramic cutting tool. ii. materials and methods a. cutting tool inserts machining tests were carried out using ti [c,n] mixed alumina ceramic cutting tool inserts on a precision lathe with variable spindle speeds and feeds. the specifications of the cutting tool inserts are presented in table1. table 1. details of cutting tool inserts specifications insert specification (iso) shape rhombic nose angle rhombic inscribed circle diameter thickness nose radius cngn 12 04 08 t01020 rhombic 80º 12.7 mm 4.76 mm 0.8 mm b. work materials the work material used in these machining studies was martensitic stainless (astm a276) steel and was hardened and tempered to hrc 42. machining studies were conducted on them. the composition of the stainless steel (astm a276) is given in table 2. table 2. composition of stainless steel – astm a276 grade by weight percentage elements c si mn cr ni p s fe weight percentage 0.09-0.15 1.0 1.0 11.5-13.5 1.0 0.04 0.03 balance c. experimental conditions machining studies were conducted on hardened martensitic stainless steelgrade astm a276 using ti [c,n] mixed alumina based ceramic cutting tool at different cutting speeds and at constant feed rate and depth of cut. experimental conditions are shown in table 3. 147 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) table 3. experimental conditions cutting speed (v) m/min. 100, 120, 140, 160, 180, 220, 240, 260, 280, 300 feed rate (f) mm/rev. 0.12 depth of cut (d) mm. 0.5 environment dry d. observations on tool wear and tool life the main objective of the present study is to evaluate the tool life of ti [c,n] mixed ceramic cutting tools on machining astm a276 steel (hrc 42) by measuring tool wear. the average flank wear measurement was observed from five machining tests. the wear measurements were taken using a toolmakers microscope (metzer-model metz 1395) with 30x magnification factor. the machining time was accurately measured with a stopwatch. flank wear is one of the main types of wear generally occur while machining hard materials. the machining was stopped periodically to measure flank wear of the cutting tool. the tool life of the cutting tool is considered as per ‘iso standard 3685 for tool life testing’ and it is the machining time of the cutting tool when the average flank wear reaches 0.4 mm. the tool life of the ti [c,n] mixed ceramic cutting tool was found out by observing the flank wear of the cutting tool at various cutting speeds. e. tool life model tool life model has been developed using gda. it minimizes an objective function and iterates several time to minimize error. the algorithm updates the model after each iteration and finally converges into local minima. the learning rate is used to specify the number of steps required to reach the local minima. the machining data obtained from turning operation was used to train the model. the trained model was used to predict tool life. the tool life of ti [c,n] mixed ceramic cutting tool on machining astm a276 steel were found out. using the tool life data, tool life models were developed using gda. for comparison, the regression model for tool life has also been developed using least square method (lsm). iii. results and discussions machine learning algorithms learn from the data and predict the output without human intervention. there are several types of machine learning algorithms and linear algorithms are used where the input parameters and output variables exhibit a linear relationship. the aim of the linear algorithm is to find the best-fit model by training the algorithm with given input parameters. the linear algorithms try to minimize the error of prediction finds the appropriate model which has minimum errors. gradient descent is one of the linear algorithms which uses minimization technique. the gda trains the machine learning model and iterates a number of times until it converges into a local minima. tool life prediction plays an important role in the machines that are connected to automated manufacturing system (ams). the change of cutting tool insert should happen at predicted times. so, tool life prediction is an important process in automated systems and the machine learning algorithms play vital role in automation. using the experimental machining data, the tool life model was developed using gda. in addition to the machine learning model, tool life model using conventional lsm was also developed for comparison. machining studies carried out and experimental data of the life and cutting speed plotted in figure1. issn: 2580-0817 journal of mechanical engineering science and technology 148 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) fig. 1. cutting speed vs. tool life of ti [c,n] mixed ceramic cutting insert a. tool life model using gradient descent algorithm tool life model using gda was developed. gda works well, if the dependent variables and independent variables have a linear relationship. the machine learning model using gda was developed using taylors’s equation vtn = constant. this equation can be slightly modified to have linear relationship. vtn = c ....................................................................................................... (1) by taking logarithm, log v + n log t = log c .................................................................................... (2) by rearranging, log t = (1/n) log c –(1/n) log v ...................................................................... (3) where v – cutting speed in m/min; t – tool life in minutes; c & n constants the above equation can be rewritten in the form of y = a+ bx, which represents the logarithmic linear relationship between cutting speed and tool life. the tool life found out from the experimental machining studies were used to develop the tool life models. using gda, the tool life model was developed and the constants of the models were found out. the gda iterates and finds out best possible model with minimum error. the algorithm was trained to predict using the given input independent variable ‘x’ and the output dependent variable ‘y’ tabulated in table 4. from the dataset given in the table, the tool life model using gda was developed. even though dataset contains less variables, it is the sample tool life model and similar larger number of industrial datasets can be used to develop tool life model with same accuracy. 0,00 5.00 10.00 15.00 20.00 25.00 30.00 80 120 280 320 t o o l l if e ( m in .) 160 200 240 cutting speed (m/min.) 149 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) table 4. machining dataset of input variable ‘x’ and the output variable ‘y’ s.no input variable ‘x’ output variable ‘y’ 1. 2 1.41664051 2. 2.07918125 1.38021124 3. 2.14612804 1.31175386 4. 2.20411998 1.27415785 5. 2.25527251 1.24303805 6. 2.34242268 1.19865709 7. 2.38021124 1.17026172 8. 2.41497335 1.13987909 9. 2.44715803 1.11058971 10. 2.47712125 1.08635983 the model was trained using gda and for every iteration, root mean square error (rmse) was found out. the number of iterations was more as smaller dataset needed more training time. the rmse vs. number of iterations is depicted in figure2. the machine learning algorithm iterations were carried out with a learning rate of 0.3, until it reached local minima. the iterations were stopped when the next iteration rmse value was greater than the current iteration value. the local minima was converged at 23610th iteration. the learning rate of the machine learning algorithm was varied to 0.1 and 0.2, to analyse the effect of learning rate for convergence to local minima. the convergence point of the local minima was observed and it was plotted in figure3. for the same dataset tool life model was developed using lsm. fig. 2. rmse vs. number of iterations the tool life models developed using gda and lsm are given below. gradient descent algorithm (gda): y = 2.788458 0.683752 x .................. (4) 0 0.5 1.0 1.5 2.0 2.5 0 5000 10000 15000 20000 25000 r m s e number of iterations issn: 2580-0817 journal of mechanical engineering science and technology 150 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) least square method (lsm): y = 2.868808 0.719076 x ............................. (5) fig. 3. number of iterations required for convergence vs. learning rate b. comparison of the tool life models the tool life model based on gda and the tool life model based on lsm were compared for the rmse. it is used to measure the difference between the predicted values and the observed or actual values. rmse is a measure of the spread out of the errors from the regression line. the rmse of the tool life model using gda and that of the tool life model using lsm is compared in figure4. from this figure, it can be observed that the tool life model using gda has lower rmse than the tool life model using lsm. it is also can be observed that the rmse error is very minimum for the gda tool life model. the validity and significance of the model was found out using coefficient of determination. the coefficient of determination is also known as r-squared (r2), assesses the linear relationship is between two variables. similarly, the adjusted r squared (r2 adj.) determines the extent of the variance of the dependent variable by all independent variables. the r2 value and r2 adj. value of tool life model using gda are: r2= 0.994084 and r2 adj. = 0.99334. it can be observed that the machine learning model has significance level of 99%. fig. 4. comparison of rmse of tool life models based using gda and lsm 0 10000 20000 30000 40000 50000 60000 70000 0 0.1 0.3 n o . o f it e r a ti o n s 0.2 learning rate 0 0.002 0.004 0.006 0.008 0.01 0.012 lsm gda r o o t m e a n s q u a r e e r r o r 151 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) c. prediction of tool life in order to validate the machine learning tool life model, machining studies were carried out and tool life were evaluated for various cutting speeds. using the machine learning tool life model, tool life were predicted for the given cutting speeds. the predicted values for the test data set and the actual values are compared and observed that the percentage of error is very minimum and the error is not more than 0.3 % in the given test. fig. 5. comparison of predicted tool life with actual tool life the average percentage of error is 0.17% and the accuracy of the model is 99.83%. even though the model is very simple, it is very effective for predicting tool life. the output data is converted to tool life and the predicted tool life and the actual tool life is presented in figure5. from this figure, it can be inferred that the predicted tool life values are very close to the actual tool life values. hence, the gda can be successfully implemented for tool life prediction. iv. conclusions machining studies were conducted using ti [c,n] mixed alumina based ceramic cutting tool on astm a276 martensitic stainless steel. the training dataset and test data were obtained by evaluating the tool life experimentally. tool life model was developed using gradient descent algorithm. for comparison, tool life model based on least square method was also developed. different learning rates were attempted to improve the performance of the model. root mean square error was evaluated with various learning rates and the convergence with minimum number of iterations occurred at a learning rate of 0.3. the tool life model was validated using r square and adjusted r square and it was found that the model had a significance level of 99%. tool life prediction were carried out using the test data and the model had an accuracy of 99.83%. the predicted tool life values are very close to the actual tool life values. the gradient descent algorithm was successfully implemented for tool life prediction. references [1] rahul, r., alok kumar, d, “a review on cutting of industrial ceramic materials”, precision engineering, vol. 59, pp. 90-109, 2019. 0 5 10 15 20 25 30 110 130 150 170 190 210 230 250 270 290 t o o l li fe ( m in ) cutting speed (m/min) predicted tool life actual tool life issn: 2580-0817 journal of mechanical engineering science and technology 152 vol. 4, no. 2, november 2020, pp. 144-152 daniel & kumar (tool life prediction of ti [c,n] mixed alumina ceramic cutting tool) [2] fei, y.h., huang, c.z., liu, h.l., zou, b., “mechanical properties of al2o3–tic– tin ceramic tool materials”, ceramic international, vol. 40 (7), pp. 10205-10209, 2014. [3] ronald l. k., and donald r. h., high chromium ferritic and martensitic steels for nuclear applications, astm international, west conshohocken, pennsylvania, usa, pp. 5-27, 2001. [4] mikołajczyka, t., nowickib, k., bustilloc, a., yu pimenovd, d., “predicting tool life in turning operations using neural networksand image processing”, mechanical systems and signal processing, vol. 104, pp. 503 – 513, 2018. [5] gouarir, a., martínez-arellano, g., terrazas, g., benardosand, p., ratchev, s., “inprocess tool wear prediction system based on machine learning techniques and force analysis”, procedia cirp, vol. 77, pp. 501 – 504, 2018. [6] wu, x., liu, y., zhou, x., and mou, a.,“automatic identification of tool wear based on convolutional neural network in facemilling process”, sensors, vol. 19, pp. 3817, 2019. [7] karandikar, j., “machine learning classification for tool life modeling using production shop-floor tool wear data”, procedia manufacturing, vol. 34, pp. 446 – 454, 2019. [8] schwenzer, m., miura, k., and bergs, t., “machine learning for tool wear classification in milling based on force and current sensors”, iop conference series materials science and engineering vol. 520, 2019. [9] hui, y., mei, x., jiang, g., tao, t., pei, c., and ma, z., ”milling tool wear state recognition by vibration signal using a stacked generalization ensemble model”, shock and vibration, vol. 2019, pp. 7386523, 2019. [10] neef, b., bartels, j., and thiede, s., “tool wear and surface quality “monitoring using high frequency cnc machine tool current signature”, 2018 ieee 16th international conference on industrial informatics (indin), 2018. [11] wu,d., jennings, c., terpenny, j., kumara, s., and gao, r.x., “cloud-based parallel machine learning for tool wear prediction”, journal of manufacturing science and engineering, vol. 140(4), pp. 041005, 2018. [12] mart ́ınez-arellano, g., terrazas, g., and ratchev, s., “tool wear classification using time series imaging and deep learning”, the international journal of advanced manufacturing technology, vol. 104, pp. 3647 – 3662, 2019. [13] kilundua, b., dehombreuxa, p., and chiementin, x., “tool wear monitoring by machine learning techniques and singular spectrum analysis”, mechanical systems and signal processing, vol. 25, pp. 400 – 415, 2019. journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 70-80 70 doi: 10.17977/um016v3i22019p070 the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel dani hari tunggal prasetiyo1, nasrul ilminnafik2*, salahuddin junus2 1postgraduate student in mechanical engineering, faculty of engineering, university of jember, indonesia 2department of mechanical engineering, faculty of engineering university of jember, indonesia *corresponding author:nasrul.teknik@unej.ac.id abstract kepuh biodiesel fuel (sterculia foetida) is an alternative fuel that can be used to replace fossil fuel. diesel fuel is performed to determine the laminar burning velocity and high flame by adding biodiesel kepuh volume of 10%, 20%, 30%. the purpose of this study was to study the effect of biodiesel and the effect of bunsen burners on the laminar burning velocity and flame height. bunsen burner is made of copper and stainless steel. testing of flame characteristics was carried out by heating the mixture of fuel and air at a temperature of 200°c. the purpose of heating the air is to prevent cooling when mixed with fuel. the mixture of fuel and air flowed into the mixing chamber and bunsen burner. the mixture of fuel and water flows into the mixing chamber and bunsen burner to form a fire. flame images were recorded using a high-speed fuji film camera with a speed of 480 fps with a resolution of 224x168. the test results were analyzed by measuring the angle and height of the flame using the freeware imagej program. the results of the b0 (diesel oil without the addition of biodiesel) fuel mixture test using copper bunsen burner produced a maximum laminar flame speed of 23.626 cm/s at φ = 0.8. the highest value of the b30 fuel mix flame (30% biodiesel + 70% diesel oil) produces a maximum flame value using a stainless steel bunsen burner with a value of 25.417 mm at φ = 1.2. the results showed that b0 in copper bunsen burner had the highest laminar burn rate. the composition of the fuel and bunsen burner affects the combustion characteristics and flame height. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: biodiesel, equivalent ratio, flame angle, flame height, laminar burning i. introduction the increase in the human population is followed by the rise in energy consumption. currently, the use of energy is more dominant in fossil energy, petroleum in particular [1]. consumption of fossil fuel oil reduces petroleum reserves of available fossil fuels [2], [3]. petroleum reserves are running low, and alternative energy sources that are renewable are being used, including biodiesel [4]. biodiesel is obtained from the esterification and transesterification by converting triglycerides into methyl esters. the process of converting vegetable oil into biodiesel is simple and requires a reaction at low temperatures [5]. biodiesel is an option to replace fossil fuels without modifying diesel engines [6]. kepuh oil is crude oil from the seeds of the kepuh tree (sterculia foetida). kepuh tree seeds are not among foods that is used as staple consumption by most people [7]. the composition of kepuh oil consists of fat (51.78%), protein (21.61%), starch (12.1%), sugar (5%), cellulose (5.51%) and ash (3.9%) [8]. kepuh biodiesel produces optimal performance in diesel engines and low exhaust emissions when compared to conventional fuels. kepuh biodiesel has the potential to be produced into biodiesel as a substitute for issn: 2580-0817 journal of mechanical engineering science and technology 71 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) fossil fuels [9]. research on the production and nature of kepuh biodiesel has been carried out by ong et al. (2013), and it is recommended to conduct further research on its combustion [14]. premixed combustion research has been carried out with castor oil [1], kapok oil [3] and biogas [10, 11]. premixed combustion requires a stationary state because it affects the stability of the flame. the stationary state of combustion occurs when the reactant speed is equal to the speed of the flame propagation. in the premixed combustion test, the stationary combustion condition occurred at an equivalent ratio = 1. the equivalent ratio greatly affects the speed of laminar combustion. the equivalent is a comparison of the stoichiometric air-fuel ratio (afr) with the actual afr [1], [13]. premixed combustion testing using a cylinder type bunsen burner on vegetable oil biodiesel showed the laminar rate would decrease when the equivalent ratio increases until blow-off occur [13]. a test by varying the equivalent ratio and fuel showed that an increase in the equivalent ratio causes the laminar rate to decrease. the decrease is due to the equivalent ratio of the rich fuel so that the angle of flame formed is smaller and the reactant speed is low. excessive air conditions may also cause a decrease in heat and combustion efficiency [1]. kepuh biodiesel fuel research is often carried out on a 4-stroke 1 cylinder diesel engine with observations on emissions, fuel consumption and engine performance tests [9], [12]. however, experiments using premixed combustion on kepuh biodiesel are rarely done. therefore, this research tries to understand the combustion characteristics of the premixed kepuh biodiesel by using an open cylinder type bunsen burner. the bunsen burners are made of stainless steel and copper. the difference in the bunsen burner material aims to determine its effect on the characteristics of kepuh biodiesel flames. excess air causes a decrease in the heat, so the combustion efficiency is less than optimal. therefore, we need a combustion media that has good thermal conductivity so that heat is not wasted. ii. material and methods the research was conducted by testing the combustion characteristics of diesel fuel blend with kepuh biodiesel. the composition of the fuel is shown in table 1. before researching the combustion characteristics, the kepuh biodiesel is tested to determine the calorific value (astm d88), density (astm d1298), viscosity (astm d3588) and (astm d88) flashpoints. table 1. composition of diesel fuel with kepuh biodiesel fuel fuel percentage b0 100% diesel fuel + 0% kepuh biodiesel fuel b10 90% diesel fuel + 10% kepuh biodiesel fuel b20 80% diesel fuel + 20% kepuh biodiesel fuel b30 70% diesel fuel + 30% kepuh biodiesel fuel 72 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) ca m e r a camera bunsen burner air heater fuel heater syringe pump silicon hose compressor mixing chamber flow meter figure 1 shows the test apparatus of laminar burning velocity and flame height. fuel was supplied to bunsen burner (10 mm in diameter and 140 mm height) by a syringe pump (1 ml/min.) through pipe heated at 200°c. air is supplied to bunsen burner by the composer through pipe heated at 200°c too. fuel vapor and air mixing in the mixing chamber and ignited on a bunsen burner. the flame on the bunsen burner was recorded using high-speed camera 480 fps for analysis. fig. 1. laminar burning velocity and flame height test apparatus. the amount of air supplied in each fuel mixture composition is shown in table 2. table 2. air supply for each fuel. φ b0 b10 b20 b30 ml/min. φ 0.8 3.722 4.056 3.657 3.565 φ 1.0,0 2.977 3.245 2.925 2.852 φ 1.2 2.481 2.704 2.438 2.377 from the flame, we obtain the height (h) and the angle of flame (α) measured in the inner flame cone, as shown in figure 2. fig. 2. testing the height and angle of flame of biodiesel thermo control issn: 2580-0817 journal of mechanical engineering science and technology 73 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) from the results obtained, the laminar burning velocity can be calculated using the equations (1) and (2) [3], [5]. .................................................................................. explanation, sl : laminar burning velocity (cm/s) v : reactant speed (cm/s) α : the angle of the flame .................................................................... explanation, v : reactant speed (cm/s) qair : air discharge (ml/min.) qfuel : fuel discharge (ml/min.) a : bunsen burner cross-sectional area (cm2) iii. results and discussion fuel characteristic the characteristics of this research include the calorific value, density, viscosity and flash point as shown in table 3. the biodiesel fuel test results have met the standard parameters of calorific value, viscosity and density so that biodiesel fuel can be used as a mixture for diesel fuel produced by pt pertamina indonesia, which is used now. table 3. fuel characteristic characteristic sni diesel fuel* kepuh biodiesel** calorific value (kal/gram) 10,602 11,100 density (kg/m3) 815-890 840 viscosity (cst) 2.0 – 6.0 3.1 flashpoint (°c) 100 85 reference : *sni diesel fuel [4]; **current research laminar burning velocity (sl) the results of the laminar burning velocity research are shown in table 4, 5, 6 and figure 3, 5 and 7. the results of the study were calculated using equations (1) and (2). equation (1) is used to calculate the value of laminar burning velocity and then to find the value of our reactant speed using equation (2). from figure 3, it is shown that the maximum laminar burning velocity is found at the b0 fuel blend than the others. the increase in laminar burning velocity at b0 is due to increased combustion energy in the fuel mixture. increased combustion energy causes (1) (2) 74 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) long-chain saturated fatty acids and glycerol to be very low. in addition, low glycerol is affected by air discharge. increased airflow causes glycerol to react quickly [3]. we observe that the air discharge at b0 is higher compared to b10, b20 and b30 the comparison of air discharge shown in table 1. fig. 3. the laminar burning velocity with stainless steel and copper bunsen burner at φ = 0.8 besides the lack of air discharge, the angle of flame at b10, b20 and b30 formed tends to be lower compared to the larger angle of flame of b0. in figure 3, the angles for each of the b0, b10, b20 and b30 fuel flames in the stainless steel bunsen burner are 17.31˚, 15.54˚, 14.51˚ and 13.37˚, respectively. whereas for the copper bunsen burners, the angles are 17.50, 15.67˚, 14.85˚ and 13.69˚ respectively. this indicates that the laminar burning velocity is proportional to the flame angle [1]. here it shows that the b0 is more combustible compared to kepuh biodiesel fuel. the laminar burning velocity values for each fuel are shown in table 4. table 4. laminar burning velocity at φ = 0.8 bunsen burner b0 b10 b20 b30 (cm/s) copper bunsen burner φ = 0.8 23.626 23.123 19.779 17.930 stainless steel bunsen burner φ = 0.8 23.527 23.094 19.461 17.410 the value of the laminar burning velocity with the copper bunsen burner is higher when compared to a stainless steel bunsen burner. copper has a better thermal conduction emissivity so that the heat of the bunsen burner copper is spread evenly and faster; the material also tends to store heat [15]. this causes the glycerol and fatty acids to break down easily [3]. the flame image at φ = 0.8 is shown in figure 4. issn: 2580-0817 journal of mechanical engineering science and technology 75 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) (a) stainless steel bunsen burner (b) copper bunsen burner fig. 4. biodiesel flame at φ = 0.8 in figure 5 it is shown the laminar burning velocity for φ = 1.0 shows the decrease in laminar burning velocity when compared to φ = 0.8 (in figure 3). the reduction in laminar burning velocity is due to an increase in the equivalent ratio, which results in a decrease in the value of the flame cone angle [1]. another factor is the decrease in reactant speed which is influenced by the increase in density and viscosity of fuel [16], [17]. the increase of density and viscosity causes the molecules to move less freely and cause the laminar burning velocity to decrease. the highest value of laminar burning velocity is from the mixture of b0 with 16.903 cm/s. this is using the copper burner as the stainless steel bunsen burner has a lower value due to stainless steel characteristic to release heat more [15]. fig. 5. the laminar burning velocity with stainless steel and copper bunsen burners at φ = 1.0 the laminar combustion velocity values for each fuel at φ = 1.0 are shown in table 5. table 5. laminar burning velocity at φ = 1.0 bunsen burner b0 b10 b20 b30 (cm/s) copper bunsen burner φ = 1.0 16.903 15.432 13.311 12.482 stainless steel bunsen burner φ = 1.0 16.752 15.281 13.072 12.187 76 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) the flame image at φ = 1.0 is quite stable and close to stochiometry. pictures of the flame are shown in figure 6. (a) stainless steel bunsen burner (b) copper bunsen burner fig. 6. biodiesel flame at φ = 1.0 fig. 7. comparison of the laminar burning velocity of stainless steel and copper bunsen burners in figure 7, it is shown the comparison of laminar burning velocity values. the values at φ = 1.2 is lower when compared to the laminar burning velocity at φ = 0.8 (figure 3) and φ = 1.0 (figure 5). laminar burning velocity values at φ = 1.2 is shown in table 6. table 6. laminar burning velocity at φ = 1.2 bunsen burner b0 b10 b20 b30 (cm/s) copper bunsen burner φ = 1.2 13.493 12.183 10.092 9.530 stainless steel bunsen burner φ = 1.2 12.834 12.007 9.917 8.903 issn: 2580-0817 journal of mechanical engineering science and technology 77 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) the laminar burning velocity at φ = 1.2 has a fuel-rich afr. the more it is rich in fuel, the more it causes the fuel not to oxidize as a whole. the remaining fuel reacts with outside air, causing diffusion combustion. this combustion at the end of the burner causes the flame angle to become smaller and in return, produces a lower laminar burning velocity value. another factor is also due to the difficulty of disentangling fatty acids and glycerol at φ = 1.2 [3]. the flame image at φ = 1.2 is shown in figure 8. (a) stainless steel bunsen burner (b) copper bunsen burner fig. 8. biodiesel flame at φ = 1.2 flame height the flame height in kepuh biodiesel can be observed in table 7 and figure 9 with stainless steel and copper bunsen burners. the height of the flame increases with the increase in equivalent ratio and fuel composition. table 7. biodiesel flame height test apparatus b0 (mm) b10 (mm) b20 (mm) b30 (mm) φ = 0.8 copper bunsen burner φ = 0.8 18.276 19.565 22.400 23.600 stainless steel bunsen burner φ = 0.8 18.800 20.142 22.600 23.913 φ = 1.0 copper bunsen burner φ = 1.0 21.002 22.400 23.333 24.167 stainless steel bunsen burner φ = 1.0 21.600 22.727 23.810 24.583 φ = 1.2 copper bunsen burner φ = 1.2 22.174 23.043 24.248 25 stainless steel bunsen burner φ = 1.2 22.733 23.821 24.783 25.417 figure 9 shows the comparison of the height of the flames. b0 fuel has a low height flame value when compared to b10, b20 and b30. the height of the flames is influenced by the characteristics of the fuel. kepuh biodiesel has a lower flash point compared to diesel fuel. this value influences the flame ignition and fuel evaporation. a low flash point causes the flame to tend to be more stable and results in a high flame increase [13]. 78 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) fig. 9. comparison of the flame height of stainless steel and copper bunsen burner fuel b30 at φ = 1.2 produced the maximum flame height. b30 flame pattern gets higher and higher until the blow-off because of an increase in the equivalent ratio so that the flame height increases. at φ = 1.2, the composition that reacts is of the rich fuel. rich fuels react by diffusion at the tip of the bunsen burner so that the flame is pushed out and causes the flame to increase [5], [10], [13]. the b30 fuel composition with the stainless steel burner has a higher maximum flame height compared to the copper burner. the height value of b30 flame on the copper bunsen burner is 25 mm while the stainless steel burner is 25.417 mm. this condition is because the stainless steel bunsen burner tends to release heat while the copper bunsen burner is more likely to store heat during the combustion reaction process. the copper bunsen burner has good thermal conductivity, and the heat of the copper burner spreads faster [15]. higher thermal conductivity in the bunsen burner wall affects the height of the fire because this heterogeneous reaction dominates and heat in the bunsen burner wall is evenly distributed so that fuel is not pushed out which causes diffusion reactions [18], [19]. v. conclusion from this laminar kepuh biodiesel combustion study, it concludes that the value of laminar burning velocity using the cylinder bunsen burner will continue to decrease in line with the increase in equivalent ratio until blow off. the maximum laminar burning velocity is found in the b0 fuel mixture due to the increased combustion energy in the fuel mixture. increased energy influence the long-chain saturated fatty acids and glycerol. at the rate of combustion of b0, fatty acids and glycerol are so low that the angle formed is large. increased flame height in the fuel mixture is due to an increase in the equivalent ratio. the maximum flame height was that of fuel mixture b30 with φ = 1.2 on the stainless steel issn: 2580-0817 journal of mechanical engineering science and technology 79 vol. 3, no. 2, november 2019, pp. 70-80 prasetiyo et al. (the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) bunsen burner due to the equivalent ratio with rich fuel and oxidator not oxidizing fully and leaving remaining fuel. this remaining fuel causes diffusion combustion. during this combustion, the remaining fuel is pushed outwards until the edge of the burner. stainless steel bunsen burners tend to have heat-releasing properties while copper bunsen burners are more likely to store heat during the combustion reaction process. references [1] d.b.n. riwu, i.n.g. wardana, dan l. yuliati., “kecepatan pembakaran premixed campuran minyak jarak – liquefued petroleum gas (lpg) pada circular tube burner”, jurnal rekayasa mesin, vol. 7, pp. 41-47, 2016. [2] m.a.a. banjari, l. yuliati, dan a. a. sonief, “karakteristik pembakaran difusi campuran biodiesel minyak jarak pagar (jathropha curcas l) etanol/metanol pada mini glass tube”, jurnal rekayasa mesin, vol 6, pp. 85-93, 2015. [3] i.k.g. wirawan, i.n.g. wardana, r. soenoko, and s. wahyudi, “premixed combustion of kapok (ceiba pentandra) seed oil on perforated burner”, ijred, vol. 3, pp. 91-97, 2014. [4] n. kharis, h. sutjahjono, h. arbiantara, d. setyawan, dan n. ilminnafik, “karakteristik biodiesel dari minyak biji randu (ceiba pentandra) dengan proses transesterifikasi menggunakan katalis naoh”, jurnal energi dan manufaktur, vol. 12, pp. 37-40, 2019. [5] h. bachtiar, b. a. fachri, and n. ilminnafik, “flame characteristics of diffusion of calophyllum inophyllum methyl ester on mini glass tube”, akademia baru., vol. 57, pp.40-47, 2019. [6] misbachudin., l. yuliati, and o. novareza, “pengaruh persentase biodiesel minyak nyamplung–solar terhadap karakteristik pembakaran droplet”, jurnal rekayasa mesin, vol. 8, pp. 9-14, 2017. 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(the flame characteristics of diesel fuel blend with kepuh (sterculia foetida) biodiesel) [11] d.s. listyadi, i. b. erawan, and n. ilminnafik, “analysis of characteristic of combustion flame from biogas fuel mixed with butane”, ijcar, vol. 7, pp. 1228412287, 2018. [12] p.p. sethusundaram, m.vijayakumar., and n. prasanna, “effect of sterculia foetida biodiesel on single cylinder four stroke diesel engine performance and emission”, journal of advances in chemistry, vol 12, pp. 4614 – 4621, 2016. [13] s. b. l. muhaya, ing. wardana, dan d. widhiyanuriyawan, “pembakaran premixed minyak nabati pada bunsen burner type silinder”, jurnal rekayasa mesin, vol. 6, pp. 45-50, 2015. [14] h.c. ong, a.s. silitonga, h.h. masjuki, t.m.i. mahlia and w.t. chong., “production and comparative fuel properties of biodiesel from non-edible oils: jatropha curcas, sterculia foetida and ceiba pentandra”, energy conversion and management, vol. 73, pp. 245–255, 2013. [15] j.wan and a. fan., “effect of solid material on the blow-off limit of ch4/air flames in a micro combustor with a plate flame holder and preheating channels”, energy conversion and management, vol. 101, pp. 552–560, 2015. [16] l. mustiadi, “karakteristik laju pembakaran minyak jarak pagar dengan penambahan partikel karbon bio”, senaspro, pp. 325-329, 2016. [17] s. sukarni, p. partono, d. krisdianto, and r. wulandari, “effect of magnetic field on diesel engine power fuelled with jatropha-diesel oil”, journal of mechanical engineering science and technology, vol. 1, pp. 44-48, 2017. [18] y. yan, h. wang, w. pan, t l. zhang, l. li, z. yang, and c. lin, “numerical study of effect of wall parameters on catalytic combustion characteristics of ch4/air in a heat recirculation micro-combustor”, energy conversion and management, vol. 118, pp. 474–484, 2016. [19] j. zhou, y. wang, w. yang, j. liu, z. wang, and k. cen, “combustion of hydrogen–air in catalytic micro-combustors made of different material”, energy conversion and management, vol. 34, pp. 3535–3545, 2009. journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 59-69 59 doi: 10.17977/um016v3i22019p059 the effect of chlorophyll concentration from papaya leaves on the performance of dye-sensitized solar cell dede rizali1*, heru suryanto2, sukarni sukarni2 1pt. techx innovations indonesia, jl. raya bojonegara km 6, cilegon, banten, indonesia 42454 2department of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang 5, malang, indonesia *corresponding author:dederizali2020@gmail.com abstract dye-sensitized solar cell (dssc) is the third generation solar cell that has sandwich structure consisted of organic dye material and other components such as titanium dioxide (tio2) semiconductor, electrolyte, and substrates (counter electrode and working electrode). the dye in the device was made from green plant chlorophyll such as papaya. this research aimed to find the influence of dye concentration from papaya leaves chlorophyll on the performance of dscc. the discussion covered the output power (pout), fill factor (ff), and efficiency (ɳ). the method in this research was explorative experimental with independent variables such as direct and indirect sunlight. the dependent variables were output power (pout), fill factor (ff), and efficiency (ɳ) from the dssc. the procedures in this research consisted of substrates preparation, tio2 paste production, dye solution preparation, electrolyte preparation, counter electrode preparation, and dssc assembly. the tests on chlorophyll concentration were conducted using spectrophotometry method while the dssc performance test used 1,000 w/cm2 halogen lamp. the results showed that 100% chlorophyll concentration resulted in 3.1295 mg/m3 chlorophyll content type a. the best dssc performance was obtained by the dssc sample that had 100% chlorophyll concentration and 1.1294 mg/m3 chlorophyll content. the direct light of dssc achieved pout of 0.9557 mw, ff of 0.07282, and efficiency of 1.499137%. the dssc with indirect light obtained pout of 0.00455 mw, ff of 0.01535, and efficiency of 0.049863%. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: chlorophyll concentration, dssc, efficiency, fill factor, papaya leaves i. introduction electricity is the main factor in supporting national development. this situation caused the electricity requirement to increase around 3% per year, from 85 twh (2014) to predictably 235 twh (2050) [1]. thus, the fuel availability in the world would gradually diminish; therefore, the efforts in developing alternative electrical energy, including renewable energy, are continuously performed. the last two decades saw the dye-sensitized solar cell (dssc) that could replace silicon solar cell as the energy converter. dssc is a solar cell that is sensitive to photo electrochemical dyes through the transfer of electric charges. the advantages of dssc, among others, are low production cost, a wide range of material, environmentally friendly, and has high efficiency [2]. changing the anode photo using titanium dioxide (tio2) could improve the dssc efficiency [3], other than using synthesis or organic dye. the dye also affects efficiency; for example, the use of ruthenium reaches 13% efficiency [4]. although ruthenium dye achieved high efficiency, it is hard to synthesis and issn: 2580-0817 journal of mechanical engineering science and technology 60 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) has a high cost that is casting doubt in applying the dye in large-scale dssc. dye that is made from plant parts such as leaves, seed, and fruit, can be used as the alternative sensitized in the dssc because they are environmentally friendly and abundant in nature. the contents of chlorophyll, beta-carotene, anthocyanin, and others in a plant can be used for sensitizer [5]. the dye is an organic compound with double conjugated bonds that generates electron transfer. in the dssc structure, dye acts as the sunlight absorber to incite electrons excitation [6]. papaya leaves are a source of chlorophyll-producing plants. the chlorophyll content in papaya leaves is quite high [7]. chlorophyll contains electrons that excite when absorbing sunlight. electrons in the dye are excited when the chlorophyll dye absorbs the photon light. then, the electrons will be transferred to the tio2 photoelectrode layer and passed on to the outer circuit of dssc because the presence of a counter electrode carbon catalyst causes electrons to travel to electrolytes which convert photon energy into electricity [8]. an organic dye influenced dssc performance. the different concentration of organic dye also affected dssc performance [9]. besides, the dssc performance is also influenced by the given light intensity. therefore, this research aimed to find the influence of various dye concentrations that were made from papaya leaves on the dssc performance in various light intensity. ii. material and methods research design this research used explorative experimental design research. it is a method that identifies the base properties of the researched material before testing. the materials were papaya leaves, fluorine-doped tin oxide substrate, titanium dioxide, acetone, distilled water, polyvinyl alcohol (pva), potassium iodide (ki), iodide (i2), and polyethene glycol (peg) 400. the dependent variables of this research were output power (pout), fill factor (ff), and the dssc efficiency (ɳ) whereas the independent variables were the dssc performance test in two conditions, direct and indirect light. preparation of transparent conductive glass the transparent conductive glass that was used here was the fto type in the size of 2.5 x 2.5 cm2. two units of transparent conductive glass were needed to make one dssc prototype. one of the glasses was used for the counter electrode, and the other was for tio2 paste, dye solution, and electrolyte. since this research used four dye concentrations from papaya leaves, there needed eight transparent conductive glasses. cutting the glasses was done using a glass cutter [7]. preparation of tio2 paste the binder solution was created by mixing the polyvinyl alcohol (pva) for 1.5 gr with 13.5 ml distilled water then stirred using a magnetic stirrer at 80℃ for around 30 min. until it thickened. the pva acted as the binding in tio2 paste. gradually, added the tio2 powder until achieved a paste with desired viscosity. binder solution adjustment aimed to get the optimised paste and was performed by controlling 7.5 ml binder solution and additional 0.5 gr tio2 powder [7]. 61 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) preparation of dye dye preparation that was made from papaya leaves chlorophyll extraction was conducted by setting the concentrations for 25%, 50%, 75%, and 100%. the first step was to prepare all the materials such as 100 gr papaya leaves and 500 ml acetone p.a solution (b/v). then, measure the papaya leaves, cleaned it, and drained. cut the leaves into small pieces and blend until smooth. the smoother the leaves mean better extraction. the blended papaya leaves then mixed with 500 ml acetone solution in the beaker glass, stirred using a magnetic stirrer for around 30 min. after, the chlorophyll will be separated from the leaves that made the solution turned green, and the leaves turned white. then, filter the solution using gauze paper (whatman filter paper) to separate the solution from the pulp and obtained 500 ml dye. to get the 25% (v/v) concentrate, there needed to mix 25 ml of papaya leaves concentration with 75 ml acetone. the 50% (v/v) concentration required 50 ml of papaya extract and 50 ml acetone. the 75% (v/v) concentration required 75 ml papaya leaves extract and 25 ml acetone. furthermore, lastly, to get 100% (v/v) concentration, there needed 100 ml pure papaya extract. next, each concentration underwent chlorophyll level test using spectrophotometry method. then, this research performed functional group in each concentration using the ftir (fourier transform infrared spectroscopy). after the tests, each concentration was stored in a closed dark bottle until it was time to make the prototype. preparation of electrolyte electrolytr was prepared by mix and stirr 0.8 gr ki 0.5 m into 10 ml peg 400 solution, then added 0.127 gr i2 into the solution until all materials dissolve entirely. the electrolyte solution was stored in a closed vial bottle [7]. preparation of counter electrode carbon counter-electrode was made by burning the substrate that would be used as the counter electrode using a candle flame that automatically formed carbon in the substrate area. dssc assembly the dssc assembly was conducted after all components were done. first, cut the fto substrate for 2.5 x 2.5 cm2. scotch tape was used to limit and shape the tio2 area for 2 x 2 cm2 using doctor blade method and trim with stirring rod. put it into the furnace at 450℃ for around 30 min. the deposited tio2 then soaked for one day in the dye solution. after they merged, dropped the electrolyte solution evenly. the last step was to unite the active electrode substrate with a counter electrode using a binder clip with 0.5 cm offset at each end of the substrate. repeat the steps for making another dssc prototype according to variations in the concentration of the papaya leaf chlorophyll dye. chlorophyll content analysis chlorophyll content analysis from each concentration variation was conducted using spectrophotometry to find the level and type of chlorophyll in each variant. dssc performance test after the dssc prototype was made for each concentration, next was testing the performance under the direct sunlight and indirect sunlight (reflected light). the light from 1,000 watt/m2 halogen lamp was used because the glow from this lamp is more optimised compared to other types. when the glow of the halogen lamp was used, the input power on issn: 2580-0817 journal of mechanical engineering science and technology 62 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) the solar cell could be obtained by multiplication between light intensity and area of dscc. the light intensity was achieved using the lux meter measurement device. the dssc performance was tested in the direct sunlight with 70,000 lux intensity while the second test used indirect light with 10,000 lux intensity. figure 1 shows the measurement by conducting a series of open-circuit voltage and short-circuit current and obtained the open-circuit voltage (voc), and short circuit current (isc). fig. 1. circuit (a) open-circuit voltage (voc) (b) short-circuit current (isc) figure 2 show the measurement using maximum voltage and maximum current that produced vm and im with loads from potentiometer so that it formed the current and voltage curves and in turn, obtained the maximum voltage (vm) and maximum current (im). fig. 2. schematic measurement circuit of vm and im the output was noted then calculated the fill factor (ff), output power (pout), and dscc efficiency (ɳ) using equation (1) to (6) using the following equation [9]. ff = 𝑉𝑚𝑝 𝑥 𝐼𝑚𝑝 𝑉𝑜𝑐 𝑥 𝐼𝑠𝑐 ............................................................................................ (1) pout = ff x 𝑉𝑜𝑐 x 𝐼𝑠𝑐 .................................................................................. (2) pout = 𝑉𝑚𝑝 𝑥 𝐼𝑚𝑝 𝑉𝑜𝑐 𝑥 𝐼𝑠𝑐 x voc x isc ......................................................................... (3) pout = vm x im............................................................................................. (4) 63 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) ɳ = 𝑃𝑜𝑢𝑡 𝑃𝑖𝑛 x 100% ........................................................................................ (5) ɳ = 𝑃𝑜𝑢𝑡 ir x a x 100%........................................................................................ (6) where: vm : maximum voltage (volt) im : maximum current (a) voc : open-circuit voltage (volt) isc : short-circuit current (a) ir : light intensity (watt/m 2) a : dssc area pin : input power (watt) pout : output power (watt) ff : fill factor ɳ : efficiency(%) iii. results and discussions chlorophyll extraction analysis figure 3 presents the papaya leaves dye in each concentration. (a) (b) (c) (d) fig. 3. papaya leaf chlorophyll with concentration of (a) 25%, (b) 50%, (c) 75%, and (d) 100% this research performed chlorophyll content level from each variant. the results are as shown in figure 4 to figure 8. fig. 4. the chlorophyll content in papaya leaf dye issn: 2580-0817 journal of mechanical engineering science and technology 64 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) the results show that most variants contain chlorophyll type a (figure 4). the plant usually has a dominant type a chlorophyll than type b. extracting the chlorophyll could use alcohol, ether, and acetone solvents [10]. chlorophyll a and b are the strongest in absorbing infrared with 600–700 wavelength and the least in absorbing green light with 500–600 wavelength [11]. the results also point that each concentration has different chlorophyll level; the higher concentration resulted in higher chlorophyll content. the sample with 25% concentration has 0.7787 mg/m3 content and sample with 50% concentration had 1.5233 mg/m3. meanwhile, 75% concentrate sample has 2.7398 mg/m3 and 100% concentrate sample has 3.1294 mg/m3. the lowest chlorophyll dye content of papaya was obtained when the chlorophyll dye concentration was 25% while the highest chlorophyll dye content was obtained when the chlorophyll dye concentration was 100%. thus, the more volume of dye from papaya leaves taken at the time of concentration, the greater the content of chlorophyll content. dssc performance analysis figure 5 shows the prototype of dscc after each prototype from each variant was tested. fig. 6. dssc prototype the dssc prototiype shown in figure 5 was tested that covered power output (pout), fill factor (ff), and efficiency (ɳ). in this research, the dssc performance tests were conducted in two conditions: direct light and indirect light. the intensities between those two conditions were also different. direct light had 70,000 lux, whereas indirect light had 10,000 lux. comparison of output power (pout), fill factor (ff), and efficiency (ɳ) direct light dssc prototype with indirect light dssc figure 6 to figure 8 present the comparison results of pout, ff, and efficiency in the dssc through direct and indirect light. 65 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) fig. 6. comparison of dssc output (pout) between direct light and indirect light fig. 7. comparison of dssc fill factor (ff) between direct light and indirect light although the comparison above shows increases according to the increased level of concentration, the energy conversion process was not optimized. for example, the sample with 100% concentration under direct light, in which the intensity was seven times than the indirect light, had ff value only four times higher than the ff under indirect light based on the division of 0.007282 direct light ff by 0.01535 indirect light ff value. this result did not correlate with the intensity ratio since there were three times the remaining efficiency residue. the pout value from the direct light was 0.9557 mw divided with the value from indirect light of 0.00455 mw, resulted in 210 mw higher value of the sample with direct light. the amount should be considered enormous. however, the efficiency from the direct light was only 30% of the indirect one. the efficiency gap was the result of the 1.499137% issn: 2580-0817 journal of mechanical engineering science and technology 66 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) efficiency of direct light divided with 0.049863% efficiency from the indirect light. achieving the 30% greater efficiency produced is not comparable to the pout produced by 210 mw when it should not be far from the generated pout. fig. 8. comparison of dssc efficiency (ɳ) between direct light dssc and indirect light observed from the intensity comparison, the sample with 100% concentration had ff from direct light with the value of 0.9557 divided by 70,000 lux resulted in 1.04 x 10-6 value. meanwhile, the indirect light ff was 1.535 x 10-6, based on the division of 0.00455 by 10,000 lux. the largest ff occurred in the sample with indirect light, and the lowest was from direct light. the results were inversely proportional considered the largest intensity from direct light. however, the indirect light had a small efficiency of 0.049863% compared to 1.499137% from direct light. the first concern correlated to the high energy usage but low ff and high efficiency. the second was the small energy usage but large ff ratio and small efficiency. all the phenomena are described in figure 9. figure 9 shows the energy conversion with voltage in the standard hydrogen electrode condition. the chlorophyll dye in the dssc prototype had electrons inside that could absorb the light when excited [13]. the electron bounds in chlorophyll dye were high or homo (highest occupied molecular orbital) with the value of 1.0 v in normal condition. when the prototype obtained photon light from the halogen lamp, the light was absorbed by the chlorophyll dye so that the electrons were excited and the photon light overcame the energy bandgap (eg). the dssc prototype with larger intensity had more substantial chlorophyll content. thus, the excited electrons were also the large amount and occurred in the prototype with 100% concentration of 3.1294 mg/m3 content and 70,000 lux intensities. meanwhile, the small light intensity would excite only some electrons, here, occurred in the prototype with 100% chlorophyll of 3.1294 mg/m3 content and 10,000 lux intensities. after the electrons were excited, the energy bounds were small or lumo (lowest unoccupied molecular) with the value 0.7 v that is also called free electron. the electrons then injected into the titanium dioxide (tio2) tape. titanium dioxide acted as the electron acceptor/collector. the energy from this injection was -0.5 v. the electrons, then, were transferred through the outer circuit of dssc to the counter electrode. 67 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) fig. 9. energy systematic diagram and dssc operating principles [12] moreover, since the counter electrode used carbon catalyst, the electrons moved to the electrolyte. the electrolyte had energy bound of 0.4 v. electrolyte redox usually made of iodide and triiodide (i-/i3-) that act as mediators to create the cycle process inside the cell. the hole that was formed in the electrolyte (i3-), due to the electron donor from the previous process, combined with electron and formed iodide (i-). the iodide was used to the donor the electron (0.4 v) in the oxidized dye (1 v) and formed an electron transport cycle. with this cycle, there was a direct conversion of light energy into electrical energy. in the process of converting photon energy into electrical energy, there is a fermi level. the fermi level is the level of energy that is filled by electrons. the fermi level during energy conversion caused the ff in the direct light dssc in this research to the left three times inefficient energy. the residual energy than was used to generate energy from each electron bound until the conversion of the photon into electrical energy. a semiconductor material has sensitive property towards temperature and dssc. the increasing temperature could reduce the dssc bandgap and would influence its parameters such as open-circuit voltage (voc). the increasing temperature linearly affects the open-circuit voltage. the magnitude of this reduction is proportional to voc. the increasing voc resulted in a lower reduction when the temperature increases. the current generated by light was increased slightly along with the increasing temperature. it due to the carriers increase that was produced thermally in the cell. the high temperatures reduced the efficiency due to more significant changes due to the desorption of the sensitizer at higher temperature [14]. therefore, in this study, the efficiency generated by direct light dssc was only 30% times that of indirect light dssc. these efficiency results were very much different from the pout value from the direct light dssc. the fermi level in the direct light dssc prototype with 70,000 lux intensity created larger energy compared to indirect light prototype with 10,000 lux intensities. since the fermi level generated voltage maximum, the direct light dssc obtained larger maximum voltage compared to indirect light. the maximum voltage influenced efficiency. the larger issn: 2580-0817 journal of mechanical engineering science and technology 68 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) maximum voltage created more substantial efficiency and vice versa. therefore, direct light dscc with 70,000 lux intensity had higher efficiency with the value of 1.499127%, whereas the indirect light had 0.049863% efficiency. iv. conclusion the conclusion was that each concentration of chlorophyll from papaya leaves in the dssc greatly influence the generated pout. the higher chlorophyll content produced a higher pout. next, the concentration also affected the resulted ff. the higher chlorophyll content resulted in higher ff. the chlorophyll content of each variation of the concentration of papaya leaf colouring in dssc dramatically affects the resulting efficiency. increasing the papaya leaf chlorophyll content from 0.7747 mg/mm3 to 3.1294 mg/mm3 were able to increase the efficiency of dssc from 0.022% to 1.499%. references [1] a. sugiyono, anindhita, l. m. a. wahid, and adiarso, bppt outlook energi indonesia 2016 bppt. 2016. [2] n. cari, a. boisandi, a. supriyanto, and r. suryana, “studi pengaruh konsentarasi poly (3-hexylthiophene)(p3ht) terhadap peningkatan efisisensi dye sentisitized solar cells,” in seminar nasional 2nd lontar physics forum, 2013. [3] w. shu, y. liu, z. peng, k. chen, c. zhang, and w. chen, “synthesis and photovoltaic performance of reduced graphene oxide-tio2 nanoparticles composites by solvothermal method,” j. alloys compd., vol. 563, pp. 229–233, jun. 2013. [4] s. mathew, a. yella, p. gao, and r. humphry-baker, “dye-sensitized solar cells with 13% efficiency achieved through the molecular engineering of porphyrin sensitizers,” nat. chem., vol. 6(3), pp. 242–247, 2014. [5] m. isah kimpa, m. momoh, k. uthman isah, h. nawawi yahya, and m. muhammed ndamitso, “photoelectric characterization of dye sensitized solar cells using natural dye from pawpaw leaf and flame tree flower as sensitizers,” mater. sci. appl., vol. 3(5), pp. 281–286, 2012. [6] d. dahlan, t. s. leng, and h. aziz, “dye sensitized solar cells (dssc) dengan sensitiser dye alami daun pandan, akar kunyit dan biji beras merah (black rice),” j. ilmu fis. | univ. andalas, vol. 8(1), pp. 1–8, 2016. [7] e. maulana, a. f. prayoga, and s. h. pramono, “pengujian dan analisis performansi dye-sensitized solar cell (dssc) terhadap cahaya,” j. mhs. tek. elektro univ. brawijaya, pp. 1–7, 2014. [8] m. k. nazeeruddin, e. baranoff, and m. grätzel, “dye-sensitized solar cells: a brief overview,” sol. energy, vol. 85(6), pp. 1172–1178, 2011. [9] z. arifin, s. soeparman, d. widhiyanuriyawan, and s. suyitno, “performance enhancement of dye-sensitized solar cells using a natural sensitizer,” international journal of photoenergy, vol. 2017, article id 2704864, 2017. 69 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 59-69 rizali et al. (the effect of chlorophyll from papaya leaves on the performance of dssc) [10] r. halim, a. hosikian, s. lim, and m. k. danquah, “chlorophyll extraction from microalgae: a review on the process engineering aspects,” international journal of chemical engineering. vol 2010, article id 391632, 2010. [11] j. b. harborne, metode fitokimia : penuntun cara modern menganalisis tumbuhan. itb, 1987. [12] a. luque and s. hegedus, handbook of photovoltaic science and engineering. wiley, 2011. [13] m. a. ridwan, e. noor, m. s. rusli, and akhiruddin, “fabrication of dye-sensitized solar cell using chlorophylls pigment from sargassum,” in iop conference series: earth and environmental science, vol. 144(1), 2018, [14] k. sharma, v. sharma, and s. s. sharma, “dye-sensitized solar cells: fundamentals and current status,” nanoscale research letters, vol. 13(381). 2018. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 91-100 91 doi: 10.17977/um016v4i22020p091 characteristics biolubricant enriched with nanoparticle additives: a review zhahra hanif sholiha*, gaguk jatisukamto department of mechanical engineering, faculty of engineering, university of jember, jember, 68121, east java, indonesia *corresponding author:zhahrahanifsholiha95@gmail.com abstract the engine movement mechanism is a system composed of machine elements that contact or rub against each other between these surfaces. surfaces that rub against each other will cause a friction force that causes wear on the surface, so it requires energy to fight the friction force. lubricants are needed to reduce friction and reduce wear rates, where lubricants are generally made of mineral materials. lubricants made from synthetic materials are non-renewable and cause environmental problems. the development of biolubricants as lubricating materials based on animal fats or vegetable oils is continuously being carried out. this study aims to observe the potential of biolubricants based on reviews from various previous research journals. the use of additives in biolubricants is also studied whether the addition of these additives can improve the characteristics of biolubricants. this study shows that the addition of certain additives to biolubricants can improve the characteristics of biolubricants. copyright © 2020. journal of mechanical engineering science and technology all rights reserved keywords: biolubricant, coefficient of friction, lubricants, viscosity, wear rate i. introduction improving a friendly environment and efficiency resistance is important in the engine movement mechanism. development of biolubricants as environmentally friendly lubricants continues to be developed to meet green tribology standards. the use of mineral-based lubricants is generally dominated by the automotive sector, which is about 80%, while the rest comes from synthetic materials and other materials [1]. the lubricating properties of mineral materials are non-renewable and can cause environmental problems. research studies on lubricants from biological materials are continuously being carried out in order to obtain lubricants from biological materials that are better than lubricants from mineral substances. sources of lubricants from biological materials consist of soybeans, cocoa, coconut, jatropha, palm oil, which generally can be grown in tropical areas [2]. biolubricants play an important role in supporting the green tribology program. green tribology is green tribology, namely the coverage of tribology related to friction, wear and lubrication to support environmental sustainability. the united states has used one-third of its energy needs to deal with energy caused by friction. the greater the frictional energy in a movement mechanism will lead to greater energy consumption and the resulting environmental impact [4]. the main review of green tribology aims to preserve and improve the quality of the environment and avoid global warming [5]. the criteria and characteristics of a lubricant must meet six basic standards, namely: viscosity index, total base number, pour point, flash point [6]. biolubricant which has a low 92 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 91-100 sholiha & jatisukamto (characteristics biolubricant enriched with nanoparticle additives) viscosity value can be improved by adding additives, its characteristics as a biolubricant become better. lubricant is a substance that is applied between two surfaces in contact with each other to reduce the friction force and wear rate on the two surfaces [7]. research on the use of cultivable biological materials as biochemical base materials continues to be studied. lubricant substitution from biological materials as a substitute for mineral materials continues to be developed to preserve nature and to increase public awareness of the importance of a green environment [8]. lubricating materials with nano-scale particles are very intensively developed so that the lubricants can reduce friction and wear. the lubrication mechanism is divided into two types: (a) direct lubrication mechanism and (b) indirect lubrication mechanism. nanoparticles are added to lubricating oil to improve its tribological properties, which can reduce the coefficient of friction and wear [9]. figure 1. shows the lubrication mechanism between two contact surfaces for nano particle lubricants. fig. 1. lubrication mechanism on two contact surfaces for lubricating nanoparticles [9]. the basic ingredients for the manufacture of lubricants are classified into three types, namely mineral lubricants, synthetic lubricants and also biolubricants (vegetable oils and animal oils). biolubricant was used as a test material in this study. biolubricant, namely animal and vegetable lubricants obtained from animal and plant fats. lubricants are generally made from mineral oil. the difference between mineral lubricants and animal and vegetable lubricants is that animal and vegetable oils contain unsaturated compounds [10]. the advantage of biolubricant lies in its ability to lubricate and has good properties on wet and humid surfaces when compared to mineral oil. the lubricant layer will provide effective protection against friction. the use of vegetable lubricants are expected to improve the characteristics of lubricants that are environmentally friendly. ii. research on lubricants a. the effect of lubricant variation on viscosity and coefficient of friction and wear rate the main function of a lubricant is to reduce friction and wear that occurs on moving objects rubbing against each other. the science of tribology is a very important part of knowing the characteristics and its application in the engineering field [11]. tribology is the issn: 2580-0817 journal of mechanical engineering science and technology 93 vol. 4, no. 2, november 2020, pp. 91-100 sholiha & jatisukamto (characteristics biolubricant enriched with nanoparticle additives) science of friction, wear, and lubricants. viscosity is one of the physical properties of a lubricant which indicates the viscosity of the lubricant [12]. the viscosity of the lubricant affects the friction efficiency of the contact surface. the greater the viscosity of a lubricant, the greater the drag force. stokes law states that a large viscosity causes a large friction force [13]. the friction force is proportional to the viscosity value of the lubricant. based on the equations of the friction mechanism formula and the stokes law, the coefficient of friction is inversely proportional to the friction force and viscosity [14-15]. table 1. variations in viscosity and coefficient of friction and wear rates [16-21] research on the correlation between the viscosity of 100oc (cst) and the coefficient of friction (cof) can be seen in figure 2. the graph shows that the greater the viscosity value of a lubricant causes the lower friction coefficient value. the results of research regarding the correlation of viscosity and friction coefficient are in line with the equation of the friction mechanism and the law of stokes, namely the greater the viscosity value, the smaller the friction coefficient value. the results of the wear test research can be seen in figure 3. the graph shows the same trendline as figure 2, namely the greater the viscosity value of a lubricant, the lower the wear value [16-21]. fig. 2. graph of viscosity coefficient of friction [16-21] lubricant viscosities (cst) @100c friction (cof) wear (mm) sae 10w/40 4.700 0.108 0.510 sae 15w/40 6.500 0.105 0.500 sae 20w/40 7.800 0.107 0.510 mineral oil 13.689 0.093 0.765 sae 40 15.000 0.114 0.520 soybean oil 7.889 0.112 4.998 palm oil 8.644 0.105 4.175 jatropha oil 8.040 0.095 3.000 stamping oil 11.400 0.075 0.650 94 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 91-100 sholiha & jatisukamto (characteristics biolubricant enriched with nanoparticle additives) fig. 3. graph viscosity – wear [16-21] b. effect of additives on characteristics armuggam et al. [22] studied the effect of rappassed oil plus tio2 additives and found that the power value was reduced by 15%. biolubricant based on vegetable oil added with tio2 additive experienced a 58.1% decrease in wear value from pure organic oil [24]. charo et al. [23] investigated mineral oil sae 10w30 plus additive mos2 obtained 20% reduced wear value. mineral soybean oil coupled with cuo additives resulted in a reduced wear value of 12% [24]. paraffinic oil with the additive mos2 decreased the coefficient of friction by 64% [25]. table 2. effect of additives on biolubricants on decreasing friction coefficient and decreasing wear rate [24-28] lubricant additives reduction of friction reduction of wear paraffinic oil mos2 64% vegetable oil tio2 58.1% rapeseed oil cuo 40% rapeseed oil tio2 15% palm oil tio2 15% 11% sae 10w30 tio2 15% sae 20w40 mos2 20% sae 5w30 mos2 50% polyalphaolefins mos2 40% soybean oil cuo 12% sae 10w40 titanium 32% sae 20w40 graphene oxide 32% sae 15w40 graphite 36% issn: 2580-0817 journal of mechanical engineering science and technology 95 vol. 4, no. 2, november 2020, pp. 91-100 sholiha & jatisukamto (characteristics biolubricant enriched with nanoparticle additives) sharma et al. [26] studied vegetable oil with tio2 added to get a reduced wear value of up to 58.1% compared to pure oil. rapessed oil with added cuo additives decreased the coefficient of friction by 40% [26]. sgroi et al. [27] studied synthetic oil sae 5w30 added with mos2 additives to get a decrease in the value of the friction coefficient of 50%. polyalphaolefins added with the additive mos2 resulted in a 40% reduction in the strength value [28]. singh et al. 2019 [29] examined the tribological performance of sae 10w/40 and sae20w/40 lubricants with the addition of titanium additives and graphene oxide. these additives can reduce the friction coefficient by 32%. improved friction behavior of sae 15w-40 lubricants with the addition of graphite particles. the addition of graphite to sae 15w-40 lubricant can reduce the friction coefficient from 33-36% [29]. c. characteristic biolubricant characteristics of biolubricant can be observed from the test results. there are several characteristics in a biolubricant, namely kinematic viscosity, viscosity index, total base number. the characteristic values of some biolubricants are shown in table 3. table 3. characteristics biolubricant [30] properties soybean oil sunflower oil rapeseed oil castor oil palm oil kinematic viscosity @40°c (cst) 32.93 40.05 45.6 220.6 40.24 kinematic viscosity @100°c (cst) 8.08 8.65 10.07 19.72 7.89 viscosity index 219 206 216 220 110 total base number (mgkohg^-1) 0.61 1.4 1.4 pour point (°c) -9 -12 -12 -27 -21 flash point (°c) 240 252 240 250 220 d. test methods the method in testing that can be used to evaluate the tribological properties of a lubricant can be seen in table 4, done by various researchers on lubricating oil. table 4. summary of test methods [31-35] lubricant test methods variation of lubricants: (1) lubricant sae 40; (2) jatropha oil (mixture)1%, 2%, 3%, 4%, 5% four ball tribotester variation of lubricants: (1) lubricant oil; (2) parafin oil; (3) biolubricant + tio2 four ball tribotester variation of lubricants: (1) commercial oil stamping; (2) comercial oil hydraulic; (3) jatropha oil; (4) rbd palm oil; (5) palm fatty acid four ball tribotester variation of lubricants: (1) mineral oil; (2) synthetic oil; (3) biolubricant comparison of data and results of previous research variation of lubricants: repricoating ratio 1:1 96 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 91-100 sholiha & jatisukamto (characteristics biolubricant enriched with nanoparticle additives) lubricant test methods (1) jatropha oil; (2) rbd palm olein; (3) palm fatty acid distillate; (4) stamping oil; (5) hydraulic oil variation of lubricants: 1. crude jatropha oil / cjo 2. syntethic ester (se) 3. mjo1 (jme:tmp = 3.1:1) 4. mjo3 (jme:tmp = 3.3:1) 5. mjo5 (jme:tmp = 3.5:1) fourball tester based on astm d4172 variation of lubricants: (1) soybean oil; (2) sunflower oil; (3) jatropha oil; (4) palm oil; (5) jojoba oil comparison of data and result of previous research variation of lubricants: 1. sae 10w40 2. sae 20w40 the preparation method is by adding nanoparticles as a synthesis material, a four ball tester and data comparison of previous research results variation of lubricants: 1. jatropha oil / sjo (100) 2. mineral oil / emo (100) 3. b20 (sjo 20 : emo 80) four ball tribotester variation of lubricants: 1. soybean oil 2. sunflower oil 1. ring compression test 2. finite element simulation variation of lubricants: 1. sae40 2. jo10 (jatropha oil 10% : sae40 90%) 3. jo20 (jatropha oil 20% : sae40 80%) 4. jo30 (jatropha oil 30% : sae40 70%) 5. jo40 (jatropha oil 40% : sae 40 60%) 6. jo50 (jatropha oil 50% : sae 40 50%) 1. cygnus wear testing four ball tester variation of lubricants: 1. sae40 80% + molybdenum dysulfide 20% electrostatic charge solid lubricant spray techniques variation of lubricants: 1. sae 40 2. palm oil observation of tool temperature, wear and surface roughness of the lathe is a basic reference for research. variation of lubricants: 1. canola oil + 1.5% graphene observation of the properties and results of grinding using a precision machining process variation of lubricants: 1. mineral oil (5cst) 2. biolubricant (rso) 1. keyence vk-x200 laser scanning microscope (clsm) 2. x-ray absorption near edge structure spectroscopy (xanes) 3. fluorescence yield (fy) 4. total electron yield (tey) variation of lubricants: 1. sae 15w-40 2. sae 15w-40 + graphite linear reciprocating tribometer variation of lubricants: 1. jatropha oil + ethylcellulose (co/ec) 2. sunflower oil + ethylcellulose (hoso/ec) 1. measurement of density and viscosity using a controlled-strain rotational rheometer 2. temperature analysis using differential scanning calorimetry research on tribological properties using ehl and stribeck-curve. variation of lubricants: 1. sae 15w-40 2. sae 20w-50 fourball tester based astm d4172 and astm d2783 issn: 2580-0817 journal of mechanical engineering science and technology 97 vol. 4, no. 2, november 2020, pp. 91-100 sholiha & jatisukamto (characteristics biolubricant enriched with nanoparticle additives) lubricant test methods variation of lubricants: 1. biofuel + sae 20w-40 2. biofuel + biolubricant rapeseed measure smoke emission levels using the avl 43 smoke meter and avl di gas analyzer variation of lubricants: 1. mineral oil – additives 2. mineral oil + 10% tmpto – t10 (trimethylolpropane trioleate) 3. mineral oil + 15% tmpto – t15 4. mineral oil + 20% tmpto – t20 5. mineral oil + 50% tmpto – t50 engine test use 43cc brush cutter 2-stroke engine variation of lubricants: 1. jatropha oil / sjo (100) 2. mineral oil / emo (100) 3. b20 (sjo 20 : emo 80) four ball tribotester iii. conclusions based on previous research studies on the use of additives in biolubricants, the following conclusions are the vegetable oil derived from plants can be used as a biolubricant, but pure biolubricant has a low viscosity so that the lubricant function as a film layer between two contact surfaces is lower when compared to mineral oil; additives need to be added to pure biolubricants to improve their viscosity, so as to reduce the friction coefficient and wear rate on the contact surface; the ability of additives to improve biolubricant characteristics varies greatly depending on the type of biolubricant and additives used; the addition of mos2 additives to paraffinic oil can reduce the value of the largest coefficient of friction, namely 64%, when compared to the combination of additives + biolubricants as follows: tio2 + vegetable oil; cuo + rapeseed oil; tio2 + rapressed oil; tio2 + palm oil. acknowledgment i gratefully acknowledge all the researchers in the field of tribology. without their contribution, this review would have been difficult to do. references [1] talib, n., and rahim, a., "the effect of tribology behavior on machining performances when using bio-based lubricant as a sustainable metalworking fluid", procedia cirp 40, pp. 504-508, 2016. 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[35] kanagasabapathi, n., balamurugan, k., and mayilsamy, k., ”wear and thermal conductivity studies on nano copper particle suspended soya bean lubricant”, journal of scientific and industrial research (jsir), vol. 71, pp. 492-495, 2012. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 82-90 82 doi: 10.17977/um016v4i22020p082 energy and exergy efficiency of double slope passive solar still jandri fan ht saragi1*, wawan septiawan damanik2 1department of mechanical engineering, faculty of engineering, universitas hkbp nommensen pematangsiantar, pematangsiantar, indonesia 2department of mechanical engineering, faculty of engineering, universitas muhammadiyah sumatera utara, medan, indonesia *corresponding author: jandrifan@gmail.com abstract solar desalination functions to filter water, both sea water and brackish water, to produce clean water that is fit for consumption with energy from the sun. solar energy is a renewable energy source that has been widely studied for its use. one of its uses is in a double slope passive solar still where the sun is the main source. energy and exergy obtained from solar energy are not all used to evaporate water in the desalination system, so it is necessary to calculate efficiency energy and exergy in the system. this study aims to obtain data on the amount of efficiency energy and exergy from the double slope passive solar still as well as the factors that affect efficiency energy and exergy. the results showed that energy efficiency was in the range of 30.20% to 55.15% and exergy efficiency was in the range of 0.93% to 5.36%. the factors that influence the amount of energy efficiency and exergy are solar intensity, basin area, basin cover area, amount of water produced and ambient temperature. copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: desalination, double slope solar still, energy efficiency, exergy efficiency, passive solar still i. introduction water is the most important component in life on earth. all living things need water as a source of life, especially for drinking. for humans themselves, the existence of water to fulfill their daily needs is very important. the need for clean water in indonesia is increasing every year. the average water requirement for each human being is 125 to 150 liters per day to meet needs, such as washing, cooking, bathing, and others [1]. recently, the problem that is often experienced is the lack of availability of clean water for consumption or daily needs, especially if it has entered the dry season, many areas lack clean water sources, including state-owned water companies that are no longer able to meet the clean water needs of their people. when the dry season arrives, the availability of clean water is very limited, on the other hand, the high intensity of the sun results in an increase in water consumption for drinking. some well owners with large amounts of water take advantage of this opportunity to make a profit by selling water to the community. for people who cannot afford water, they only rely on cloudy river water for household needs. one of the renewable energy sources is solar energy. solar energy is the largest source found on earth even in the solar system. the use of solar energy as renewable energy can reach 57% [2]. currently the use of solar energy in technology is growing rapidly. many 83 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) companies engaged in technology use solar energy as their energy source, including automotive manufacturers, power plants and electronic equipment. one of the uses of solar energy as an energy source to produce clean water is the desalination system [3]. the basic principle of desalination is to evaporate water into condensate. one of the factors that causes water to evaporate is by providing heat energy [4][5]. the advantage of the water desalination used is that it is able to produce clean water that can be used to meet daily water needs such as drinking, cooking, washing and so on. in addition, this desalination tool is easy to maintain and can be used in areas that lack clean water with high solar intensity. the thermal energy used to evaporate water comes from solar energy through radiant heat transfer. in the desalination process, not all of the thermal energy obtained from the sun is used to evaporate water into condensate. this is what makes it necessary to know how much energy efficiency can be used to evaporate water. the greater the efficiency of energy use, the greater the amount of water produced by the desalination system [6]. the quality of the energy used to evaporate water into condensate water is called exergy. exergy in a double slope passive solar still shows the amount of energy used to evaporate water which is also influenced by the ambient temperature so that the system is in equilibrium with its environment. the value of exergy greatly affects the evaporation and condensation processes. exergy efficiency shows the amount of energy that can be converted into work/effort to evaporate water into condensate water from the total solar exergy that occurs in the system [7]. the amount of efficiency energy and exergy in solar desalination devices has been studied before, including research conducted by chandrashekara and yadav which obtained an internal energy efficiency of 57.1% [8], a study conducted by tiwari and sahota, showed that energy efficiency and exergy efficiency varied between 5.4-54.8% and 0.4-10.7% [9], research conducted by yari, mazareh, and mehr with the magnitude of energy efficiency and daily exergy efficiency of 6.86% and 16.65% [10] and research conducted by sahota and tiwari with 37.78% energy efficiency and 4.92% exergy efficiency [11][12]. the research conducted has differences with previous studies where the ambient temperature and solar intensity are different. previous research was conducted in india with a higher ambient temperature and daytime solar intensity than in indonesia. ii. material and methods the research method used was experimental. the design double slope solar still for experiment is shown in figure 1 and and figure 2. the basin in the desalination device is made of aluminum composite panel with a thickness of 3 mm. the basin is coated with styrofoam and the outside is coated with aluminum foil which prevents heat from escaping from the basin. the basin cover is made of clear glass material with a thickness of 3 mm with a size of 1 x 1 m. the basin is 2000 mm long and 1000 mm wide. at the bottom of the basin a thermocouple is placed to measure the temperature of the water and on the wall of the basin a thermocouple is placed to measure the temperature of the water vapor. on the glass part, 2 thermocouples are placed on the outside and inside so that the thermocouple used in this study is 6. the slope angle of the basin which is covered by glass is 15o at the top so that the water is condensate. in table 1, the dimensions, sizes and symbols used are presented. the basin position is placed towards sunrise and sunset in order to obtain maximum solar intensity. the basin functions as an evaporator where in the basin there is an increase issn: 2580-0817 journal of mechanical engineering science and technology 84 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) in temperature caused by the basin cover made of clear glass. a thermocouple is installed on the inner side of the basin lid or the direction of the sunrise, which measures the temperature of the cover, and two thermocouples are installed on the basin lid that is facing west or the direction of the sun. in addition to thermocouples, other measuring instruments used are the solar intensity sensor and wind speed sensor, each of which is placed beside the basin. data collection time was recorded every 1 hour with data output in ms form. excel. table 1. dimensions, sizes, and symbols symbol value symbol value ab 1,932 m x 1 m αg 0,05 kg 0,78 (w/moc) αb 0,8 lg 0,003 m αw 0,6 ki 0,039 (w/moc) ∈w 0,95 li 0,02 m ∈g 0,95 θ 15o σ 5,67 x 10-8 (w/m2k4) x 0,2595 age 1 m x 1 m mw 38,640 kg agw 1 m x 1 m fig. 1. design double slope solar still data collection was carried out from 08.00 am to 06.00 pm. at the beginning of data collection, water is entered into the basin until it reaches a height of 0.02 m by looking at the control glass on the side of the basin, then begins to record the initial temperature of the water, basin cover, ambient temperature, wind speed, solar intensity and temperature in the basin. . beside the basin there is a reservoir that holds seawater and is used when the water in the basin decreases by opening the shutoff tap. the bottom side of the glass has a groove that is made as a place for condensate water to escape to the reservoir under the basin. the water in the basin will get heat from the sun through the surface of the cover glass which is condensate storage cover glass 1,2,3,4,5,and 6 is thermocouple sun clean water outlet control glass sea water u u 85 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) made to the west and east to get the maximum solar intensity. when the water temperature increases, the water will evaporate. the temperature of the glass will be cooler than the temperature of the water due to the convection heat transfer between the surface of the cover glass and the surrounding air. moisture condenses and condensate water will stick to the inner surface of the cover glass. because the angle of the glass surface to the basin is made 15o so that the water will flow into the channel where the water comes out to the water reservoir which is below the basin. fig. 2. double slope solar still 2.1. heat transfer coefficient the calculated heat transfer coefficient is radiation heat transfer coefficient, convection heat transfer coefficient and evaporative heat transfer coefficient are stated as follows: 1) radiation heat transfer coefficient radiation heat transfer coefficient can be calculated using the formula [9][12]:      546273273 22  giwgiweffrwg tttth  .................................................. (1) 2) convection heat transfer coefficient convection heat transfer coefficient is calculated as follows [9][12]:      3 1 5 10689.2 273 884.0          w wgiw giwcwg px tpp tth ........................................................ (2) where,                 w w t p 273 5144 317.25 exp .............................................................................. (3)                   gi gi t p 273 5144 317.25 exp .............................................................................. (4) issn: 2580-0817 journal of mechanical engineering science and technology 86 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) 3) evaporation coefficient evaporation coefficient is calculated by the following formula [9][12]:            giw giw cwgewg tt pp hh 016273.0 .............................................................................. (5) 4) desalination water desalinated water can be calculated as follows [9][13][14]:   l tth m giwewg ew 3600.   ....................................................................................... (6) where,    ctforv o v txxl 70 46 106166.71 101615.3    .................................................... (7)       ctforv vv o v tx txtx xl 70 39 274 6 107974.4 103132.1104779.9 1 104935.2                      ............ (8) 2.2. energy and efficiency energy hourly of system energy used to obtain distilled water is given as follows [9][11][15]:      bgiwwewgwgiewewgeenhourly atthtthe  , ......................................................... (9) and the thermal efficiency per hour can be expressed as follows [9][11][16][17]:      %100 3600 .. x xtiatia lxmm swgwsege ewwewe th          ............................................................... (10) 2.3. exergy and efficiency exergy exergy value can be obtained by the concept of entropy which is derived from the second law of thermodynamics. exergy efficiency is the ratio of exergy output to exergy input, and is stated as follows [9][14] [18]: inputx outputx ex e e  ....................................................................................................... (11)                                 4 3 1 3 4 1 s a s a swgwsegesunxinputx t t t t tiatiaee .............................. (12) where ts is the sun's temperature 6000 k, whereas for exergy output can be written as follows[9][11][14][15]:                        273 273 ln273 2 gi w agiw b ewgevapxoutputx t t ttt a hee ................................. (13) 87 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) iii. results and discussions energy and exergy in the desalination system comes from solar energy. figure 3 shows a graph of the amount of energy and energy efficiency produced in a double slope passive solar still. in the figure 3, it can be seen that the increase and decrease in energy and energy efficiency are directly proportional. on the second day, the energy efficiency used to evaporate water in the system was 30.20% of the total energy produced, which was around 1.23 kwh. in this case, there is about 2.84 kwh of energy not used to get clean water. this is because the testing time is only carried out until 06.00 pm so that data is no longer recorded after that time. on the fourth day, the total energy generated in the system was 18.89 kwh, amounting to 47.85% or only 9.04 kwh of energy used to evaporate water. the fifth day is a day where the efficiency of thermal energy used is very high, namely 55.15% of the total energy produced of 16.65 kwh. fig. 3. graph of energy and efficiency energy fig. 4. graph of exergy and efficiency exergy 0 10 20 30 40 50 60 0 1 2 3 4 5 6 7 8 9 10 day 1 day 2 day 3 day 4 day 5 day 6 day 7 day 8 e ff ic ie n c y e n e r g y ( % ) e n e r g y ( k w h ) day energy efficiency energy 0 1 2 3 4 5 6 0.00 0.10 0.20 0.30 0.40 0.50 0.60 day 1 day 2 day 3 day 4 day 5 day 6 day 7 day 8 e ff ic ie n c y e x e r g y ( % ) e x e r g y (k w h ) day exergi efficiency exergy issn: 2580-0817 journal of mechanical engineering science and technology 88 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) figure 4 shows a graph of the exergy and exergy efficiency of a double slope passive solar still. from the data obtained, it was found that the exergy value and the lowest exergy efficiency occurred on the second day. the exergy efficiency on the second day was 0.93%. the magnitude of this exergy efficiency indicates that the energy that can be converted into work / business is 0.02 kwh or 0.93% of the total solar exergy that occurs in the system during the test time, which is 2.01 kwh. the low energy, exergy, energy efficiency and exergy efficiency on the second day are caused by the low solar intensity at that time so that the energy and exergy in the system is smaller than the other test days. the exergy efficiency on the fifth day was the largest exergy efficiency at the time of testing, which was 5.36%. the magnitude of this exergy efficiency shows that the energy that can be converted into work / business is 0.52 kwh or 5.36% of the total solar exergy that occurs in the system during the test time, which is 9.70 kwh. the thermal energy contained in a double slope passive solar still is influenced by the radiation heat transfer coefficient, convection, evaporation and the amount of condensate water produced during the process. meanwhile, energy efficiency is strongly influenced by the solar intensity, the cross-sectional area of the basin cover and the amount of condensate water produced. the magnitude of the exergy value is highly dependent on the ambient temperature and the solar intensity and the magnitude of the exergy efficiency value is strongly influenced by the area of the basin cover, the solar intensity, the evaporation heat transfer coefficient, the water temperature in the basin, and the ambient temperature. to increase the efficiency value, what needs to be done is to reduce the surface area of the glass or add coolant to the glass surface so that the amount of water produced is greater and the efficiency will be even greater. iv. conclusions the data from the test results show that the amount of energy and energy efficiency occurring on the second day is the lowest energy and energy efficiency during the test with an energy magnitude of 1.23 kwh and an efficiency of 30.20%. on the fourth day, the energy produced was the largest at 18.89 kwh, while the largest energy efficiency was on the fifth day with an efficiency of 55.15%. the largest exergy in the system occurred on the fifth day with a magnitude of 0.52 kwh with an exergy efficiency of 5.36% and the lowest occurred on the second day with a magnitude of 2.01 kwh with an exergy efficiency of 0.93%. the factors that affect the value of energy and energy efficiency as well as exergy and exergy efficiency in a double slope passive solar still are solar intensity, basin area, basin cover area, amount of water produced and ambient temperature. nomenclature ab = basin area of solar still (m 2) age = surface areaof condensingcover of east side of solar still (m 2) agw = surface area of condensing cover of west side of solar still (m 2) hcwg = convective heat transfer coefficient from water to glass surface (w/m 2 oc) hewge = evaporative heat transfer coefficient from basefluid to east side glass cover (w/m 2 oc) hewgw = evaporative heat transfer coefficient from basefluid to west side glass cover (w/m2 oc) hrwg = radiative heat transfer coefficient from water to glass surface (w/m 2 oc) 𝐼(𝑡) = solar intensity (w/m2) 89 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 82-90 saragi & damanik (energy and exergy efficiency of double slope passive solar still) ise = solar intensity on east side of condensing cover (w/m 2) isw = solar intensity on west side of condensing cover (w/m 2) l = latent heat of vaporization (j/kg) ṁewe = the results obtained from the eastern system (kg) ṁeww = the results obtained from the western system (kg) pgi = partial pressure at glass (n/m 2) pw = partial vapor pressure at water surface (n/m 2) ta = ambient temperature ( oc) tgie = temperature of inner surface of the east side glass cover ( oc) tgiw = temperature of inner surface of the west side glass cover ( oc) tgi = temperature of inner surface ( oc) tv = vapor temperature ( oc) tw = basefluid temperature ( oc) ts = sun temperature ( oc) σ = stephan–boltzman coefficient (w/m2k4) 𝜀eff = effective emissivity 𝜂th = thermal efficiency (%) references [1] saragi, j. h. t., napitupulu, f. h., nasution, a. h., and ambarita, h., “exergy analysis of double slope passive solar still,” iop conf. ser. mater. sci. eng., vol. 725(1), 2020. 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[18] rahbar, n., gharaiian, a., and rashidi, s., “exergy and economic analysis for a double slope solar still equipped by thermoelectric heating modules an experimental investigation,” desalination, vol. 420, pp. 106–113, may 2017. journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no 1, july 2017, pp. 32-37 32 doi: 10.17977/um016v1i12017p032 the strength of moulding sand consisting of a mixture of bentonite, tapioca flour, and sago flour as a new binder formula to improve the quality of al-si cast alloy andoko1, riana nurmalasari1, m. alfian mizar1, retno wulandari1, poppy puspitasari1, avita ayu permanasari1 1department of mechanical engineering, faculty of engineering, universitas negeri malang, semarang street no. 5, malang, east java, indonesia corresponding author: *andoko.ft@um.ac.id abstract the major factors determining the quality of sand casting products are the base sand and the composition of the sand mould and the binding material. in the foundry industry, the most commonly used binder for creating sand moulds is bentonite. however, the price of bentonite is likely to keep rising. this study aimed at discovering a new binder formula associated with the effect of binder composition i.e. bentonite, tapioca flour, and sago flour on the basis of its mechanical and physical properties. the new formula was expected to be a better binder in the production of sand moulds, resulting in high-quality casting products with minimal defects. moreover, it is probable to be much more economical than bentonite. this research focused on testing the moulding sand composition with a number of different binders, i.e. bentonite, tapioca flour, and sago flour, each in a different proportion. the mixture of the moulding sand with each of the three binders will be tested in terms of its mechanical properties including compressive, shear, and tensile strength. based on the test results, sago flour has the highest dry compressive strength of 28.6 n/cm2, whereas bentonite has the highest wet compressive strength, i.e. 11.83 n/cm2 and the highest wet shear strength i.e. 3.16 n/cm2. the binder with the highest dry shear strength is tapioca flour with 18.16 n/cm2. regarding the tensile strength value, bentonite has the highest wet tensile strength of 0.85 n/cm2, while sago flour has the highest dry tensile strength of 1.73 n/cm2.. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: moulding sand, bentonite binder, tapioca flour, sago flour i. introduction rapid technological development has influenced an increased demand for productions, one of which utilises aluminium. as stated by [1], aluminium has been used in a wide variety of products ranging from household furniture to aircraft industry. [2] pointed out that aluminium is lightweight metal with good corrotion resistance. in addition to its corrotion resistance, low density, and good electrical conductivity, aluminium will posses superior physical and mechanical properties if it is combined with certain elements [3]. some of those properties have made aluminium the most commonly used material in production industry. one of the production processes utilising aluminium is metal casting. metal casting is the most important initial process in metal industry [4]. the casting process is performed by melting metals in the melting furnace, pouring it into a mould, and allowing it to solidity until it can be removed from the mould. [5] stated that metal casting is a process in which metals are melted into liquid at a certain temperature, and then poured into the mould prepared beforehand to form the desired shape. casting systems and processes cannot be separated mould. in general, sand mould is the most popular among others types of moulds [6]. in manufacturing sand moulds, the sand is undergone a process of compaction [7]. moulding sand is formed from a mixture of sand, binder and other additional materials. moulding sand is the most frequently used component in metal casting process due to its low production cost, reusability, thermal resistance, ease of operation, and acceptable quality [8]. sand mould casting process is carried out through several stages. the initial stage is placing pattern in the sand to form a mould cavity; molds are usually prepared by compressing the sand [6]. the next stages are as follows: creating a gating system, pouring molten metal into the mould, allowing the molten metal to solidify, breaking up the mould and removing the casting, and cleaning the casting product [8]. mailto:*andoko.ft@um.ac.id issn: 2580-0817 journal of mechanical engineering science and technology 33 vol. 1, no. 1, july 2017, pp. 32-37 andoko et.al (the strength of moulding sand consisting of a mixture of bentonite) the process of metal casting is always associated with defective castings. a number of casting defects commonly occurred are uneven surface hardness, porosity and other defects caused by a collapsed mould. the major cause of defects in the casting process is the properties of the mould, such as low permeability, low compressive strength, low sintering point, and inappropriate sand grain distribution [9]. furthermore, mould might affect the metal hardness and shape [4]. it is in line with [1] who stated that there are many factors influencing sand casting products, some of which are the composition of the mould and the design of the gating system; they should be meticulously determined to prevent the occurrence of defects and to obtain optimum casting products. green sand casting is known for its low-cost production. however, due to its low-strength mould, casting defects can be found mostly in the products of green sand casting in which clay is used as the binder. in order to avoid the aformentioned shortcoming, dry sand can be used as a possible alternative, but it takes a long time for the casting to completely dry. thus, as an attempt to produce a mould that can dry up a short time, this following step can be taken, i.e. by utilising a type of binder which has no drawbacks such as the emergence of gas defects, bad fire resistance, costly production, and complex mold production process. several materials that can be used as special binders are water-glass, resin, cement, flour, and many more [10]. binder, as a vital element in the composition of sand moulds, will affect the quality of casting products [11]. in the present study, the researchers combined bentonite with two types of flour, i.e. tapioca flour and sago flour, as a binding agent of the moulding sand. this mixture was expected to generate a binder formula with a high level of binding that can minimise any potential defects in the casting products. the casting method employed was gravity casting due to the fact that it is a relatively easy and uncomplicated method since molten metal can be transferred into the entire extremities of the mould cavity only by the force of gravity [12-16]. moreover, gravity casting produces succesful castings [17]. there has been a multitude of researches on the composition of moulding sand, one of which was conducted by [18]. through his research, [18] found that the amount of moulding sand had an impact on the surface of the aluminium casting products which could be seen from the level of surface roughness. another research, conducted by [19], showed that the level of clay contained in the moulding sand significantly affected the smoothness and the tensile strength of the casting products. [20] further pointed out that there was a difference in the permeability of mixtures containing various amount of water; the optimum permeability of a mixture containing 10.5% water was 0.233 gr/(cm2/min). in addition, there was an effect of different amount of water to the compressive strength; optimum compressive strength obtained from a mixture containing 9% water was 0.619 kn/cm2. there was an impact of the various amount of water in the mixture of green sand and bentonite on the permeability and the compressive strength of the moulding sand. the mixture of green sand with bentonite consisting 10% water resulted in the most optimum permeability of 54.63 cm3/min and the compressive strength of 50.25 kn/m2. in addition to researches on the composition of moulding sand, there have been a number of previous researchers on the various types of moulding sand. one example was carried out by [21] who analysed the properties of green sand (silica sand, bentonite and water), molasses sand (silica sand, bentonite and molasses), and river sand (river ceper sand and water). the findings suggested that green sand had the highest permeability of 19.5 cm3/min, whereas river sand had the lowest permeability of 1.5 cm3/min. the sand with the highest percentage of graphite was molasses sand with 24.6%, while the lowest was river with 16.26 %. based on the measurement of graphite, green sand had the longest graphite particles with 79.7 μm, whereas river sand has the shortest with 31.38 μm. in terms of the void quantity, the highest number was in river sand (0.65%) and the lowest was in green sand (0.47%). furthermore, the matrix structure of green sand was ferritic while molasses sand was pearlitic. green sand had the highest binding tension of 1.59 n/m2, but the lowest hardness of 89.42 hrb. on the other hand, molasses sand had the lowest of 1.43 n/m2 but the highest hardness 93.8 hrb. the surface of the casting product made of molasses sand was soft and bright, whereas the one made of river sand was rough and dark. despite those distinctive properties, the three kinds of moulding sand possessed the same impact strength of 0.050 j/mm2. the macro images of each specimen showed that they displayed relatively the same fracture. referring to the previous study on fluidity conducted by [28], it was suggested that the higher the pouring temperature and the thicker the casting is, the longer the fluidity is. this study examined the 34 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 32-37 andoko et.al (the strength of moulding sand consisting of a mixture of bentonite) effect of pressure to fluidity on adc 12 using high pressure diecasting technique. the testing on fluidity was undertaken by employing birmingham method and by means of several moulds in the form of plates with different thickness. next, [13] has conducted a study on how the amount of bentonite contained in the moulding sand affects the surface evenness of the casting products and the tendency for aluminium defects. the finding of the micro structure test showed that the casting product with the smallest surface defect is the one made of a mould containing 8% of bentonite. the casting product made of malang sand and containing 10% of bentonite displayed a number of defects: misrun and cold shut (causing molten metal unable to completely fill the mould cavity), sand inclusion, blow hole, pin hole, crush or drop (causing the form of fins, swells, and casting with inaccurate pattern), shrinkage, mould erosion, and rat tail. ii. method the design of this current study is pre-experimental, namely one-shot case study. the necessary data in the test of moulding sand’s compressive, shear, and tensile strength, and permeability was obtained by examining malang sand in which binding matterials had been added. each sample was duplicated three times. the testing samples have complied with with sni 15-0312-1989. several instruments to collect the necessary data were sand rammer, universal strength machine, electrical scale, and heater. the data analysis technique used in this research is descriptive analysis, which sheds light on the comparison of three groups of moulding sand specimens, each of which was given different binder in the process of moulding sand testing. the strength value of each group was averaged out, and the results were compared to the other groups. then, the comparison results of each moulding sand testing were analysed. iii. results and discussion the tests in this study have revealed that bentonite has the highest wet compressive strength of 11.83 n/cm2 and sago flour has the highest dry compressive strength of 28.6 n/cm2. there have been several notable researches that offer support for these findings. the research conducted by [22], for instance, showed that the addition amount of bentonite affected the compressive strength; the more bentonite was used, the higher compressive strength would be. this happened because an increased amount of bentonite would increase the production of silicon dioxide (sio2) as well. next, [4] argued that the amount of bentonite influenced the level of permeability and compressive strength. the more bentonite was added to the mixture of sand, the more pores within the sand grains were filled, resulting in a decreased permeability and an increased compressive strength. [22] further pointed out in his research that there was an effect of the rise in the amount of bentonite on higher compressive strength. the lowest compressive strength of the specimen type a without bentonite was 15.47 kn/m2 or 157.750 gr/cm2. the explanation of this finding is that if there is no addition of silicon dioxide (sio2) to the moulding sand, then the compressive strength will be decreasing. the lowest compressive strength of the specimen type d with 70 gr of bentonite was 74.57 kn/m2 or 760.405 gr/cm2. in other words, the more bentonite was, the more silicon dioxide (sio2) would be generated and hence the higher compressive strength. in metal casting industry, one of the top priorities is managing the cost of production in order to produce high-quality castings at minimum costs. [6] argued that not only the base sand but the binding agent should be reasonably priced to minimise the production cost. bentonite is a binder which has the highest wet compressive strength but relatively costly. one viable alternative the researcher suggested is the use of a mixture of bentonite, tapioca flour, and sago flour. this mixture has 6.7 n/cm2 of compressive strength, which has fulfilled the acceptable standard i.e. 3.45-15.17 n/cm2 [23]. issn: 2580-0817 journal of mechanical engineering science and technology 35 vol. 1, no. 1, july 2017, pp. 32-37 andoko et.al (the strength of moulding sand consisting of a mixture of bentonite) table 1. results of comparing wet compressive strength and dry compressive strength binder wet compressive strength (n/cm2) dry compressive strength (n/cm2) bentonite 11.83 12.16 tapioca flour 5.06 25.16 sago flour 4.9 28.6 b 5% + ts 5% b 5% + tk5% 6.3 6.51 b 5% + ts2,5% + tk 2,5% 6.7 7.51 b2% + ts 4% + tk 4% 5.5 9.71 a research on the use of bentonite mixed with malang sand has been carried out and its findings showed that this mixture generated wet and dry compressive strength of 5.9 and 7.63 (n/cm2) respectively, wet and dry shear strength of 3.08 and 2.7 (n/cm2) respectively, and wet and dry tensile strength of 0.43 and 0.48 (n/cm2) respectively. the sand permeability using bentonite was 190 [27]. a previous study conducted by [29] revealed that the use of different kinds of bentonite mixed with green sand affects the permeability level. the average permeability of using bentonite ultra bent–a, ultra bent–b and bk was 66.00, 76.00, and 60.00 respectively. moreover, these different mixtures affected the strength of the moulding sand as well. the findings showed that different variation of bentonite produced unequal wet compressive strength; the average compressive strength generated by the use of ultra bent –a was 103.67 kn/m2, ultra bent –b was 100.17 kn/m2, and bk was 78.40 kn/m2. in addition to a series of tests on wet compressive strength, the test on dry compressive strength has been undertaken. the highest dry compressive strength of sago flour was 28.6 n/cm2. the sand being dried is more likely to have increasing strength than in wet condition because the water absorbed into the surface of sand grains is drained off [6]. the testing results of the wet and dry shear strength value are shown in the table 2. bentonite had the maximum wet shear strength with a value of 3.16 n/cm2, and a mixture of bentonite and sago flour had a value of 2.53 n / cm2. this mixture can be used as an alternative binder since its wet shear strength value has met the standard of acceptable shear strength of moulding sand i.e. 1.04-4.83 n/cm2 [23]. the dry shear strength value has also been calculated and it was found that tapioca flour had the highest dry shear strength with a value of 18.16 n/cm2. the shear strength of the moulding sand is closely related to its strength when molten metal flows into the mould cavity. table 2. comparison between wet shear strength and dry shear strength binder wet shear strength (n/cm2) dry shear strength (n/cm2) bentonite 3.16 5.86 tapioca flour 2.13 18.16 sago flour 2.18 6.9 b 5% + ts5% 2.53 3.1 b 5% + tk 5% 2.36 7.83 b 5% + ts 2,5% + tk 2,5% 1.9 6.78 table 3. results of comparing the wet tensile strength and dry tensile strength binder wet shear strength (n/cm2) dry shear strength (n/cm2) bentonite 0.7 0.75 tapioca flour 0.85 1.73 sago flour 0.52 0.53 b 5% +sts 5% 0.48 0.6 b 5% + tki 5% 0.45 0.65 b 5% + ts 2,5% + tk 2,5% 0.58 1.03 b2% + ts 4% + tk 4% 0.35 1 36 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 1, july 2017, pp. 32-37 andoko et.al (the strength of moulding sand consisting of a mixture of bentonite) the findings of the tests on wet and dry tensile strength are shown in table 3. tapioca flour has the highest value of both wet and dry tensile strength of 0.85 n/cm2 and 1.73 n/cm2 respectively. upon this ground, a binder made of tapioca flour can serve as an effective alternative to bentonite due to fact that it has met the criterion of appropriate tensile strength i.e. 0.69-4.14 n/cm2. according to [6], lack of tensile strength leads to the mould being fragile, while excessive tensile strength will prevent casting shrinkage, cause cracks, and lead to difficulty in breaking off the mould. a research on the use of tapioca flour as an alternative to bentonite done by [8] showed that the wet compressive strength of the moulding sand was 5.06 (n/cm2) and the dry compressive strength was 25.16 (n/cm2). those values, in line with [23], were considered reaching the standard of acceptable wet compressive strength, i.e. 5-22 psi or 3.45 to 15.17 n/cm2. furthermore, the wet and dry shear strength of tapioca flour is 2.13 (n/cm2) and 18.16 (n/cm2) respectively, while the wet and dry tensile strength is 0.85 (n/m2) and 1.73 (n/cm2) respectively. according to [23], those numbers have already met the standard of adequate tensile strength, which is 1-6 psi or 0.69 to 4.14 n/cm2. the results of this study proved that tapioca flour can be used as an alternative to bentonite as a binder. generally, tapioca flour has similar characteristics to sago flour. this is in accordance with the statement of [24] both tapioca and sago flour have adhesive properties and can form hard glue-like paste. metal casting involving sago flour as an alternative binder has been sparsely performed. there has been done a research in which sago flour was used as a binder for briquetting; 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[29] purwono, andika agus. 2005. pengaruh variasi campuran kadar air pada pasir cetak basah dengan bahan pengikat bentonit terhadap permeabilitas dan kekuatan tekan, (online), (http://www.pustakaskripsi.com), diakses 18 februari 2015. http://www.pustakaskripsi.com), journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 51-58 51 doi: 10.17977/um016v3i22019p051 synthesis and applications of hematite α-fe2o3 : a review muhamad muhajir1, poppy puspitasari1,2*, jeefferie abdul razak3 1mechanical engineering department, universitas negeri malang, no. 5 semarang street., malang, 65142, indonesia 2centre of advanced materials and renewable energy, universitas negeri malang, no. 5 semarang street, malang, 65142, indonesia 3center of smart system and innovative design, fakulti kejuruteraan pembuatan, universiti teknikal malaysia melaka, hang tuah jaya, 76100, durian tunggal, melaka, malaysia *corresponding author:poppy@um.ac.id abstract this article reviewed the hematite α-fe2o3. it focuses on its material properties, nanostructures, synthesis techniques, and its numerous applications. researchers prepared the hematite nanostructure using the synthesis methods such as hydrothermal, and, further, enhanced it by improving the techniques to accommodate the best performance for specific applications and to explore new applications of hematite in humidity sensing. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: application, hematite, material, structure, synthesis i. introduction nano-sized materials and magnetic properties are attracting sufficient attention to scientific interest and have broad application potentials [1], [2]. when the particle is smaller than a nanometer, it changes the magnetic properties and generates new phenomena such as magnetic resistance, superparamagnetism, large coercivity, the decrease of curie/neel temperature, and a low or high magnetization [3], [4]. the causes that make the differences are the severance of exchange bonds between atomic surfaces, large surface/volume ratios, surface roughness, and symmetry breaking. it is even more particular for small particles’ core induced with antiferromagnetic and ferromagnetic by surface spin to dominate magnetic properties. given the importance of antiferromagnetic nanomaterial technology, magnetic synthesis systems with nanoscale and crystallinity dimensions attract the attention of researchers. many researchers encourage the effort in new methods and exploring new nanostructures to improve the performance of various applications and technologies in the current industry. hematite (αfe2o3), as the most stable iron oxide with n-type semiconductor properties (for example = 2.1ev), under ambient conditions attracts scientific and technological interests. therefore, there needs a study of hematite’s effective cost and corrosion as electrode material in photoelectrochemical cells, catalysts, and sensing elements in gas sensors and humidity sensors [5]. this review of nanostructured hematite (αfe2o3) was different from other studies and previously published works. some of the things written in this article are the fundamental properties of nanostructured hematite, a summary of the synthesis methods, the potential 52 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 51-58 muhajir et al. (synthesis and applications of hematite α-fe2o3 : a review) options to exploit hematite and further possible improvements using nanostructured hematite. ii. material properties fe2o3 is a ferromagnetic mineral in dark red color and easily contaminated by acids. fe2o3 has various polymorphs of more than one crystal structure forms. the multiple phases of crystal structure in fe2o3 such as α and γ refer to the octahedral coordination geometry, where fe at the center bounds to six oxygen ligands. the α-fe2o3, also called hematite, has a rhombohedral structure similar to the corundum structure (α-al2o3). this structure is the most common form in the steel industry. hematite mineral is as the primary extraction element of naturally occurring iron. the γ-fe2o3 usually occurs as a magnetite mineral with cubic structure. this mineral is metastable and convertible from the alpha phase at high temperatures. the β stage is a cubic body part that is centered, metastable, and equivalent to the alpha phase at temperatures above 500°c (930°f). fe2o3 is an oxide mineral with semiconductor properties through bandgap averaging 2.1 ev and absorbs ~40% of sunlight [5]. iii. nanostructure of α-fe2o3 studies in hematite’s nanostructures consist of various synthesis processes. nanostructures that grow during the synthesis process depend on factors such as synthesis method, type of precursor, stabilizer, and substrate. additionally, there are other parameters, including variations in temperature and time during the synthesis process. these nanostructures are benefitting various applications because of their unique structural, optical, and electrical behaviors. the α-fe2o3 nanostructures are nanorod arrays, as shown in figure 1 [6], hematite-shaped flowers, micro cubes [7], nanowires [8], nanotubes [9], nanoflakes [10], [11], nanoparticles [12], [2], and nanorod arrays [13], [14]. the applications of its nanostructure reach many utilities such as electrochemical photo water separation, gas sensors, photocatalytic, and lithium-ion batteries. figure 1 shows some morphology of the hematite nanostructures using fe-sem. iv. synthesis of hematite’s nanostructure the commonly used main methods in the combination of nanomaterial α-fe2o3 to obtain the desired nanostructures are vapor-phase-based synthesis, deposition, and liquidphase-based methods. this section only focuses on the most common liquid-based synthesis method and how it changes the morphology and properties of α-fe2o3. the liquid-phase method in the synthesis of α-fe2o3 includes sol-gel, electrochemical deposition, hydrothermal, and solvothermal. the decision to choose this method is because iron oxide is cheaper, most stable, non-toxic, and environmentally friendly. among various liquid phase synthesis methods, the synthesis of α-fe2o3 nanostructures commonly uses electrochemical deposition and hydrothermal techniques. electrochemical deposition is a process in which the layer of metal, oxide, or salt easily attach to the conductor substrate surface using simple electrolysis of solution contains the desired metal ions or their chemical complexes. meanwhile, solvothermal is a synthesis technique of single crystals from solutions in thick-walled steel beams (autoclaves). hydrothermal synthesis is a technique that crystallizes in solution at high temperature and issn: 2580-0817 journal of mechanical engineering science and technology 53 vol. 3, no. 2, november 2019, pp. 51-58 muhajir et al. (synthesis and applications of hematite α-fe2o3 : a review) high pressure. this method produces hematite nanostructures with different morphologies including nanoparticles, microcubes, nanorods, nanorod flower-like and needle-like structures. in most cases, α-fe2o3 hydrothermal synthesis begins with the preparation of a solution containing precursors, stabilizers, and deionization (di) of water as a solvent. the mixed solution then poured into a schott bottle or teflon-line autoclave with high temperature (up to 200°c) for specific hours. after stopping the reaction, the autoclave is cooled naturally at room temperature before continuing to the next characterization step [5]. fig. 1. nanostructure of α-fe2o3; (a) microcubes, (b) nanowires, (c) nanotube, (d) nanoflakes, (e) nanorods, (f) microstructure orientation, (g) sea-urchin shaped, and (h) worm-shaped hydrothermal synthesis influences the formation of nanocrystalline. particle size increases with reaction time. the reaction time of more than 6 hours gives the maximum particle size at acidic ph, which provides a better condition for growth step with the dehydration process [12]. other researchers also carried out a similar method where zn+ controlled the formation of α-fe2o3 microcubes with a constant diameter of 250 nm, and the morphological results showed regular structure [15]. meanwhile, the reaction time after 4 hours did not affect micromorphology. furthermore, the reaction temperature did not significantly affect the particle size and shape of the synthesized hematite microcube. the appropriate zn+ ion concentration to control the size and shape of nanostructures accurately formed zn-doped α-fe2o3. the developed gas sensor shows a high response, good selectivity, and fast recovery time for acetone at a working temperature of 240°c. li et al. (2009) grew a single crystal hematite nanorod using direct mixing of 1.2propane diamine into the solution containing fecl3 which was stirred for 15 min. then transferred the slurry mixture to a hydrothermal stainless-steel autoclave. the sample received at 180°c for 16 hours [16]. mulmudi et al. (2011) obtained hematite nanorods on 54 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 51-58 muhajir et al. (synthesis and applications of hematite α-fe2o3 : a review) a fluorine oxide (fto) glass substrate using the hydrothermal technique that utilized urea as a ph regulator [17]. in this synthesis, fecl3 acted as a precursor and urea acted as the ph regulator. the solution was enclosed in a glass bottle and heated at 100°c for 24 hours. the fto glass substrate was placed vertically in glass vials with a conductive edge facing the vial wall. after the reaction, the nanostructure on the substrate was thoroughly rinsed in di water and annealed at 500°c for 30 min. to get the desired phase. the xrd test results revealed a pure hematite phase after annealing at 500°c for 30 min. with incoming direction [110]. another synthesis declared that hydrothermal in which di water dissolved the fecl3 (0.015 mol) and nano3 (0.1 mol), and the solution that was heated in a closed glass bottle at 100°c for 2 hours produced uniform flower-like architecture with a diameter of 3-5μm [18]. each structure consisted of many nanorods in parallel with the average diameter of around 100 nm and an average length of about 900 nm. the structure of the hematite worm nanorods was formed by two steps in-situ annealing at 550°c and 800°c of ß-feooh nanorods, grown directly on transparent conductive oxide glass [19]. a hollowed porcupineshaped spines nanostructured hematite obtained by a hydrothermal process using fecl3 and na2so4 as raw material with a temperature treatment of 600°c for 2 hours [20]. the hematite nanostructures consisted of well-averaged nanorods with an average length of about 1μm growing radially with hollow interiors. v. applications of α-fe2o3 hematite receives much attention because of its promising characteristics for many applications in electronic, optical, and photonic devices. the interests focus on studies of hematite and hematite as photoelectric chemical solar cell material (pec) [6], [8], [10], [11], [17], [21], and [22]. besides, it is a cost-effective, environmentally friendly, and highly efficient approach, also demonstrating chemical stability above a wide ph range suitable for photocatalytic applications [9], [18]. the diameter size and porosity of hematite nanorods also affect the magnetization properties, which are more sensitive in particle less than 20 nm [13]. also, hematite nanorod was applied to formaldehyde gas sensors (hcho) and lithiumion batteries, which proved that the performance of both electrochemical and gas sensor properties is highly dependent on the diameter size and surface area of brunauer emmettteller (bet). because of the hollow interior and the meeting point between nanorods, hollowed sea-urchin shaped nanostructures facilitate the diffusion of test gases and improve gas kinetics with oxygen, which shows high gas sensing response, short response and recovery time, and long term stability in detecting ammonia, formaldehyde, trimethylamine, acetone and ethanol [20]. in general, there are two types of humidity sensors: relative humidity sensors (rh) and absolute humidity sensors. most humidity sensors are relative humidity, classified into three basic types of humidity sensors: humidity sensors based on ceramics, semiconductors, and polymers. furthermore, absolute humidity sensors are categorized into two classes: solid humidity sensor and mirror-cold hygrometer [23], [24]. polymer humidity sensors can be divided into two basic categories based on sensing mechanisms: resistive type and capacitive type. interdigitated electrodes are used to assemble resistive or capacitive humidity sensors. the structure of capacitive humidity sensors generally consists of four layers of different materials. the thin polymeric film acts as a dielectric herb of the capacitor. changes in relative humidity measured in capacitance are proportional to the polymer/dielectric properties [24]. therefore, the capacitance value increases when water molecules are absorbed into the active polymer dielectric. issn: 2580-0817 journal of mechanical engineering science and technology 55 vol. 3, no. 2, november 2019, pp. 51-58 muhajir et al. (synthesis and applications of hematite α-fe2o3 : a review) in making this device, there are many attempts to increase the sensitivity of the humidity sensor using various types of nanostructured materials and different engineering techniques. they improve the properties of nanomaterials using sno2 [25], tio2 [26], ceo2 [27], and zno [28] [30]. the high sensitivity of the humidity sensor requires a large surface area of nanostructures and better surface morphology for good carrier transportation. the application of relative humidity sensors has been expanded more and more in various fields using these materials, including hematite α-fe2o3 which falls into ceramic (inorganic) materials. the metal oxide-based ceramic type humidity sensor is the most promising material for the application of humidity sensors compared to polymer type-based sensors because of the advantages in mechanical strength, thermal capability, physical stability and resistance to chemical attack. pelino and cantalini have reported a review on humidity sensors and the principle, fabrication and application of si-doped hematite (α-fe2o3) through the sintering method [31] and further analysis of the effect of silica in hematite [32]. because of its intrinsic characteristics in mechanical strength and chemical resistance in most environments, ceramics are significant among other materials and are widely used to meet industrial requirements for sensing devices. the application of pure and doped hematite humidity sensors has been shown to show exceptional moisture sensing properties. increasing the sensitivity of a hematite-based moisture sensor to metal doping can create surface defects or oxygen voids that increase the adsorption of water vapor through high charge densities. hematite-based na+ sensors have been found to show a significant response to rh with fast recovery times among other metal ions, such as li+, mg+, ba+, and sr+ [33]. in another study, a group of researchers found that sr-doped hematite was obtained to achieve sensitivity in 75-100 rh% in air, due to the high porosity of sr-doped hematite seed, which is suitable for use to measure soil water content [34]. based on the literature, the α-fe2o3 nanomaterial hematite has not been widely discussed for the application of humidity sensors in many research publications, especially on increasing the sensitivity and transport of carriers in humidity [35]. therefore, there is a broad view for us to begin the study of the fabrication and characterization of α-fe2o3 nanorod-based humidity sensor arrays to achieve high surface area nanostructures with a high carrier transport. vi. conclusions this article presented an overview of nanostructured hematite (α-fe2o3), which focused on material properties and various nanostructures, specific synthesis methods in hydrothermal techniques, and applications that are useful for current technological demands. previous studies on the structure of hematite nanorods showed strong potential as a sensing element in humidity sensors. based on this literature, the humidity sensor is one of the prospective applications that has not been widely studied using the structure of hematite nanorods. references [1] a. zeleňáková, v. zeleňák, š. michalík, j. kováč, and m. w. meisel, ‘structural and magnetic properties of coo-pt core-shell nanoparticles’, physical review b, vol. 89(10), pp. 104417, 2014, doi: 10.1103/physrevb.89.104417. 56 journal of mechanical engineering science and technology issn 2580-0817 vol. 3, no. 2, november 2019, pp. 51-58 muhajir et al. 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[35] t. a. blank, l. p. eksperiandova, and k. n. belikov, ‘recent trends of ceramic humidity sensors development: a review’, sensors and actuators, b: chemical. vol. 228, pp. 416-442, 2016, doi: 10.1016/j.snb.2016.01.015. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 1-13 1 doi: 10.17977/um016v4i12020p001 physical behavior of thermally affected bronze and brass samiul kaiser1 and mohammad salim kaiser2* 1department of civil engineering, bangladesh university of engineering and technology, dhaka-1000, bangladesh 2directorate of advisory, extension and research services, bangladesh university of engineering and technology, dhaka-1000, bangladesh, tel.: +88-02-9663129; fax: +88-02-9665622 *corresponding author: mskaiser@iat.buet.ac.bd abstract the physical behavior of thermally affected cast copper, aluminum bronze and brass has been studied by subjecting to heating isochronally for one hour at a range of 600°c. it shows that solid-solution hardening takes place into the al added bronze and zn added brass metal. due to heating al forms hard and brittle intermetallic of copper aluminates into the bronze metal which responses some age-hardening effects. the electrical conductivity of the metals increases initially through heat treatment due to stress relieving and finally decreases due to formation of intermetallic precipitates. the color of the heated samples are also studied through tristimulus color parameter ‘l*’, ‘a*’, and ‘b*’ values which were analyzed and evaluated in matlab software. it is found that incorporation of al and zn affects the color of cast cu. the overall change of color occurs with increasing heating temperature due to chemical changes like oxidization, intermetallic formation, dissolution of phases, precipitation coarsening and recrystallization. due to change of hardness and microstructural properties of the experimental metals, the sound intensity level also decreases at high heating temperature. a microstructural study confirms that the cast alloys content the different phases of grains and bring about recrystallized status under heating at 500°c for one hour. copyright © 2020. journal of mechanical engineering science and technology all rights reserved keywords: conductivity, color, cu-alloys, microstructure, precipitates, sound i. introduction achieving the better properties alloying elements are applied to pure metal [1-3]. alloying has a significant impact on increasing or reducing the different physical, mechanical and electrical properties, namely hardness, strength, corrosion, electric and thermal conductivity of metal [4, 5]. the elements are added for improving one property which may affect other properties inadvertently. here, a good procedure is solid solution strengthening of copper [6]. al bronze is an alloy where aluminum is added to copper. the resulting alloy shows stronger and harder behavior than both of pure metals. addition of zinc to copper forms brass which also follows the same. but al is more effective rather than zn in case of strengthening copper and also has a greater detrimental effect on electrical and thermal conductivity [7, 8]. compositions vary, but most modern bronze consists of up to 12% al. in case of brass metal which range of available solid-solution compositions up to 35% zn. tin, mg, ni and si can also be added to strengthen copper [9-11]. however, variation in color is found when alloying elements are added to cu, which depends on the composition. pure copper shows a reddish-brown appearance. brass consists of zinc, iron and lead, and its color can differ from reddish to greenish to brownish-gold 2 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) depending on the varying amount of those constituents. nickel silver, formed by nickel, zinc, iron, lead and manganese, may have a grayish-white to silver appearance [12, 13]. apart from uniqueness in color, copper also has great sound producing characteristics. because of this property, it is used as the main ingredient in cymbals. sn, ni or zn at least one or other elements are alloyed to copper for producing the cymbals. the trace amount silver may be included in the alloys for better performance, but they are carefully controlled to avoid degradation in sound potential [14, 15]. this study expresses the role of alloying elements on copper-based alloys such as aluminum bronze and brass on physical properties like hardness, conductivity, color, sound, microstructure etc. under different heating condition. the equal ten weight percent of each al and zn alloying element was added into copper to isolate the influence of a single alloying element on different properties. ii. material and methods the present study was involved with copper, aluminum bronze and brass metals. commercial pure copper of 3000gm was used to develop the experimental copper. pure copper of 2700gm and pure aluminum of 300gm was used for developing the aluminum bronze and similarly pure copper of 2700gm and pure zinc of 300gm was taken for brass. they were melted in a clay-graphite crucible at 1300±15°c with the help of natural gas-fired pit furnace. a steel mould of 20×100×150 in millimeter was prepared. it was coated inside with a film of water-clay and preheated at 200°c. then the melts were homogenized by stirring and poured at 1200°c in that preheated mould. the chemical compositions of cast copper, bronze, and brass were analyzed by spectrochemical method, and it is listed in table 1. a shaper machine was used to skin out the surface of the cast samples, and 3 mm ⨯ 20 mm ⨯ 20 mm size of coupon was produced from the samples for microhardness and electrical conductivity measurement. similarly, the dimension of 8 mm ⨯ 25 mm ⨯ 35 mm and 5 mm ⨯ 65 mm ⨯ 75 mm was produced for measuring the optical properties and sound intensity level, respectively. the alloy samples were isochronally heated at different temperatures up to 600°c for one hour. the samples were polished with sic abrasive papers of rough one and then the finish one of 1500 grits. after each heat treatment, the microhardness measurements were performed on the polished samples with a micro vickers hardness tester. one kg load for 10 seconds was used for the knoop indenter. at least seven reading of hardness were taken from different places for each sample. electrical conductivity of those heat-treated samples was also measured using a type 979 electric conductivity meter. the images of the heated samples are taken with dslr camera for examine the visual changes. the images of the samples are analysed through matlab software for determining the tristimulus color parameter ‘l*’, ‘a*’, and ‘b*’ values. the changes of these values with respect to different temperatures are shown graphically. a wooden platform was used to measure the sound intensity level of these bell-metal plates. the differently heated metal plates were hanged through a pair of chain and a bearing ball of stainless steel was used to imply force on the metal plates to create sound. an industrially usable digital sound level meter of model “digital sound level meter as804” was used to measure the sound intensity level. the optical metallographic examinations were performed in the standard method. the highly polished specimens were etched in a solution containing ammonium hydroxide and hydrogen peroxide (3%) in 1:1 ratio. the microstructures of etched samples issn: 2580-0817 journal of mechanical engineering science and technology 3 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) were examined using an optical microscope, and some micrographs were viewed and captured. table 1. chemical composition by wt % of experimental copper, bronze, and brass metals metal al zn pb sn fe ni mn si cr sb cu copper 0.001 0.000 0.010 0.004 0.033 0.001 0.000 0.000 0.001 0.000 bal bronze 9.601 0.023 0.013 0.009 0.078 0.007 0.009 0.004 0.007 0.079 bal brass 0.013 10.300 0.012 0.007 0.057 0.005 0.009 0.004 0.007 0.005 bal iii. results and discussions isochronal heating the variation of microhardness after heating isochronally at different temperature of copper, bronze, and brass metals are shown in fig. 1. it is observed that al added bronze metal had shown marginally ageing response. pure cu and zn bearing brass metal have however shown a continuous softening at increasing heating temperatures, with the sudden drop of hardness beyond 250ºc. the experimental results clearly designate that the ageing response exposed by the bronze metal is due to addition of al. during casting and heating, various intermetallic phases are formed by the reaction of al and cu. specially al4cu9 and cu3al2 intermetallic are responsible for the higher hardness of the bronze metal [16]. in case of brass metal, higher hardness is attributable to solute hardening of the zinc solute atoms. softening occurs at initial stage of heating due to stress reliving. at midway stage of heating, bronze metal shows a modest decrease of the hardness due to dissolve of gp zones before formation of metastable phase into the bronze metal [17, 18]. at the high heating temperature, the structures with coarse grains and increased size of precipitates responsible for lower hardness. fig. 1. variation of microhardness due to isochronally heating of copper, bronze, and brass for one hour 0 100 200 300 400 500 600 50 100 150 200 250 300 m ic ro h a rd n e s s , h v temperature, o c copper bronze brass 4 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) the variation of electrical conductivity under different heating temperature of the copper, bronze, and brass metals are depicted in fig 2. initial increase of conductivity is due to stress relieving in the experimental metals. after heating at high temperature, the subsequent drop in conductivity is due to the formation of fine precipitates [19]. fig. 2. variation of thermal conductivity due to isochronally heating of copper, bronze, and brass for one hour color behavior due to heating of copper, bronze, and brass metal, the change of color is examined by tristimulus color parameter ‘l*’, ‘a*’ and ‘b*’ values which are plotted in fig 3 to fig 5 respectively. the ‘l*’ value vs heating temperature graph shows that up to 100°c, there is an increase in ‘l*’ value (fig 3). beyond this temperature, the value starts to decrease greatly up to 250°c and then shows an increase at the higher temperature. the ‘a*’ value vs heating temperature graph indicates the increase of ‘a*’ value up to 100°c and then a minute decrease at higher heating temperature (fig 4). at the initial stage the change of ‘b*’ value shows a similar increased fashion of ‘a*’ up to 100°c (fig. 5). the higher heating temperature at 500°c shows a sudden increase of ‘b*’ values. this study has demonstrated that the increases of ‘l*’ values of the experimental metals due to oxide formation on the surface at a temperature of 100°c. in case of copper, it delayed because of the oxygen diffuse into copper at 200°c in the air [20]. at the intermediate stage of heating, the decrees of ‘l*’ values occurs due to dissolution of some phases present into experimental metals. final stage of heating the bronze and brass metals show the higher ‘l*’ values because of precipitation formation [21]. after heating at 100°c, ‘a*’ and ‘b*’ values of the experimental metals change because of surface oxidation. with the increasing of heating temperature, the oxide layer also enlarged, up to a point. then the layer begins to decompose as the copper gives up the oxygen faster than it reacts. at higher heating temperature, the metal begins to burn from complete heat. at the initial stage a dull, almost invisible red, then a very visible red, then the beginning of orange, and then it melts [22, 23]. 0 100 200 300 400 500 600 10 20 30 40 80 90 100 110 c o n d u c ti v it y , % ia c s temperature, o c copper bronze brass issn: 2580-0817 journal of mechanical engineering science and technology 5 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) fig. 3. change of tristimulus color parameter l* due to isochronally heating of copper, bronze, and brass for one hour fig. 4. change of tristimulus color parameter a* due to isochronally heating of copper, bronze, and brass for one hour 0 100 200 300 400 500 600 74 76 78 80 82 84 86 88 90 l * fr o m b la c k ( 0 ) to w h it e ( 1 0 0 ), a u temperature, o c copper bronze brass 0 100 200 300 400 500 600 -6 -4 -2 0 2 4 6 8 10 12 a * fr o m g re e n ( -) t o r e d ( + ), a u temperature, o c copper bronze brass 6 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) fig. 5. change of tristimulus color parameter b* due to isochronally heating of copper, bronze, and brass for one hour acoustic response behavior variation of sound intensity level with heating temperature of cast copper, bronze, and brass metal are representing in fig. 6. at the room temperature, the sound intensity level is almost close for all the metal. clearly pure copper creates lowest sound intensity with heating temperature, and sudden drop of sound intensity is observed beyond 400ºc. in the case of bronze and brass initially improvement of sound level due to precipitates formation and decreases at high temperature due to precipitates coarsening and recrystallization. zn added brass metal shows a continuous increase from its initial value in acoustic response during impact with the increase in heating temperature up to 400ºc and after that it also suddenly drops which follows the pattern of hardness curve discussed in the previous investigation. this occurred because of precipitation coarsening and recrystallization effect. al added bronze metal shows better response than brass at higher heating temperature due to higher hardness [15, 24]. pure materials typically show the lower strength compared to those which are alloyed with other elements. the alloying elements form different intermetallic phases into the alloys, which reduce the movement of dislocations within the structure. in case of bronze and brass al and zn go to interstitial sites in the lattice which make the obstruction of dislocation movement. so, bronze and brass are achieved the higher strength compared with pure copper. it is also responsible for the formation of grain structure and sizes as well as alloy hardness. very hard, homogenous and extremely durable materials are always favorable for producing inferior sound [25, 26]. observed from the intensity comparison, the sample with 100% concentration had ff from direct light with the value of 0.9557 divided by 70,000 lux resulted in 1.04 x 10-6 value. meanwhile, the indirect light ff was 1.535 x 10-6, based on the division of 0.00455 by 10,000 lux. the largest ff occurred in the sample with indirect light, and the lowest was 0 100 200 300 400 500 600 0 5 10 15 20 25 30 b * fr o m b lu e ( -) t o y e ll o w ( + ), a u temperature, o c copper bronze brass issn: 2580-0817 journal of mechanical engineering science and technology 7 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) from direct light. the results were inversely proportional considered the largest intensity from direct light. however, the indirect light had a small efficiency of 0.049863% compared to 1.499137% from direct light. the first concern correlated to the high energy usage but low ff and high efficiency. the second was the small energy usage but large ff ratio and small efficiency. all the phenomena are described in figure 9. fig. 6. variation of sound level due to isochronally heating of copper, bronze, and brass for one hour optical images observation the optical images of copper, bronze, and brass samples heated at different temperatures were recorded, and they are put on show in figure 7. the images demonstrate that the varying temperature plays a great role in the color deviation of the samples. after heating at 100°c, the color change is noticeable, and it is because of surface oxidation as well as the evaporation of water molecules from the surface [27, 28]. at room temperature, polished copper is a reddish-brown color. initially forms a brown-black layer of cuprous oxide and next a blue-green layer of cupric oxide. with increasing the heating temperature, the oxide layer also enlarges. these layers display a fixed color for individual metals. after heating at 500°c, the colour has changed drastically because of the chemical change through recrystallization and grain growth of the experimental materials [29]. finally, the sample has got its natural state in terms of color. 0 100 200 300 400 500 600 90 95 100 105 110 115 120 s o u n d l e v e l, d b temperature, o c copper bronze brass 8 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) copper bronze brass 25°c 100°c 200°c 300°c 400°c 500°c 600°c fig. 7. optical images of the color variation due to isochronally heating of copper, bronze, and brass for one hour issn: 2580-0817 journal of mechanical engineering science and technology 9 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) optical microscopic observation the optical microstructure of cast cu, al bronze and brass metals is shown in fig. 8. the microstructure of cast copper usually consists of very different sizes of non-uniform grains (fig. 8.a). it is because of the reactivity nature of coppers as the surface cracking, porosity, and the formation of internal cavities are high [30]. the microstructure of cu-10al is found to consist of three phases, namely α-phase, β-phase or retained martensitic β′-phase and surrounded by four different types of fe-rich intermetallic numerous κ-phases (fig. 8.b) [31]. the microstructure of cu-10zn alloy reveals the presence of a single solid phase which consists of a solid solution of zinc in alpha copper (fig. 8.c). this is predictable as zinc has a complete solid solubility in copper up to 35%, which is well documented on the cu-zn phase diagram [32]. fig. 8. optical micrograph of cast a) copper, b) bronze, and c) brass fig. 9 shows the optical micrographs of the experimental alloys after heated at 500°c for one hour. copper grains consist of some annealed twins because of recrystallization behavior of cu, and those annealed twins traverse through the grain completely (fig. 9.a) [33]. the microstructure of cu-10al alloy at the same heat-treated condition contains large numbers of κ precipitates (fig. 9.b). the portion of the α phase into the microstructure becomes amplify. the spaces between polyhedral grains begin to resemble a discontinuous network. the grains consist of annealing twins with circular particles of κ precipitate. dendritic structure with a few precipitates may be visible. from fig. 9.c it can be seen that heated at 500°c for one hour cu-10zn alloy grain size of is higher than the original pure copper due to grain growth at elevated temperature. grains with a few twins and precipitates 25m zn in αsolid solution 25m different grain size 25m α k-phases β ( c ) ( b ) ( a ) (b) (a) (c) 10 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) on boundaries are observed for the heated alloy. the microstructure is a mixture of recrystallized grains and coarse non-recrystallized grains. a homogenized recrystallized microstructure is observed in cu-10zn alloy as well as in pure cu. fig. 9. optical micrograph of cast alloys heated at 500°c for 1 hour, a) copper, b) bronze, and c) brass iv. conclusion pure copper, aluminum bronze, and brass metals were obtained by casting flowed by isochronally heating for one hour at different temperature regimes. from the experimental results, it is understandable that the presence of al and zn significantly increases the hardness of bronze and brass due to solid-solution hardening. additionally, al forms hard and brittle intermetallic during heating which improves the hardness of the bronze metal. as a result sound property also improved. in the case of color behavior, it is also improved through the addition of alloying elements like al and zn. as cast microstructure shows different phases of grains but heating at 500°c for 60 minutes all the alloys reach recrystallized state. acknowledgement all the facilities were provided by the directorate of advisory, extension and research services of bangladesh university of engineering and technology, dhaka-1000 which are gratefully praised and acknowledged. 25m ( a ) ( b ) ( c ) 25m 25m (a) (b) (c) issn: 2580-0817 journal of mechanical engineering science and technology 11 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) references [1] h. chandler, “metallurgy for the non-metallurgist,” asm international, 4th edition, materials park, oh, usa, 2006. 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[30] g. benchaban, z. boumerzoug, t. gloriant and i. thibon, “microstructural characterization and recrystallization kinetics of cold rolled copper,” physica b: condensed matter, vol. 406 (10), pp. 19731976, 1973. [31] m.s. kaiser, “ageing behaviour of minor sc and zr doped cast cu-10al alloys”, international journal of engineering and information systems, vol. 3 (11), pp. 7-14, 2019. issn: 2580-0817 journal of mechanical engineering science and technology 13 vol. 4, no. 1, july 2020, pp. 1-13 kaiser & kaiser (physical behavior of thermally affected bronze and brass) [32] e.e. igelegbai, o.a. alo, a.o. adeodu, and i.a. daniyan, “evaluation of mechanical and microstructural properties of α-brass alloy produced from scrap copper and zinc metal through sand casting process,” journal of minerals and materials characterization and engineering, vol. 5 (1), pp. 18-28, 2017. [33] y. wu, s. huang, q. chen, b. feng, d. shu and z. huang, “microstructure and mechanical properties of copper billets fabricated by the repetitive extrusion and free forging process,” journal of materials engineering and performance, vol. 28 (4), pp. 2063-2070, 2019. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 153-163 153 doi: 10.17977/um016v4i22020p153 moisture reduction of honey in dehumidification and evaporation processes anang lastriyanto1*, sasongko aji wibowo1, erwan2, firman jaya3, jati batoro4, dewi masyithoh5, j.s.a lamerkabel6 1department of agricultural engineering, brawijaya university, malang, indonesia 2department of animal husbandry, university of mataram, mataram, indonesia 3department of animal products technology, brawijaya university, malang, indonesia 4department biological sciences, brawijaya university, malang, indonesia 5department of animal husbandry, islamic university of malang, malang, indonesia 6department of agrotechnology of pattimura university, ambon, indonesia, *corresponding author:asenthil123@gmail.com abstract the high water content of honey can lead to fermentation and accelerate the deterioration of honey. one way to prevent fermentation in honey is to reduce the water content of honey. there are several ways to reduce the water content of honey, namely through a dehumidifier and evaporation. this study aimed to examine the relationship of reduced water content towards time in between dehumidifier and evaporation processes. the research method uses an exponential equation model to determine the value of the constant (k). the constant value (k) is used to predict the rate of reduction in moisture content between the dehumidifier and evaporation processes. the results showed that the water content value after the dehumidifier and evaporation process had met the international standard (si) with a moisture content value of less than 19 %. the initial moisture content of honey before processing was 21.335 %, then after going through the process, the moisture content of honey in the dehumidifier and evaporation processes were 16.397 % and 14.625 %, respectively. the processing time required for decreasing the water content of honey in between dehumidification and evaporation processes also shows a very significantly difference; in the dehumidifier process, the process takes 720 min. while in the evaporation process, it is 50 min. the exponential equation to determine the constant value of k (1/min.) for the dehumidifier is y = 21.262e0.00037x with the value of regression r2 = 0.9943. while the exponential equation formula to determine the constant value of k (1/min.) in the evaporation process is y = 21.961e-0.007x with the regression value represent r2 = 0.9262. copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: dehumidifier, evaporation, honey, moisture content i. introduction honey is considered as a natural food ingredient that has an essential role and have been utilized by human in everyday life since thousands of years ago. honey is a natural liquid that generally has a sweet taste produced by honey bees (apis sp.). it was a flower nectar that collected by bees, in which they will broke it down into simple sugars that are stored inside the honeycomb [15]. the honeys that are produced by honey bees are serves as food supply for their colony. the amounts of honey are abundant during the flowering season and it’s stored inside nest cells as a food supply when the dry season comes. bees produce honey with nectar materials, a liquid containing sugar secreted by plant nectar glands. honey is one of the sweetener that is widely consumed by humans because of its nutritional content. most 154 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) of honey consists of sugar and enzyme complex that allows biochemical reactions to occur. these mechanisms of biochemical reactions will affect the quality of honey, resulted in the changes of the composition, taste, aroma, viscosity, and color. honey has high level of hygroscopic properties, means it is very easy to absorb water from the environment surrounded. thus, the direct contact of air, will increasing honey's moisture content. the high-moisture content of honey can lead to fermentation and accelerate the deterioration of honey. according to the indonesian national standard (sni), 8664 of 2018, the moisture content in honey acceptable by fao (food and agriculture organization) must be less than 22 %, while according to international standards (si) the permissible moisture content of honey is less than 19 %. there is a way to prevent fermentation in honey by reducing honey's moisture content until approximately less than 20 %. a wide range of heating temperatures ranging from 30 to 140 °c for a few seconds to several hours has been practiced by honey producers worldwide to reduce the honey moisture content in honey until it is reaches a value below 20 % in order to prolong their shelf life. on the other hand, heating with high temperatures could affects honey quality, such as the hydroxy methyl furfural (hmf) content and its enzymatic activity, which acts as parameters in determining the honey's quality. the closed system treatment will minimize the volatile fragrance loss during heating processes. the temperature used during heating process will have a significant effect on its moisture content. honeys that are processed at 60 °c had higher (rh) relative humidity 17.98 % compared when they’re heated at 70 °c and 80°c, has the humidity value 17.06 % and 16.40 %, respectively. in which thus temperature had no significant effect on honey moisture content that are packed in glass jars, plastic jars, and poly pack bags. storage method and condition has substantial impact on honey’s moisture content. honey’s moisture content will reduce to 16.41 % when it stored in plastic bottles, while when honeys are stored in poly packaged bag, it is reduced, so it becomes 16.63%. with the initial honey’s moisture content value as big as 18.10 %. these results were observed after 12 months of storage time [2]. the experiments conducted by zarei has resulted in lowering honey's moisture content to less than 20 % after 30 min. of heating at 90 °c [14]. they concluded that the increasing number in temperature is directly proportional to the honey’s moisture content reduction rate. however, heating honey above 90 °c is strongly discouraged due to the cause of caramelization in sugars contains in honey [4]. there are some methods that are used to reduce honey's moisture content, such as utilizing a dehumidifier and through evaporation. dehumidifier is a tool used to control the amount of water vapored in a room. this machine can be either portably or permanently installed in a room. dehumidifier can reduce the relative humidity (rh) level at honey dryer room. the temperature used is usually around 45 °c, but the drying time is relatively very long. other way to reduce honey’s moisture content is using evaporation. evaporation is a technique used to evaporate water in a tube by using a pressure below 1 atm or in a vacuum condition. furthermore, water can evaporate at temperatures less than 100 °c. thus, makes the time used in evaporation method is relatively faster than the dehumidifier method. gill has developed a small-scale honey dehydrator to reduce honey's water content from 25.2 % to becomes 16.4 %. the experiments carried out to reduce the moisture of honey using air drying at room temperature [3]. hot water is discharged in a water jacket around the honey pot to heat the honey. the heated honey pumped through a filter with 122 holes uniform in size, 0.5 cm diameter to form a honey stream through which the drying air passes to remove the honey’s moisture content. the honey flow helps them to increasing the honey's surface issn: 2580-0817 journal of mechanical engineering science and technology 155 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) to be exposed with the air. the maximum drying speed per square meter of honey exposed to drying air at 40 °c is 197.0 g/ hour-m2 while the minimum result (74.8 g/ hour-m2) corresponds to air drying at room temperature 8 -17 °c. yap et al., has developed a desiccant honey dehydrator that heat and dried the air to reducing honey's moisture content using desiccant bed silica gel. re-circulation is used to extend the utilization period in using desiccant bed. moisture reduction was carried out by dehumidified process at 35 °c and 45 °c. resulted in the reduction of honey’s moisture content in the outdoor area. the maximum humidity evaporation rates using dehumidified air, the utilization of ambient air, and by reduce the humidity in an open container at 45 °c are 132 g/hour-m2, 78.7 g/hour-m2, and 52 g/hour-m2 respectively [13]. the other experiment has been examined the evaporation process from raw honey and studied its dynamics process. the research was conducted for three years, using 79 samples of raw honey collected, 79 samples of dehydrated honey, and 69 samples of ripe honey. all of the honey sample was dehydrated using an air dehumidifier. the water content of honey decreased from 22.9 % to 15.95 % in 36 hours [6]. while linkon et al., studied a honey reducer using falling film evaporator. in this multieffect evaporation system, raw honey preheated at (40 – 45) °c and then filtered through an 80 μm polypropylene microfilter. the honey is heated to (60 – 65) °c in order to destroy the osmophilic yeast cells, held the temperature at 60 °c to evaporate the honey moisture content under vacuum condition, and then cooled down before passing the settling tank for further bottling step. the system can process around 300 kg of honey per day. honey samples from three species viz. a., cerana, a., mellifera, and a. dorsata processed in the system. has resulted in the reducing amount of water content in honey from 22.5 % to 18.5 % for a. cerana honey, the reducing value has reached from 21.5 % to 18.5 % for a. mellifera honey, and water content of a. dorsata honey has been through reduction from 24.5 % to 19.5 % [5]. it has been observed that the higher the water content in honey, the higher the percentage of reduction needed at the same time. besides, the more the reduction occurs in honey’s moisture content, there is an increasing number in reducing the sugar value, unit weight, and etc. singh and singh, use heated coils to exchange the heat after recirculated in hot water into honey. the honey is heated until 49°c and then pumped into a 1.2 m × 2.4 m evaporation pan, then heated until 35°c using an air heater. in the form of a thin film with a thickness of 0.025-0.04 m, the honey poured on the pan, the moisture content removed by blowing air onto the pan. in trials, around 75 kg of honeys were dried until its moisture content becomes 17 % in 1 hour using two electric fans [11]. the reducing amount of honey’s humidity stored in vats by heating the chamber until it reached 45 °c using wood stove. the heat in the room will increases the temperature of the honey until 32 °c. a portable air compressor made from 0.95 cm copper pipe, will produced bubbles to even the temperature distribution in honey. warm air is supplied to each barrel to evaporate water from the honey. the fan moves the humid air above the barrel towards the wood stove to remove moisture from the room. the system runs for 19 hours, which resulted in reducing the moisture content from 18.5 % to 17.7 % [7]. other study suggested a method used to minimize the pilled of honey’s moisture content in vats. the barrel was placed in a room and heated until (27 – 30) °c. dehumidifier will absorb the excess moisture from the air. a proper ventilation and ceiling fan for each room will beneficial for adequate air circulation to reduce the humidity [9]. 156 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) ramli et al., made an equipment consisted of a closed housing with an inlet port on the top side and an outlet port on the bottom edge. the honey will enter the inlet port and flows downward across a series of trays arranged in a zigzagged manner up to the outlet port. a metal screen is used on each tray to spread the honey evenly throughout the tray. there are a coil and an evaporator heater used to dry and warm the air circulated over the honey layer to remove moisture. this process claimed in reduced honey's water content from 20 % to 18.5% with an airflow rate around 28 m3/min. and a temperature used around 49 °c [10]. zarei et al., designed a small-scale honey moisture reduction system consisting of a rotating stainless-steel cone with 0.60 m in diameter and 0.65 m in high arranged in an isolated chamber. portable blowers use to supply hot and filtered air. the moisture content of honey was reduced from 25.50 to 22.50 %. that process occurred in a single operation with the air temperature at (65-67) °c was introduced into the system [15]. platt and ellis, have removed moisture from honey using dehumidifier with a thin contact film rotating disc at a speed of 10 rpm. hot air is blown at (45 – 75) °c. the 1,468 g of honey with air velocity at 0.22 m / min. was reduced from 26.6 % to 15.2% in 2 hours in the humidifier. this treatment was reduced honey’s moisture content from 29.6 to 16.9 % in 1 hour when honey flow was 15.3 -16.0 g/min. with airflow at 50 °c and relative humidity value reached 27 % [1], [8]. determination of the value of constant (k) using the exponential equation model can predict the rate of evaporation of water in the dehumidifier and evaporator. the constant speed of evaporation of water (k) indicate that the machine uses the evaporation principle. research on k by this far has focused on drying principle. the aim of this study is to examine the relationship between water content reduced along with the increasing time in between dehumidifier and evaporation processes and comparing the most effective way in reducing honey’s moisture content among both of them and determine the value of the constant (k) using the exponential equation model to estimate the rate of moisture content evaporation during the process. so that in the future, this study can be used in invented the most appropriate and effectives way in degrading honey’s moisture content to produce high quality honey. ii. materials and methods a. materials and equipments the tools used in this research were a set of the 1-liter capacity of water jet vacuum evaporator, a portable dehumidifier with dimensions of 35x32x27 cm. other supporters. while the material used is pure honey obtained from the province of east nusa tenggara as much as 5 liters. the research was conducted at the lastrindo engineering laboratory in malang from march april 2020. b. methods the test is carried out by observing the rate of evaporation of water content in the honey using a dehumidifier and an evaporator. the test was carried out in 2 stages, the first stage with a dehumidifier and the second with an evaporator. 1. dehumidifier the first stage of the drying process uses a dehumidifier. the honey used comes from ntt forests. the 133.556 g honey sample was divided into three samples then poured into trays. the three samples were replicates 1, 2, and 3. the sample weights in plates a, b, and issn: 2580-0817 journal of mechanical engineering science and technology 157 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) c were 43.309 g, 44.846 g and 45.401 g, respectively. the initial moisture content measurement was carried out before the three samples were entered into the dehumidifier. measurement of water content was carried out two times; then, the average obtained to obtain the sample's initial water content value. after being averaged, the initial water content of honey was obtained. this initial water content is used as the ho value for the three samples to be dried using a dehumidifier. furthermore, the observation was carried out by weighing each sample's weight every 1 hour (60 min.) once until the 12 hour (720 min.)—the rh value set to the lowest condition (ce) on the dehumidifier setting. temperature is measured using a type k thermocouple connected to omron ecwl 5. furthermore, any reduction in water content can be estimated by the mass balance equation (equation 1) concerning the law of conservation of mass, i.e., mass is not created and not destroyed. inflow = outflow + accumulation h = 1 ( mo × 100−ho 100 mn ) ×100 ......................................................................... ....... (1) where: h = water content (%) ho = initial moisture content (%) mo = mass of starting material (gram) mn = mass of material in the n-hour (gram). 2. evaporation the second stage uses the evaporation method. the evaporator used in this research is the prototype scale evaporator. the tool is equipped with a vacuum pump jet and an evaporator tube. the evaporator tube used is a heat-resistant pyrex glass flask. the heating stove design was placed above the water bath. the honey ingredient used is honey obtained from ntt; the honey is the same type as the honey used for the dehumidifier sample. the 133.556 g honey sample used for the evaporation experiment was the same as the sample used for the dehumidifier process. the initial moisture content of honey is measured before the evaporation process. then the honey is put into the evaporator and run. the vacuum pressure used is 7.8 kpa, and the temperature set on the control box is 45 oc. the stove flame will automatically decrease when the honey's temperature in the room exceeds 45 oc so that the heat remains constant. taking honey samples to measure the water content was carried out every 10 min., then recording the water content reduction during the evaporation process. sampling is complete when the measured honey water content has reached the equilibrium point. 3. determine the rate of evaporation how to determine the constant rate of evaporation of water in both the dehumidifier and evaporator is analogous to the method of determining the constant on drying, with the following steps: 1. looking for massive data every specific time without interrupting the process. 2. converting weight data to dry basis moisture data. 3. based on the evaporation conditions at the relevant temperature, the equilibrium water content ∞ can be determined. 158 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) 4. calculating the ratio of free water content (mr) of free water, namely the ratio of free water content at time t to free water content at time 0. 5. plotting the data on the semi-log curve based on the exponential equation, then determining k based on the curve's slope. in simple terms, the calculation steps above refer to newton's law of cooling solids with a decrease in equation 2. dt dθ = −k(t − t∞) .................................................................................................. (2) where: t = temperature (°c), θ = time (min.), t∞ = equilibrium temperature (°c) from the above equation, an equation can be made to estimate the evaporation of water in drying honey. if the temperature t is expressed in terms of the water content of honey h (%), then equation 2 can be made into equation 3. dh dθ = −k(h − h∞) ................................................................................................... (3) where, h = honey water content (%), h∞ = equilibrium moisture content (%), k = constant of water evaporation (1 / unit time). furthermore, equation 3 is made into equation 4. dh h−h∞ = −kdθ (4) integration of equation 4 with the initial (θ = 0) and final (θ = θ) boundary states into equation 5. h−h∞ ho−h∞ = exp[−kθ] ................................................................................................(5) based on equation 5, it can be seen the value of θ with equation 6 as follows. θ = 1 k ln h−h∞ ho−h∞ .........................................................................................................(6) where, h−h∞ ho−h∞ = moisture ratio based on equations 5 and 6, the constant value (k) can be known to estimate the rate of evaporation of water during the process of decreasing the water content of honey. iii. results and discussions reducing the water content of honey is very important to maintain its quality because honeys are known for its hygroscopic properties, which means that it can absorb the water from the air so that honey will gain in the water content. as the result, honey will damage due to the fermentation process when it stored for a long time. the water content of honey issn: 2580-0817 journal of mechanical engineering science and technology 159 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) permitted by indonesian international standard (sni) to be able to marketed in the market place must be less than 22 %, while the percentage permitted by international standard, it must be less than 19 % in order to be allowed to circulate in the market. the results showed that reducing the water content of honey using two difference processes, dehumidifier and an evaporator to comparing its effectiveness in reducing the water content along with the increasing number of time in those different processes. the results depict with a constant value of k (1/min.) using exponential equations to estimate the rate of reduction in water content during the two tools drying process. a. reducing the moisture content of honey processed using dehumidifier and evaporation method this research is focused in reducing the moisture content of honey using two different methods, dehumidifier process and evaporation process. figure 1 showed the dehumidifier process of honey placed on the trays in order to reduce its moisture content. while figure 2 showed evaporation process of honey inorder to reduce its moisture content. figure 3. below are explaining the comparison of honey’s moisture content reduced rate in between dehumidifier an evaporation method a long with the duration of processes. figure 1. dehumidifier use to decrease the amount of moisture content in honey sample fig. 2. the evaporator used to lower the moisture content in honey 160 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) fig. 3. the reduction rate of water content in honey after processed using dehumidifier (red line) and evaporation (blue line). b. reducing the moisture content of honey using dehumidifier method based from figure 3, the graph shows the average reduction rate of of honey’s moisture content after processed using dehumidifier (red line) and evaporation (blue line). the initial water content was measured using a moisture analyzer, and the value is 21.335 %. using dehumidifier method, te average rh (relative humidity) value per hour was 38 %. the temperature sensor installed on the dehumidifier reads 45 oc. furthermore, based on the mass equilibrium formula in equation 6, the reduction of water content at the point up to 720 min. or 12 hours during drying is reaching the value 16.397 %. the figure 2 also obtained the value of constant (k), reached a value of 0.00037 (1/min.). this value is obtained from the exponential equation y = 21.262e-0.00037x, with the regression value shown is r2 = 0.9943. the constant k value is the rate of evaporation of water content per unit time (min.) during the dehumidifier process. it can be seen that the evaporation rate is meager in the dehumidifier. the constant k value shows the rate of evaporation of moisture per unit time (min.) during the dehumidifier process in honey. c. reducing the moisture content of honey using evaporation method in figure 2 and figure 3, evaporation was used to evaporate the water contained in the honey. the working principle of the evaporator machine used (figure 2) is the decreasing number of pressure in the room below 1 atm will reduce the boiling point of water (<100oc) following with the lowering number of pressure value in the room. the statement goes along with the results that are shown in figure 3. based on figure 3, the lowering value of moisture content in honey's after processed with the evaporator (figure 2) shows that the value of honey initial moisture content before evaporation process 21.335 %. after evaporation conducted, honey's final moisture content value is decrease and reached 14.625 %, as long as 50 min. in evaporation process conducted with the vacuum pressure value is 7.8 kpa. the measurement of water content level in honey was done every 10 mins using a moisture analyzer. furthermore, the figure 3 also obtained a constant value k of 0.007 (1/min.). that has been obtained from the equation y = 21.961e-0.007x, with a regression value r2 = 0.9262. the constant k value issn: 2580-0817 journal of mechanical engineering science and technology 161 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) indicate the rate of evaporation of water content level in honey per min. during the evaporation process. comparing the results from the graph in figure 3, the evaporation rate of honey’s moisture content using dehumidifier process is lower compare in using evaporator method in evaporates the honey moisture content. thus, using evaporator will give the time effectiveness in lowering honey’s moisture content. d. comparison of dehumidifier and evaporation processes this study examines two methods used in reducing the moisture content in honey. the honeys that are obtained from farmers usually has a high-water content. thus, in order to be able to be circulated in the market place, moisture content in honey needs to be lowered below the indonesian national standard (sni) or international standard (si) to avoid the fermentation process of honey. the study is focused in comparing the reducing value of honey moisture content using two different methods, dehumidifier process and evaporation process. the comparison of lowering honey moisture content using dehumidifier and evaporation are shown in table 1. table 1. comparison between the dehumidifier process and the evaporation process no observed process dehumidifier evaporation 1. initial water content (%) 21.335 21.335 2. final water content (%) 16.397 14.625 3. processing time (min.) 720 50 4. constant value (1/min.) 0.00037 0.007 5 regression (r2) 0.9943 0.9262 from the table 1, it can be seen that both of the final results lowering the number of honey moisture content using two different evaporation methos have met the international standard value < 19 %, with the final value of honey moisture content after treated using dehumidifier and evaporation processes respectively represent 16.397 % and 14.625 %. the processing time required in the lowering the honey moisture content using two different methods, dehumidifier and evaporation shows a significant difference because there is a difference in pressure value. in the dehumidifier method, the process takes 720 min. with a non-vacum pressure value 101.3 kpa, while in the evaporation process takes 50 min. with a vacuum pressure value 7.8 kpa. the highlight of the study is that the vacuum conditions helps in lowering the evaporation time by reducing the pressure. thus, when it’s come in industrial scale application, the evaporation method is gives more effectiveness compare to the dehumidifier method because this method lowering the energy by lowering the pressure in order to reduce the moisture content in honey. the exponential equation were used to determine the constant value of k (1/min.) in order to estimate the rate of evaporation of honey moisture content. iv. conclusions this study show that the moisture reduction rate of honey in evaporation based on moisture reduction constant around 15 – 20 times compare with demudification. based on exponential equa, moisture reduction constant k in the dehumidifier process is 0.00037/ min. and 0.007/min. with the regression r2 = 0.9943 in humidification and r2 = 0.9262 in evaporation. 162 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 153-163 lastriyanto et al. (moisture reduction of honey in dehumidification and evaporation processes) acknowledgement i want to express my gratitude to everyone who contributed and support me during my research, my team and especially to the lpdp institution. this work would never have been possible without the support and the fund from educational fund management institution (lpdp) during the research and final project. references [1] ellis, m., “lowering the moisture content in small lots of extracted honey”. american bee journal, vol. 127(3), pp. 182-183, 1987. [2] ghazali, n. s. m., yusof, y. a., ling, c. n., othman, s. h., manaf, y. n. a., and baroyi, s. a. h. m., “the application of clay pot for moisture reduction of geniotrigona thoracica stingless bee honey”, international journal on advanced science, engineering, information and technology, vol. 9, pp. 2028-2034, 2019. 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[15] [bsn] badan standardisasi nasional, madu sni 8664: 2018 ics 65.020. 99, 2018. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 14 doi: 10.17977/um016v4i12020p014 thermal design optimization of shell-and-tube heat exchanger liquid to liquid to minimize cost using combination bell-delaware method and genetic algorithm reza setiawan1*, františek hrdlička2, prihadi setyo darmanto3, vera pangni fahriani4, suciani rahma pertiwi5 1department of mechanical engineering, universitas singaperbangsa karawang, jl. h. s. ronggowaluyo, karawang, 41360, indonesia 2department of energy engineering, czech technical university in prague, technicka 4, praha, 16607, czech republic 3department of mechanical engineering, institut teknologi bandung, jl. ganesha 10, bandung, 40132, indonesia 4department of chemical engineering, universitas singaperbangsa karawang, jl. h. s. ronggowaluyo, karawang, 41360, indonesia 5department of electrical engineering, universitas singaperbangsa karawang, jl. h. s. ronggowaluyo, karawang, 41360, indonesia *corresponding author: reza.setiawan@ft.unsika.ac.id abstract shell-and-tube heat exchanger is designed to satisfy certain requirements such as heat transfer capability, allowable pressure drop and limitation of size. beside such requirements, it is important to consider economical point of view to get the lowest total cost. in this study, computational program and optimization for thermal design shell-and-tube heat exchanger were built for liquid to liquid with no phase change process in four variables design parameters using bell-delaware method. the design variables were tube size, tube length, baffle cut to shell inside diameter ratio and central baffle spacing to shell inside diameter ratio. the genetic algorithm was used as optimization method to get lower solution for economical point of view. the results from two study cases show that the genetic algorithm got lower total cost from the original design. the total cost decreased 28.83% in first study case and 52.56% in second study case from the original design. copyright © 2020. journal of mechanical engineering science and technology all rights reserved keywords: bell-delaware, genetic algorithm, minimizing cost, optimization, shell-and-tube heat exchanger i. introduction the heat exchanger is an important equipment in the industrial process. one of their types has widely used in industrial energy, petroleum industry and chemical process industry. it is designed based on their characteristics and conditions of fluids, and some design is possible to appear similarly for a particular purpose. in such design, heat transfer capability and pressure drop may similar although they have different dimension and arrangement construction. because it is possible to get many variants design shell and tube through differences of construction, it is better to have design considering economical point of view. the design should consider total cost from investment and operational cost. the cost of investment is defined as a cost for manufacturing of shell and tube and cost of operation is defined as a cost which is needed along the operational process, and actually, it 15 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 setiawan et al. (thermal design optimization of shell-and-tube heat exchanger liquid to liquid) is a cost for pumping power. the design with low total cost will have a significant impact to expense for producers and users because it commonly is used for a long time or around ten years. in the other hand, computational processes are developed rapidly, and one of them is global random search methods. the uniqueness of this method can find a global optimum point in all problems of optimization. genetic algorithm is adapted from natural processes. the genetic algorithm mimics from natural process to transmit heredity characteristics from a parent to an offspring by genes in chromosomes. in addition, the method can be used easier to be implemented for the iterative calculation of optimization because some supporting mathematical software can help to build algorithms. the calculation process combined with the best method and supporting software, can solve the design, which has the cheapest cost. their components are different depending on type shell and tube particularly. but main components are shell, tubes, front-end head, rear-end head and baffles as shown in fig. 1. fig. 1. main parts of shell-and-tube heat exchanger [1] there are many standards of shell-and-tube heat exchanger. tubular exchanger manufacture association (tema) standards are widely recognized in many producers and consumers around the world to be used as a standard. tema standards are made by engineering principles, researchers and experiences in process design, manufacture and installation to assist designer, engineers and users to work. tema standards cover fabrication tolerances and performance information, installation, operation and maintenance, mechanical standards, vibration standards, thermal relations and recommended good practices [1]. some researchers used algorithms to the optimization of a heat exchanger. extensive advanced optimization techniques were applied. trial and error were conducted in various parameter design and operation, and it is very useful to the industry [2]. the study of optimization using particle swarm algorithm in double pipe was employed micro-finned tubes using number of micro-fins from 10 to 60, micro-fin height varying from 0.0 to 0.5 mm and the micro-fin helix angle between 5 and 30° [3]. grey wolf optimization algorithm reduced total cost using relatively low computing time [4]. elitist-jaya algorithm in first case reduced 32.855% and in the second case reduced 5.21% from simulations result compared to original design for continuous parameter optimization [5]. in the current investigation, multi-objective optimization of bees algorithm hybrid and particle swarm purposed to acquire the maximum effectiveness, and the minimum cost was simultaneously employed. seven decision parameters were length in hot and cold side, frequency of fin, number of fin layers, thickness of fin, fin height, and fin lance length [6]. gravitational search algorithm was developed from economic point of view. the algorithm was applied to two cases compared to the original data and other algorithms. the total cost could be reduced by 22.3% issn: 2580-0817 journal of mechanical engineering science and technology 16 vol. 4, no. 1, july 2020, pp. 14-27 as compared to the original data the gravitational search algorithm could be successfully applied for design optimization [7]. ii. material and methods procedure to design is conducted through some steps. the step is started with input data mass flow rate and temperature both shell and tube side as well as on inlet and outlet respectively. and then calculations are executed to get overall heat transfer coefficient and pressure drops. fig. 2. design procedure of shell-and-tube heat exchanger [8] spesification, design duty, make energy balance if needed to calculate unspecified flow rates of temperatures collect physical properties assume value of overall coefficient uo,ass decide number of shell and tube passes, calculate ? tlm, correction factor f and ? tm determine heat transfer area required: ao = q/uo,ass ? tm decide type, tube size, material layout assign fluids to shell or tube sheet calculation number of tubes calculate shell diameter estimate tube-side heat transfer coefficient decide baffle spacing and estimate shell-side heat transfer coefficient calculate overall heat transfer coefficient including foulling factors, uo,cal 0 < (uo,cal – uo,ass)/uo,ass < 0.3 estimate tube and shell side pressure drop pressure drop within spesification? estimate cost of exchanger can design be optimazed to reduce cost? accept design set uo,ass = uo,cal yes yes yes no no no 17 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 setiawan et al. (thermal design optimization of shell-and-tube heat exchanger liquid to liquid) along calculation processes, assumption and some designer decision are given such as assuming the overall heat transfer coefficient and deciding of some construction type. if the value of overall heat transfer after calculation is less than 30% of the ratio between overall calculated and assumption values of heat transfer while pressure drop does not exceed reasonable limits prescribed, then the design is accepted to be used [8]. another design may be needed if a designer considers getting a lower cost of heat exchanger. procedure to design is conducted through some steps. the step is started with input data mass flow rate and temperature both shell and tube side as well as on inlet and outlet respectively. and then calculations are executed to get overall heat transfer coefficient and pressure drops. along calculation processes, assumption and some designer decision are given such as assuming the value of overall heat transfer coefficient and deciding of some construction type. if the value of overall heat transfer after calculation is less than 30% of the ratio between overall calculated and assumption values of heat transfer while pressure drop does not exceed reasonable limits prescribed, then the design is accepted to be used [8]. another design may be needed if a designer considers getting a lower cost of heat exchanger fig. 3. methodology for heat exchanger optimization [1] alternate design: construction types, flow, arrangements, surface selection, etc. designer constraints and design variables problem specifications including customers constraints and design variables total constraints and design variables for optimization problem changed geometry and/ or operating conditions specified by design variables heat transfer and pressure drop evaluation thermophsical properties fixed operating conditions geometrical properties scaled j and f factors objective function and constraints evaluation optimization strategy for redefining the design variables problem formulation heat exchanger design computer programs optimization package optimum solution issn: 2580-0817 journal of mechanical engineering science and technology 18 vol. 4, no. 1, july 2020, pp. 14-27 the program has four variables that are outer tube diameter, tube length, baffle cut to shell inside diameter ratio and baffle spacing to shell inside diameter ratio. bounds the program for the four variables are described in table 1. the first bound, tube outer diameter is taken from bwg standard, which is used correspond to tema standard for tube size. the minimum value of outer tube diameter considers cleaning process and vibration of tubes. the cleaning process in the tube can be done with minimum tube size 0.01905 m and vibration also will be reduced using minimum tube size 0.01905 m [9]. the second bound, range of pipe length depends on space to be expected on size. the third bound, baffle cut to shell inside diameter ratio uses ratio the value ranging from 15% to 45%. it is set to support tubes mechanically against sagging and possible vibration [9]. and the fourth bound, baffle spacing to shell inside diameter ratio uses ratio the value ranging from 20% to 80%. maximum tema standard for baffle spacing is also 80%. it is also used to avoid failure due to tube vibration where it occurs in unsupported tube length more than 80% [9]. table 1. bounds of variables variable minimum value (m) maximum value (m) tube outside diameter (do) 0.01905 0.051 tube length (l) 1 10 baffle cut to shell inside diameter ratio 0.15 0.45 baffle spacing to shell inside diameter ratio 0.2 0.8 the methodology is divided into three main parts which are problem formulation, design and computer program and optimization package, as presented in fig. 3 recently, it is possible to get design with minimum cost and satisfied on some constraints by commercial software using optimization methods. equations for heat transfer in tube side have many forms. the equation can be selected exactly using a validity statement and reynolds number. some correlations heat transfer coefficient in tube side for no phase change process are expressed as follows [10]. for ( ret prt di l )1/3 (µ / µw) 0.14 < 2 hi = 3.66kt / d (1) for ( ret prt di l )1/3 (µ / µw) 0.14 > 2 for ret < 2100 hi = (kt / di) 1.86 ( ret prt di l )1/3 (µ / µw) 0.14 (2) for 2100 < ret < 10 4 hi = (kt / di) 0.116 (ret 2/3 – 125) prt 1/3 (1 + di / l) 2/3 (µ / µw) 0.14 (3) for ret > 10 4 hi = (kt / di) 0.027 ret 0.8 prt 0.4 (µ / µw) 0.14 (4) heat transfer in shell side for no phase change is calculated using bell-delaware method. it is more complex, but it is accurate enough. the bell-delaware method compares to an ideal tube bank, consider leakage through leakages and bypass flows. so, calculation 19 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 setiawan et al. (thermal design optimization of shell-and-tube heat exchanger liquid to liquid) of bell-delaware method will consider correction factors. heat transfer in shell side can be found by eq. 5 [1]. ho = hid jc jl jb js jr (5) total pressure drop is the summation of pressure drop from tube and shell side. pressure drop in tube side commonly due to frictions and indentations along tubes. pressure drop for all tubes can be obtained by eq. 6 [11]. δpt = vt 2/2 ( 4ft l di + 2.5) npρt (6) pressure drop in shell side is calculated using bell-delaware method which is evaluated from cross-flow tip baffle to tip baffle. pressure drop in shell side is commonly due to dividers from baffle and frictions along flow in shell side. pressure drop in shell side is the sum of pressure drop from the central section, window area and inlet-outlet area considering some correction factors. pressure drop in shell side can be determined by eq. 7 [1]. δps = [(nb – 1)δpb,idrb + nbδpw,id]rl + 2δpb,id (1 + nr.cw nr.cc )rbrs (7) the estimated cost of a heat exchanger is got from the summation of investment and operational cost. the total cost can be expressed by eq. 8 [12]. ctot = cinv + cop (8) the investment cost is used as the initial cost to make a shell-and-tube heat exchanger. it can be especially determined for shell material and tube material by eq. 9, eq. 10, eq. 11, eq. 12 or eq. 13 [13]. for material (shell: carbon steel and tube: carbon steel) cin = 6411 + 329.7a 0.80 (9) for material (shell: carbon steel and tube: stainless steel) cin = 7731 + 372a 0.85 (10) for material (shell: stainless steel and tube: stainless steel) cin = 8000 + 259.2a 0.91 (11) for material (shell: carbon steel and tube: titanium) cin = 12821.9 + 562a 0.92 (12) for material (shell: titanium and tube: titanium) cin = 16027 + 640a 0.93 (13) the operational cost has been used for an operational process for a lifetime of a heat exchanger. actually, operational cost is used for pumping power due to pressure drop in shell and tube side. operational cost is calculated considering inflation rate and efficiency of the pump. operational cost due to inflation rate effects for the lifetime can be determined by eq. 14 [14]. cop = ∑ co (1+ λ)k ny k=1 (14) issn: 2580-0817 journal of mechanical engineering science and technology 20 vol. 4, no. 1, july 2020, pp. 14-27 operational cost for annual current cost is calculated considering operation hours. it can be determined by eq. 15 [14]. co = p kel τ (15) where pumping power considering efficiency of pump can be calculated using eq. 16 [14]. p = ( ṁt δpt ρt + ṁs δps ρs ) 1 η (16) process of genetic algorithm is started with defined initial parameters. the process continues until maximum number of iteration and satisfy the criteria. a flow process for genetic algorithm is illustrated by flow chart in fig. 4. begin initialize population stop fitness reproduction crossover mutation increment generation no yes fig. 4. principle process of genetic algorithm [15] genetic algorithm is a search algorithm which is built an imitating mechanism of natural selection principles of darwin for the survival of the fitness. genetic algorithm mimics natural process to transmit heredity characteristics from a parent to an offspring by genes in chromosomes. the process will continue from a parent to offspring to get the best individual. the best individual represents an optimal solution [15]. flow process for genetic algorithm is illustrated by flow chart in fig. 4. iii. results and discussions a. first case study the first case study is a kerosene liquid in shell side and crude oil in tube side. both shell and tube are made of stainless steel. energy cost for shell and tube is set as 0.12 €/kwh and interest rate is set as 10% per year. working hour is set as 7,000 hours/year and the lifetime is set as 10 years with the efficiency of pump 0.7 [11]. data of fluids and physical properties are known for both stream sides. the data of each stream are mass flow rate, temperature inlet and outlet, density, viscosity, thermal 21 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 setiawan et al. (thermal design optimization of shell-and-tube heat exchanger liquid to liquid) conductivity, specific heat and fouling resistance. the data of each stream is detailed in table 2. table 2. first case study: data of fluids and physical properties [11] ṁ (kg/s) th (oc) tc (oc) ρ (kg/m3) µ x 105 (pa.s) k x 102 (w/mk) cp (j/kg) rf x 104 (m2k/w) shell side: kerosene 5.52 199.0 93.3 850 40 13 2,470 61 tube side: crude oil 18.80 37.8 76.7 995 358 13 2,050 61 the original design from the first case study uses pattern of square tube arrangement, one shell pass, four tube passes, tube pitch equal to 1.25 of outer tube diameter and baffle spacing equal to 0.24 of inner diameter shell [11]. optimization of the first case study was carried out by genetic algorithm. comparison of the result optimization to original data is presented in table 3. table 3. design comparison of the first case study to original data parameters original data genetic algorithm tube layout (o) square 30 n (shell) 1 1 np (passes) 4 2 nt (tubes) 158 202 do (m) 0.025 0.01905 di (m) 0.020 0.01619 ds (m) 0.539 0.400 pt (m) 0.031 0.02381 lbc (m) 0.127 0.133 lc (m) 0.063 l (m) 5.983 5.293 a (m2) 74.21 64.18 δtlm (k) 84.55 84.55 f 0.89 0.89 vt (m/s) 1.523 0.906 vs (m/s) 0.483 0.615 gt (kg/m2s) 1,515.4 901.2 gs (kg/m2s) 410.6 522.6 prt 5.6 5.6 prs 7.6 7.6 ret 8,468 40,762 res 25,344 24,890 q (w) 1,441,156 1,441,156 hi (w/m2k) 1,086 2,112.9 ho (w/m2k) 978.9 745.1 u (w/m2k) 268.1 309.9 δpt (pa) 53,195 7,900 δps (pa) 25,344 16,550 p (w) 1,671 367 cin (€) 21,054 19,438 cop (€) 8,920 1,894 ctot (€) 29,974 21,332 https://id.wikipedia.org/wiki/simbol_euro https://id.wikipedia.org/wiki/simbol_euro https://id.wikipedia.org/wiki/simbol_euro issn: 2580-0817 journal of mechanical engineering science and technology 22 vol. 4, no. 1, july 2020, pp. 14-27 optimization process using genetic algorithm has been successfully minimizing total cost on the first case study. algorithm methods have been decreasing the total cost of the shell-and-tube heat exchanger 28.83% using genetic algorithm from the total cost of original data, as mentioned in table 7. total cost decreases on the first case study due to decreasing total investment and operation cost. in this case, total operational cost decreases 78.77% using genetic algorithm. total investment cost decreases 7.68% using genetic algorithm from total operational cost and total investment cost of original data. fig. 5. cost comparison of first case study value of overall, tube side and shell side heat transfer coefficient tends higher than original data. results of overall heat transfer coefficient increases 15.60% using genetic algorithm from overall heat transfer of the original data. for heat transfer in tube side, the results increase 94.56% using genetic algorithm from original data. for heat transfer in shell side, the results increase 23.88% using genetic algorithm from the original data. overall heat transfer increases compared to original data because heat transfer area is smaller than the original data. it affects increasing value of heat transfer coefficient in shell and tube side, as presented in fig. 6. fig. 6. heat transfer coefficient comparison of first case study 21.054 8.920 29.974 19.438 1.894 21.332 0 5.000 10.000 15.000 20.000 25.000 30.000 35.000 investment cost operation cost total cost c o st ( € ) first case study: kerosene crude oil original data genetic algorithm 1.230 6.186 9.779 987 2.497 4.850 0 2.000 4.000 6.000 8.000 10.000 12.000 overall shell side tube side h e a t t ra n sf e r c o e ff ic ie n t (w /m 2 k ) first case study: kerosene crude oil original data genetic algorithm 23 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 setiawan et al. (thermal design optimization of shell-and-tube heat exchanger liquid to liquid) pressure drop tends to decrease in the tube side. pressure drop in tube side decreases 85.15% using genetic algorithm from the original data. pressure drops in shell side increases 28.87% using particle swarm algorithm from original data. as appears in fig. 7, it happens because velocity both in tube and shell side is decreased. fig. 7. pressure drop comparison of first case study b. second case study the second case study is a distilled water in shell side and raw water in tube side. both shell and tube are made of stainless steel. energy cost for shell and tube is set as 0.12 €/kwh and interest rate is set as 10% per year. working hour is set as 7,000 hours/year and the lifetime is set as 10 years with the efficiency of pump 0.7 [11]. data of fluids and physical properties are known from both stream sides. the data of each stream are mass flow rate, temperature inlet and outlet, density, viscosity, thermal conductivity, specific heat and fouling resistance. the data of each stream is detailed in table 4. table 4. second case study: data of fluids and physical properties [11] ṁ (kg/s) th (oc) tc (oc) ρ (kg/m3) µ x 105 (pa.s) k x 102 (w/mk) cp (j/kg) rf x 104 (m2k/w) shell side: distilled water 22.07 33.9 29.4 995 80 62 4,180 17 tube side: raw water 35.31 23.9 26.7 999 92 62 4,180 17 optimization of the second case study was carried out by genetic algorithm. comparison of the result optimization to original data is presented in table 5. optimization process using genetic algorithm has been successfully minimizing total cost on the first case study. algorithm methods have been decreasing total cost of 52.56% using genetic algorithm from the total cost of original data, as mentioned in table 9. total cost decreases on the first case study due to decreasing total investment and operation cost. in this case, 25.355 53.195 16.550 7.900 0 10.000 20.000 30.000 40.000 50.000 60.000 shell side tube side p re ss u re d ro p ( p a ) first case study: kerosene crude oil original data genetic algorithm issn: 2580-0817 journal of mechanical engineering science and technology 24 vol. 4, no. 1, july 2020, pp. 14-27 total operational cost decreases 89.91% using genetic algorithm. total investment cost increases 12.39% using genetic algorithm from total operational cost and total investment cost of original data. table 5. design comparison of the second case study to original data parameters original data genetic algorithm tube layout (o) triangular 30 n (shell) 1 1 np (passes) 2 2 nt (tubes) 160 388 do (m) 0.019 0.01905 di (m) 0.0152 0.01619 ds (m) 0.387 0.536 pt (m) 0.023 0.02381 lbc (m) 0.305 0.346 lc (m) 5.904 3.030 l (m) 0.156 a (m2) 56.35 70.22 δtlm (k) 6.31 6.31 f 0.94 0.94 vt (m/s) 2.436 0.887 vs (m/s) 1.022 0.601 gt (kg/m2s) 2,433.6 885.7 gs (kg/m2s) 1,016.9 597.7 prt 6.2 6.2 prs 5.4 5.4 ret 40,207 15,588 res 17,155 14,233 q (w) 415,137 415,137 hi (w/m2k) 9,799 4,849.7 ho (w/m2k) 6,186 2,497.2 u (w/m2k) 1,230 987.1 δpt (pa) 65,657 6,052 δps (pa) 88,520 9,849 p (w) 6,120 618 cin (€) 18,162 20,413 cop (€) 31,589 3,188 ctot (€) 49,751 23,601 value of overall, tube side and shell side heat transfer coefficient tends lower than original data. results of overall heat transfer coefficient decreases 19.75% using genetic algorithm from overall heat transfer of the original data. for heat transfer in tube side, the results decrease 50.51% using genetic algorithm from original data. for heat transfer in shell side, the results decrease 50.51% using genetic algorithm from the original data. overall heat transfer decreases compared to original data because heat transfer area is smaller than the original data. it affects increasing value of heat transfer coefficient in shell and tube side, as presented in fig. 9. https://id.wikipedia.org/wiki/simbol_euro https://id.wikipedia.org/wiki/simbol_euro https://id.wikipedia.org/wiki/simbol_euro 25 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 1, july 2020, pp. 14-27 setiawan et al. (thermal design optimization of shell-and-tube heat exchanger liquid to liquid) fig. 8. cost comparison of second case study fig. 9. heat transfer coefficient comparison of second case study fig. 10. pressure drop comparison of second case study 18.162 31.589 49.751 20.413 3.188 23.601 0 10.000 20.000 30.000 40.000 50.000 60.000 investment cost operation cost total cost c o st ( € ) second case study: distilled water raw water original data genetic algorithm 268 979 1.086 310 745 310 0 200 400 600 800 1.000 1.200 overall shell side tube side h e a t t ra n sf e r c o e ff ic ie n t (w /m 2 k ) second case study: distilled water raw water original data genetic algorithm 88.520 65.657 9.849 6.052 20.000 40.000 60.000 80.000 100.000 shell side tube side p re ss u re d ro p ( p a ) second case study: distilled water raw water original data genetic algorithm issn: 2580-0817 journal of mechanical engineering science and technology 26 vol. 4, no. 1, july 2020, pp. 14-27 pressure drop tends to decrease in the tube side. pressure drop in tube side decreases 90.78% using genetic algorithm from the original data. pressure drops in shell side decrease 89.67% using genetic algorithm. as appears in fig. 10, it happens because velocity both in tube and shell side is decrease. iv. conclusion the program of calculation could be design shell-and-tube heat exchangers tube layout 30o, 45o and 90o. building codes of efficient algorithm for computational calculation and correspond to tema standards has been done, sequences algorithm in computational process were work properly and define tema standards into algorithm such as bwg tube standard, minimum value of 1.25 tube pitch to outer tube diameter ratio and maximum value 80% baffle spacing to shell inside diameter ratio. the estimate cost is provided for made of carbon steel, stainless steel, titanium and the combination of their materials. the program has been applied for solving two thermal design shell-and-tube heat exchangers. the first case is a kerosene and crude oil fluids, the results show that program can reduce 28.83% for genetic algorithm of the total cost from the original data. the second case is a distilled water and raw water, in which the result shows that program can reduce 52.56% for genetic algorithm of the total cost from the original data. references [1] r. k. shah, and d. p.sekulic, fundamentals of heat exchanger design, john wiley & sons, inc., new jersey, 2003. 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[15] r. k. arora, optimization algorithms and applications, crc press taylor & francis group, florida, 2015. journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 101 doi: 10.17977/um016v4i22020p101 optimization of stir casting of aluminum matrix composites (amcs) with filler of recycled glass powder (rgp) for the mechanical properties yusup hendronursito1*, tumpal ojahan2, anang anshori2, asep yunanto2 1research unit for mineral processing, jl. ir. sutami km. 15 tanjung bintang lampung selatan, 35361, indonesia 2department of mechanical engineering, faculty of engineering, university of malahayati – lampung, indonesia *corresponding author: yusuph_ugm07@yahoo.com abstract a study of making aluminum matrix composites (amcs) uses recycled glass powder (rgp) as a filler has been carried out through the stir casting process. the experimental design uses the taguchi method of 3^3 orthogonal array l9 with the parameters of powder size (20>x> 80, 80>y> 200, 200>z> 325), percentage of filler vs matrix (2%, 7%, 12%), and stirring time (30 seconds, 3 minutes, 12 minutes). the optimum conditions for the hardness of al-grp composites were obtained from specimens with mesh powder size parameters 200> z> 325, the percentage of glass vs aluminum powder was 12% wt, stirring time was 12 minutes. the experimental factor that has the greatest contribution to the hardness value of al-grp composites is the size of glass powder of 73.77%, followed by the percentage of glass powder to aluminum by 19.98%, and the stirring time of 1.21%. the optimum experimental parameters for tensile strength can be obtained from specimens with particle size parameters of 20> x> 80, the percentage of glass powder to the weight of aluminum 12%, and the stirring time of 30 seconds. the biggest contribution to the tensile strength value of the al-grp composite was the stirring time of 72.71%, followed by the percentage of glass powder to aluminum by 13.67%, and the size of the powder was 9.97%. copyright © 2020. journal of mechanical engineering science and technology. all rights reserved. keywords: aluminum, composite, glass powder, mechanical, taguchi method i. introduction aluminum matrix composites (amcs) are a material that continues to be developed in the automotive and aircraft industries because it has several advantages such as high hardness, good strength to weight ratio, corrosion resistance, and so on [1]. the addition of filler in the form of sic to amcs has been shown to have an effect on superior mechanical properties. silicon carbide or carborundum is a derivative of silicon compounds with the molecular formula sic. this material is formed by the covalent bonding of the elements si with c. the production process for sic is complex and requires high energy which causes high costs. synthesis of sic at least requires a temperature of 1200oc at the furnace through microwave sintering furnace, plasma sintering, and hydrothermal processes to deform the sio2 and c bonds into sic [2] – [6]. meanwhile, the synthesis of sic using low temperatures is still a challenge for researchers [7]. alternative materials are researched to obtain maximum results. the use of waste materials, such as glass waste, needs to be studied more deeply. mailto:yusuph_ugm07@yahoo.com issn: 2580-0817 journal of mechanical engineering science and technology 102 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) glass has a dominant content of si, so in this research, an experiment conducted on adding glass powder to aluminum composites. a reinforcing filler made from glass powder or what is often referred to as recycled glass powder (rgp) is one of the most widely used research materials as a reinforcement filler in composites [8]. the addition of rgp material as a filler in composites has been shown to reduce the expansion of the silica reaction so that the volume of the composite material is smaller [8]. the use of glass waste as a filler was also studied, stating that the use of glass waste can produce high strength and can reduce the porosity of composite materials [9]. the hardness of the oxide glass ranges from 5 to 7 on the mohs scale, the highest obtained in silica glass. while the hardness of sio2 and cao.sio2 glass reaches 635 kg/mm 2 and 650 kg/mm2 [10]. so it is possible to use it as a reinforcement that can be used to increase the hardness of aluminum matrix composites where the hardness of used aluminum waste based from piston is only 54 hrb or equivalent to 98.4 kg / mm2 [11]. besides having the advantages that have been mentioned in several studies above, the use of waste as a composite material will provide an alternative to waste treatment, especially glass waste. ii. material and methods the aluminum matrix used comes from automotive waste aluminum in the form of motor vehicle pistons. rgp as filler material is obtained from beverage glass bottles that have been refined on a ballmill machine and sieved to obtain the particles size. the casting method uses stirr casting, as shown in figure 1. fig. 1. experimental schematic of stir casting machine [12] the experimental design uses the taguchi method of orthogonal array design l9 with 9 specimens. the parameters used in this study include powder size (mesh), percentage of glass powder to the weight of aluminum (%), and stirring time (minutes). the parameter design using the taguchi method can be seen in table 1. s/n ratio large the better, optimizing by equation 1. s n = −10 log [ 1 n ∑ 1 yi2 n i=1 ] ........................................................................................ (1) where n = number of observations and y = observed data 103 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 the choice of level in variable powder size is based on the classification of size groups which are divided into 3 groups, namely large, medium, and small particle sizes. group 1 has a particle size of 840 μm to 177 μm, group 2 with a particle size of 177 μm to 74 μm, and group 3 with a particle size of 74 μm to 37 μm. particle sizes greater than 1 μm allow less perfect integration with the matrix due to the influence of heat on the stirr casting process. table 1. taguchi: l9 orthogonal array no. sample a b c run order powder size % powder vs al stirring time 1 20 > x > 80 2% 30 seconds 2 20 > x > 80 7% 3 minutes 3 20 > x > 80 12% 12 minutes 4 80 > y > 200 2% 3 minutes 5 80 > y > 200 7% 12 minutes 6 80 > y > 200 12% 30 seconds 7 200 > z > 325 2% 12 minutes 8 200 > z > 325 7% 30 seconds 9 200 > z > 325 12% 3 minutes sample testing to determine the optimization of the process that has been designed includes mechanical tests in the form of hardness and tensile strength. the hardness test uses the rockwell hardness tester while the tensile strength test uses the universal testing machine (utm) ht 2402 with a capacity of 100 kn at the non metal material laboratory, bptm lipi by following the astm e8-m standard. iii. results and discussions a. taguchi analysis for composite hardness hardness testing is carried out on the sample at several points and take the average value for taguchi and anova analysis. the hardness value obtained from an average of three times the test, as shown in table 2. the results of the taguchi analysis include the s/n ratio and means value are shown in table 3 and figures 2 3. the ranking of each experimental factor is shown in table 3 where powder size gets the first rank, percentage of grp powder to basalt 2nd rank, and stirring time 3rd rank. this rating shows the most dominant value on the test results, in this case the hardness of the composite. main effects plots for means show the average value of each parameter and the levels that can be achieved. the highest average value for factor a is obtained from level 3, factor b is obtained from level 3, and factor c is obtained at level 3. from the main effects plot graph for the average value in figure 2, it can be seen that factor a indicates the existence of increase in the average score at each level. hendronursito et al. (optimization of stir casting of aluminum matrix composites) issn: 2580-0817 journal of mechanical engineering science and technology 104 vol. 4, no. 2, november 2020, pp. 101-114 table 2. results of hardness testing no sample experimental parameters hardness test results (average) a (powder size) b (% powder vs al) c (stirring time) hrb 1 1 1 1 58 2 1 2 2 60 3 1 3 3 72 4 2 1 2 78 5 2 2 3 81 6 2 3 1 88 7 3 1 3 83 8 3 2 1 87 9 3 3 2 92 table 3. response larger is better of s/n ratios for hardness value experiment factors response for levels in factor parameters 1 2 3 ranking a (powder size) 35.99 38.30 38.82 1 b (% powder vs al) 37.16 37.51 38.44 2 c (stirring time) 37.65 37.56 37.90 3 fig. 2. main effects plot for means to the hardness value fig. 3. main effects plot for s/n (larger is better) ratio to the hardness value the effect of the size of the glass powder as a filler shows an increase from the size of 20>x> 80 of 63.33 hrb to 82.33 hrb at the powder size of 80>y>200 and it increases again when the powder size is 200> z> 325 to 87.33 hrb. the change in powder size from large to smaller sizes has a directly proportional effect on the average value of hardness. the smaller of the size, the greater the average hardness obtained. likewise in factor b, it can be seen that the average value is directly proportional to the level used. at level 1 the percentage of glass powder to aluminum is 2% w/t, has an average hardness value of 73 hrb,increases to 76 hrb at level 2 with the percentage of glass powder to aluminum is 7% w/t, and again increases to 84 hrb at level 3 with the percentage of glass powder to hendronursito et al. (optimization of stir casting of aluminum matrix composites) 105 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 aluminum is 12% w/t. however, it is different in factor c; there is a value that goes up and down at level 1 and falls at level 2 and rises to reach a peak at level 3. level 1 of c parameter, namely the stirring time of 30 seconds, gives an average hardness value of 77.67 hrb and decreased to 76.67 hrb when stirring for 3 minutes. from the s/n ratios graph in figure 3, it can be seen that the optimum conditions are at the following parameters and levels: a3b3c3. the optimum conditions for a3b3c3 represent the sample with the following parameters, a3 is the size of the mesh powder 200> z> 325, b3 is the percentage of glass powder vs aluminum is 12% w/t, and c3 is the stirring time of 12 minutes. b. analysis of variance (anova) for composite hardness anova using the minitab 17 software can be used to determine the significant parameters that affect the hardness results. the variables used in this experiment include a (rgp size in mesh), b (percentage of glass powder vs aluminum), c (stirring time). this significant effect can be seen from the p-value obtained from the results of data processing. important requirements in drawing conclusions based on data or statistical groups are as follows: if the p-value > α, then hypothesis zero (ho) is accepted, and hypothesis one (h1) is rejected. if the p-value < α, then hypothesis zero (ho) is rejected and hypothesis one (h1) is accepted. the α value in the experiment was set at 5%. the null hypothesis of the anova test states that there is no relationship between the independent variable and the dependent variable. this means that in the formulation of the hypothesis being tested is the conclusion that it is not true that the independent variable affects the dependent variable. the alternative hypothesis (h1) states that there is a relationship between the independent variable (x) and the dependent variable (y) under study. this means that in the formulation of the hypothesis, the conclusion is that the results of the h1 calculation will be used as the basis for searching research data. the anova test results are shown in table 4. from these results, the p-value is obtained from the smallest value to the largest value, respectively, are parameter a with a value of 0.000, parameter b with a value of 0.001, and parameter c with a value of 0.323. this concludes that for parameter a and parameter b then ho is rejected and h1 is accepted. the size of the powder and the percentage of glass powder on aluminum have a significant effect on the hardness of the composite. while the parameter c value of p-value is greater when compared to α = 5%. so that in this study, the stirring time did not have a significant effect on the hardness of aluminum composites. the analysis of anova, the pvalue in accordance with the taguchi test in table 3, which shows the highest ranking is obtained from parameter a (grain size of glass powder). based on figure 4, the experimental factor that has the largest contribution to the hardness value of al-grp composites is the size of glass powder of 73.77%, followed by the percentage of glass powder to aluminum by 19.98%, an error of 5.04%, and stirring time of 1, 21%. based on the taguchi test of the s/n ratios value, the optimum grain size to use was 200>z>325 mesh. a filler with good characteristics will have positive effect on the composites made. the rgp filler has a high hardness that will increase the hardness distribution of the aluminum matrix composite. the presence of harder filler and well bonded rgp particles in aluminum matrix that impede the movement of dislocations increases the hardness of amcs [13]. hendronursito et al. (optimization of stir casting of aluminum matrix composites) issn: 2580-0817 journal of mechanical engineering science and technology 106 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) table 4. anova test results on the hardness (hrb) of al-grp source df seq ss adj ss adj ms f-value p-value regression 3 1049.97 1049.97 349.99 31.39 0.001 a (powder size) 1 815.66 815.66 815.66 73.15 0.000 b (% powder vs al) 1 220.9 220.9 220.9 19.81 0.007 c (stirring time) 1 13.41 13.41 13.41 1.2 0.323 error 5 55.76 55.76 11.15 total 8 1105.73 the contribution of each factor to the hardness value of the al-grp composites is shown in figure 4. fig. 4. contribution of experimental factors to the hardness of al-grp composites based on table 5, it is known that the coefficient of determination r-square is 0.9496, which is the square of the correlation coefficient "r" which is 0.9745. the coefficient of determination of 0.9496 indicates the independent variable (x) simultaneously (together) affects the dependent variable (y) by 94.96%. while the remaining 5.04% is influenced by other variables outside the regression equation or other variables that are not included in the experimental parameters. the magnitude of the influence of this other variable is called error. the value of r-sq, which is close to the value of 100%, indicates that the influence of the independent variable (x) is getting stronger on the dependent variable (y). table 5. output model summary model summary for transformed response s r-sq r-sq (adj) press r-sq (pred) 3.33935 94.96% 91.93% 156.242 85.87% the formula for predicting the hardness value of al-grp composites in terms of the factors and levels used in this experiment are as follows: hrb = 77.667 – 14.333 a_1 + 4.667 a_2 + 9.667 a_3 – 4.667 b_1 – 1.667 b_2 + 6.333 b_3 + 0.0 c_1 – 1.000 c_2 + 1.000 c_3 ........................................... (2) 73.77% 19.98% 1.21% 5.04% contribution of factor experiment for hardness value rgp size percentage rgp vs al stirring time 107 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) from equation (2), it can be seen that the value of hardness without independent variables (a, b, c) is predicted to be at a value of 77 hrb. important factors that affect the value of hardness which is indicated by the high regression coefficient values, namely a1 and a3. this is in accordance with the ranking obtained from table 3. it is also seen that the factor that is not too influential is the length of stirring (c) with a small regression coefficient value. in addition to predicting the hardness value obtained by multiplying the number against the experimental factor, it can also be predicted the value of hardness through the relationship of two parameters used, for example, the interaction between parameter a and parameter b (a vs b), parameter a with parameter c (a vs c), and parameter b with parameter c (a vs c). based on figure 5, the contour plot of the hardness value of the interaction of parameter a and parameter b, it can be seen that the highest hardness value is symbolized in the dark green area. this area is obtained when the level on parameter a and parameter b increases. fig. 5. prediction of the relationship between a vs b and the resulting violence fig. 6. prediction of a vs c relationship to the resulting violence in the contour plot of hardness obtained from the interaction of parameter a and parameter c as shown in figure 6, it can be seen that the highest hardness value can be issn: 2580-0817 journal of mechanical engineering science and technology 108 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) obtained in parameter a starting at level 2 to 3, but parameter c is the choice of level that can be used from level 1 to level 2.5. the prediction of the relationship between b vs c and the resulting hardness can be seen in figure 7. the area bordered by dark green is the area with the highest hardness value, more than 90 hrb. when seen in the picture, this area is very narrow. this is in accordance with the significant contribution and influence that these two parameters contribute less and less significant effect on violence. fig. 7. prediction of the relationship between b vs c and the resulting violence c. taguchi analysis for composite tensile strength the results of the test for the tensile strength of the al-grp composite sample are shown in table 6. the highest tensile strength was obtained from sample 6th is 11.24 n/mm2. sample 6th was obtained from various parameters and levels of a2b3c1, with parameters of glass powder grain size 80>y>200, percentage of glass powder vs aluminum 12% w/t, stirring time 30 seconds. while the lowest value is obtained from sample 4th with a tensile strength value of 2.76 n/mm2. sample 4th was obtained from a2b1c2 parameters, namely glass powder grain size 80>y>200, percentage of glass powder vs aluminum 2% w/t, stirring time 3 minutes. table 6. tensile strength results no sample experimental parameters tensile strength (n/mm2) a (powder size) b (% powder vs al) c (stirring time) 1 1 1 1 9.55 2 1 2 2 4.66 3 1 3 3 8.14 4 2 1 2 2.76 5 2 2 3 2.81 6 2 3 1 11.24 7 3 1 3 4.15 8 3 2 1 8.15 9 3 3 2 3.66 109 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) the response data from the tensile test results are then processed to create a response table for the average tensile strength and the s/n ratios table. the results of data processing are shown in table 7 and figure 8 9. table 7 shows the ranking of factor parameter. it has shown the stirring time give the best ranking followed by percentage of glass powder and powder size, respectively. table 7. response of s/n ratios larger is better (db) for tensile strength experiment factors response for levels in factor parameters 1 2 3 ranking a (powder size) 17.06 12.94 13.95 3 b (% powder vs al) 13.59 13.52 16.83 2 c (stirring time) 19.61 11.15 13.18 1 the effect of reducing the grain size of glass powder from mesh 20> x> 80 to 200> z> 325 causes the average tensile strength of the composites to decrease by 28.59%. the tensile strength of the composite decreased from 7.45 to 5.32 n/mm2. meanwhile, by increasing the percentage of glass powder from 2% w / t to 12% by weight of aluminum, it can increase the tensile strength from 13.59 n/mm2 to 16.83 n/mm2. however, the percentage of 7% wt of glass powder to aluminum decreased slightly by around 0.07 n/mm2. however, this value tends to be small, namely around 0.5%, the graphical trend that is increasing with the addition of the percentage of glass powder. in the parameter of stirring time, there was a decrease in the tensile strength value of the al-grc composite by 47.83%. stirring time of 30 seconds gives the highest average tensile strength value of 9.647 n/mm2, presented in figure 9. s / n ratio analysis shows the effect of the most optimum experimental parameters that can be obtained from the experimental parameters, namely a1b3c1. a1b3c1 parameter represents particle size 20> x> 80, percentage of glass powder to weight of aluminum 12%, and stirring time 30 seconds. fig. 8. effect of experimental factors on s/n ratios larger is better for tensile strength fig. 9. the main effects of experimental factors on the average tensile strength of the al-grp composite issn: 2580-0817 journal of mechanical engineering science and technology 110 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) d. analysis of variance (anova) for composite tensile strength the anova test results are shown in table 8. from these results, the p-value from the smallest to the largest value is parameter c with a value of 0.048, parameter b with a value of 0.211 and parameter a with a value of 0.268, respectively. this concludes that in parameter c, ho is rejected and h1 is accepted. the duration of stirring has a significant effect on the tensile strength of the composite. while parameter a and parameter b, the pvalue is greater when compared to α 5%. so that in this study, the grain size of glass powder and the percentage of glass powder on the weight of aluminum did not have a significant effect on the tensile strength of aluminum composites. the analysis of anova shows conformity to the ranking results obtained from table 7. anova analysis, the pvalue for the conclusion of the hypothesis taken is in accordance with the taguchi test, which shows that the highest ranking is obtained from parameter c (stirring time). table 8. anova test results on tensile strength (n/mm2) of al-grp composites source df seq ss adj ss adj ms f-value p-value a (powder size) 2 8.027 8.,027 4.014 2.73 0.268 b (% powder vs al) 2 11.006 11.006 5.503 3.75 0.211 c (stirring time) 2 58.521 58.521 29.26 19.93 0.048 error 2 2.936 2.936 1.468 total 8 80.49 the contribution of each factor to the tensile strength value of the al-grp composite is shown in figure 10. fig. 10. contribution of experimental factors to the tensile strength of al-grp composites based on figure 10, the experimental factor that has the greatest contribution to the tensile strength value of al-grp composites is the stirring time of 72.71%, followed by the percentage of glass powder to aluminum by 13.67%, powder size of 9.97%, and 3.65 %. based on the taguchi test of the s/n ratios value, the optimum stirring time is 30 seconds. the stirrer rotation makes a vortex effect that draws the particle into the aluminum melt. the filler needs to be subjected to constant centrifugal currents over a certain period of 9.97% 13.67% 72.71% 3.65% contribution of factor experiment for tensile strength grp size % grp vs al stiring time error 111 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) time to achieve dispersion all through the aluminum melt. longer stirring time produces more agitation in the molten composite, which increases the tendency to form more porosity. there is an optimum range of stirring time to achieve uniform distribution with least porosity. if stirring continues beyond the optimum range, the gas absorbability of the molten aluminum will increase. thus, the formation of porosity becomes unavoidable [14]. based on table 9. output model summary, it is known that the coefficient of determination r-square is 0.9435 which is the square of the correlation coefficient "r", which is 0.9816. the coefficient of determination of 0.9435 indicates that the independent variable (x) simultaneously (together) affects the dependent variable (y) by 94.35%. while the rest, 5.65% is influenced by other variables outside the regression equation or other variables that are not included in the experimental parameters. the magnitude of the influence of this other variable is called error. the value of r-sq, which is close to the value of 100%, indicates that the influence of the independent variable (x) is getting stronger on the dependent variable (y). table 9. output model summary model summary for transformed response s r-sq r-sq (adj) press r-sq (pred) 1.21156 96.35% 85.41% 59.449 26.14% the formula for predicting the tensile strength of the al-grp composite in terms of the factors and levels used in this experiment are as follows: tensile strength = 6.124 + 1.326a_1 0.521a_2 0.804a_3 0.638b_1 0.918b_2 + 1.556b_3 + 3.522c_1 – 2.431c_2 – 1.091c_3 ............................................. (3) from equation (3), it can be seen that the value of tensile strength without independent variables (a, b, c) is predicted to be at a value of 6.124 n/mm2. important factors that affect the value of tensile strength which is indicated by the high regression coefficient values, namely c1 and c2. this is in accordance with the ranking obtained from table 3. it is also seen that the factor that is not too influential is the particle size (a) and percentage of grp (b) with a small regression coefficient value. in addition to predicting the tensile strength obtained by multiplying the number against the experimental factor, it can also be predicted the value of tensile strength through the relationship of the two parameters used, for example, the interaction between parameter a and parameter b (a vs b), parameter a with parameter c (a vs c), and parameter b with parameter c (a vs c). based on figure 11, the contour plot of the tensile strength from the interaction of parameter a and parameter b, it can be seen that the tensile strength is symbolized in the dark green area with a tensile strength value greater than 3 n/mm2 obtained from parameter a level 2 and parameter b level 2. the area with a high tensile strength value is very narrow and the tensile strength value obtained is also very small (above 3 n/mm2). it can be understood from the previous explanation that these two parameters (parameter a and parameter b) do not contribute simultaneously to the tensile strength value of the algrp composite. issn: 2580-0817 journal of mechanical engineering science and technology 112 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) fig. 11. contour plot of parameter a vs parameter b to tensile strength in the contour of tensile strength plot in figure 12, which is obtained from the interaction of parameter a and c, it can be predicted that the highest tensile strength value is obtained from parameter a at any level as long as it interacts with parameter c level 2.5 to level 3. this is in accordance with the explanation contribution of parameter c, which holds the highest and most significant contribution to tensile strength. fig. 12. prediction of a vs c relationship to the resulting violence fig. 13. prediction of the relationship between b vs c and the resulting violence the prediction of the relationship between b vs c and the resulting tensile strength can be seen in figure 13. the area bordered by dark green is the area with the highest tensile 113 journal of mechanical engineering science and technology issn 2580-0817 vol. 4, no. 2, november 2020, pp. 101-114 hendronursito et al. (optimization of stir casting of aluminum matrix composites) strength, more than 3 n/mm2. it can be predicted that the highest tensile strength value is obtained from any level of parameter b as long as it interacts with parameter c level 2.5 to level 3. this is in accordance with the explanation of the contribution of parameter c, which holds the highest contribution and has the most significant effect on tensile strength. iv. conclusions the manufacture of aluminum matrix composites (amcs) made from aluminum matrix with glass powder reinforcing filler has been carried out by the stirr casting process using a variety of experimental factors designed using taguchi and analyzed using the help of minitab 17 software. the optimum conditions for the hardness of al-grp composites were obtained from specimens with particle size parameters 200> z> 325, the percentage of glass vs aluminum powder was 12% w / t, stirring time was 12 minutes. the experimental factor that has the greatest contribution to the hardness value of al-grp composites is the size of glass powder of 73.77%, followed by the percentage of glass powder to aluminum by 19.98%, and the stirring time of 1.21%. the optimum experimental parameters for tensile strength can be obtained from specimens with particle size parameters of 20> x> 80, the percentage of glass powder to the weight of aluminum 12%, and the stirring time of 30 seconds. the biggest contribution to the hardness value of the al-grp composite was the stirring time of 72.71%, followed by the percentage of glass powder to aluminum by 13.67%, and the size of the powder was 9.97%. acknowledgement the first author is the main contributor, while the other authors are the member contributors to this paper. the authors full thank to mr. gusri akhyar ibrahim who give knowledge about design experiment, especially in taguchi and analysis of variance. tensile and hardness testing is carried out using testing services in the indonesian institute of sciences lipi laboratory. references [1] sahin, y., and murphy, s., "the effect of fiber orientation of the dry sliding wear of borsic reinforced aluminum alloy", journal of materials science, vol. 31, pp. 5399 – 5407, october 1996. 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[13] rahman, m.h., and al rashed, h.m., "characterization of silicon carbide reinforced aluminum matrix composites", in 10th international conference on mechanical engineering, icme 2013, procedia engineering, 103-109. [14] moses, j.j., dinaharan, i., sekhar, s.j., "predicting the influence of process parameters on tensile strength of aa6061/tic aluminum matrix composites produced using stir casting", transactions of nonferrous metals society of china, vol. 26 (6), pp. 1498-1511, june 2006. journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 49-52 49 doi: 10.17977/um016v1i22017p049 formula of moulding sand, bentonite and portland cement toimprove the quality of al-si cast alloy andoko1, a *, poppy puspitasari1, avitaayupermanasari1 and didinzakarialubis1 1department of mechanical engineering, faculty of engineering, universitas negeri malang aandoko.ft@um.ac.id abstract a binder is any material used to strengthen the bonding of moulding sand grains. the primary function of the binder is to hold the moulding sand and other materialstogether to produce high-quality casts. in this study, there were four binder compositions being tested, i.e. 5% bentonite + 5% portland cement, 4% bentonite + 6% portland cement, 6% bentonite + 4% portland cement, and 7% bentonite + 3% portland cement. each specimen was measured for its compressive strength, shear strength, tensile strength and permeability. the highest compressive strength was obtained fromthe specimen composed of 6% bentonite+ 4% portland cement. the highest shear strength was obtained from the moulding sand with 7% bentonite+ 3%portland cement. the highest tensile strength was obtained fromthe specimen contained 5% bentonite+ 5% portland cement. the specimen composed of 5% bentonite + 5% portland cement had the lowest permeability of 131 ml/min, while that of 6% bentonite + 4% portland cement had the highest permeability of 176 ml/min.. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: bentonite, portland cement, strength of moulding sand. i. introduction. casting systems and processes cannot be separated from moulds. to date, sand mouldis the most popular among other types of moulds [1]. in manufacturing sand moulds, the sand is undergone a process of compaction. moulding sand is formed from a mixture of sand, binder and other additional materials [2]. moulding sand is the most frequently used component in metal casting process due to its low production cost, reusability, thermal resistance, ease of operation, and acceptable quality [2]. sand moulded casting is carried out through several stages, such as placing a pattern in the sand to form a mould cavity [3]. green sand casting is known for its low-cost production. however, due to its low-strength mould, cast defects are often found in the products of green sand casting in which clay is used as a binder. in order to avoid this shortcoming, dry sand can be used as a possible alternative, but it takes a long time for the casting to completely dry. thus, as an attempt to produce a mould that can dry up in a short time, this following step can be taken, i.e. by utilising a type of binder which has no drawbacks such as the emergence of gas defects, poor fire resistance, costly production, and complex mould production process [1]. several materials that can be used as special binders are water-glass, resin, cement, flour, and others. binder, as a vital element in the composition of sand moulds, certainly affects the quality of casting products. as a binding agent, bentonite is most commonly used alone[4]. in this study, the casting process involved the combination of bentonite and portland cement as the moulding sand binder. this mixture was expected to generate a binder formula with a high level of binding that can minimise any potential defects in the casting products [4].the standard composition of a binder is usually 7.5 9.1% bentonite and 3.7 – 4.5% water [3]. also, other ingredients such as charcoal powder, flour, petroleum coke, or graphite flour by 1% are sometimesadded to create a smooth casting surface and allow easy casting removal [1]. portland cement [5] is a moulding sand binder that can solidify itself and is composed of 85-88% silica sand, 6-12% cement,and 4 -8% water [6,7].it can also be added witha hardenersuch as molasses or calcium chloride as much as 50-100% of the total amount of cement. mailto:andoko.ft@um.ac.id 50 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 49-52 andoko et.al (formula of moulding sand, bentonite and portland cement toimprove) table 1. compressive, shear, and tensile strength of sand moulds with different compositions type of testing 5%b + 5%pc 4%b + 6%pc 6%b + 4%pc 7%b + 3%pc compressive strength 7.20 7.03 8.13 7.93 shear strength 2.60 2.70 2.63 2.86 tensile strength 0.51 0.51 0.51 0.46 ii. material and method. data were collected through sand identification, compression, tensile and sheartesting, and permeability testing. the sand was combined with different amount of bentonite and portland cement, i.e. 5% bentonite (b) + 5% portland cement(pc), 4% bentonite (b) + 6% portland cement(pc), 6% bentonite (b) + 4% portland cement (pc), and 7% bentonite(b) + 3% portland cement (pc). the results of strength and permeability testing of each variation were averaged and compared.as a follow-up, a morphology testusing the scanning electron microscope (sem) was performedto identify the surface shape produced by the formula above. iii. results and discussion. based on the test results, this section discusses the effect of variations in the binder composition of the moulding sand to improve the quality of casts. several tests were carried out to assess the compressive, shear, and tensile strength, permeability and surface morphologyof sand mould composed of different amounts of bentonite (b) and portland cement (pc) as the binder. the results of compression, shear, and tensile testingare presented in table 1. a. compression testing on the moulding sand the compression testing on the specimen composed of 5% bentonite and 5% portland cement showed that it had a compressive strength of 7.2 (n/cm2) or 72 kn/m. the compressive strength of themouldcomposed of 4% bentonite and 6% portland cement was 7.03 (n/cm2); this value inkn/m2 in line with tjitro and hendri was 70.3 kn/m2. the specimen composed of 6% bentonite and 4% portland cement had a compressive strength of 8.13 (n/cm2) or 81.3 kn/m2. the combination of 7% bentonite and 3% portland cement generated a mould with a compressive strength of 8.3 (n/cm2) or 83 kn/m2. [8] stated that the ideal of compressive strength of green sand mouldis between 0-1.0kg/cm2. therefore, the four specimenscan be considered of having an ideal compressive strength (0> 0.0073-0.0083 <1 kg/cm2)[9]. b. shear testing on the moulding sand to measure the maximum shear strength, each sand mould was subjected to shear loading until it was damaged or broken. if the shear strength of a mould is low, the molten metal will flowthrough the mouldwallandwash away the sand, causing sand erosion and inclusion [3].the standard shear strength is 1.5-7 psi. based on the shear testing result, the sand mould composed of 5% bentonite and 5% portland cement had a shear strength of 2.8 (n/cm2) or 28 kn/m2. theshear strength of that composed of 4% bentonite and 6% portland cement was 2.7 (n/cm2) or 27 kn/m2. the combination of 6% bentonite and 4% portland cementgenerated a sand mould with a shear strength of 2.63 (n/cm2) or 26.3 kn/m2.the shear strength of the specimen contained a mixture of7% bentonite and 3% portland cement was 2.86 (n/cm2) or 28.6 kn/m2. in sum, the shear strength of the four specimens has fulfilled the standard of shear strength of a sand mould, i.e. 1.5-7 psi or 1.044.83 n/cm2 [10]. c. tensile testing on the moulding sand the tension testing was performed to determine the maximum tensile strength of the moulding sand per unit area until broken. low tensile strength will cause mould shrinkagedue to the volume contraction of the molten metal. according to [11], the standard tensile strength of amoulding sand is 1-6 psi. the tensile testing on the specimen composed of 5% bentonite and 5% portland cement showed that it had a tensile strength of 0.51 (n/cm2) or 5.1 kn/m2. the tensile strength of the mould composed of 4% bentonite and 6% portland cement was 0.51 (n/cm2) or 5.1 kn/m2. the specimen composed of 6% bentonite and 4% portland cement had a tensile strength of 0.51 (n/cm2) or 5.1 kn/m2. the combination of 7% bentonite and 3% portland cement generated a mould with a tensile issn: 2580-0817 journal of mechanical engineering science and technology 51 vol. 1, no. 2, november 2017, pp. 49-52 andoko et.al (formula of moulding sand, bentonite and portland cement toimprove) strength of 0.46 (n/cm2) or 4.6 kn/m2. as already stated by heine (1976:95), moulding sand should have a tensile strength of 1-6 psi or 0,69-4,14 n/cm2. the strength testing (compressive, shear, tensile) was followed up with the sem testing. the results of sem analysis on four moulds made of mixtures with different concentrations of sand, bentonite and portland cement are presented in figure 1. d. permeability testing permeability testing was carried out to determine the ability of the moulding sand to transmit fluid or gasesthrough unit area of specimen per unit time (ml/cm2). the low permeability of moulding sand causes difficulty for air to pass through the grains. as a result, when molten metal is poured, gases/air cannot escape and hence defect in the casting.in contrary, gases can come out much more easily in a mould with high permeability [12]. however, if the permeability is too high, the molten metal poured can seep in between the sand grains and result in a rough surface on the casting [12]. figure 1.moulding sand 5% b + 5% pc figure 2.moulding sand 4% b + 6% pc figure 3. moulding sand 6% b + 4% pc figure 4. moulding sand 7% b + 3% pc table 2. the permeability of moulding sand specimen permeability 6% b + 4% pc 176 ml/minute 5% b + 5% pc 131 ml/minute 4% b + 6% pc 131 ml/minute 7% b + 3% pc 151 ml/minute 52 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 49-52 andoko et.al (formula of moulding sand, bentonite and portland cement toimprove) iv. conclusions. taken together, the findings and discussion of this research suggest the following conclusions. 1. among the other three specimens, the moulding sand combined with 6% b + 4% pc had the highest compressive strength (8.13 n/mm2), whilethat with 5% b + 5% pchad the lowest compressive strength (7.2 n/mm2) 2. the highest shear strength was obtained from the moulding sand mixed with 7% b + 3% pc (2.86 n/mm2), while the lowest shear strength was obtained fromthat with 6% b + 4%pc(2.6 n/mm2). 3. the highest shear strength of 0.51 n/mm2 was obtained from three variations of sand mixture, i.e. 5% b + 5% pc, 4% b + 6% pc, and 6% b + 4% pc, while the lowest shear strength was obtained from that with 7% b + 3% pc had the lowest compressive strength (0.46 n/mm2) 4. based on the results of the compression, shear, and tensile testing, all specimens are considered to have satisfied the criteria for ideal moulding sand. references [1] a. i made, “pengaruh jenis pasir cetak dengan zat pengikat bentonit terhadap sifat permeabilitas dan kekuatan tekan basah cetakan pasir(sand casting),” j. ilm. tek.mesin,vol. 4, no. 2, pp. 132–138, 2010. [2] j.choma, l. osuchowski, m. marszewski, a. dziura, and m. jaroniec, “developing microporosity in kevlar®-derived carbon fibers by co2 activation for co2 adsorption,” j. co2 util., vol. 16, pp. 17–22, dec. 2016. [3] d.koch, “bentonites as a basic material for technical base liners and site encapsulation cut-off walls,” appl. clay sci., vol. 21, no. 1–2, pp. 1–11, apr. 2002. [4] “27,226 search results all(bentonite) sciencedirect.” [online]. available: http://www.sciencedirect.com/science?_ob=articlelisturl&_method=list&_articlelistid1215843383 &_sort=r&_st=13&view=c&md5=3ef21220f0538507c2b7cd83d73eb8a2&searchtype=a. [accessed: 08jun-2017]. [5] “modelling and optimization of the sound absorption of wood-wool cement boards sciencedirect.”[online].available:http://www.sciencedirect.com/science/article/pii/s0003682x1730433 4. [accessed: 06-sep-2017]. [6] c. lee, s. park, d. lee, i.-m. lee, and h. choi, “viscosity and salinity effect on thermal performance of bentonite-based grouts for ground heat exchanger,” appl. clay sci., vol. 101, pp. 455– 460, nov. 2014. [7] y. c. flores, g. c. cordeiro, r. d. toledo filho, and l. m. tavares, “performance of portland cement pastes containing nano-silica and different types of silica,” constr. build. mater., vol.146, pp. 524–530, aug. 2017. [8] t. thyagaraj and d. soujanya, “polypropylene fiber reinforced bentonite for waste containment barriers,” appl. clay sci., vol. 142, pp. 153–162, jun. 2017. [9] a. yustres et al., “comparison of the hydrogeochemical and mechanical behaviours of compacted bentonite using different conceptual approaches,” appl. clay sci., vol. 141, pp. 280–291, jun. 2017. [10] g. barast, a.-r.razakamanantsoa, i. djeran-maigre, t. nicholson, and d. williams,“swelling properties of natural and modified bentonites by rheological description,” appl. clay sci., vol. 142, pp. 60–68, jun. 2017. [11] s. zhao, x. ding, m. zhao, c. li, and s. pei, “experimental study on tensile strength development of concrete with manufactured sand,” constr. build. mater., vol. 138, pp. 247–253, may 2017. [12] m. nojoomizadeh and a. karimipour, “the effects of porosity and permeability on fluid flow and heat transfer of multi walled carbon nano-tubes suspended in oil (mwcnt/oil nano-fluid) in a microchannel filled with a porous medium,” phys. e low-dimens. syst. nanostructures, vol. 84, pp. 423–433, oct. 2016. http://www.sciencedirect.com/science?_ob=articlelisturl&_method=list&_articlelistid1215843383 http://www.sciencedirect.com/science/article/pii/s0003682x1730433 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 87-95 87 doi: 10.17977/um016v7i12023p087 effect of temperature variations of corn (maize) oil biodiesel on torque values and thermal efficiency of diesel engines suardi*, rodlian jamal ikhwani, ade putri rezki aulia department of naval architecture, kalimantan institute of technology, balikpapan, 76127, indonesia *corresponding author:suardi@lecturer.itk.ac.id article history: received: 19 pebruary 2023 / received in revised form: 5 may 2023 / accepted: 7 june 2023 available online 28 june 2023 abstract the trend of consumption of hydrocarbon fuels in indonesia, which is increasing every year, is not accompanied by the amount of production, which is decreasing. alternative fuels to reduce dependence on hydrocarbon fuels. one form of alternative fuel is biodiesel, which is made from corn (maize) oil. corn oil itself, if processed, can be an option for clean and environmentally friendly energy option and that is the main objective of this research is to determine the performance of biodiesel corn oil on diesel engines. the method used in this study is an experimental method where corn oil biodiesel is tested directly on a testing machine. the data from the test results will be used to find the torque and thermal efficiency values so that the engine performance values for each fuel variation can be identified. the results of the study obtained the engine performance value, namely the highest torque was on diesel oil fuel 4.57 n.m. the highest thermal efficiency value achieved at the b30 fuel sample at a temperature of 60 °c with the thermal efficiency of 17.4%. with these results, it can be concluded that engine performance with corn oil fuel can be used as an alternative fuel to replace hydrocarbon fuel. copyright © 2023. journal of mechanical engineering science and technology. keywords: biodiesel, corn (maize) oil, temperature, thermal efficiency, torque value i. introduction indonesia ranks 14th as a country with the level of consumption of fossil fuels in the world, with a total consumption of 1,470,000 barrels per day, while indonesia's total oil production is 692,000 barrels per day [1]. according to a source from the minister of energy and mineral resources of indonesia, indonesia's oil reserves will only last for the next 9.5 years [2]. this has prompted the government to encourage research on environmentally friendly fuels such as biodiesel. biodiesel is an environmentally friendly fuel source that can be an alternative to fossil fuels [3]. as a country with a tropical climate, indonesia makes its soil fertile for various kinds of plants, one of which is corn, which can be processed into corn oil biodiesel. indonesia's corn production data for 2020 reaches 22,500,000 tons [4], while the total world corn oil production is 3,189,137 tons, and indonesia is capable of producing around 7,417 tons [5]. various kinds of research related to biodiesel have been carried out, some of which is the production of biodiesel from waste cocking oil (wco), whose research results state that the use of wco biodiesel does not harm engine performance [6]. studies of the potential of algae [7] and the potential of animal oil to become biodiesel indicate that animal oil with a mixture of up to b60 can provide a good thermal efficiency value for the engine as well as 88 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 87-95 suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) a low emission value compared to fossil fuels [8]. biodiesel production from pome (palm oil milf effluent) results good engine performance values compared to diesel fuel [9]. the research that uses corn oil (maize) also gives good performance values for diesel engines [10]. research states that one tonne of corn kernels contains as much as 0.5 to 0.6 sugar, which can be converted into bioethanol, a clean raw material for biodiesel production [11]. all of these studies show that biodiesel can be used as an alternative fuel that is environmentally friendly, renewable, low in emissions, and able to answer concerns about the oil crisis that is already in sight. the viscosity of biodiesel fuel is its primary characteristic worth emphasizing. a study shows that the viscosity of biodiesel is higher than that of diesel fuel. the viscosity of diesel fuel is in the range of 2.5 – 3.2 cst at 40 °c, while biodiesel is 1.3 – 6 cst [12]. another study states that the viscosity value of biodiesel, especially palm oil mill effluent (pome), is 4.98 cst higher than the viscosity of diesel fuel, namely 1.8 – 4.1 cst, which affects the value of engine performance [13]. the more biodiesel added to diesel fuel will also increase the viscosity of the fuel. the high viscosity makes the fuel transfer pump work harder, and the fuel pick-up process will not be perfect. to make the engine not work harder, the fuel viscosity must remain within the astm standards d445 [14]. the viscosity of biodiesel can be reduced by increasing the temperature of the fuel [14] so that biodiesel safe to apply to the engine. in terms of engine performance, biodiesel can provide good performance, but that does not mean that biodiesel is a perfect and flawless fuel. in a study that tested the effect of using biodiesel on diesel engines used in fishing boats, the torque and power generated by engines with biodiesel fuel (b30) are slightly lower when compared to diesel fuel. in addition, the use of b30 makes the properties of changing engine lubricating oil. the results of the study stated that iron and aluminum metal content was found in the lubricating oil at 0.7% and 19.8%, respectively. chromium content was also found in the same sample. it also found cases of loosened piston rings and journal bearings experiencing wear [15]. the international maritime organization (imo), an agency under the auspices of the united nations, has set a target of reducing world carbon emissions by 40% in 2030 and 70% in 2050 [16]. by looking at the facts about the urgent need for new energy to replace hydrocarbon fuels and efforts to make the environment cleaner from bad pollution, the main purpose of this research is to test the performance of biodiesel corn oil directly on diesel engines. ii. material and methods the method used in this research is an experimental method of testing fuel samples directly on the engine. similar research has also been carried out by converting waste cooking oil (wco) into biodiesel, the results of which also provide good performance value for the engine, especially in terms of saving fuel consumption by around 45% [17]. corn oil samples were prepared in three variations with turpentine oil, namely 30%, 50%, and 70%. the results obtained were that at full load, corn oil was able to provide a greater thermal efficiency value of 15% compared to using 100% hydrocarbon fuel [18]. the fuel samples used were pure diesel, b30 with a temperature variation of 50 °c, and b30 with a temperature variation of 60 °c. after the density and viscosity values of the fuel are known, then proceed to the next stage, namely testing on a test machine. b30 fuel with two temperature variations was tested on diesel engines. the data taken during engine testing includes voltage, current, fuel consumption, and time of fuel consumption. the specifications of the diesel engines used in this study can be seen in table 1. issn: 2580-0817 journal of mechanical engineering science and technology 89 vol. #, no. #, july 20##, pp. ##-## suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) table 1. the specifications of engine [9],[10]. engine model yanmar tf 75/85 series type of engine no of cylinder displacement continuous power compression ratio specific fuel consumption (sfc) volume per injection tf 85mh 1 cylinder 4 stroke 493 cc 7.5 kw/2200 rpm 1:18 171 gr/hp h 0.07 ml engine tests were carried out on direct diesel engines with engine specifications according to table 1 with variations of pure diesel fuel (without biodiesel mixture), b30 with a temperature variation of 50 °c, and b30 with a temperature variation of 60 °c. data collection was carried out in testing diesel motors, which aims to determine the performance of diesel motors. the data taken during the trial included voltage, current and time values. this test uses 20 ml of fuel for each variation, starting from setting the engine speed to 1000 rpm, with a variety of loading from 1000 watts to maximum load (4000 watts). after the data was obtained in the form of current, voltage, and time values, calculations were carried out based on the formula previously described to obtain values for power (kw), specific fuel consumption (kg.kw.h), torque (n.m), and thermal efficiency (%). the machine testing scheme can be seen in figure 1. fig. 1. schematic diagram of experimental engine set-up [19] iii. results and discussions the research stage that must be carried out was to make a fuel sample that will be tested on a diesel engine. the sample is b30, a mixture of 30% corn oil and 70% diesel fuel. these samples were then made in two temperature variations, namely 500 c and 600 c. the two fuel samples were then tested for their viscosity and density values. table 2 shows the density and viscosity values of biodiesel fuel according to pt pertamina. 90 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 87-95 suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) table 2. biodiesel specifications [20] characteristic unit min value max value methods density gr/ml 0.815 0.88 astm d4052/1298 viscosity cst 2 5 astm d445 fig. 2. fuel samples. a) pure diesel oil, b) corn (maize) oil b30 a) b) c) fig. 3. a) b30 temperature measurement, b) testing the density of b30 using a pycnometer, c) testing the viscosity of b30 using a viscometer figure 2 shows two fuel samples, namely pure diesel oil and b30, while figure 3a shows the process of measuring the temperature of the previously heated b30 fuel. figure 3b shows the process of testing the density of the fuel using a pycnometer, and figure 3c shows the process of testing the viscosity of the b30 fuel sample with a temperature variation of 50 c and 60 c. the results of testing the viscosity and density of the fuel can be seen in table 3, which shows that the density and viscosity values of b30 fuel are not included in the standard fuel determined by pt pertamina, according to table 2. table 3. density and viscosity of b30 biodiesel with temperature variations of 50 °c and 60 °c. pertamina standard biosolar (b30) biodiesel corn oil b30 characteristic unit min value max value temp.(oc) result methods density gr/ml 0.815 0.88 50 0.92 astm d4052/1298 60 0.91 viscosity cst 2 5 50 6.2 astm d445 60 5.8 b30 (corn (maize) oil 30% and pertamina dex 70% pure diesel oil (pertamina dex) issn: 2580-0817 journal of mechanical engineering science and technology 91 vol. #, no. #, july 20##, pp. ##-## suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) 1. engine performance testing the engine test is carried out to determine the resulting engine performance value based on the variation of the fuel used. the data obtained in the engine testing process were used to find the value of power, torque, sfc, and engine thermal efficiency. table 4 shows the engine test result data. table 4. engine test result data in four load conditions fuel load (watt) v (volt) a (ampere) time (s) v (volt) a (ampere) time (s) v (volt) a (ampere) time (s) 750 rpm 1000 rpm 1250 rpm diesel oil 1000 72.2 3.26 308 112.4 3.37 211 138.1 3.47 165 2000 65.5 3.29 224 88.6 3.42 166 78.9 3.48 146 3000 53.5 3.45 210 63.2 3.68 162 58.3 4.17 144 4000 40.4 4.5 190 51.8 4.94 155 50.1 5.88 138 b30 50 °c 1000 72.8 2.03 348 115.7 2.43 260 149.5 2.95 233 2000 68.5 2.68 302 104.6 2.75 205 94.7 3.24 209 3000 59.7 3.02 298 75.7 3.07 165 65.2 4.32 162 4000 45.9 3.68 280 60 3.68 141 54.4 4.34 140 b30 60 °c 1000 66.5 3.18 357 114.2 2.76 232 140 2.97 166 2000 62 3.22 322 88.6 3.46 220 88.2 3.52 155 3000 54.5 4 267 66.5 3.86 214 61 4.34 152 4000 39.36 4.45 289 52.3 5.33 183 49.5 5.74 146 2. performance analysis of diesel engine after testing the engine and obtaining the value of voltage, current, and time of fuel consumption, it can be determined the value of torque, sfc, and the value of thermal efficiency. comparative analysis between torque and load one of the commonly used engine performance parameters is torque. the torque itself indicates the quality of the fuel. whether it can provide a large torque value or not, the greater the torque affect the engine power. figure 4 shows a graph of the ratio of torque to load with a variety of fuels, namely diesel without heating, b30 with a temperature of 50 °c, and b30 with a temperature of 60 °c at 750 rpm where the largest value is diesel fuel without heating at a load of 1000 watts with the torque value is 3.75 n.m. the smallest value is found in the b30 fuel with a temperature of 50 °c at a load of 1000 watts with a torque value of 2.36 n.m. figure 4 shows the ratio of torque to load with a variety of fuels, namely diesel without heating, b30 with a temperature of 50 °c, and b30 with a temperature of 60 °c at 1000 rpm. the largest value is diesel fuel without heating at a load of 1000 watts with the torque value is 4.52 n.m, while the smallest value is found in the b30 fuel with a temperature of 50 °c at a load of 4000 watts with a torque value of 2.64 n.m. figure 4 also shows the ratio of torque to load with various fuels, namely diesel without heating, b30 with a temperature of 50 °c, and b30 with a temperature of 60 °c at 1250 rpm, where the largest value is diesel fuel without heating at a load of 1000 watts with the torque value is 4.57 n.m, 92 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 87-95 suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) while the smallest value is found in the b30 fuel with a temperature of 50 °c at a load of 4000 watts with a torque value of 2.25 n.m. fig. 4. graph of torque vs load based on a variation of speed figure 4 shows the lowest average torque value found in the b30 fuel variation with a temperature of 50 °c at 750 rpm and 1000 rpm, so the power generated is also quite low. however, at 1250 rpm, the torque value has increased at a load of 1000 watts to 3000 watts. the average highest torque value is found on pure diesel fuel without heating at 750 rpm, 1000 rpm, and 1250 rpm at minimum load. then, the b30 fuel with a temperature of 60 °c produces the highest torque value at 1000 rpm at maximum load. this affects the power generated is greater. comparative analysis of thermal efficiency vs power figure 5 shows the comparison of thermal efficiency to the load with a variety of fuels, namely diesel without heating, b30 with a temperature of 50 °c, and b30 with a temperature of 60 °c at 750 rpm where the largest value is found in the b30 fuel with a temperature of 60 °c at a load of 1000 watts with a thermal efficiency value of 0.128%. the smallest value is found in diesel fuel without heating at a load of 4000 watts with a thermal efficiency value of 0.058%. issn: 2580-0817 journal of mechanical engineering science and technology 93 vol. #, no. #, july 20##, pp. ##-## suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) figure 5 shows the comparison of thermal efficiency to the load with a variety of fuels, namely diesel without heating, b30 with a temperature of 50 °c, and b30 with a temperature of 60 °c at 1000 rpm, where the largest value is found in diesel fuel without heating at a load of 1000 watts with a thermal efficiency value of 13.5%, while the smallest value is found in the b30 fuel with a temperature of 50 °c at a load of 4000 watts with a thermal efficiency value of 5.3%. it also shows the comparison of thermal efficiency to load with a variety of fuels, namely diesel without heating, b30 with a temperature of 50 °c, and b30 with a temperature of 60 °c at 1250 rpm. the largest value is found in the b30 fuel with a temperature of 50 °c at a load of 1000 watts with a thermal efficiency value of 17.4%, while the smallest value is found in the b30 fuel with a temperature of 50 °c at a load of 4000 watts with a thermal efficiency value of 5.6%. fig. 5. graph of thermal efficiency vs load based on a variation of speed iv. conclusions the results of this study indicate that with variations in the mixture of diesel oil and corn oil (maize) fuel, it can be used as an alternative fuel to reduce dependence on hydrocarbon 94 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 87-95 suardi et al. (effect of temperature variations of corn oil biodiesel on efficiency of diesel engines) fuels. variations in temperature between b30 at 50 °c and 60 °c affects the viscosity and density values of the fuel. the higher the fuel temperature, the more values and density increase. b30 fuel at 50 °c and 60 °c have the viscosity value of 6.2 cst and 5.8 cst, respectively. the density of b30 at 50 °c and 60 °c are 0.92 gr/ml and 0.91 gr/ml, respectively. the performance value on the b30 at 60 °c indicates the highest torque of 4.75 n.m, and a thermal efficiency value of 17.4% is obtained. acknowledgment i express my high appreciation to all parties who have helped in this research until the end. i hope this research can help other researchers develop alternative energy for engines in the future. references [1] s. widi, “indonesia’s oil consumption up 5.22% in 2021,” 2022. https://dataindonesia.id/sektor-riil/detail/konsumsi-minyak-indonesia-147-jutabarel-per-hari-pada-2021 (accessed feb. 18, 2023). 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[20] pertamina, spesification produk bbm, bbn & lpg. 2020, p. 23. journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 7-12 7 doi: 10.17977/um016v2i12018p007 mechanical properties and permeability of sand casting moulds with eggshells binder maryam sharifi jebeli1, wahyu kurnianto 2, and wahono 2 1 physics department, isfahan university of technology, iran 2 department of mechanical engineering, faculty of engineering, universitas negeri malang *mshjebeli@gmail.com abstract this research aimed to analyse whether or not eggshell could be a potential addition to sand mould composition as a binding material together with bentonite. different amounts of eggshell material, i.e. 4%, 7%, 10% and 3%, were added to each sample. this study was a type of pre-experimental design called the one-shot case study. among all sand moulds under study, sample 3 10% es in dry conditions had the highest tensile, compressive and shear strengths of 0.09 kg/cm2, 3.11 kg/cm2 and 1.13 kg/cm2, respectively. the results of the permeability test with heat treatment at 110˚c for 60 minutes showed that sample 3 10% es had a permeability value of 178.3 ml/min. copyright © 2018journal of mechanical engineering science and technology all rights reserved keywords: mechanical properties, permeability, sand mould, eggshell i. introduction metal casting is a work piece shaping method involving a series of process, i.e. melting the material through heating and pouring it into a mould to produce the desired shape in the work piece. to date, the use of sand moulds remains the most preferable option due to its low-cost feedstock, variety of sizes and compositions, and recyclability [12]. one of the most commonly used materials in metal casting is aluminium. according to the october 2015 world economic outlook (imf), aluminium is ranked 3rd as the primary base metal, with a global sales value of usd 90 billion per year (ministry of industry of republic of indonesia, 2016). the most common form of metal casting is sand casting, where the sand mix is composed of silica sand, bentonite, water, carbon, and waterproof powder. the binding agent used in sand casting is generally bentonite only. according to [9], bentonite is used extensively as a binder in sand mould production because it has the required properties, i.e. generating a high binding strength and turning into clay when wet and becoming hard when dry, hence easy to work with for mould making. in this study, the binder consisted of bentonite and eggshell powder. eggshells are dominantly used in beauty products and fertilizers because of its high levels of calcium; they have not been considered as a potential material in the foundry industry. the chemical content of eggshells represents 11% of the total egg weight, which is composed of calcium carbonate (94%), calcium phosphate (1%), organic matter (4%), and magnesium carbonate (1%) [7]. a study involving limestone as one of the binders used and found that this material had a calcium content beneficial as a binding agent [3]. limestone was chosen since it could be hardened after being mixed with water. ii. method this study was a type of pre-experimental design called the one-shot case study, in which a group of subjects were given treatment and then observed [13]. the research design is presented in figure 1. mailto:*mshjebeli@gmail.com 8 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 7-12 maryam sharifi jebeli1et.al (mechanical properties and permeability of sand casting moulds with eggshells binder) fig. 1. research design where: x1 = 4% eggshell and 3% bentonite x2 = 7% eggshell and 3% bentonite x3 = 10% eggshell and 3% bentonite y1 = permeability y2 = tensile strength y3 = compressive strength y4 = shear strength the independent variables in this study were the ratios between silica sand and eggshells (x1, x2, x3) in the sand mould mixture, involving three different amounts of silica sand (88%, 85% and 82%) and eggshells (4%, 7% and 10%). 4. the dependent variables in this study are permeability (y1), tensile strength (y2), compressive strength (y3), and shear strength (y4). the control variables included 5% water, eggshells with a mesh size of 200 or fineness level of 0.02 mm and 3% bentonite mixed with silica sand with a mesh size of 40 or fineness level of 0.4 mm. iii. results prior to testing the sand moulds, the eggshells were tested using xrd to determine the contents of elements in these additional materials. the results are presented in figure 2 and table 1. fig. 2. phase identification of eggshell nanopowder without sintering at 1100˚c table 1. phase identification of eggshell nanopowder without sintering at 1100˚c pos. [˚2th.] height [cts] fwhm [˚2th] d-spacing [å] rel.int. [%] 29.4265 1606.40 0.1378 3.03541 100.00 issn: 2580-0817 journal of mechanical engineering science and technology 9 vol. 2, no 1, july 2018, pp. 7-12 maryam sharifi jebeli1et.al (mechanical properties and permeability of sand casting moulds with eggshells binder) table 2. properties of eggshell nanopowder from xrd result and scherer equation material x-ray diffraction intensity (counts) fwhm (rad) d-spacing (å) crystallite size (nm) raw eggshell nanopowder 1606.40 0.1378 3.03541 59.7912 the results of xrd testing showed that the eggshell nano powder not being synthesised and sintered at 1100˚c had a crystallite size of 59.7912 nm presented in table 2. this is in line with the hall-petch law stating that the smaller the crystallite size, the harder the material [6]. a. testing of mechanical properties the strength of materials consists of: 1) tensile strength tensile strength refers to the maximum stress that a material can bear when being stretched or pulled before it fails. 2) compressive strength compressive strength is the capability of a sand mould to withstand the compressive force given by the flow of molten metal poured into the cavity moulded according to a pattern of the desired shape. 3) shear strength shear strength is the ability of sand to resist sliding forces. it is the internal resistance of the sand along the slide plane. the compositions of sand mould samples in this study are as follows: 1. 4% eggshell, 3% bentonite, 88% silica sand and 5% water (sample 1 4% es) 2. 7% eggshell, 3% bentonite, 85% silica sand and 5% water (sample 2 7% es) 3. 10% eggshell, 3% bentonite, 82% silica sand and 5% water (sample 3 4% es) b. mechanical properties of sand moulds in wet conditions figure 3 shows the analysis results of the strength of each sand mould. according to [16], the strength of sand moulds in wet conditions could increase along with increasing bentonite content and reach the maximum value with a certain bentonite concentration. this suggests that the addition of different amounts of binder produces different strengths. as also stated by herwido (2016: 79), the concentration of the binding material can make a significant difference to the strength of the sand mould. fig. 3. mechanical properties of sand moulds in wet conditions 10 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 7-12 maryam sharifi jebeli1et.al (mechanical properties and permeability of sand casting moulds with eggshells binder) c. mechanical properties of sand moulds in dry conditions fig. 4. mechanical properties of sand moulds in dry conditions among all samples, sample 3 10% es had the highest tensile, compressive and shear strengths. the highest tensile strength was 0.068 kg/cm2, but it is still below the predetermined standard of 0.07-0.42 kg/cm2. the highest compressive strength was 0.74 kg/cm2; this strength level has met the standard compressive strength ranges of 0.35-1.54 kg/cm2. the highest shear strength was 0.28 kg/cm2; this number is within the acceptable range of standards, i.e. 0.10-0.49 kg/cm2. as a comparison, [8] conducted research on the mechanical properties of a sand mold composed of 85% silica sand, 10% bentonite and 5% water and found that it had tensile, compressive and shear strengths of 0.06 kg/cm2, 0.54 kg/cm2 and 0.022 kg/cm2, respectively. in sum, this present study revealed that a mixture of 10% eggshell and 3% bentonite could reduce the use of excessive amounts of bentonite. among all sand moulds under study, sample 3 10% es had the highest tensile, compressive and shear strengths shown in figure 4. the highest tensile strength was 0.09 kg/cm2, which is considered reaching the standard ranges of 0.07-0.42 kg/cm2. the highest compressive strength was 3.1 kg/cm2; this strength level has met the standard compressive strength ranges of 1.5-17.5 kg/cm2. according to [11], the addition of limestone (caco3) to concrete made of lapindo mud had an effect on the compressive strength of concrete; the higher the concentration of limestone used, the higher the compressive strength. the highest shear strength was 1.13 kg/cm2; this number is below the acceptable range of standards, i.e. 0.100.49 kg/cm2. previous research conducted [15] revealed that a sand mould made of 10% bentonite, 82% silica sand and 5% water had tensile, compressive and shear strengths of 0.07 kg/cm2, 1.2 kg/cm2 and 0.5 kg/cm2, respectively. [2] pointed out that sand moulds composed of natural binders could be used to improve the mechanical properties of aluminium alloy casting. moreover, [8] found that a sand mould composed of 85% silica sand, 10% bentonite and 5% water had a tensile strength of only 0.05 kg/cm2, a compressive strength of 1.3 kg/cm2 and a shear strength of 0.3 kg/cm2. this present study revealed that a mixture of 10% eggshell and 3% bentonite could reduce the use of bentonite in the mixture. d. permeability of sand moulds permeability test is a test conducted to determine the capability of a sand mould to allow gas and steam pass through the sand mould. casting defects occur because the optimal conditions are not met during the casting process [5]. therefore, moulding sand with high permeability is essential to allow the escape of gases during the pouring of molten metal into the mould. [10] stated that the volume of air/gas passing through the sand mould should be determined using the permeability meter. the permeability value should not be too low or too high. all samples showed that 5% water was the optimum amount to bind well shown in figure 5. issn: 2580-0817 journal of mechanical engineering science and technology 11 vol. 2, no 1, july 2018, pp. 7-12 maryam sharifi jebeli1et.al (mechanical properties and permeability of sand casting moulds with eggshells binder) fig. 5. results of permeability testing on sand moulds according [1], the low permeability of moulding sand results in difficulty for air to flow through the sand grains. as a result, when molten metal is poured, gas/air cannot escape and hence defects in the casting. conversely, if the permeability is too high, the molten metal can enter into the gaps between sand grains, causing a rough casting surface. the above explanation suggests that the excessive concentration of binding material can form smaller gaps between sand grains, making it difficult for air to pass through. however, if the amount of binder is too little, air can flow much more easily due to larger gaps. in this study, therefore, a low amount of binder resulted in large gaps in sample 1 4% es and hence an easy flow of air through the sand grains. in contrast, sample 3 10% es which contained a high concentration of binder had narrow gaps, causing difficulty for air to pass through the sand grains. previous research found that a combination of 5% bentonite and 5% portland cement resulted in permeability of 176 ml/min [1]. in another study, a composition of 7% bentonite and 2% fly ash produced a permeability value of 231.67 ml/min (herwido, 2016). in general, sample 3 10% es in dry conditions had the highest mechanical strengths but the lowest permeability although the value is slightly higher than the standard ranges of 50-170 ml/min. in this study, therefore, the composition of sample 3 10% es in dry conditions is considered the most suitable for metal casting. sand moulds in dry conditions, in fact, have improved mechanical strengths because the water absorbed in the sand grain surface is removed. [14] further pointed out that the use of sand mixed with clay as the binder in dry conditions could generate higher permeability and strength than that in wet conditions. in addition to having high mechanical properties, sample 3 10% es had a permeability value close to the predetermined standard value or range in metal casting. therefore, the composition of sample 3 10% es is particularly suitable to be applied for mould making in metal casting. iv. conclusion the results and discussion above have led to the following conclusions. among all sand moulds under study, sample 3 10% es in dry conditions had a permeability value suitable for use in metal casting, i.e. 178.3 ml/min. also, sample 3 10% es had the highest tensile, compressive and shear strengths of 0.09 kg/cm2, 3.11 kg/cm2 and 1.13 kg/cm2, respectively. v. references [1] andoko et al. 2017 ‘formula of moulding sand, bentonite and portland cement toimprove the quality of al-si cast alloy’, journal of mechanical engineering science and technology, 1(2), pp. 49–52. 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[12] saikaew, c. and wiengwiset, s. 2012. ‘optimization of molding sand composition for quality improvement of iron castings’, applied clay science. elsevier b.v., 67–68, pp. 26–31. doi: 10.1016/j.clay.2012.07.005. [13] sugiyono. 2013. metode penelitian pendidikan (pendekatan kuantitatif, kualitatif dan r&d). bandung: alfabeta. [14] surdia, tata & chijiwa, kenji. 1980. teknik pengecoran logam. jakarta: pradnya paramita. [15] susmarinda s.h. 2014. analisis variasi nbahan pengikat dalam pasir cetak malang terhadap kekuatan pasi cetak dan permebilitas. malang. universitas negei malang [16] yu, w. et al. 2009. ‘preparation and experiments for a novel kind of foundry core binder made from modified potato starch’, materials and design, 30(1), pp. 210–213. doi: 10.1016/j.matdes.2008.03.017. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 59-65 59 doi: 10.17977/um016v7i12023p059 designing a naabsa class tanker ship with bottom protection from ground victor a. kulesh, mathias b. prasetio*, fam chung hiep department of marine technology and transport, polytechnic institute, far eastern federal university. address: 10, ajax bay, russky island, vladivostok, 690922, russian federation. *corresponding author: mathiasbimop@gmail.com article history: received: 9 april 2023 / received in revised form: 11 may 2023 / accepted: 15 may 2023 available online 9 june 2023 abstract indonesia is the world's largest archipelago country with a high potential for economic development and top producer and exporter of palm oil. as an archipelago country, the most efficient cargo transportation routes are through rivers and seas. designing and building tankers, taking into account the specifics of the operation, are relevant. the paper considers the issues of designing a tanker for the transportation of crude palm oil with a defined operation area and route. the general concept of the vessel is proposed, taking into account the restrictions on the navigation area and draft for operation in the river. particular attention is given to the issues of strengthening the hull in terms of overall longitudinal strength, as well as the bottom and the propeller-steering complex in terms of interaction with the ground. an external structural protection (esp) from the ground was developed, and comparative calculations of the stress-strain state of the compartment and esp structures were performed. the effectiveness of the solution for protecting the hull from direct contact with the ground is shown, and outlined ways for the possible development of tanker projects for the conditions. copyright © 2023. journal of mechanical engineering science and technology. keywords: external structural protection, fem analysis, grounding resistance, naabsa, tanker i. introduction the republic of indonesia is the largest archipelago country in the world. it is located between the indian and pacific oceans. indonesia is ranked 4th in the world by population (after china, india, and the usa), with a population of 280 million people. indonesia has a rich shelf zone with biological and other resources (figure 1a), with a total area of 1.92 million km2 and 13.6 thousand islands. the share of the oil industry in indonesia is $292 billion, and it is an important part of the country's economy (29%) – 16th in the world and 1st in southeast asia. oil and gas exports bring 20% of the country's income, ranking 3rd in the list of major exported goods after coal and palm oil [1]. indonesia is the world leader in palm oil production, with 46 million tons worth $18 billion annually. other major export commodities are rubber ($4 billion), coffee ($1.4 billion), seafood, etc. [1]. the planned route of the tanker is the port of palembang (departure) and the port of priok (jakarta) (figure 1b). the navigation range is 500 nautical miles, including the river section – 54 miles, then narrow bangka strait – 100 miles, and then in the open java sea – 346 miles. 60 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 59-65 kulesh et al. (designing a naabsa class tanker ship with bottom protection from ground) a) b) fig. 1. map of indonesia (a) and the planned navigation area of the tanker (b) the minimum depth of the musi river is 4.5 meters [2], with tide up and downs that can reach up to 2 m. this determines the probability of contact with the ground and partial drainage. the draft of the tanker was adopted 4 m, taking into account the margin for structural protection from the ground. there are no bridges on the considered section of the river, and no height restrictions are required. the narrow bangka strait separates the islands of sumatra, and bangka has the lowest depth of 7.5 m. the java sea is relatively shallow, and its average depth is 40 m [3]. the java sea is characterized by great thermal stability with an annual average temperature of 28 °c and deviations up to 3 °c. [3]. ii. material and methods 1. general conception of the tanker taking into account the conditions of the operating area, the dimensions of the tanker are length 90 m, width 15 m, side height 5 m, and draft 4 m, displacement 5037 t. the main cargo is palm oil. the possibility of modifying the tanker for crude oil transportation is also taken into account. additionally, the issues of restrictions on the navigation area and the class of the vessel naabsa1 were considered according to the rules of the russian maritime register of shipping (rs) [4, 5]. the vessel is a 2-screw, with a tank and a 3-tier superstructure in the stern. in the area of the cargo area, there is an elevated main deck (height of 1 m), double bottom (height of 1 m), and double sides (width of 0.9 m) equipped. the transverse spacing is 700 mm in the cargo area. the longitudinal spacing is 600 mm. floors and frames through 3-4 spacings. the hull has 9 transverse bulkheads and 1 longitudinal one. the side view of the vessel and the cross-section diagram are shown in figure 2. in the first stage, loads and general requirements for the size of connections are determined according to the rules [5]. the lining of the bottom and cheekbones is 10 mm thick. the flooring of the second bottom is 9 mm thick. floors and zygomatic brackets with a thickness of 10 mm. checking the overall strength of the hull showed that there is a shortage for the i limited navigation area (200 miles away), and it was decided to use steel with 235 yield strength for bottom and sideboard construction and high-strength steel with 315 mpa for the elevated main deck and its longitudinal beams [15]. then the total longitudinal strength is provided with a margin of 12.1%. issn: 2580-0817 journal of mechanical engineering science and technology 61 vol. 7, no. 1, july 2023, pp. 59-65 kulesh et al. (designing a naabsa class tanker ship with bottom protection from ground) fig. 2. side view and midship section concept of the tanker hull 2. hull reinforcements for naabsa1 class and ground landing in the second stage, the task of strengthening the hull for safe contact with the ground and compliance with the naabsa1 class was solved [5]. additionally, the issues of the influence of the external structural protection of the hull were considered. based on the results of calculations and in the absence of an esp, it was obtained: increase the thickness of the lining of the bottom and cheekbones to 11 mm, the flooring of 2 bottoms up to 10 mm; increase the longitudinal bottom beams no 2-8 from diametrical plane (dp) from the half-column 18a to 20b [9]. 3. external structural protection design the operation of vessels in rivers increases the possibility of interaction with the ground. to avoid accidents and damage to the hulls, the bottom is most often damaged. therefore, protecting the bottom from direct contact with the ground is important [6]. the works [11,12] show the advantages of a trapezoidal esp with overhangs. the parameter of the esp was achieved by following methods by kulesh v.a. and pham trung hiep [8-10], and for such a form, the decision was made in figure 3a. a) b) fig. 3. cross section of esp (a) and closing sections of the esp (b) the esp includes 4 elements: a horizontal support strip, a vertical sheet, an inclined sheet, and internal brackets (through 2 spacers) with a length of 49 m on the parallel mid62 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 59-65 kulesh et al. (designing a naabsa class tanker ship with bottom protection from ground) body of the ship (figure 3b). vertical and inclined strips are connected to the bottom lining through lining strips. 4. fem analysis the ship's hull compartment was modeled using the solidworks program [13]. the model was created as a fragment of ¼ compartment. the design of the compartment and its loading conditions were assumed to be symmetrical with respect to the diametral plane. the set of the compartment included different types of bracing sections: tees (keel, bottom stringers, carlings, beams, and bulkhead frame racks), bulb strips (frames, bottom longitudinal beams, above-deck longitudinal beams, idle racks, and horizontal bulkhead shelf). the compartment boundary conditions shown in figure 4a are fixed along the section in the diametral plane (no displacements and no rotations), fixed on the transverse bulkhead (no shifts or turns), reference geometry along the cross-section of the middle of the compartment (no rotations around the y axis). the mesh used is standard and solid, with a global size of 200 mm and a tolerance of 3.8 mm [14], shown in figure 4b. a) b) fig. 4. fixtures (а) and mesh (b) a) b) fig. 5. case 1 tank without cargo (а) and case 2 tank with cargo (b) issn: 2580-0817 journal of mechanical engineering science and technology 63 vol. 7, no. 1, july 2023, pp. 59-65 kulesh et al. (designing a naabsa class tanker ship with bottom protection from ground) the analysis of the stress-strain state of the compartment under the action of soil was performed, and 2 cases are considered: 1. tank without cargo (figure 5a.); 2. tank with cargo (figure 5b.). the soil is different and has many properties, but for this study, we take the calculated nominal resistance of the soil; 300 kpa is assumed (we take an average of 100-600 kpa). the load on the compartment from the ground side was 8357 kn. iii. results and discussions the calculation is presented in table 1. the highest stresses in the floor are 192 mpa when the tank is filled. stresses in double bottom longitudinal, stringer and stiffner connection also increased significantly caused by the pressure of the filled cargo tank. the maximum deflections along the horizontal keel are 0.19 mm (figure 6a) and along the decking of the second bottom 0.23 mm (figure 6b) for case 1 and case 2, respectively. table 1. maximum stresses (mpa) in structural elements no element case 1 case 2 1 c o m p a rt m e n t vertical keel 79 80 2 bottom longitudinal beams 95 99 3 stringer 24 59 4 floor 136 192 5 double bottom longitudinal beams 52 101 6 stiffener 40 103 7 bracket bilge keel 25 25 8 keel bracket 131 144 9 horizontal keel 114 113 10 bottom skin 43 66 11 e s p lining plate 1 104 101 12 vertical plate 82 72 13 horizontal support strip 64 64 14 lining plate 2 100 100 15 inclined sheet 42 43 16 internal brackets 94 100 17 maximum deflection, mm / location 0.19 / horizontal keel 0.23 / double bottom the stresses differences in esp (external structural protection) of case 1 and case 2 are identical. all of the maximum stresses are below the maximum yield strength of the material of 235 mpa. analysis of the results of fem calculations showed: 1. tanker with esp under the most severe conditions (full draining at the highest weight) receives a relatively high level of stress in the bottom floors up to 82% of the yield stress in the filled tank scenario; 2. the stresses in the esp elements are less significant up to 6% of the yield stresses in the vertical plate and in the internal bracket3%; 3. for relatively large vessels, the conditions with a partial transfer of the reaction of the soil simultaneously to the hull and to the esp are especially important and provide opportunities for obtaining acceptable design solutions in terms of dimensions, weight, and stresses. this design solution was also developed from previously researched by prasetio et al. [9]. 64 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 59-65 kulesh et al. (designing a naabsa class tanker ship with bottom protection from ground) a) b) fig. 6. diagram of deflection of case 1 (a) and case 2 (b) iv. conclusion as a result of the work, a tanker concept is proposed for the considered operating conditions. the necessity of increasing the overall longitudinal strength of the hull and the local strength of the bottom is shown. the directions and objectives of the development of this project are related to the technical and economic performance indicators, taking into account loading options and clarifying design concepts for protection from the soil. references [1] a.v. popov, economy of indonesia: special state and development prospects. institute of oriental countries, 2019. 372 p (original document in russian). [2] s. sunarso, impact of sailing route in musi river flow. gema teknologi, vol. 16, no. 1, diponegoro university, indonesia. 2010. 8 p (original document in indonesian). [3] j.r. durand, d. petit. the java sea environment, m. potier, and s. nurhakim (eds.), in biodynex. biology, dynamics, exploitation of the small pelagic fishes in the java sea, agency for agricultural research and development-orstom-eu. 1995, pp. 14-38 [4] v.a. kulesh, fundamentals of the design of marine hulls. guidelines for the implementation of the course project in the discipline “the design of the hull of sea vessels.” dvgtu, vladivostok, 2007. 70 p (original document in russian). [5] rules for the classification and construction of sea vessels. russian maritime register of shipping. rmrs, saint petersburg, 2022. 337 p. [6] o.e. surov, h.c. fam, and a.s. vorobyova, external constructive protection of ships from soil. modern technologies in shipbuilding and aviation education, science and production: a collection of reports of the all-russian scientific and practical conference, nizhegorsk state technology university named r. e. alekseev. nizhny novgorod. 2021. pp 46-51 (original document in russian). [7] v.a. kulesh and h.c. fam. structural protection of ship from soil. proceedings of the krylovsky state scientific center. issue no. 1. saint petersburg. 2022, pp. 113 – 119 issn: 2580-0817 journal of mechanical engineering science and technology 65 vol. 7, no. 1, july 2023, pp. 59-65 kulesh et al. (designing a naabsa class tanker ship with bottom protection from ground) (original document in russian) [8] v.a. kulesh and h.c. fam. interaction of ships with ground: teaching aid. politechnic institute fefu. vladivostok, 2021. 33p (original document in russian). [9] m.b. prasetio, h.c. fam, k.v. elkina, v.a. kulesh. research design of a tanker for the seas and rivers of indonesia, taking into account interactions with the ground. regional scientific and practical conference “youth and scientific and technical progress” istp. vladivostok, 2022, pp. 1022-1026. [10] m.b. prasetio, h.c. fam, and v.a. kulesh. analysis of the resistance to movement of a large tanker with regard to external structural protection from ground. regional scientific and practical conference “youth and scientific and technical progress” istp. vladivostok, pp.1017-1021. [11] v.a. kulesh, o.e. surov, and h.c. fam. patent no. 215629 russian federation. bottom protection device with a longitudinal system when landing on the ground. fefu applicant, 2s. [12] v.a. kulesh, o.e. surov, and h.c. fam. patent no. 216642 russian federation. bottom protection device with a transverse framing system when landing on the ground. fefu applicant, 11s. [13] v.g. bugaev and d.v. tung. information technologies in the life-cycle of marine engineering: teaching aid. politechnic institute fefu. vladivostok, 2021. 145p (original document in russian). [14] class guideline for finite element analysis. dnv gl. dnv gl as, berum, norway 2015. 93 p. [15] technical specification 5.961-11605-95. rolled steel shaped for shipbuilding. bulbs profile. central research institute of km "prometheus". moscow, 2017. journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 13-15 13 doi: 10.17977/um016v2i12018p013 pine flower waste innovation as a plant based program augmented reality ayik bela saputra 1*, imam muhtarom 1, ni’matul rochmaniyah 2, ardhana iswari citra padmi 2 and ika rahmawati 3 1 bachelor program, mechanical engineering department, universitas negeri malang 2 bachelor program, electrical engineering department, universitas negeri malang 3 bachelor program, accounting department, universitas negeri malang *saputra.ayik22@gmail.com abstract indonesia one of the tropical countries in the world can not be separated from environment problems like other developing countries. one of the causes of declining environment quality is the decline of forests in indonesia. in 2009, indonesia’s forest area was by more than half, to about 88 million hectares. by the year 2013 the number is about 82 million hectares. one of the efforts to promote environment education is to familiarize planting plants to children from an early age from the school environment to the family environment. therefore it is necessary an alternative in the form of planting media that can be used as a trigger tool of environmental care attitude and can feel the sensation of planting that educative by utilizing pine flower waste as an attractive and environmentally friendly planting medium. besides as a planting medium is also intended as a instructional media especially elementary school students to high school students. this is because the planting medium has a goal to give an educative impression through information on plant species being planted and to increase awareness of the surrounding environment. if used as a medium of learning this planting media will bring up information about the plant being planted by way of scanning pot characters with gadgets then information about the classification of plants, root shapes, stems, leaves, flowers, how copyright © 2018journal of mechanical engineering science and technology all rights reserved keywords: planting media, environmental education, pine flower waste i. introduction indonesia's forests are generally dominated by various types of plants. one of the most supportive crops of this country's forests is pine trees. pine type of merkusi is a versatile tree plant species because almost all parts of this plant can be utilized by human [6]. this matter is also in harmony with government focus which is promoting environmental education for the sake of world sustainability. according to environmental education should be able to educate individuals, who are responsive to the rate of technological development, understand the problems in the biosphere, and productive, productive skills to maintain and sustain nature [1]. ii. research method in the making of planting media or production process begins with research on environmental care, caring values and type of ornamental plant. then do the character management of the plant type. the next stage of making outline of planting media as well as aligning and making pots, shown in figure 1. after the pot is completed and the augmented reality program will be testimony to the target of elementary school students up to college. the testimony aims to determine the level of success and how big the pot enthusiasts. after that it will be depicted in a graph and drawn a conclusion. mailto:saputra.ayik22@gmail.com 14 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 13-15 ayik bela saputra et.al (pine flower waste innovation as a plant based program augmented reality) fig. 1. pot shape and augmented reality program fig. 2. potential character fig. 3. enthusiasts iii. results and discussion a. potential character pot pot made 150 units with bear, angry bird, turtle, olaf, and cow. the most popular potted characters are bear-shaped pots as much as 34.3% while the least preferred is the shape of tortoise and cattle, which is 14.9%. for more details can be seen in figure 2. issn: 2580-0817 journal of mechanical engineering science and technology 15 vol. 2, no 1, july 2018, pp. 13-15 ayik bela saputra et.al (pine flower waste innovation as a plant based program augmented reality) b. enthusiasts meanwhile, when viewed from the most current enthusiasts is the number of elementary school students is a number of 53.7% and the lowest is from college enthusiasts, ie 9%. if described in figure 3. based on the figure 2 and 3, graphs can be in the know that the shape of planting media in the form of pot many types of enthusiasts. means for now media planting that aims to raise awareness of environmental education is still realized only for elementary school children whereas for higher need to be modified again form the character pot. media learning is a technology used as a messenger to be used as the interests of the process learning [2]. while the media has always been an important element of instruction, in today's technology dominated society the paly an even more pivotal role in id [4]. the use of real-life learning media that combined with matching cooperative learning is influenced [7]. people gathering information, distributing ideas and answering questions have begun to shift to electronic media, as evidenced by 85% of teenagers in 2008 [5]. this has led to the creation of innovative media literacy to address these issues. learning media can be used well in both formal and non-formal conditions. the use of instructional media is for additional support of instruction and instruction in the class. every instructional media application should be unique in any case and be guided by both general learning principles and the context in which the media is used [3]. learning media are usually deliberately designed to make the learning environment more interesting. iv. conclusion the shape of pot characters has an influence on pot enthusiasts, because the form is more childish so the demand is among the children so for the future need in the media planting more innovative again so that the demand to the level of adult so that environmental education can be realized. although environmental education starts early but for the elderly need to be increase awareness about the importance of environmental education through planting media one of them. real-shaped splitting media has greater attractiveness when compared with non-real-learning media forms. v. references [1] barlia, lily,teori pembelajaran lingkungan hidup disekolah dasar. subang: royyan press, 2008 . [2] fikriyaturrohmah and nurakiki, pengembangan media pembelajaran interaktif hands-on equation berbantu komputer pada materi persamaan linier satu variabel untuk siswa kelas vii, 2010. [online]. [3] naz and akbar, use of media for effective instruction its importance : some consideration, "journal of elementary education",18 (1) 35-40, 2011. [4] k. richey and tracey, the instructional design knowledge base theory, reserach and practice, "routledge taylor and francis group new york and london", 2011. [5] l. young, learning: connection traditional and media literacies in 21 st century learning, journal of media literacy education, 4 (1) 70-81, 2012. [6] a. arel, isolasi senyawa utama kulit batang tumbuhan pinus dari ekstrak etil asetat, "jurnal ilmiah formasi", 12 (2) 27-35, 2016. [7] suwardi, the effect of the use of real these media in cooperative learning type group investigation on the ability of identifying styles and movement students of class iv sdn ii pogalan trenggalek, "simki pedagogia", 1 (1) 1-7, 2017. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 1 doi: 10.17977/um016v5i12021p001 electrochemical corrosion properties of ternary al and quaternary zr added bell metal in 0.1m nacl solution sakib al razi khan1, mohammad ashfaq hossain1, maglub al nur1, mohammad salim kaiser2* 1department of mechanical engineering, bangladesh university of engineering and technology, dhaka, 1000, bangladesh 2directorate of advisory, extension and research services, bangladesh university of engineering and technology, dhaka, 1000, bangladesh, tel.: +88-02-9663129; fax: +88-02-9665622 *corresponding author: mskaiser@iat.buet.ac.bd abstract the electrochemical corrosion property of ternary al and quaternary zr added bell metal in 0.1m sodium chloride solution has been experimentally conducted at room temperature. electrochemical impedance spectroscopy (eis) method and potentiodynamic polarization technique are used to carry out the electrochemical investigation. microhardness test is also conducted for all three alloys and it reveals that al addition increases the hardness of bell metal due to the formation of different intermetallic precipitates of cu and al. optical micrograph as well as scanning electron micrograph have also been studied to characterize their surface condition. it is found that zr addition refines the grain structure of the alloy and results in increase of hardness. the eis study reveals that the corrosion resistance is seem to be augmented with the addition of ternary al and quaternary zr to bell metal. the potentiodynamic polarization curves disclose that both ternary al added and quaternary zr added alloy show better corrosion performance than the base bell metal alloy due to the formation of stable aluminium oxide film. the current density (icorr) of base bell metal showed higher value than both ternary al added and quaternary zr added bell metal alloys. the corrosion potential (ecorr) and the open circuit potential (ocp) were seen to be moved to the more positive direction for the al and zr added alloys. microstructure and sem study of the alloys after corrosion revealed a formation of an oxide film on the surface of the ternary al and quaternary zr added alloys, the probable cause of which is the presence of al in the respective alloys. copyright © 2021. journal of mechanical engineering science and technology. keywords: bell metal, corrosion, eis, sem, tafel i. introduction bell metal is an alloy of copper where the secondary alloying element is tin. tin has favorable melting point and also has strengthening ability, thereupon when it is added to copper its strength increases as well as it helps to attenuate the rate of corrosion [1]. in bell metal the compositional ratio of copper to tin is approximately 4:1 for most of the cases. bell metal is famous for its unique resonance of sound and therefore most of the musical instruments are made of this promising alloy [2-4]. other than fabrication of cymbals and percussion instruments, this unique metal is used in war industries as well as making cannons, weapons, forge tools etc. [5]. due to its attractive color, this alloy material has also a large extent of use in making utensils, pottery, coins, vessels, ornaments, monuments, sculptures, statues etc. [6, 7]. bell metal alloys are conventionally found in gear, bushing or bearing type applications due to its ability to endure high strengths and heavy loads [8]. this 2 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 alloy has also many industrial applications such as production of pump impellers, bridge plates, piston rings, seal rings, steam fittings and so on [9]. corrosion is a phenomenon where breakdown of the metal occurs due to electrochemical reactions. it is degradation of materials’ properties due to interactions with environments. metal is converted into another compound such as oxide or salt by that reaction and leads to loss in desirable properties [10-12]. when tin is added to copper it forms oxides very rapidly which can perform as a superficial shear-strength film and has the ability to attenuate corrosion. however, at accelerated condition the thin oxide layer can be penetrated and come off due to the high value of corrosion. for this very reason, the corrosion resistance of bell metal can be further improved by alloying with other elements [8]. electrochemical impedance spectroscopy analysis is a method of measuring the ac impedances with monitoring the current response when a stimulus of ac voltage is applied to an electrochemical cell. tafel polarization technique gives insight of estimating the corrosion current (icorr), corrosion potential (ecorr) and corrosion rate. with the technological advancement of modern era, these two techniques have become widely popular because of their fast analysis and non-destructive nature [13-16]. the application of bell metal has been extended to variety of above-mentioned industrial employments. particularly in marine based applications such as ship propellers, valve components, heat exchangers used in diesel marine engines, seawater-corrosion holds a significant issue. it is found from different literature that if different ternary or quaternary element is added to copper-based alloys, its property changes significantly. but it is rare to find any literature where the effect of both al and zr additions has been investigated particularly into bell metal, much less so of their electrochemical corrosion behavior. in this study ternary al and quaternary zr are added to bell metal to investigate its strength and density property as well as to find out the effect of these additions on electrochemical corrosion behavior in 0.1m nacl solution through eis and tafel polarization techniques. micrographic analysis of the damaged surfaces of the alloys are also investigated after the electrochemical experiment. a conventional microscope and sem are used to study the effect of corrosion on the evolution of microstructures before and after corrosion in the experimental alloys due to the change in their chemical history. ii. material and methods three samples of bell metal were fabricated individually through continuous casting and melting process where the alloy 1 corresponds to the base bell metal, alloy 2 represents the ternary al added bell metal and alloy 3 stands for the ternary al and quaternary zr added bell metal. in the process of preparation of the bell metal alloys, the commercially pure copper, tin, aluminium and zirconium were selected for casting. melting was done in a claygraphite crucible in a natural gas fired pit furnace under suitable flux cover. to fabricate the alloy 1, 2500gm of copper and 700gm of tin were melted in the clay-graphite crucible while for alloy 2, 74gm of aluminium was added by dipping it into another molten metal of 2500gm copper and 700gm tin. consecutively al+10wt% zr master alloy of 74gm was added to another molten copper-tin where the individual composition of copper and tin were as same as the alloy 1 and alloy 2 for making the alloy 3. all three alloys were casted individually. the terminating melting temperature was maintained at about 1300±15°c using infrared thermometer. three molds of stainless steel were preheated at 200°c. the size of the molds was 20mm × 150mm × 150mm. water with clay mixture was used inside of those molds to prepare a coating layer and then the melts were poured into them. khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) issn: 2580-0817 journal of mechanical engineering science and technology 3 vol. 5, no. 1, july 2021, pp. 1-16 khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) conventional optical emission spectroscopy (oes) method was used to determine the chemical composition of the alloys and the analysis are specified in table 1. after that machining was done on the alloys to remove natural oxide film from the exterior. rectangular samples (35mm x 13mm x 4mm) of the alloys were fabricated from the cast products. to prepare a smooth and refined surface the samples were polished with emery papers of 300, 600, 800 and 1200 grits. micro vickers hardness tester was used to determine the hardness of experimental alloys. several indentations were taken applied with 1 kilogram load for the time duration of 10 seconds through a knoop indenter for each sample at different surface locations. a conventional optical microscope optika was used to characterize the microstructures of the alloys. a wet polishing machine with velvet clothed wheel with the addition of alumina powder was used to make scratch free polished surface. acetone was applied to clean the surface. ammonium hydroxide and 3% hydrogen peroxides were used as etchant which were taken in a ratio of 1:1. the whole experiment had been conducted at room temperature. electrochemical impedance spectroscopy of the experimental alloys was studied through a computerized gamry framework tm series g 300™ and series g 750™ potentiostat/ galvanostat/zra. to prepare 0.1 molar concentrated solution of sodium chloride, demineralized water, and analytical reagent grade nacl were taken where the ph of the solution was kept neutral. to conduct electrochemical experiment three electrode cell arrangements had been used. a mercury coated with hg2cl2 and kcl as electrolyte type conventional calomel electrode is prepared as reference electrode. the other two electrodes used were platinum electrode as a counter electrode and experimental alloy sample as working electrode. in case of working electrode, a wire was connected to the experimental sample and only 6.5mm x 4mm surface was kept open to the nacl solution while the rest of the surfaces were kept protected by teflon tape. before creating open circuit potential, the sinusoidal voltage amplitude was set for 5mv. the frequency range of the experiment was set up for 100khz to 0.2hz. for ensuring better accuracy in result, the sodium chloride solution was refreshed time to time throughout the whole experiment period. the experiment was allowed to terminate from open circuit potential and thereupon a data analysis software echem analyst was used to design equivalent circuits whichever fit the best for them. after matching properly with the equivalent circuit from the response data, the value of corresponding circuit components: solution resistance (rs), corrosion resistance (rp) and effective double layer capacitance (cp-eff) had been calculated. the potentiodynamic polarization experiment was also conducted using identical experimental setup used for the eis study. the range of potential was set from -1 to +1v vs reference electrode. the selected scan rate was 0.50 mv/s. hence the setup was allowed to generate a steady state open circuit potential. as soon as the experiment was over, the corresponding tafel plot was generated. the corrosion potential (ecorr) in millivolt, corrosion current (icorr) in micro ampere and corrosion rate in mils penetration per year (mpy) were measured from the tafel polarization plot for all of the experimental alloys. the sample surfaces were seen to be damaged after the experiment and so they were characterized under both conventional optical microscope and scanning electron microscope. the equation used to determine the rate of corrosion rate following astm standard g 102 (equation 1): 𝐶𝑜𝑟𝑟𝑜𝑠𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 = icorr × k × e. w. d × a … … … … … … … … … … . (1) where, icorr = corrosion current in amperes 4 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) k = constant which designates the units of the rate of corrosion (here, k = 128800 mpy from astm standard g 102) e. w. = equivalent weight in grams per equivalent d = density of the sample in grams per cubic centimeters a = exposed surface area in square centimeters table 1. chemical composition of the experimental alloys (wt%). sn pb fe ni al si cr zr mn cu alloy 1 24.935 0.000 0.000 0.019 0.005 0.001 0.004 0.000 0.001 bal alloy 2 25.444 0.000 0.012 0.018 1.165 0.007 0.003 0.000 0.001 bal alloy 3 25.008 0.010 0.020 0.018 1.170 0.002 0.004 0.240 0.002 bal iii. results and discussions a. microhardness test the microhardness test results of the experimental alloys are shown in figure 1. the graph depicts that pure bell metal (alloy 1) shows the least hardness. the ternary al added bell metal (alloy 2) shows a bit higher hardness while the ternary al and quaternary zr added bell metal (alloy 3) shows the highest value of microhardness. bell metal shows considerable hardness value due to the presence of high tin content [17]. but it is evident that the microhardness of the bell metal increases with the ternary addition of aluminium and it further increases due to quaternary addition of zirconium. al is known to cause significant hardening when added to cu-sn alloys [18]. this hardening is caused by the formation of intermetallic precipitates formed by the reaction between al and cu during solidification of the alloy. al2cu, al4cu9 and cu3al2 are among the intermetallic compounds responsible for the increase in hardness of the alloy [19]. addition of zr is also known to increase the hardness and strength of copper alloys [20]. through grain refinement the formation of intermetallic compounds such as al3zr attributes to the increase in hardness of the alloy [21]. fig. 1. variation of hardness and density of the alloys at room temperature issn: 2580-0817 journal of mechanical engineering science and technology 5 vol. 5, no. 1, july 2021, pp. 1-16 khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) figure 1 also shows the density of all three alloys, representing the variation of density with the alloying addition of al and zr. as the density of al is less than that of cu, the density of the bell metal decreases due to the ternary addition of al. the density increases slightly with quaternary addition of zr in alloy 3, as the density of zr is a bit higher than that of al. b. impedance measurement table 2 shows the experimental results from electrochemical impedance spectroscopy (eis) test. table 2. electrochemical impedance spectroscopy (eis) test results alloy composition solution resistance [rs in ω] polarization resistance [rp in ω] effective double layer capacitance [cp(eff) in µf] open circuit potential [ocp in v/sce] goodness of fit alloy 1 46.93 551.2 12.15 -0.0698 0.0039 alloy 2 39.76 714.1 9.33 -0.0457 0.0174 alloy 3 40.81 789.7 8.47 -0.0431 0.0209 the experimental data obtained from the potentiostatic eis test were simulated through echem analyst data analysis software thereupon several equivalent circuits were modeled from which the best fitted one is presented in figure 2. rs denotes the ohmic solution resistance of the electrolyte where rct represents the charge transfer resistance which is also equivalent to the polarization or corrosion resistance [22]. cpe represents the constant phase element from which effective electrical double layer capacitance value has been obtained [23]. the nyquist plots of the corresponding equivalent circuit model are represented in figure 3 for all three experimental bell metal alloys. in figure 3 the imaginary part of the impedance component (z") corresponds to the y-axis where the real part of the impedance (z') corresponds to the x-axis. the responses are obtained in the model of capacitiveresistive semicircle for the experimental alloys. fig. 2. electrical equivalent circuit diagram of the impedance data for experimental alloys 6 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) fig. 3. nyquist plots for experimental bell metal alloys in 0.1m nacl solution at room temperature bode plots for all three bell metal alloys are shown in figure 4 where the curves are drawn zmod against applied frequency. zmod represents the total impedance behavior. from table 2 it is found that the range of rs varies between 39-47ω. therefore, it can be said that there is no significant change observed for rs values while eis testing. in fact, the solution resistance values are seemed quite minor compared to that of polarization resistance. polarization resistance depends on the working electrode while the solution resistance depends on the solution used for the electrochemical experiment. table 2 reveals that in 0.1 m nacl solution, addition of ternary al and quaternary zr in the bell metal alloy enhanced the polarization resistance (rp). for alloy 1, the polarization resistance (rp) value is 551.2ω and increased to the value of 714.1ω through the addition of ternary al to the bell metal (alloy 2). alloy 3 showed slightly increased value of polarization resistance (rp) compared to alloy 2 which is almost 789.7ω. it is reasonable to assume that the enhanced polarization resistance depicts an increment in the corrosion resistance of bell metal through the ternary and quaternary additions [24, 25]. fig. 4. bode plots for the experimental alloys in 0.1m nacl solution at room temperature issn: 2580-0817 journal of mechanical engineering science and technology 7 vol. 5, no. 1, july 2021, pp. 1-16 the effective double layer capacitance (cp-eff) of alloy 1 is 12.15µf. with ternary addition of al and quaternary addition of zr, the value of effective double layer capacitance was decreased for both cases. the steady state open circuit potential of base bell metal is -0.0698v which is the most negative among all three of them. the ocp value of alloy 2 is -0.0475v while alloy 3 shows slightly more positive value of -0.0431v. it is reasonable to assume that the variation of the open circuit voltage is caused by both of the ternary al and quaternary zr additions. c. potentiodynamic polarization analysis the results of potentiodynamic polarization analysis conducted from the electrochemical tests is shown in table 3. table 3. potentiodynamic polarization analysis results alloy composition icorr [µa] ecorr [mv] corrosion rate [mpy] alloy 1 16.9 -213 27.92 alloy 2 3.4 -171 5.72 alloy 3 3.02 -72.3 4.99 figure 5 represents the potentiodynamic polarization curves of bell metal alloys in 0.1m nacl solution. with the addition of both ternary al and quaternary zr, anodic current density of bell metal alloys were seen to be attenuated due to the deceleration of the anodic reaction. this ternary and quaternary additions caused the formation of micro-galvanic cells in alpha matrix. the intermetallic precipitates of al2cu, cu3al2 and al4cu9 are most likely to be formed in ternary al added alloys [26]. in case of quaternary zr addition, cu9zr2 and al3zr intermetallics are formed [27, 28]. corrosion potential difference between alpha matrix and secondary constituents can create due to the formation of those intermetallics which leads to the generation of different micro-galvanic cells [29]. for the base bell metal alloy 1 corrosion potential (ecorr) is -213mv, which is the most negative potential among the alloys investigated. in case of alloy 2, ternary al addition made the corrosion potential (ecorr) shifted towards positive value, following that with the addition of quaternary zr for alloy 3, corrosion potential (ecorr) is seemed to be gone to more noble direction. it is also found from the potentiodynamic analysis that the addition of al and zr in bell metal reduced the corrosion current (icorr). the corrosion current (icorr) value of bell metal alloy 1 in 0.1 molar sodium chloride solution was 16.9 µa, and in case of alloy 2 this value decreased to 3.4 µa with the addition of ternary al. alloy 3 showed the lowest corrosion current (icorr) value of 3.02 µa among all three alloys. potentiodynamic polarization test also offers the corresponding corrosion rate in mpy for all three alloys, and it is seen that the corrosion performance of both ternary al and quaternary zr added alloys were found to be higher than that of base bell metal. it is seen that the alloy 1 showed corrosion rate of 27.92mpy where it is decreased to 5.72mpy for alloy 2. in case of base bell metal alloy 1 a thin film of copper oxide forms while on the other hand for alloy 2, along with copper oxide film, a film of aluminium oxide also forms because of additional ternary al component [30]. aluminium oxide is more stable and works as a protective layer where copper shows weaker interaction with oxygen [31]. moreover, the enthalpy of formation of aluminium oxide is less than that of copper oxide. the lower the enthalpy of formation of a substance, the lower the energy level of the substance and the lower the energy level of the substance, the more khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) 8 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 stable the substance is. that is why aluminium oxide can be said to be more stable than copper oxide. vargel [32] has reported that aluminium as a naturally passive metal, forms two superimposed colorless oxide layers: the first one is internal-compact-amorphous barrier layer which forms within a few milliseconds and the other one is external layer, generally called protective layer which grows on top of the first one. all these result in increased strength of the protective film layer for alloy 2 where the ternary al addition plays the key role. this is the reason behind the better corrosion performance of alloy 2. in case of alloy 3 the corrosion rate is found to be 4.99mpy. the quaternary addition of zr accelerated the alloy to more positive corrosion performance than alloy 2. it is because the corroded elements which tend to present in grain boundaries are refined due to the grain refining ability of zr and the grains became well distributed [33]. so ternary al added alloy 2 and quaternary zr added alloy 3 both seemed to be less prone to corrosion than that of base bell metal alloy 1. fig. 5. tafel polarization curves of the experimental alloys in 0.1m nacl solution d. optical micrographic investigation figure 6a, 6b and 6c show the optical micrographs of the polished and etched surface of the experimental alloys. from the micrograph it is seen that the microstructure of alloy 1 consists of island-like grains of alpha (α) phase particles with beta (β) phase along the grain boundaries (figure 6a). this is the typical microstructure of a bell metal alloy. the tin content in the bell metal is not high enough to form a complete beta (β) phase [34]. figure 6b shows the optical micrograph of the polished and etched ternary al added alloy 2. the addition of al changes the island-like grain structure of bell metal. instead, long dendritic arm structure is seen in the alloy. the presence of aluminium causes the formation of this long dendritic arm microstructure in alloy 2 [35, 36]. addition of zr also influences the microstructure of the alloy, as we see visible changes in the micrograph of alloy 3. figure 6c shows the optical micrograph of polished and etched quaternary zr added alloy 3. in the micrograph it is seen that the dendritic arm structure appears to be more refined, due to the presence of zr. zirconium is a grain refiner [37]. it is commonly known to cause grain refinement of copper alloys when added in small amount [38]. the zirconium present in alloy 3 reacted with the cu and al to form cu9zr2 and al3zr intermetallic compounds respectively [25, 26]. grain growth of the alloy is restricted due to the formation of these khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) issn: 2580-0817 journal of mechanical engineering science and technology 9 vol. 5, no. 1, july 2021, pp. 1-16 intermetallic precipitates [39]. this causes the grain structure to be refined and more evenly distributed. fig. 6. optical micrograph of the experimental polished cast alloys a) alloy 1, b) alloy and c) alloy 3 the optical micrographs in figure 7a, 7b and 7c show the scratched surface of the experimental alloys before immersion into the corrosion medium. figure 7a and 7b show the micrographs of the scratched surface of alloy 1 and alloy 2 respectively. the addition of al changes the island-like grain structure of alloy 1 and transforms it to a long dendritic arm structure. this change in microstructure can be characterized by the increased dark tone in the micrograph of alloy 2. figure 7c shows the optical micrograph of the scratched surface of alloy 3. in this micrograph the refined grain structure of the alloy can be characterized through the even distribution of the dark tones or patches on the scratched surface of alloy 3. figure 8a, 8b and 8c show the optical micrograph of the alloy surfaces after corrosion. significant corrosion was observed after the electrochemical corrosion study. in figure 8a the micrograph of alloy 1 after corrosion shows the evidence of concentrated attack at different locations of the surface caused by dissolution of the corrosion products into the surrounding environment. in comparison figure 8b and 8c show that the corrosion taking place on the surface of alloy 2 and alloy 3 respectively were much more uniform with less localized pit formation. further investigation of the micrographs of alloy 2 and 3 show a complete disappearance of the polished marks which suggests a formation of oxide film layer on their surfaces. it is evident that the corrosion product remains on the surface of the alloy because of the lack of dissolution into the surrounding environment. it can be seen from the micrograph of alloy 3 that the corrosion products are much evenly distributed. the probable cause behind this is the refined grain structure of the quaternary zr added alloy 3. khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) ( a ) (c) 100m (a) (b) 10 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) fig. 7. microstructure of experimental alloys a) alloy 1, b) alloy 2 and c) alloy 3 before corrosion fig. 8. microstructure of experimental alloys a) alloy 1, b) alloy 2 and c) alloy 3 after corrosion [the circled zones indicate the formation of localized pits on the alloy surfaces after corrosion. as it can be seen alloy 2 and 3 show less localized pit formation.] ( (a) ( c ) 100m (b) (c) (a) (b) 100m (c) issn: 2580-0817 journal of mechanical engineering science and technology 11 vol. 5, no. 1, july 2021, pp. 1-16 khan et al. (electrochemical corrosion properties of ternary al and quaternary zr added bell metal) the micrographs suggest that alloy 2 and 3 show better resistances to corrosion and one possible cause of this could be the formation of aluminium oxide at the corroding interface [40]. as it is seen from literature, due to aluminum addition, the formation of dense aluminium oxide layer at the corroding surface can effectively enhance the corrosion resistance of the alloy [41]. in addition, the corrosion resistance of alloy 3 can be attributed to the microstructural variations caused by the presence of zr in the alloy [42, 43]. e. sem observation the sem images showing the damage surface morphology of the experimental alloys. alloy 1, 2 and 3 are presented in figure 9a, 9b and 9c respectively. from the sem images it is seen that there are evidence of corrosion of intermetallic compounds on the surface of all examined samples. the sem image of the bell metal alloy 1 shows the evidence of localized corrosion and discrete pits can be seen on the sample surface. it is also observed that the rough polish marks before immersion into the corrosion medium are visible in the sem images of alloy 1. it is probable that the pit formation occurred due to the intermetallic compounds dissolving out of the alloy surface into the surrounding environment. this is the same reason behind the visibility of the rough polish marks on the surface of the alloy. it can also be concluded that the pit formation was caused by selective dissipation of the second phase particles of the alloy. fig. 9. sem images show the damage surface morphology of as-corroded (a) alloy 1, (b) alloy 2 and c) alloy 3 [the red circles in (a) indicate the pit formation in alloy 1 after corrosion. the red arrows in (a) indicate the rough polish mark on the surface of alloy 1. the red rectangular zones in ‘b’ and ‘c’ indicate the corrosion products and oxide films remaining on the surface of alloy 2 and alloy 3 respectively. as it is seen the oxide film in alloy 3 is much denser and more uniformly distributed.] ( c (c) (a) (b) 12 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 1-16 one of the main corrosion product of alloy 1 is copper oxide [44]. it is reasonable to assume that the copper oxide formed during corrosion did not work as a protective layer for the alloy and was dissolved into the solution. sem images of ternary al added alloy 2 and quaternary zr added alloy 3 shows a more uniform form of corrosion. in figure 9b the sem image of alloy 2 shows that the polish marks are less visible on the surface of the alloy. it is also seen from the sem image that most of the corrosion products remain on the sample surface and there were no dissolution of corrosion products into the surrounding matrix. it is reasonable to opine on the basis of literature and previous works that due to small amount of ternary al addition, aluminium oxide was formed on the surface of the alloy [45]. this aluminium oxide acted as a protective layer on the corroding interface, causing the corrosion rate to be less than that of alloy 1 [41]. it is also suggested that the aluminium oxide formed was stable and it remained on the surface. the sem image of alloy 3 shows a similar case of corrosion products remaining on the surface of the alloy due to presence of ternary al. in addition, due to grain refinement effect of zr, the corrosion product formation were more evenly distributed on the surface of alloy 3. the finer grain size also improved the corrosion resistance of the alloy [46]. it can be concluded from the sem images that alloy 2 and 3 showed better corrosion resistance than alloy 1, while alloy 3 showed a more uniform corrosion on its surface. these changes in corrosion performances of the alloys can be attributed to their respective alloying additions. iv. conclusions the effect of ternary al and quaternary zr addition on the electrochemical corrosion behavior of bell metal has been conducted. the alloying addition of ternary al decreased the density of bell metal alloy because al itself has a low value of density compared to cu and sn. but the hardness value was increased due to the formation of al2cu, cu3al2, al4cu9 intermetallic precipitates. quaternary zr addition accelerated the hardness even more due to its grain refining effect. the eis result shows that higher charge transfer resistance (rct) has been obtained in case of both al and zr added alloys. from tafel polarization curve it is found that the ternary al and quaternary zr addition reduced the corrosion rate (mpy) of bell metal by creating stable film of aluminium oxide. following that they also showed very low value of current density (icorr) compared with the base bell metal alloy. the corrosion potential (ecorr) and the magnitude of open circuit potential (ocp) were found to be gone to more noble direction for them. the microstructure and sem study showed that the base alloy suffered a more severe form of corrosion, as there were evidence of localized corrosion taking place. due to dissolution of corrosion product into the surrounding matrix, there were formation of pits on the alloy surface. in contrast the ternary al added alloy and quaternary zr added alloy showed better resistance to corrosion, characterized by the corrosion products still remaining on the alloy surfaces and a lack of dissolution into the surrounding matrix. moreover, the zr added alloy showed a more uniform form of corrosion due to its more refined grain structure. acknowledgement the authors are thankful to directorate of advisory, extension and research services (daers), bangladesh university of engineering and technology, dhaka, bangladesh and pilot plant and process development centre (pp & pdc), bcsir, dhaka, bangladesh for providing the laboratory facilities. khan et al. 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(electrochemical corrosion properties of ternary al and quaternary zr added bell metal) [45] ding, p.j., lanford, w.a., hymes, s., murarka, s.p., “effects of the addition of small amounts of al to copper: corrosion, resistivity, adhesion, morphology, and diffusion”, journal of applied physics, vol. 75(7), pp. 3627-3631, 1994. [46] song, g., stjohn, d., “the effect of zirconium grain refinement on the corrosion behaviour of magnesium-rare earth alloy mez”, journal of light metals, vol. 2(1), pp. 1-6, 2002. journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.18-28 18 doi: 10.17977/um016v3i12019p018 study on the thermal distortion, hardness, and microstructure of st 37 steel plate joined using fcaw maijuansyah1, yanuar rohmat aji pradana1*, gaguk jatisukamto2, and solichin1 1mechanical engineering department, universitas negeri malang, jl semarang 5, malang, 65145, indonesia 2mechanical engineering department, universitas jember, jl kalimantan 37, jember, 68121, indonesia *corresponding author: yanuar.rohmat.ft@um.ac.id abstract this study sets out to investigate the distortion angle, microstructure, and hardness of st 37 steel plate weld joint produced by fcaw using the welding current of 80, 110, and 140 a. by using flat position, co2 and e71t-1 wire were utilized as a shielding gas and electrode filler, respectively. the distortion angle measurement was done on 3 different locations of the welded sample perpendicular to weld direction by using bevel protractor. the micro vickers tests were then applied gradually at the crosssectional surface with a distance of 0, 5, 10 and 15 mm from weld centerline using the load of 300 g for indentation time of 15 s. a series of microstructural observations was subsequently directed on cross-sectional weld joint regions including base metal, heat-affected zone (haz) and weld metal to investigate the microstructural transformation. from the results, it can be observed that increasing welding current can reduce the hardness at all indentation regions as well as inducing a higher level of thermal distortion occurred on a weld joint, especially at haz. the microstructural transformation was also observed at sample welded using various welding current. both heat input and cooling rate subjected to the welded sample played an important role to characterize their properties. copyright © 2019. journal of mechanical engineering science and technology all rights reserved keywords: hardness, microstructure, thermal distortion, welding current i. introduction welding becomes an important part on industrial technology growth due to its important role in metal fabrication and engineering. by involving thermal energy, the region around weld metal undergo the metallurgical change, residual stress enhancement, and thermal distortion. to reduce these disadvantage effects, the correct and optimal of both welding procedure and parameter were highly needed [1]. one of the widely used welding processes is flux core arc welding (fcaw). this process is mostly applied on metal fabrication industry because of its advantages, such as higher deposition rate, less affected on rust, simpler and highly adaptable, less-skilled operator requirement and higher productivity among other welding processes [2]. based on a study conducted by aloraier et al. (2006), reparation industries applied fcaw instead of mmaw because of their excellences for years [3]. welding parameter on fcaw, namely current, voltage, welding speed, polarity, and protecting gas flow rate turn into an influential factor on the joint characteristics. the level of penetration was largely determined by the current, voltage, and welding speed applied during welding, with the deep penetration was resulted by welding using 19 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) high current and voltage [4]. on the other hand, welding parameters also have a decisive factor in microstructural change on the weld joint. therefore, it is possible to find the different microstructure between weld metal and its base metal due to the different heat input obtained along the welding direction [5]. another study was also proved that the welding current affected the microstructure and hardness distribution along the joint cross-section [6]. distortion can be very harmful to the weld quality because it induces inaccurate joint shape. therefore, it requires additional reparation cost. on the ship-making industries in australia and new zealand utilizing high strength steel as raw material, welding distortion becomes a significant problem. the welding institute (twi) revealed that the cost for repairing welding distortion reached almost 30% of the total production cost [7]. based on this problem, the ideal condition screening had been conducted by researchers to investigate the thermal distortion and find the best parameter to minimize this phenomenon, where, the suitable parameter combinations were needed to obtain negligible distortion occurred [8]. considering the information's above, the effect of heat input on joint microstructure, hardness, and distortion of st 37 welded by fcaw was investigated on this study. the different welding current was utilized, representing the heat input variation. ii. material and method experiments were conducted by applying several tests on fcaw joint of st 37, namely distortion angle measurement, microstructural observation, and hardness test. the base material on this study included 10 mm-thick st 37 structural steel plate with the alloy composition of 0.063 % c; 0.621 % mn; 0.031 % p; 0,158 % si; and 0.039% cu. the paired edge of the plate was firstly prepared to form v-shape having the angle of 60o, the root face of 1.5 mm, and 1 mm gap between each root face. afterward, the fcaw (rillon 350a) was applied on the prepared edge utilizing the filler electrode wire based on aws e71t-1 standard having the composition of 0.18% c; 1.75% mn; 0.90% si; 0.03% p; and 0.03% s. the voltage was set at range of 15-25 v. by selecting flat position, the welding current was varied into 80, 110, and 140 a with the constant welding speed proportional to the selected current. the active gas of co2 was also applied to cover the weld pool along with the process with the constant gas flow rate of 15 lpm. distortion measurement was then done on 3 different locations of the sample perpendicular to weld direction by using bevel protractor as illustrated in figure 1. the distortion angle (angular shrinkage), α, was recorded by comparing the lower side of the unconstrained metal plate to horizontal reference line extended from weld tableconstrained plate interface. before microstructural observation and hardness test of the weld joint, the weld sample was cut into the small piece (55 x 10 x 10 mm) based on din 50103. the micro vickers indentations were then applied gradually at the cross-sectional surface with the distance of 0, 5, 10 and 15 mm from weld centerline. this process was done using eseway type digital microvickers th721. during the hardness investigation, indentation load of 300 g for 15 s was constantly used at all test points. issn: 2580-0817 journal of mechanical engineering science and technology 20 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) to evidence the phenomena possibly found on both distortion angle measurement and hardness test, a microstructural observation was subsequently directed on crosssectional weld joint regions including base metal, heat-affected zone (haz) and weld metal. before capturing the microstructural topography of weld joint, the cross-sectional surface was firstly polished using sand paper having grit from #150 to #5000. on the next step, the target area for observation was etched using a mixture of 95% alcohol and 5% hno3 for 10s. the observation was then conducted with 1400 times of magnification using a nikon japan 59520 optical microscope. fig. 1. distortion measurement utilizing (a) angular shrinkage measurement at (b) 3 test locations perpendicular with the weld direction of the sample. iii. results and discussion distortion angle analysis information regarding the distortion angle measurement of as-weld sample using the different welding currents is described in figure 2. 80 90 100 110 120 130 140 2.0 2.2 2.4 2.6 2.8 3.0 80 a 110 a 120 a d is to rt io n a n g le ( o ) welding current (a) fig. 2. distortion angle curves of sample welded as a function of welding current representing a thermal distortion 21 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) the measurement was conducted at 3 different locations (beginning, middle, and end of weld) with a constant gap for each test perpendicular with the weld direction and the results of each measurement and their average values are listed on table 1. the angle was considered as the representation of thermal distortion due to the presence of residual stress at the weld joint. table 1. distortion angle of sample welded using welding current of 80, 110, and 140 a. welding current (a) distortion angle (o) average (o) beginning middle end 80 2 2.13 2.2 2.11 110 2.33 2.43 2.57 2.44 140 2.7 2.83 2.9 2.81 figure 2 indicates that by using fcaw, the distortion angle becomes larger proportional with the higher welding current used. this was caused by the enrichment of residual stress amount, especially at haz, as a function of heat input [9]. the heat input elevation was induced by higher welding temperature resulted from the higher current. by giving the spontaneous thermal heating, melting, and cooling during welding, each region of haz had received a different amount of heat energy. therefore, it experienced various degree of thermal expansion and subsequent contraction by inhomogeneity cooling rate inducing a non-uniform strain at a particular area. this remained as residual stress after the weld joint was cooled down into room temperature in the form of tensile and compression stress [10]. the greater residual stress formation was generated by the greater degree of heat input. because the presence of distortion on weld joint is undesirable, the selection of optimum welding parameters is very important to minimize this phenomenon without sacrificing the appropriate mechanical properties [8]. from the figure 2, the distortion angles are distinct for each measurement point of similar sample and remain higher at the end line measurement where the highest value is found at the end line of each sample welded using 80, 110, and 140 a with 2.2; 2.57; and 2.9o, respectively. this result can be explained by the higher heat input obtained of the end line in comparison with the two other locations due to the additional heat transferred from previous weld exposure. therefore, the welding temperature remained higher at the end of the welding area. in case of the increase heat input at the end line, the residual stress-inducing distortion was higher as well [11]. microstructure analysis the temperature of weld metal during welding is approximately 1500 oc. st 37 steel containing 0.063% c makes this type of steel is included as hypo eutectoid steel (0.0080.83% c). above the crystallization temperature, the phase will transform into austenite while ferrite and pearlite phases will be found at room temperature [12]. on this study, in general point of view, the brightand dark-etched grain was observed indicating the presence of ferrite and pearlite phases issn: 2580-0817 journal of mechanical engineering science and technology 22 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) fig. 3. microstructure appearance of joint welded by fcaw using the current of 80 a at (a) weld metal, (b) haz, and (c) base metal with 1400 times magnification. fig. 4. microstructure appearance of joint welded by fcaw using the current of 110 a at (a) weld metal, (b) haz, and (c) base metal with 1400 times magnification. figure 3(a) shows the presence of acircular ferrite at weld metal of 80 a sample indicated by the appearance of dark, needle-like shaped ferrite [13]. this made the hardness value of weld metal reached 284.1 hv or higher than the raw material (260.7 hv) due to the significant phase transformation occurred in the weld metal. furthermore, this phenomenon was also affected by the e71t-1 wire application, possibly forming a new compositional combination with the base metal, where the wire material became the dominant composition due to its function as weld filler. on the other hand, heat input induced by the current of 80 a also played an important role in the 23 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) microstructural transformation and hardness enhancement on the weld metal. from the figure, the acircular ferrite was dominant phase compared with the others, working as an interlocking structure to impede the dislocation movement [14]. acircular ferrite is generally formed at around 650oc and possess the higher toughness than other microstructures [12]. one of the factors affected acircular ferrite formation is the presence of inclusion caused by oxidation particle inside the melting metal. this could be occurred due to several aspects, such as base metal composition, electrode, shielding gas, air-condition, and flux [14]. fig. 5. microstructure appearance of joint welded by fcaw using the current of 140 a at (a) weld metal, (b) haz, and (c) base metal with 1400 times magnification. at the weld metal region, the phases transformed using the currents of 110 and 140 a (figure 4(a) and 5(a)) were the mixture of widmanstatten ferrite and acircular ferrite. the acircular ferrite amount was lower compared with the 80 a sample because it substituted into widmanstatten ferrite. the latter phase was formed at 750-650oc [15] and induced the hardness reduction, to the value of 240.4 and 227.5 hv at samples welded using 110 and 140 a, respectively. these phenomena can be attributed by the different level of heat input received for each sample, where the larger grain was formed if the higher welding temperature was achieved in the weld metal causing lower cooling rate compared with the lower current. at haz for all current variations (figure 3(b), 4(b), and 5(b)), the presence of pearlite was dominant alongside the ferrite phase caused by the growth of pearlite grain from its base metal at elevated temperature during welding thermal cycle. the hardness test showed that haz provide the higher hardness value at all variations compared with their base metal counterparts with 262.7; 236.9; and 193.6 hv at sample welded using 80, 110, and 140 a, respectively. by applying higher heat input, the hardness was observed to be lower at haz. it may be caused by excessive grain growth at higher heat input, consequently reducing its hardness [12][15][16]. during weld metal cooling, the issn: 2580-0817 journal of mechanical engineering science and technology 24 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) base metal temperature increased because the base metal acted as a heat sink. therefore, a low thermal gradient and cooling rate occurred at high heat input. thus the larger grain of pearlite can be formed from austenite [13][15]. such pearlite size enlargement became the reason for the hardness reduction. less-significant phase transformation induced by thermal cycle effect was found on the base metal of all current variations where the bright-etching phase, ferrite, and darketched phase, pearlite, were still observed from microstructure image as found on 80 a sample (figure 3(c)). however, the relatively large hardness reduction up to 173.2 hv was detected for sample welded using higher heat input of 140 a at the distance of 15 mm from weld centerline indicating grain coarsening and homogenizing occurred instead of phase transformation in the microstructural state. it can be explained by the size development of pre-existing ferrite colony along with the size reduction of pearlite grain due to high heat input conducted from weld metal, indicating these currents generated larger haz [12]. the size development of 110 and 140 a was relatively similar, as depicted in figure 4(c) and 5(c). generally speaking, the hardness of base metal showed the lower value compared with haz because the pearlite size reduction during the welding thermal cycle, and the reduction level was proportional with heat input given [17]. hardness analysis the hardness test was conducted on room temperature at the distance of 0, 5, 10, and 15 mm from weld centerline using an indentation load of 300 g. the indentation was taken from these points representing the region of weld metal, haz and base metal. the hardness test results are listed in table 2, and the hardness curves as a function of test distance and fcaw welding current are further described in figure 6. table 2. hardness of sample welded using different current of 80, 110, and 140 a. welding current (a) hardness (hv) 0 mm 5 mm 10 mm 15 mm 80 284.2 262.7 237.8 246.9 110 240.4 236.9 193.1 180.5 140 227.5 195.6 193.7 173.2 raw material 260.7 the results on table 2 demonstrates that the welded joint performs different results in case of hardness compared with the raw material where the hardness of weld metal and haz at 80 a sample have the higher values, but it remains lower at the other points of all variations. this phenomenon indicates the microstructural evolution after the welding process, as the current played an important role to characterize the microstructure and hardness distribution [6]. when the test conducted at weld metal, the significant elevation of hardness was occurred at sample welded using 80 a compared with that of 110 and 140 a samples. the compositional difference of e71t-1 filler wire with the base metal varied the mechanical properties of weld metal with the base counterparts because the wire dominantly filled the weld bead up to the weld root gap. due to the higher c and other alloying elements on the wire, at low heat input, the cr-carbide was deposited, thus 25 journal of mechanical engineering science and technology issn: 2580-0817 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) enhance the hardness at weld metal [18]. this property enhancement was also consistent with a previous study conducted by katherasan et al. (2012) [19]. contrary, the hardness reduction on identical location was found on sample welded using both 110 and 140 a with 240.4 and 227.5 hv, respectively, caused by the relatively high heat input given during welding. this parameter induced the microstructural change as depicted in figure 3(a), 4(a), and 5(a) where the presence of both widmanstatten and lower amount of acircular ferrite (compared with that found on weld metal of 80 a sample). the widmanstatten ferrite enrichment had a responsibility of these hardness reductions [13]. 0 5 10 15 180 200 220 240 260 280 80 a 110 a 120 a time : 15 s load : 300 g h a rd n e s s ( h v ) distance from weld centerline (mm) fig. 6. hardness curves of welded joint as a function of welding current the hardness evolution of haz is similar with those on weld metal as illustrated in figure 6, where the hardness of haz as results of welding using 80 a shows the value of 262.7 hv, or still higher than the raw material. the haz hardening was related to the high-temperature gradient and cooling rate due to low heat input possibly causing the grain refining on this region [15][16][20]. as shown in figure 3(b), the microstructure of haz welded is dominated by small and irregular pearlite grain inducing the hardness elevation. on the other hand, with the value of 236.9 and 195.6 hv at haz of 110 and 140 a sample, the hardness of this region was determined to be lower than 80 a sample, even the raw material. the grain growth and coarsening of predominantly ferrite, and a lower amount of pearlite from its base metal by using higher heat input induced the hardness reduction. by comparing the haz microstructure on both of sample welded using 110 and 140 a, the pearlite acting as dislocation inhibitor is found to be lower at 110 a sample as shown in figure 4(b), and 5(b). on the test taken at the distance of 10 and 15 mm from weld centerline representing the base metal hardness, it can be seen that no significant microstructural change and only ferrite and pearlite grain coarsening, or homogenizing, was observed as illustrated from the figure 3(c), 4(c) and 5(c). by using low heat input induced by the current of 80 a, the hardness difference between raw material and base metal after welding was issn: 2580-0817 journal of mechanical engineering science and technology 26 vol. 3, no. 1, july 2019, pp.18-28 maijuansyah et al. (study on the thermal distortion, hardness and microstructure of st 37 welding) relatively low. however, at higher heat input generated by the currents of 110 and 140 a, the hardness reduction became obvious at the range of 173.2-193.7 hv compared with raw material (260.7 hv). although the base metal temperature was not sufficient to reach recrystallization temperature (a1), the heating at sub-a1 was still able to modify the microstructure in case of homogenizing, coarsening, and internal stress relieving with the higher effect can be achieved with the higher temperature/heat input [12]. it is consistent with the phenomenon occurred where the base metal hardness of 140 a sample reached the lowest point on 15 mm among all variations with 173.2 hv. iv. conclusions by using fcaw method, st 37 steel plate having the thickness of 10 mm had been successfully joined involving aws e71t-1 electrode wire as a filler and co2 as the shielding gas. based on distortion angle measurement, micro vickers test and observation by optical microscope on the weld joint using the welding current of 80, 110, and 140 a, the results can be concluded as follows: (1) the distortion angle becomes larger, proportional with the higher welding current used indicating the increase of residual stress amount, especially at haz, as a function of heat input; (2) the microstructural evolution was observed on weld metal and haz where the weld metal was dominated by acircular ferrite at sample welded using 80 a, and additional phase of widmanstatten ferrite was observed on samples welded with higher current. the ferrite and pearlite grain were found on haz, and the amount was varied by welding current while no significant phase transformation identified on base metal, and (3) the hardness value was strongly influenced by welding current applied with the higher hardness curve was achieved by lower current representing lower heat input, where the highest value was obtained from weld metal of 80 a sample with 284.1 hv. the hardness was also decreased when the indentation was taken at further location from weld centerline. references [1] duniawan, a & sutrimo. “effect of welding speed and heat input on mechanical properties of weld metals on saw welding of astm a29 carbon steel”. yogyakarta: akprind yogyakarta, 2010. 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[20] samir, y. m. “investigation on effect of heat input on cooling rate and mechanical property (hardness) of mild steel weld joint by mmaw process”. international journal of modern engineering research, vol. 5, no. 3, pp. 34-41, 2015. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 76-86 76 doi: 10.17977/um016v7i12023p076 analysis of fire and smoke spread in ki hajar dewantara auditorium, state university of jakarta, using fire dynamics simulator pratomo setyadi, ariq harits arrizq* department of fire safety engineering, faculty of engineering, universitas negeri jakarta jl. rawamangun muka rt.11/rw.14, jakarta timur, 13220, indonesia *corresponding author: ariqharits27@gmail.com article history: received: 3 march 2023 / received in revised form: 4 may 2023 / accepted: 7 june 2023 available online 22 june 2023 abstract fire behavior and smoke spread are influenced by various factors, including the amount and condition of combustible material, ventilation openings, and ceiling height. a high amount of combustible material in the auditorium poses a significant fire hazard, hence, efforts need to be made to minimize the risk. one approach is to use computational fluid dynamic software, such as fire dynamics simulator (fds), to model fire combustion. in this research, it provides an overview of the heat release rate (hrr) of fires that occur as well as the effect of differences in ceiling height and the effect of ventilation on fire spread. this research employed polyurethane foam, commonly used for auditorium seats, as the sample material. furthermore, it modeled two fire points, one on the 9th floor and the other on the 10th floor, in the middle of seat rows. the development of fire in the modeling was described by the results of visualization, hrr, burning rate, and temperature rise. these results provided insight into the speed at which fire and smoke spread. the starting point on the 9th floor had the highest flame spread rate due to the ceiling jet phenomenon, where a high amount of combustible material caused the ceiling temperature to increase, producing a heat flux that could burn surrounding seats. in both scenarios, the smoke spread rapidly toward the ventilation openings. however, it was denser on the 9th floor as the starting point was farther from the ventilation openings, and the smoke on the 10th floor was less dense. copyright © 2023. journal of mechanical engineering science and technology. keywords: auditorium, ceiling, fds, hrr, polyurethane foam, temperature, ventilation i. introduction according to the decree of the state minister of public works with number 11/kpts/2000 concerning technical provisions for fire management in urban areas, the auditorium falls under fire hazard risk classification 4. this classification signifies a high fire hazard risk due to the presence of a large quantity and content of combustible materials [1]. based on data from the dki jakarta provincial statistics agency, 429 buildings caught fire in 2020. a significant number of these fire incidents were caused by electrical disturbances or cigarette butts [2]. unfortunately, fire has recently occurred in indonesia, particularly in auditorium, including the rri auditorium building in jember in 2022 due to an electrical short circuit [3], the nusa cendana university auditorium in kupang in 2021 due to an electrical short circuit [4], and the ppop ragunan auditorium building in jakarta in 2019 caused by cigarette [5]. based on the magnitude of activities and losses resulting from fire, it is imperative to take measures to prevent its outbreaks by understanding the characteristics of fire and smoke spread. some of the factors influencing the characteristics of fire and smoke spread include combustible material, structure, air openings, etc. 77 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) with the development of technology, a device called the fire dynamics simulator (fds) can be used to determine the characteristics of fire and smoke spread during its occurrence in a particular location. this device provides information on the rate of heat release, smoke spread, and temperature, which enables the prediction of the potential fire phenomenon and can also help in conducting a review of the fire safety aspects of the auditorium. previous research supported the use of this technology, for example, valasek and glasa (2017) modeled a fire in a cinema or auditorium with an area of 12 m x 16 m for 60 seconds. it was found that the temperature continued to increase beyond 370°c within 20 seconds, and the reat release rate (hrr) reached 400 kw, while smoke filled the ceiling of the room [6]. huang et al. (2018) discovered that the hrr in a cinema can reach 10.000 kw within 900 seconds, and the polyurethane foam material poses a significant danger [7]. research on this phenomenon, flame spread in motorcycle parking areas compiled by nanda yola, concluded that the wind and the starting point of the fire can affect the speed of its spread [8]. the research conducted by ria sari, difference in fuel location, indicated that the number of combustible material sources, the distance between them, and the compartment system influenced fire spread [9]. this practical engineering approach allows the modeling of fire, which provides valuable insights into the level of danger posed and an additional review of the safety aspects of ki hajar dewantara building auditorium. this research was conducted by modeling a fire in the auditorium of ki hajar dewantara building, due to its very large capacity and various activities. in this research, it will provide an overview of the hrr of fires that occur as well as the effect of differences in ceiling height and the effect of ventilation on fire spread. the hrr obtained from each simulation was also emphasized, accompanied by the visualization of the fire and smoke distribution. although various materials were in the room, limitations were considered for the performance of this analysis. in this case, concrete, wood, gypsum, polypropylene, acoustic panel and polyurethane foam were the materials used in the fire modelling data. polyurethane foam is used as a fuel due to its high flammability, compared to other materials. this foam was the most abundant material in the room, leading to the possibility of continuous fire distribution. in addition, this research will describe the level of fire hazard and fire spread caused by differences in ceiling height. and will present the difference in full development time due to differences in fire location with ventilation. this research is grouped into several categories, section 1 described the introduction and objectives of the research. section 2 presents the experimental method, and section 3 describes the results and discussion of the analyzed fire modeling. meanwhile, section 4 focuses on the conclusions obtained from the experimental results. ii. material and methods 1. research method this qualitative research modeled a fire scenario involving polyurethane foam chairs in ki hajar dewantara auditorium, state university of jakarta, using fds software is shown in figure 1. at the beginning of the process, a preliminary analysis was conducted to select the room to be modeled. this was supported by identifying the problem with the experimental location. to support the determination of appropriate methods for solving the identified problems, a literature review was also conducted. additionally, various observations, such as room size, materials, and their respective values, were obtained. issn: 2580-0817 journal of mechanical engineering science and technology 78 vol. 7, no. 1, july 2023, pp.76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) fig. 1. research method flowchart fds is a computational fluid dynamics (cfd) model that utilizes numerical modeling to solve the navier-stokes equations applicable to low-velocity fluid (ma<0.3), smoke, and heat movement flow caused by fire [10]. on the other hand, smokeview is fds companion program that can generate images and animations from fds literacy results. in recent years, this program has advanced to be able to realistically visualize fire and smoke [11]. fig. 2. fds workflow 79 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) figure 2 gives an overview of how data files used by the nist fire dynamics simulator and smokeview are related. a typical procedure for using fds and smokeview is to : (1) set up an fds input file, a file with a .fds extension (e.g., a file named “casename.fds”). (2) run fds. (e.g. by typing fds < casename.data at a command line). the fire model fds then creates one or more output files with extensions .smv, .part, .sf, .q, .bf, .iso . these files are the smokeview file, particle file, slice file, plot3d file, boundary file and isosurface file, respectively. (3) run smokeview to analyze the output files 2. mesh meshing is the process of dividing the fluid component to be analyzed into small and discrete elements [12]. in fds, the mesh was calculated based on several parameters, namely the total hrr (q), air density (p∞), gravity (g), ambient temperature (t∞), and the specific heat of the air. due to the large diameter of the fire and the hrr that could vary over time, the mesh produced was relatively coarse. however, the mesh could be refined by considering the size of the combustible material or obstruction in the modeling, leading to a smaller mesh size without reducing the resolution of the object [10]. 𝐷 ∗= ( �̇� 𝜌∞ 𝐶∞ 𝑇∞ √𝑔 ) 2 5 ………………...………………………………………………(1) in this scenario, data with a domain of 24 m x 14 m x 11 m were used for mesh modeling, and it consisted of a total hrr (q) of 559 kw for polyurethane foam material, measured using a cone calorimeter that met the iso 5560 standards [13]. the air density (p∞) at normal temperature and not exceeding 50 km above the surface was 1,293 kg/m³ [14], and gravity (g) was 9.81 m/s². the initial temperature in the room, or ambient temperature (t∞), was 301 k. the calculation showed that the maximum mesh that could be used with a relatively coarse resolution was 0.19 m. due to the size of the room modeled, the rendering process took a long time, implying that a mesh with a relatively coarse resolution of 0.15 m was used to determine the possibility of fire phenomena occurring. it is crucial to note that the rendering process for this model took up to 2 months. 3. modeling the state university of jakarta auditorium had an area of 432 m² and a height of 11 m. the walls were 0.2 m thick, and there was only one inlet air ventilation opening measuring 2 x 0.7m, as well as three outlet air ventilation openings measuring 0.5x0.5 m. fire in the modeling was assumed to occur during the day when the doors were closed, and there were no people inside. according to the ignition handbook, the fire could be caused by several sources, including cooking equipment, heating equipment, electrical, smoking materials (cigarettes), or other factors such as negligence and arson [15]. in addition, previous fire incidents in the auditorium were caused by electrical and cigarette sources [3] [5]. the chair geometry was assumed to be 0.5x0.5 m in size with a depth of 1.5 m, and the straight rows of chairs did not follow the original slope because fds software could only model objects with straight or rectilinear geometry. the chair material was made of polyurethane foam and followed the modeling geometry standard specified, with a twocushion chair shape [16]. the determination of the starting point of fire was crucial and was based on certain criteria that posed the highest level of risk in the event of fire outbreak. according to the fire triangle theory, the presence of oxygen and combustible materials were the primary factors that contributed to the growth of fire. furthermore, drysdale and macmillan reported that issn: 2580-0817 journal of mechanical engineering science and technology 80 vol. 7, no. 1, july 2023, pp.76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) fire spread could be significantly exacerbated by blocked airflow caused by walls [17]. since this building housed numerous people, the accessibility of the exit route was a critical consideration when determining the fire modeling scenario for the starting point of the fire. consequently, the fire modeling scenario for this origin is described in table 1. table 1. fire modeling scenario scenario starting point of fire model name 1 close to the exit and in the middle of a row of seats on the 9th floor modeling 1 2 close to ventilation and access doors and in the middle of a row of seats on the 10th floor modeling 2 4. data collecting polyurethane foam was the recommended choice for combustible material due to its highly flammable nature compared to other materials and also because of the limitations of fds, which could only simulate one combustion reaction at a time. additionally, polyurethane foam fell under the category of fast-spreading materials [18]. hrr experimental calculations discovered that a polyurethane foam chair could burn completely in less than two minutes [13], [19]. the material data used are highlighted in table 2. table 2. material data material specific heat conductivity density reference temperature heat of reaction heat of combustion concrete 0.880 1.40 2300 polypropylene 1.9 0.24 940 43300 wood 2.38 0.17 800 19500 acoustic panel 1.0 0.06 200 18965 foam 2.0 0.04 100 295 847 27000 gypsum plaster 1.0 0.50 500 source: [17],[19],[20] after all, data had been recorded in notepad, the command prompt that appeared on the desktop during fds installation was used. iii. results and discussions 1. data analysis of fire modeling i heat release rate the figure 3 is the hrr in fire modeling 1. modeling 1 showed the stages of fire, which included growth, flashover, full development, and decay. the figure also supported the discovery of drysdale that in a compartment of fire with limited ventilation, the full development period was shorter than the ones with sufficient ventilation [17]. this was due to the depletion of combustible material or oxygen, which reduced the combustion rate. the 81 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) hrr in figure 5, the growth period occurred from 5 to 574 seconds, with a range of 45-700 kw. the pre-flashover period in this modeling took longer because the smoke layer temperature, concentration, and hrr reached a quasi-steady state [21],[22]. when the conditions were sufficient, a flashover occurred, leading to a significant increase in heat due to the concentration of monoxide, which reached a peak of up to 70,000 kw. during the post-flashover or decay period, the hrr returned to a quasi-steady-state phase but did not reach 0 kw. this was because the burning combustible material was still generating heat, and the combustion continued until the combustible material and oxygen available in the room were exhausted [22]. fig. 3. hrr graph of modeling 1 fire and smoke spread in table 3, it was observed that the fire spread followed the shape of the ceiling. the fire occurred on the 9th floor, with a ceiling height of 2.7 m. in a multi-story building with a low ceiling height, the fire could rapidly spread from the floor to other open rooms [21]. table 3 shows the final phases of the ceiling jet, namely the pre-flashover and postflashover vented periods. during the pre-flashover period, the smoke layer had descended to fire source and suppressed it due to oxygen depletion in the smoke layer. conceptually, smoke is the residual combustion product of pyrolysis or a hot plume. at 585 seconds, as the smoke continued to accumulate, the temperature significantly increased because the smoke layer temperature around the ceiling had reached a critical value of around 600°c [22]. this temperature increase caused a heat flux of 20 kw/m, igniting objects with surfaces directly facing the smoke in a short time in the room [20]. at 630 seconds, the fire reached the fullydeveloped hrr period at its peak, where unburned gas had accumulated on the ceiling, causing flames and heat in the compartment ranging from 700°c-1200°c. in the absence of any extinguishing efforts, fire tended to burn continually until the available combustible material and oxygen had been exhausted [23]. when the vent opening had not contained sufficient oxygen, fire entered the decay period. the hrr decreased proportionally to the decrease in oxygen concentration, but the temperature continued to increase for some time because the compartment contained smoke from the combustion pyrolysis, which had a high concentration and heat and could become a new combustible material [24]. 0 10000 20000 30000 40000 50000 60000 70000 80000 0 7 0 1 4 0 2 1 1 2 8 1 3 5 1 4 2 1 4 9 0 5 1 1 5 2 4 5 3 6 5 4 9 5 6 2 5 7 4 5 8 7 5 9 9 6 1 2 6 2 5 6 3 7 6 5 0 6 6 2 6 7 5 6 8 8 7 0 0 7 7 0 8 3 0 9 0 0 h e a t r e le a se r a te ( k w ) time (s) issn: 2580-0817 journal of mechanical engineering science and technology 82 vol. 7, no. 1, july 2023, pp.76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) table 3. fire spread in modeling 1 s p re a d s e c . 565 585 630 the visualization of the smoke spread in line with the fire is presented in table 4. table 4. smoke spread in modeling 1 s p re a d s e c . 5 100 630 table 4 shows how quickly the smoke spread, contributing significantly to the destruction of specific building components, such as structures, equipment, and stored goods with low fire resistance [25]. within the first five seconds of fire plume/ceiling jet, the smoke moved horizontally along the shape of the ceiling, and the buoyant gases spread radially beneath the ceiling in a relatively thin layer. after hitting the wall at 100 seconds, the smoke began to turn downward, accumulating under the ceiling until it pressed towards the fire source, with some of the smoke moving towards the 10th floor. at 630 seconds, the smoke had filled the entire room, and its temperature had risen to 600°c, causing the post-flashover phase and igniting surrounding objects on fire [20]. 2. data analysis of fire modeling 2 heat release rate the hrr in fire modeling 2 (figure 4) shows the hrr value rose from 50 kw to 5000 kw between 5 to 238 seconds, and also increased rapidly to 1300 kw at 259 seconds. the hrr peak point in this modeling occurred at 410 seconds, with hrr exceeding 30,000 kw. 83 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) this was followed by a decrease to 10,000 kw at 432 to 900 seconds. notably, during this decrease, there was a brief spike due to the complex combustion behavior of the polyurethane foam composite material [26], [27]. figure 4 also validated the discovery of drysdale (2011) that compartment fire with sufficient ventilation or close to its source had a longer fully-developed phase. in modeling 2, the fully-developed phase occurred between 260 to 432 seconds, with an hrr range of 12000-3000 kw. this was in contrast to modeling 1, which had a relatively short fullydeveloped period of 60 seconds. the time from the growth period to flashover was shorter, taking only 250 seconds compared to modeling 1, which took up to 560 seconds. although the hrr in modeling 2 was not higher than in modeling 1, the fire did not spread through the ceiling because its height on the 10th floor was higher than on the 9th floor [21]. fig. 4. hrr graph of modeling 2 spread of fire and smoke in table 5, the distance between fire source and the ventilation was relatively small, and the ceiling height was 5.5 m. in the event of fire, the spread was not extensive and could be contained within the room or only spread to the area adjacent to its source [21]. in this scenario, fire tended to move towards the chair that was higher than the burning chair, then spread towards the wall and reached the ceiling. although the temperature of fire reached 700°c, it did not spread to burn all the seats on the 10th floor due to the ceiling height being high enough to prevent heat propagation. in table 6, the speed and density of smoke accumulation were only observed on the 10th floor, which was different from modeling 1 where smoke rapidly filled the entire auditorium with high density due to the proximity of ventilation to fire source. the smoke was emitted through the roof opening, and at 5 seconds, the thin smoke reached the ceiling, continuously growing until it covered the ceiling on the 10th floor along with the number of burning seats. the smoke continued to build up and filled the 10th floor until 500 seconds. 0 5000 10000 15000 20000 25000 30000 35000 0 2 2 4 3 6 5 8 6 1 0 8 1 3 0 1 5 1 1 7 3 1 9 4 2 1 6 2 3 8 2 5 9 2 8 1 3 0 2 3 2 4 3 4 6 3 6 7 3 8 9 4 1 0 4 3 2 4 5 4 4 7 5 4 9 7 6 0 1 7 1 3 8 0 1 h e a t r e le a se r a te ( k w ) time (s) issn: 2580-0817 journal of mechanical engineering science and technology 84 vol. 7, no. 1, july 2023, pp.76-86 setyadi & arrizq (analysis of fire and smoke spread in ki hajar dewantara auditorium, using fds) table 5. fire spread in modeling 2 s p re a d s e c . 5 300 400 table 6. smoke spread in modeling 2 s p re a d s e c . 5 100 500 iv. conclusions flame spread is influenced by factors such as the location and amount of combustible material, ceiling height, etc. specifically, the ceiling jet phenomenon causes fire spread, and a room with a low ceiling height experience faster and more extensive fire spread following the shape of the obstacle. meanwhile, in a room with a high ceiling height, the fire only spreads in the room and is easier to extinguish. in case a room has poor ventilation or a large distance between fire source and ventilation, fire tends to take longer before reaching the flashover period, but the fully-developed period is shorter. this leads to denser smoke spread and increased room temperature as the smoke fills the room faster and traps the burning room. in an area with good ventilation or ventilation close to the fire source, fire can quickly reach the flashover period, but the fully-developed period is prolonged. the 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[27] a. f. baguian, s. k. ouiminga, c. longuet, a.s. c. bretelle et al., “influence of density on foam collapse under burning,” polymers (basel), vol. 13, no. 1, p. 13, dec. 2020, doi: 10.3390/polym13010013. journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 20-26 20 doi: 10.17977/um016v2i12018p020 properties of cassava starch based bioplastic reinforced by nanoclay nanang eko wahyuningtiyas 1,2* and heru suryanto 2 1 environmentalist, samarinda, kalimantan timur, indonesia 2 department of mechanical engineering, faculty of engineering, universitas negeri malang *nanang.ftum@gmail.com abstract synthetic synthetic plastic is chemical materials which cause severe environmental problems. incinerating plastic waste leads to release of hazardous gases, which is not good for humans. bioplastic can help reduce the dependence on fossil fuels and petroleum, that bioplastic can solve the problem of synthetic plastic use. this research aims to define the properties of the cassava starch-based bioplastic reinforced by nanoclay. methods were experimental with bioplastic component of cassava starch, glycerol as plasticizer and nanoclay as reinforcement. the bioplastic was analyzed using xrd, tensile test, moisture absorption, biodegradability, and compared with another bioplastic. the results show that the addition of nanoclay into bioplastic results increasing the tensile strength of bioplastic also increases from 5.2 mpa to 6.3 mpa. this research revealed that complete degradation of nanoclay reinforced bioplastic could be achieved on the 6th day. copyright © 2018journal of mechanical engineering science and technology all rights reserved keywords: biodegradability, nanoclay, starch-based bioplastic, tensile strength i. introduction bioplastic bioplastic is very important to use because able to maintain a sustainable environment and to prevent the disposal synthetic plastic wastes [1] that damaging the ecology includes the lands, waterways, and air pollution from plastic combustion. synthetic plastic takes 50 years to decompose in nature, whereas bioplastic requires 10 to 20 times faster to decompose in nature [2]. in 2014, the production of bioplastic around the world was 1.7 million tons [3] and will increase to reach 6.2 million tons by 2018 [4]. in indonesia, synthetic plastic consumption reaches 5.2 million tons in 2016, but bioplastic consumption is lower than 52,000 tons or 1% of synthetic plastic consumption [5]. bioplastic is a potential environmentally friendly material to reduce the usage of petroleum-based plastic. starchbased bioplastics were the most utilized bioplastic, due to their low co2 emission [4] and able to decompose by microorganisms as well as cellulose and lignin [6]. thermoplastic starch is a polymer made of starch or natural polymer renewable [7], through the process thermomechanical treatment in the mixed of suitable plasticizers, such as glycerol [8]. starch is a renewable source of packaging technology [9], due to its abundance, low cost, and ecofriendliness [10] [11] [12]. cassava contains a large amount of starch, which is capable of bioplastic production [2]. bioplastic from cassava starch lower price as compared to other starches, so it becomes a great potential for bioplastic. indonesia as the third-largest producer of cassava in the world [13] has the great potency to realize the bioplastic as a material substitution to synthetic plastic through exploring more deeply about cassava starch-based bioplastic. besides the advantages, the cassava starch-based bioplastic has some limitations such as high production cost [14], high water affinity [15], and poor mechanical properties [14], due to of the intramolecular and intermolecular bonds in the starch [7]. some of the techniques conducted to improve the mechanical properties and to reduce high water affinity especially in bio-based packaging application through adding organic fillers (nanocomposites), such as using nanofibers, nanotube, nanowhisker and nanoclay [16]. mailto:*nanang.ftum@gmail.com issn: 2580-0817 journal of mechanical engineering science and technology 21 vol. 2, no 1, july 2018, pp. 20-26 nanang eko wahyuningtiyas and heru suryanto (properties of cassava starch based bioplastic reinforced by nanoclay) nanoclay in the forms of clay is abundant in nature, versatility, and respectability toward the environment [17]. nanoclay can reinforce bioplastic in order to enhance mechanical properties, enhance their mechanical water resistance, decrease of water vapor permeability and flame retardance [15] [16] [17] when silicate component of nanoclay layers are well dispersed in the bioplastic [18]. hence, the aim of the research was to investigate the properties of cassava starchbased bioplastic reinforced by nanoclay. ii. material and method a. material the cassava starch obtained from a local source, malang, east java, indonesia was used as bioplastic material. glycerol with a concentration of 98% was used as a plasticizer supplied by cv. makmur sejati, malang, east java, indonesia. surface modified nanoclay containing 25-30% (w/t) trimethyl stearyl ammonium was provided by the sigma aldrich. b. bioplastic synthesis glycerol with concentration 1.5 % (v/v) was dissolved into the distilled water of 98.5 ml while stirred on a magnetic stirrer at 900 rpm for 5 min. the solution was added nanoclay by concentrations of 5.0% (b/b) and heated on a hot magnetic stirrer for ±45 min at ±80°c. the homogenizing process was conducted using ultrasonic wave 20 khz for 30 min. after sonication process, solution was added with cassava starch by the concentration of 5.0% (b/v) then heated on a magnetic stirrer at ±80°c while being stirred at 900 rpm for 45 min. bioplastic solution was poured into the mold then dried in an oven at 50°c for 24 h, and finally kept in a desiccator [2]. c. xrd analysis xrd analysis was conducted using pananalitical type x-pert pro diffractometer system at room temperature. the diffracted intensity of cukα radiation with wavelength (λ) of 1.54 å was recorded between 2° and 60° with a scanning rate of 0.02° per step at 30 ma and 40 kv. d. mechanical properties the tensile strength of nanoclay reinforced bioplastic was determined using a tensile tester with a load capacity of 50 n. bioplastic was cut with size 50 x 5 mm2 then prepared at a mounting card as shown in figure 1. specimens were clamped at both the ends then pulled with a constant speed of 0.025 ms-1 [19].. e. water absorption the water absorption measurements were carried out at a relative humidity of 80% at room temperature using astm d570-98. the water absorption test identified the ability of bioplastic to absorb the water [20]. dried nanoclay reinforced bioplastic cut into 10 x 10 mm2 and weighed for initial weigh. the moisture absorption data of nanoclay reinforced bioplastic was obtained by placing the sample in a bath of distilled water for 24 h at ambient temperature. after that, the sample was removed and wiped off and immediately weighed again as final weigh. the water absorption capacity of nanoclay reinforced bioplastic can be calculated using equation 3 based on 5 replications. water absorption = x 100% (3) 22 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 20-26 nanang eko wahyuningtiyas and heru suryanto (properties of cassava starch based bioplastic reinforced by nanoclay) fig. 1. tensile test specimens using the mounting card for bioplastic sheet f. biodegradability the the biodegradable behavior of nanoclay reinforced bioplastic was determined using soil burial decomposition test [21]. nanoclay reinforced bioplastic were cut into 10 x 10 mm2, then, buried in the ground at 80-mm depth; the burial duration varied from 1 to 7 days. prior to burial, the initial weight was determined and the final weight (weight after decomposition) of the bioplastic was measured. the decomposition of each sample was determined by equation 4 for weight loss [2]: biodegradability = x 100% (4) iii. results and discussion a. xrd analysis figure 2 shows diffractogram of cassava starch bioplastic and nanoclay reinforced cassava starch bioplastic. peak diffraction of cassava starch bioplastic was about 2θ of 16.89° and 19.63°. cassava starch is a semi-crystalline material consisting of crystal units and amorphous units [22]. after reinforced by nanoclay of 5.0% (b/b), peak diffraction of the shift were about 2θ of 16.65° and 19.69° was due to the intercalated and exfoliated process. the intensity of peak located at 19.69° was an increase because of additional intensity from nanoclay having high peak located at 19.8° [23]. the thermoplastic cassava enters the clay galleries and forces apart the platelets resulting the increase of d-spacing [24]. the increase in the d-spacing exhibit the change in the formation of a composite structure with the intercalated of thermoplastic chains in the nanoclay layers gallery. as more polymers insert into the clay galleries and push the layers even further. when a complete exfoliated structure of nanocomposite is reached, the xrd peak becomes wider [25] [26]. the phenomenon of exfoliated is desirable for the improvement of mechanical properties [27]. the addition of nanoclay can increase crystallinity because the nanoclay play as a nucleating agent and accelerates the crystallization process resulting in a higher crystallinity [28]. b. mechanical properties figure 3 shows the curve of tensile properties that indicate increasing the tensile strength of bioplastic due to the addition of nanoclay. nanoclay makes the interface transfers the load or stress from bioplastic to nanoclay through intercalation mechanism. fig. 2. diffractogram of (a) nanoclay reinforced cassava bioplastic 5.0% (b/b) (b) bioplastic cassava starch -0.2 0 0.2 0.4 0.6 0.8 -1 4 9 14 fo rc e (n ) elongation % issn: 2580-0817 journal of mechanical engineering science and technology 23 vol. 2, no 1, july 2018, pp. 20-26 nanang eko wahyuningtiyas and heru suryanto (properties of cassava starch based bioplastic reinforced by nanoclay) fig. 3. tensile test curve: a. cassava starch-based bioplastic, b. nanoclay reinforced bioplastic 5.0% (b/b) table 1. mechanical properties of cassava starch based bioplastic and nanoclay reinforced bioplastic sample tensile strength (mpa) elongation (%) young’s modulus (mpa) cassava starch based bioplastic 5.2 11.9 71.64 nanoclay reinforced bioplastic 5.0% (b/b) 6.3 13.5 47 increasing nanoclay addition in bioplastic cause lower tensile strength due to a large number of nanoclay particles tend to agglomerate into larger particles, which affect the intercalation effect of nanoclay particles in the polymer (bioplastic) [29]. young’s modulus bioplastic from cassava starch and nanoclay reinforced bioplastic 5.0% (b/b) was decreased in table 1, due to glycerol as plasticizers increase nanoclay reinforced bioplastic 5.0% (b/b) flexibility that has the ability to reduce internal hydrogen bonding between polymer chains, resulted in bioplastic with lower young’s modulus and high flexibility [30]. increased bioplastic tensile strength, due to increasing xrd peak intensity that correlating with enhancing the crystallinity of cassava starch based bioplastic. the crystallinity of polymer affects various chemical properties and physical technologies and there is also a correlation between crystallinity and mechanical strength of polymer [31] c. moisture absorption addition of nanoclay 5.0% (b/b) into bioplastic enhances the water absorption shown in figure 4. the crystalline regions offer less free volume than amorphous regions in the nanoclay reinforced bioplastic so that air and gas vapor will be more difficult to enter [32] and due to also its hygroscopic nature of nanoclay [33] which easily absorbs h2o [18]. absorption of h2o causes the galleries to expand and the nanoclay to swell [34], that nanoclay reinforced bioplastic is more hydrophilic. d. biodegradability the addition of nanoclay has enormous potential to either increase rate of decomposition until 6 days in figure 5. nanoclay reinforced bioplastic 5.0% (b/b) increase the amount of decomposition, that could be, due to aluminum lewis acid site from nanoclay that can catalyze during the process of hydrolysis. also, the presence of nanoclay increased the substrate polarity and water absorption which enhanced the heterogenic rate of hydrolysis decomposition [18] [34] [35]. moreover, cassava starch-based bioplastic increase the hydrophilicity through eliminating the regular crystalline structure from nanoclay reinforced bioplastic, facilitated the attack of microorganism into the bulk of nanoclay reinforced bioplastic [36], that cause hydroxyl groups in the silicate layers initiated heterogeneous hydrolysis after absorbing water from the compost, that creates nanoclay reinforced bioplastic 5.0% (b/b) decomposition into very small fragments and eventually disappeared with the compost [18]. decomposition in soil based on the diffusion of living microorganisms in aqueous soils [36]. the effect of nanoclay can speed up the decomposition process. 24 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 20-26 nanang eko wahyuningtiyas and heru suryanto (properties of cassava starch based bioplastic reinforced by nanoclay) fig. 4. the rate of moisture absorption of nanoclay reinforced bioplastic fig. 5. results of nanoclay reinforced bioplastic decomposition testing table 2. decomposition duration of some plastic-types sample decomposition times references bioplastic cassava starch filler nanoclay 5.0% (b/b) 6 days this study bioplastic cassava starch 12 days [2] bioplastic cassava starch filler chitosan 8 days [37] bioplastic potato starch 5 days [38] bioplastic corn starch 7 days [39] bioplastic gluten 50 days [10] synthetic plastic > 50 years [40] decomposition of bioplastic from cassava starch reinforced with nanoclay 5.0% (b/b) (6 days) slower from bioplastic from potato starch (5 days), but faster from bioplastic from cassava starch filler chitosan (8 days), bioplastic from corn starch (7 days), bioplastic from cassava starch (12 days), bioplastic from gluten (50 days), and synthetic plastic as shown in table 2. iv. conclusion this research has demonstrated the potential to use bioplastic from cassava starch reinforced with nanoclay from renewable resources. nanoclay in cassava starch bioplastic enhanced the peak structure of bioplastic which this structure able to increase the tensile strength and reduce water absorption of bioplastic. v. acknowledgments we are grateful to the ministry of research, technology, and higher education, indonesia, and the universitas negeri malang that supporting this study through pdupt program with contract no. 1.3.32/un.14/lt/2018. vi. references [1] n. e. wahyuningtiyas, h. suryanto, e. 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[40] h. k. webb, j. arnott, r. j. crawford, and e. p. ivanova, “plastic degradation and its environmental implications with special reference to poly(ethylene terephthalate),” polymers (basel)., vol. 5, pp. 1– 18, 2013. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 2, november 2023, pp. 96-105 96 doi: 10.17977/um016v7i22023p096 study on effect of 3d printing parameters on surface roughness and tensile strength using analysis of variance faqih fadillah1, heru suryanto2*, and suprayitno1 1master program of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang 5 malang, east java, indonesia 2centre of advanced material and renewable energy, universitas negeri malang, jl. semarang no. 5, malang, 65145, indonesia *corresponding emails: heru.suryanto.ft@um.ac.id article history: received: 8 january 2023 / received in revised form: 22 march 2023 / accepted: 30 march 2023 available online 31 july 2023 abstract fused deposition modeling of 3d printing is the process of making workpieces or parts by adding filaments to each layer. some indicators of a high-quality product of 3d printing are the precisions dimensions, the surface roughness, and tensile strength. this research aims to find the parameters most affecting surface roughness and tensile strength. the research design used an experimental method with input parameters: (1) print speed (15-35 mm/s), (2) print temperature (200-210c), (3) layer height (0.1 – 0.3 mm), (4) infill line directions (0-90), and dependent variables were surface roughness and tensile strength. the data distribution used the l9 orthogonal array, and the statistic analysis used anova. material uses nanographite-reinforced polylactic acid (pla) filament. the results indicate that print parameters that significantly affect surface roughness are layer height and infill line directions. the best surface roughness on the layer height parameter is 0.1 mm, and the infill line directions parameter is 90. based on anova analysis, print speed, print temperature, and layer height do not significantly affect tensile strength, but infill line directions significantly affect tensile strength. the best tensile strength on infill line directions is 90. the best average tensile strength with nanographite-reinforced pla filament is 38.56 n/mm2, with 35 m/s print speed, 205 c print temperature, 0.1 mm layer height, and 90 infill line direction parameter. the best average surface roughness with nanographite-reinforced pla filament is 0.66 µm, with 35 m/s print speed, 205 c print temperature, 0.1 mm layer height, and 90 infill line direction parameter. copyright © 2023. journal of mechanical engineering science and technology. keywords: 3d print, anova, nanographite, polylactic acid filament, roughness, tensile strength i. introduction the flow chart of making a product generally consists of ideas, designs, prototypes, performance tests, and implementation. prototypes aim to evaluate the products before they are implemented and manufactured in mass production. prototypes are made in small quantities so that the additive manufacturing process is prioritized over other manufacturing processes. additive manufacturing is efficient and effective for small amounts of products [1]. in addition, creating complex models using additive manufacturing can eliminate jigs and fixtures. additive manufacturing has several types, one of which is fdm (fused deposition modeling). type fdm of additive manufacturing is the process of making workpieces or parts by adding filaments to each layer. additive manufacture is appropriate if applied to 97 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no.2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) prototypes that make the manufacture of varied parts and small quantities. additive manufacturing has a cheaper and more consistent process price. as an illustration, additive manufacturing can make parts cheaper than injection molding processes in the range of 4000 to 12000 parts with a production cost of 2.1 €/part, in injection molding cheaper with parts above 12000 with a production price range below 2 €/part [2]. additive manufacturing does not require a longer process. additive manufacturing can make a simple process so that it requires two methods (raw material and component manufacturing), compared to traditional manufacturing, which requires three methods (raw materials, part manufacturing, and assembly parts). besides that, in making parts, it is necessary to combine several machines for complicated shapes [2]. two hundred million users predicted in 2026, 3d printing is predicted to grow from 18% to 32% (2018 to 2026) with usd 7-23 billion to usd 51.77 billion [3]. factors affecting the print result are the material, machine, and setting parameters. the quality of 3d print objects is affected by setting parameters, setting the distance of the reference point, and choosing a filament with the appropriate adhesion [4]. setting parameters of 3d printing greatly affects print quality. the lower layer height has an impact on increasing tensile strength, smoothness, and dimensional accuracy of 3d print objects, but affects the long print time [5]. some parameters like print speed (ps) and print temperature (pt) need to be tested. surface roughness and topography are the main parameters that indicate the accuracy of components. however, the average surface roughness (ra) of arithmetic samples made by material extrusion varies between 9 and 40 μm, which can be categorized as poor surface roughness [6]. layer height (lh) or thickness affects the surface quality and dimensions of the workpiece more than other parameters such as ps and pt [7]. in previous studies, researchers discussed the effect of ps, pt, and lh on surface roughness. it is necessary to show the contribution of print speed, printing temperature, layer thickness, and infill line directions to the tensile strength and surface roughness. the goal of this research is to find the parameters that most affect surface roughness and tensile strength. ii. material and methods this research was an experimental study, experimental data distribution used l9 (33) orthogonal arrays. statistical analysis used the analysis of variance (anova). the anova method was utilized to understand the percentage of contribution of each parameter. anova analysis was used to find the critical factor for a specified response [8]. in this research, data distribution used l9 (33) orthogonal arrays because it was more cost-effective than the full factorial method [9]. variable independent and dependent is shown in figure 1, and the level of the dependent variable is shown in table 1. fig. 1. independent variables and dependent variables issn: 2580-0817 journal of mechanical engineering science and technology 98 vol. 7, no. 2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) table 1. variables and data distribution variables code unit variations print speed ps mm/s 15 25 35 printing temperature pt c 200 205 210 layer height lh mm 0.1 0.2 0.3 infill line directions ild  0 45 90 the object of this study was the astm d638 type iv specimen with pla material. the design of the l9 (34) orthogonal array with three replications as shown in table 2. table 2. design of experiment l9 orthogonal array no ps pt lh ild ps pt lh ild 1 -1 -1 -1 -1 15 mm/s 200 c 0.1 mm 0 2 -1 0 0 0 15 mm/s 205 c 0.2 mm 45 3 -1 1 1 1 15 mm/s 210 c 0.3 mm 90 4 0 -1 0 1 25 mm/s 200 c 0.2 mm 90 5 0 0 1 -1 25 mm/s 205 c 0.3 mm 0 6 0 1 -1 0 25 mm/s 210 c 0.1 mm 45 7 1 -1 1 0 35 mm/s 200 c 0.3 mm 45 8 1 0 -1 1 35 mm/s 205 c 0.1 mm 90 9 1 1 0 -1 35 mm/s 210 c 0.2 mm 0 the study used nanographite-reinforced polylactic acid (pla) filament with the specifications as shown in table 3. the print process uses a 3d printer (creality ender 3 prusa i3) with a diameter of a single nozzle is 0.4 mm. table 3. characteristic of nanographite-reinforced pla filament for 3d print print temp. (c) 190 – 210 tensile strength (n/mm 2 ) 33.8 bed temp. (c) no heat/(60—80) elongation at break (%) 10.39 density (g/cm 3 ) 1.09 modulus young (n/mm 2 ) 3.4 the surface roughness (ra) was measured in a surftest sj-310 series (mitutoyo, japan), and the tensile strength test was conducted in jtm-uts210 computer servo universal testing machine (2t) using the standard of astm d638 type iv [10] as shown in figure 2. the statistical analysis used in this study was a three-way anova (three-lane anova). a three-lane anova is used to test the mean differences of three or more sample groups with three independent variables and one dependent variable. in this study, anova analysis used minitab software. the hypotheses of this study are: h0 = there is no difference between the average n groups. h1 = there is a difference between the average n groups. the interpretation of c is: 99 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no.2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) if the p-value is less than α = 0.05, so h1 is accepted, or h0 is rejected if the p-value is more than α = 0.05, so h0 is accepted, or h1 is rejected fig. 2. tensile test specimen astm d638 type iv if the test results show h0 (no difference), then the follow-up test (post hoc test) is not carried out. on the other hand, if the test results show h1 (there is a difference), then a further test (post hoc test) must be carried out. iii. results and discussions the data of roughness and tensile strength of 3d-printed product is shown in table 4. table 4. roughness and tensile strength of the 3d-printed product run roughness (ra) tensile strength (n/mm 2 ) 1 2 3 1 2 3 1 3.21 6.44 4.97 31.17 26.56 22.48 2 9.78 14.09 10.63 35.71 35.39 24.37 3 3.21 2.31 2.24 31.95 27.46 31.71 4 1.60 6.24 5.08 30.29 38.69 33.87 5 18.91 12.56 18.60 30.34 25.00 26.93 6 2.01 2.34 14.91 31.35 35.92 40.99 7 18.26 10.85 22.72 24.91 20.46 28.66 8 1.09 0.52 0.36 38.26 35.58 41.84 9 7.85 26.38 33.10 32.29 26.61 32.48 analysis of surface roughness anova analysis of the surface roughness of 3d-printed product is shown in table 5. table 5. anova analysis results for surface roughness of the 3d-printed product source df adj ss adj ms f-value p-value ps 2 232.72 116.358 3.64 0.047 pt 2 12.47 6.237 0.19 0.825 lh 2 433.30 216.649 6.77 0.006 ild 2 723.68 361.840 11.31 0.001 error 18 575.93 31.996 total 26 1978.10 issn: 2580-0817 journal of mechanical engineering science and technology 100 vol. 7, no. 2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) the interpretation of data from the anova results is shown in table 6. table 6. interpretation of anova results for average surface roughness of the 3d-printed product source p-value decision interpretation ps 0.047 < 0.05 h0 is rejected there is a difference in average surface roughness at a ps of 15; 25, and 35mm/s. pt 0.825 > 0.05 h0 is accepted there is no difference in average surface roughness at pt of 200; 205, and 210c lh 0.006 < 0.05 h0 is rejected there is a difference in average surface roughness on lh of 0.1 mm, 0.2 mm, 0.3 mm ild 0.001 < 0.05 h0 is rejected there is a difference in the average surface roughness in ild of 0, 45, 90. the analysis results in table 6 show that the 3d printing parameter variables (ps, pt, lh, and ild) that affect the surface roughness of 3d-printed product is the ps and lh [11] and ild. from the summary model obtained r-square by 70.88 %, this means that the value of the influence of ps, pt, lh, and ild on surface topology is 70.88% while other variables influence the remaining 29.12%. the grouping information results are shown in table 7, and the simultant test results using the tukey test are shown in table 8. they show that ps of 15 mm/s, lh of 0.1 mm, and ild of 90 have a small average value, so that is a smooth surface. table 7. grouping information using the tukey method and 95% confidence ps lh ild ps n mean grouping lh n mean grouping ild n mean grouping 35 mm/s 9 13.46 a 0.2 mm 9 12.75 a 0 9 14.67 a 25 mm/s 9 9.14 a b 0.3 mm 9 12.18 a 45 9 11.73 a 15 mm/s 9 6.32 b 0.1 mm 9 3.98 b 90 9 2.51 b table 8. tukey simultaneous tests for differences means ps lh ild difference of levels difference of means adj p-value difference of levels difference of means adj p-value difference of levels difference of means adj p-value 25 15 mm/s 2.82 0.552 0.2 0.1 mm 8.77 0.011 45 0 -2.94 0.526 35 15 mm/s 7.14 0.039 0.3 0.1 mm 8.20 0.017 90 0 -12.15 0.001 35 25 mm/s 4.32 0.263 0.3 0.2 mm -0.57 0.976 90 45 -9.22 0.008 table 9 indicates that ps of 15 mm/s have a difference with ps of 35 mm/s; lh of 0.1 mm has a difference with lh of 0.2 mm and 0.3 mm; ild of 90 have a difference with lh of 0 and 45. 101 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no.2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) table 9. interprestasi data tukey simultaneous for surface roughness of the 3d-printed product difference of levels adjusted p-value decision interpretation print speed 25 15 mm/s 0.552>0.05 h0 accepted there isn’t a difference between ps 25 and 15 mm/s 35 15 mm/s 0.039<0.05 h0 rejected there is a difference between ps 35 and 15 mm/s 35 25 mm/s 0.263>0.05 h0 accepted there isn’t a difference between ps 35 and 25 mm/s layer height 0.2 0.1 mm 0.011<0.05 h0 rejected there is a difference between lh 0.2 and 0.1 mm 0.3 0.1 mm 0.017<0.05 h0 rejected there is a difference between lh 0.3 and 0.1 mm 0.3 0.2 mm 0.976>0.05 h0 accepted there isn’t a difference between lh 0.3 and 0.2 mm infill line directions 45 0 0.526>0.05 h0 accepted there isn’t a difference between ild 45 and 0 90 0 0.001<0.05 h0 rejected there is a difference between ild 90 and 0 90 45 0.008>0.05 h0 rejected there is a difference between ild 90 and 45 figure 3 show the grouping of lh with topographic results. 0 1000 2000 3000 4000 -60 -40 -20 0 20 40 60 s u rf a c e t o p o g ra p h y ( µ m ) measurement length (µm) 1 st parameter 6 th parameter 8 th parameter 0 1000 2000 3000 4000 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 s u rf a c e t o p o g ra p h y ( µ m ) measurement length (µm) 2 nd parameter 4 th parameter 9 th parameter (a) (b) 0 1000 2000 3000 4000 -60 -40 -20 0 20 40 60 s u rf a c e t o p o g ra p h y ( µ m ) measurement length (µm) 3 rd parameter 5 th parameter 7 th parameter (c) fig. 3. topographic graph with lh of (a) 0.1 mm; (b) 0.2 mm; (c) 0.3 mm. issn: 2580-0817 journal of mechanical engineering science and technology 102 vol. 7, no. 2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) based on figure 3, lh of 0.1 mm has a better surface than lh of 0.2 mm and 0.3 mm. lh of 0.1 mm has a good surface because each print has a small height, so the nozzle output is also small and the result smoother. the smaller the print height, the better the results obtained, but the longer the printing time. the lh, followed by the nozzle diameter, are the process parameters that greatly influence the arithmetical mean height (ra) [12]. analysis of tensile strength the result of anova of tensile strength of the 3d-printed product is shown in table 10. table 10. anova analysis results for tensile strength of the 3d-printed product source df adj ss adj ms f-value p-value ps 2 39.32 19.66 1.16 0.337 pt 2 91.13 45.57 2.68 0.096 lh 2 193.14 96.57 5.68 0.012 ild 2 174.10 87.05 5.12 0.017 error 18 306.29 17.02 total 26 803.99 the interpretation of data from the anova results is shown in table 11. from the summary model, it is obtained r-square by 61.90%. this means that the value of the influence of print speed (ps), print temperature (pt), layer height (lh), and infill line direction (ild) on tensile strength (y) is 61.90% while other variables influence the remaining 38.1%. table 11. interpretation of the anova analysis for tensile strength data of 3d-printed product source p-value decision interpretation ps 0.337 > 0.05 h0 accepted there is no difference in tensile strength at ps of 15; 25, and 35 mm/s pt 0.096 > 0.05 h0 accepted there is no difference in tensile strength at pt of 200; 205, and 210 c lh 0.012 < 0.05 h0 rejected there is a difference in tensile strength at print layer heights 0.1; 0.2, and 0.3 mm ild 0.017 < 0.05 h0 rejected there is a difference in tensile strength at print infill line directions 0; 45 and 90 based on anova analysis, ps and pt have no significant effect on tensile strength. other variables influence based on the remaining r-square (38.1%). other possible influencing variables, such as material and filament diameter, need to be investigated. based on anova analysis, layer height (lh) and infill line direction (ild) significantly affect tensile strength. 3d printing type fdm has the best tensile strength at the 90-angle print (parallel to the tensile axis) and has poor tensile strength when the print angle is below 50 [13]. 3d print of fdm makes shapes by adding layer by layer with a pattern like arranging fibers, therefore the best tensile strength is a tensile force that is parallel with the fibers. 103 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no.2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) (a) (b) fig. 4. (a) force and displacement of the 3d-printed specimen; (b) nanographite-reinforced pla filament the force and displacement graph of a 3d-printed product using astm d638 type iv is shown in figure 4. the graph shows the material printed from pla has brittle properties, different from pla as raw material that have ductile properties. the average tensile strength of nanographite-reinforced pla filaments is 34.705 n/mm2. nanographite-reinforced pla filaments more strong than pla filaments with 13.22 n/mm2 [14]. the ultimate tensile strength decreases as the printing angle becomes smaller or the layer becomes thicker. this theoretical model and experimental method can also be applied to other 3d printing materials fabricated by fdm or sla techniques [15]. the tensile test of pla with the astm d638 specimen results shows that parts printed at a raster angle of 0° exhibit higher tensile strength than parts printed at a raster angle of 90° [16]. the tensile test was performed to measure the effect of different raster angles, layer height, and raster width [16]. iv. conclusions the four dependent variables (print speed, print temperature, layer height, and infill line direction) that have a significant effect on surface roughness are print speed, layer height, and infill line direction. from the follow-up post hoc test, the most superior parameter of print speed, layer height, and infill line direction are 15 mm/s, 0.1 mm, and 90, respectively, which indicates the highest level of surface smoothness. based on anova analysis, print speed (ps) and print temperature (pt) have no significant effect on tensile strength. successively the effect of prints speed (ps), print temperature (pt), layer height (lh), and infill line direction (ild) on tensile strength, as seen from the p-value, is 0.47; 0.825; 0.006; and 0,001, respectively. in the future, this nanocomposite filament can be applied to product which needs better surface finishing. acknowledgment the authors would like to appreciate the universitas negeri malang, which provides the facilities to conduct the research and drtpm through the research grant scheme pps-ptm with contract number of 20.6.88/un32.20.1/lt/2023. 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0 20 40 60 80 100 f o rc e ( k g f) displacement (mm) 1 2 3 4 5 6 7 8 9 3d print astm d638 type iv tensile test specimens 0 1 2 0 10 f o rc e ( k g f) displacement (mm) 1 2 3 4 nanographite-reinforced polylactic acid filaments issn: 2580-0817 journal of mechanical engineering science and technology 104 vol. 7, no. 2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) references [1] s. farah, d. g. anderson, and r. langer, “physical and mechanical properties of pla, and their functions in widespread applications — a comprehensive review,” adv. drug deliv. rev., vol. 107, pp. 367–392, 2016, doi: 10.1016/j.addr.2016.06.012. [2] d. s. thomas and s. w. gilbert, “costs and cost effectiveness of additive manufacturing: a literature review and discussion,” gaithersburg (usa): national institute of standards and technology, pp. 1–96, 2015. [3] s. wickramasinghe, t. do, and p. tran, “fdm-based 3d printing of polymer and associated composite: a review on mechanical properties, defects and treatments,” polymers (basel)., vol. 12, no. 7, pp. 1–42, 2020, doi: 10.3390/polym12071529. [4] h. wu and t. t. chen, “quality control problems in 3d printing manufacturing : a review,” rapid prototyp. j., vol. 24, no. 3, pp. 607-614, 2018, doi: 10.1108/rpj-022017-0031. [5] g. percoco, l. arleo, g. stano, and f. bottiglione, “analytical model to predict the extrusion force as a function of the layer height, in extrusion based 3d printing,” addit. manuf., vol. 38, no. july 2020, 2021, doi: 10.1016/j.addma.2020.101791. [6] r. i. campbell, m. martorelli, and h. s. lee, “surface roughness visualisation for rapid prototyping models,” cad comput. aided des., vol. 34, no. 10, pp. 717–725, 2002, doi: 10.1016/s0010-4485(01)00201-9. [7] e. taşcıoğlu, ö. kıtay, a. ö. keskin, and y. kaynak, “effect of printing parameters and post‑process on surface roughness and dimensional deviation of pla parts fabricated by extrusion‑based 3d printing,” j. brazilian soc. mech. sci. eng., vol. 44, p. 139, 2022, doi: https://doi.org/10.1007/s40430-022-03429-7. 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[12] i. buj-corral, x. sánchez-casas, and c. j. luis-pérez, “analysis of am parameters on surface roughness obtained in pla parts printed with fff technology,” polymers (basel)., vol. 13, no. 14, pp. 1–20, 2021, doi: 10.3390/polym13142384. [13] t. yao, j. ye, z. deng, k. zhang, y. ma, and h. ouyang, “tensile failure strength and separation angle of fdm 3d printing pla material: experimental and theoretical analyses,” compos. part b eng., vol. 188, no. november 2019, p. 107894, 2020, doi: 10.1016/j.compositesb.2020.107894. [14] m. syaifuddin and h. suryanto, “the effect of multi-extrusion process of polylactic acid on tensile strength and fracture morphology of filament product,” j. mech. eng. sci. technol., vol. 5, no. 1, pp. 62–72, 2021, doi: 10.17977/um016v5i12021p06. [15] t. yao, z. deng, k. zhang, and s. li, “a method to predict the ultimate tensile 105 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no.2, november 2023, pp. 96-105 fadillah et al. (study on effect of 3d printing parameters on surface roughness and tensile strength) strength of 3d printing polylactic acid (pla) materials with different printing orientations,” compos. part b eng., vol. 163, no. july 2018, pp. 393–402, 2019, doi: 10.1016/j.compositesb.2019.01.025. [16] s. r. rajpurohit and h. k. dave, “analysis of tensile strength of a fused filament fabricated pla part using an open-source 3d printer,” int. j. adv. manuf. technol., vol. 101, pp. 1525–1536, 2019, doi: https://doi.org/10.1007/s00170-018-3047-x. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 66-75 66 doi: 10.17977/um016v7i12023p066 the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304 plate yanuar rohmat aji pradana*, raka afrianto, chandra hairat abdul rahman, andoko department of mechanical and industrial engineering, universitas negeri malang, semarang st. no. 5, malang, 65145, east java, indonesia *corresponding author: yanuar.rohmat.ft@um.ac.id article history: received: 4 may 2023 / received in revised form: 8 june 2023 / accepted: 9 june 2023 available online 15 june 2023 abstract the focus of today’s machining industry is on how to maintain high productivity and low cost achieved by high tool life during the operation. laser cutting is considered the right solution because it offers cutting speeds of up to 170000 mm/min through a non-contact process regardless of the workpiece material hardness. the aim of this study is to analyze the effect of cutting speed on the surface texture aspects namely surface roughness, kerf shape, and dross height on the stainless steel 304 plate after laser cutting. the nitrogen laser was utilized with the cutting speed of 400, 1700, and 2000 mm /min and the average roughness (ra) was then measured using a surface roughness tester. on the other hand, the top, middle, and bottom area of the kerf surface as well as the dross height were analyzed by scanning electron microscopy (sem). the highest ra value was resulted at cutting speed of 2000 mm/min with 2.965 ± 0.05 μm while the lowest was at 1400 mm/min with 2.522 ± 0.16 μm. in parallel, the ra was found to be higher when subjected gradually from the top to bottom zone. the kerf surface also proved that the top zone is dominated by the cutting zone, while the middle and bottom zone are characterized by the transition and deformation zone respectively. the width between kerf lines increased when the higher cutting speed was performed. additionally, the larger dross height was found at the cutting speed of 1400 mm/min with 32.75 ± 5.21 μm and then degraded gradually at the higher cutting speed. the heat input and laser capability in exposing the material thickness are responsible for determining the corresponding surface texture aspects. copyright © 2023. journal of mechanical engineering science and technology. keywords: cutting speed, dross height, kerf shape, nitrogen laser, stainless steel 304, surface roughness. i. introduction traces of conventional technology in the railway manufacturing industry experience machining problems in alloy metals, one of which is stainless steel 304 for side wall components of bangladesh mg (meter gauge) train [1]. it is proven that stainless steel alloy 304 is difficult to be processed with conventional machining due to its high hardness which can reach 145-155 hb [2]. such properties lead to the accumulation of high amounts of heat and mechanical stress at the edges of the cutting tool at high cutting speed. increased temperature and cutting force can certainly lead to cutting tool failure [3]. to answer these challenges, non-conventional machining with zero tool-workpiece contact is introduced as the solution. one of the non-conventional machining techniques is laser cutting because it is able to achieve a cutting speed of 170000 mm/min regardless the hardness of the material [4]. mailto:yanuar.rohmat.ft@um.ac.id 67 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) laser cutting is a thermal-based machining technology that uses coherent light as a source for cutting and can be applied to cut many kinds of metal and alloy such as stainless steel, aluminum, copper, etc. the mechanism of laser cutting material disposal is absorption, melting, and vaporization [5]. during vaporization, the material melted by the laser beam is evaporated from the melting area with the help of assisted gas such as nitrogen, oxygen, and atmosphere air. nitrogen gas is largely applied for cutting stainless steel for many applications [6]. the common dross height achieved by using nitrogen, oxygen, and air are 0.12, 0.27, 0.32 μm, respectively, because nitrogen can exothermically react better in aluminum at 830 °c compared to oxygen and atmospheric air [7]. the parameters to determine the quality of surface texture include cutting speed, laser power, and gas pressure [8], where the key indicators playing an important role in the formation of the surface topography of stainless steel 316 cut is cutting speed [9]. cutting speed is considered more objective in the range of 1400 to 2000 mm/min against stainless steel 304 thickness 3 mm. the results obtained implied that the regression analysis was successfully applied with an accuracy of 82.7% on surface roughness and 71.67% on kerf width. based on the results of the anova, the minimum surface roughness was achieved at a cutting speed of 2000 mm/min, laser power of 600 w, and gas pressure of 0.4 bar, while the minimum kerf width was shown at similar level of cutting speed and laser power 600 w but at the gas pressure of 0.5 bar. the surface roughness and kerf width increased as the higher laser power and cutting speed were applied [5] the other aspects of surface texture besides kerf width are surface roughness, kerf surface, and dross height [10]. the results of cutting abrasive water jet cutting on the top zone of aluminum alloy have better surface quality compared to the bottom zone illustrating that there is a difference in the quality of surface roughness and kerf surface at different thickness zones [11]. additionally, dross is created due to uneven distribution of vaporization which causes stuck in the bottom zone. dross is easily found in the bottom zone of stainless steel 316l cutting [9]. based on these phenomena, surface texture is important to be considered because it affects aesthetics, tribological considerations, corrosion resistance, assembly considerations, and increased fatigue life [12]. based on the purpose of laser cutting utilization during component manufacturing primarily through machining, it can be expressed as an attempt to achieve predetermined characteristics of product quality within the constraints of equipment cost and time. rajesh, et al [5] examined and optimized the kerf width and surface roughness of stainless steel 304. however, the study is limited only in a single area of cutting thus it is unable to provide a comprehensive point of view in surface texture aspects under laser cutting parameter variation. in this study, the surface roughness and kerf surface examination were subjected to top, middle, and bottom zones. additionally, along with the kerf surface, the dross height measurement was performed visually using microscopic observation. ii. materials dan method stainless steel plate of aisi 304 having dimensions of 1500 x 1000 x 3 mm was prepared for the workpiece material. based on the material specification, the aisi 304 contained 17.5-19.5% cr, ≤ 0.07% c, ≤ 1% si, ≤ 2% mn, 0.45% p, ≤ 0.015% s, ≤ 0.11% n, and 8-10.5% ni. the laser machine trulaser 3060 fiber was used to cut the plate workpiece. the cutting speeds were set at the value of 1400, 1700, and 2000 mm/min. during the cutting process, a nozzle with a diameter of 1.5 mm at angle of 90° was used under nitrogen exposure. moreover, the gas pressure, laser power, and stand of distance issn: 2580-0817 journal of mechanical engineering science and technology 68 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) were constantly maintained at 0.3 bar, 600 w, and 1.5 mm respectively. the cutting was done for three times of repetition for each cutting speed to ensure the data validity. after the laser cutting was completed, the surface roughness measurement was conducted using mitutoyo surface roughness tester based on iso 4287 standard. the scanning length was taken for 0.8 mm at 3 different locations for each specimen. in parallel, the kerf surface and dross height were analyzed using scanning electron microscope (sem) according to astm c1723 standard with 200 times of magnification. the surface roughness and kerf surface observation were subjected to three different locations based on the material thickness covering top, middle, and bottom zones. figure 1 shows the location of surface roughness and kerf surface test. fig. 1. surface roughness and kerf surface testing locations. (unit: mm) iii. results and discussion 1. surface roughness the results from surface roughness test are listed in table 1. table 1. average surface roughness (ra) with cutting speed variations cutting speed (mm/min) ra (µm) average ra (μm) top middle bottom 1400 1.815 2.695 3.055 2.522 ± 0.05 1700 2.095 2.780 3.170 2.682 ± 0.21 2000 2.170 3.170 3.555 2.965 ± 0.16 based on table 1, each cutting speed is divided to top, middle, and bottom. at the cutting speed of 1400 mm / min, the ra smallest value is in the top zone of 1.815 μm. this value continues to increase in the middle zone of 2.695 μm and the bottom zone of 3.055 μm. turning to the cutting speed of 1700 mm/min, the top zone ra is 2.095 μm and the value increases to the bottom zone with ra of 3.170 μm. similarly, the cutting speed of 2000 mm/min shows the smaller ra at top zone with value of 2.170 μm when compared to the middle zone (3.170 μm) and bottom zone (3.555 μm). it indicates that the ra is higher in a 69 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) deeper cutting zone in all cutting speeds. on the other hand, the increase in ra also occurs when the cutting speed increases. it can be concluded that both cutting speed and location determine the ra value of the cutting surface. to simplify the data presentation, figure 2 shows the relationship between cutting speed and ra in different locations. fig. 2. relationship between cutting speed and surface roughness (ra) in different locations. the main finding in this study is an increase in average surface roughness (ra) (top, middle, and bottom) along with the increase in cutting speed, as shown in table 1, compared to previous studies. the previous research reported that the minimum surface roughness is found at the highest cutting speed of 200 mm/min which is contradictive with the results of the current study. it may because the different characteristics between n laser and co2 laser. moreover, the current study can provide a more complex illustration in the effect of location representing the depth of laser exposure [5]. according to tosun et al. [11] and alsoufi et al. [13], the top zone is called smooth zone while middle and bottom zone are called transition and rough zone. the top zone is dominated by better cutting mechanisms because the process of absorption, melting, and vaporization occurs smoothly and quickly. turning to the middle zone of laser penetration for absorption begins to be disrupted. as a result, remelting takes more time while the nozzle immediately rushes to move due to an increase in cutting speed. thus, it causes a decrease in the quality received in the ra of the middle zone. it finally gets worse when moving to the bottom zone. the chance of absorption received by the bottom zone is getting smaller and the cutting process relies on the remaining laser penetration received in the middle zone. at the bottom zone the possible mechanism characterizing the cutting surface is only deformation [11], [13]. this deformation certainly causes the width between kerf lines to be larger when compared to the middle zone, moreover with the top zone [7]. the phenomenon can also be explained from temperature point-of-view. the heat input received by the top surface is theoretically higher than the that at the bottom one inducing a decrease in temperature at the deeper region. the decrease is due to a decrease in laser energy received by the bottom one due to the absorption by the upper material region. the heat transfer process that occurs during cutting is convection. this heat transfer occurs when the melting process forming a pool and penetrates downward (driven by laser power and gravity). materials in middle zone will melt when the material receives heat due to the issn: 2580-0817 journal of mechanical engineering science and technology 70 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) expansion channeled from the top zone. considering this phenomenon, laser energy is more difficult to penetrate to the bottom zone. the insufficient heat distribution reduce the cutting ability resulting in the enhancement of surface roughness at the deeper zone [14]. the results also implies that the reduction in the volume occurs during material disposal mechanism when the cutting speed increases. by enhancing the cutting speed, the heat received by a unit area of material is reduced due to the shorter time of laser exposure. the decrease in heat reduces formed melting pool [15]. the decrease is well caused by the extensive shear deformation and cutting force generating faster cutting and shortening the kerf width [3]. thus, the narrower kerf width generates the larger kerf lines in a constant area inducing rough contour and finally measured as a high ra [7]. the surface roughness results can be a meaningful recommendation for manufacturing industry, such as train company to produce their components (roof, sidewall, end wall, underframe, and bogie) through laser cutting. 2. kerf surface the kerf surface evaluation was done as supplementary evidence in explaining the surface roughness evolution. microscopic observation by sem is able to show further the surface texture in an obvious way. figure 3 shows the kerf surfaces produced by different laser cutting speed in different locations. fig. 3. sem images showing kerf surfaces of cutting zone generated by the cutting speed of 1400 mm/min at (a) top, (d) middle, (g) bottom; 1700 mm/min at (b) top, (e) middle, (h) bottom zone; and 2000 mm/min at (c) top (f) middle (i) bottom zone. 71 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) from figure 3, it implies that by using nitrogen laser cutting, the enlargement of distances between kerf lines is obvious in all zones (top, middle, and bottom) as the response of cutting speed enhancement. on the other hand, by considering the cutting depth, the distance becomes significantly larger when the observation is conducted at a deeper location. this result is relevant with the previous research on al 6061-t6 and 7075-t6 cutting using abrasive water jet, where the surface roughness was increased because of cutting speed rise. moreover, the kerf surface quality at the top zone is far better than the bottom one resulting the lower surface roughness [11]. top zones as shown in figure 4 (a), (b), and (c) are called cutting zones. from figure 4, the increase of cutting speed causes the distance between kerf lines to increase from 70.309; 84.014; and 97.743 μm. the increase of width between kerf lines at the top zone is due to a decrease in heat exposure per area as the cutting speed increases [16]. the laser absorbed material in the top zone becomes unbalanced due to an increase in cutting speed. increased cutting speed has the effect of increasing cutting force which consequently has an impact on the rise of shear deformation in the cutting zone [3]. the kerf line formed is dominated by fluctuations and oscillations that cause vertical direction due to laminar flow, but still experience tilt due to drag force as cutting speed increases [17]. the increase in cutting speed also induce the increase of the kerf line slope [16]. turning to the middle zone as presented in figure 4 (d), (e), and (f), it appears that as the cutting speed increases in this zone there is also a significant change compared to the top zone. the formed kerf line began to disappear, in line with the theory called the transition zone [11]. the decrease in the number of kerf lines is caused by a decrease in energy during the cutting process. the decrease in energy results in the decreasing of areas of melting, fluctuation, and oscillations to focus on forming the same kerf line as the top zone [18]. this is evidenced by the flow change occurring in the middle zone from laminar (top zone) to turbulent (bottom zone) [11]. increasing cutting speed causes both a decrease in energy and an increase in cutting force causing the width enlargement between kerf lines. moreover, the kerf valley surface is decreasing as well [19]. the gas pressure ability to evaporate the melt pool drops because the rise of cutting speed limits of the time span of melting and evaporation state [18]. subsequent exposures to the bottom zone as depicted in figure 4 (g), (h), and (i) indicates that the kerf surface pattern formed resembles a deformation mark and has been in accordance with the theory called the deformation zone [11]. the increase in the depth of the cutting zone using laser cutting causes more dominant in deformation mechanism. the increase in deformation is caused by a decrease in heat energy limiting the laser penetration to the bottom zone [20]. this results in less laser energy reaching the bottom zone after energy absorption by upper material zone [21]. this deformation certainly causes the width between kerf lines to be enlarged compared to the middle one and moreover with the top zone [7] [19]. this is also influenced by the less ability of gas pressure to evaporate the material as cutting speed increases [18]. 3. dross height the amount of dross height data obtained from the test results using the sem test is divided into the first and second points of each sample. the dross height measurement results are presented in figure 4 and table 2. issn: 2580-0817 journal of mechanical engineering science and technology 72 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) fig. 4. (a) illustration of dross height geometry for measurement and sem images of dross height generated by the cutting speed of (b) 1400, (c) 1700, and (d) 2000 mm/min table 2. dross height measurement results as the function of cutting speed. cutting speed (mm/min) dross height (µm) average dross height (µm) first point second point 1400 36.43 29.06 32.74 ± 3.68 1700 23.25 20.41 21.83 ± 1.42 2000 10.28 9.45 9.86 ± 0.41 based on table 2 and figure 4, the results show that the average dross height increases as the higher cutting speed is applied. the cutting speed of 1400 mm/min results in the highest dross height with an average of 32.74 ± 3.68 μm while the dross height at a cutting speed of 1700 mm/min averages at 21.83 ± 1.42 μm. on the other hand, the cutting speed of 2000 mm/min produces the lowest dross height with an average of 9.86 ± 0.41 μm. to simplify the information, the effect of cutting speed on dross height is presented visually in figure 5. based on figure 5, it can be seen that the dross height data is divided into three cutting speed values. dross height with the highest value of 36.43 μm at a cutting speed of 1400 mm/min and the lowest value of 9.45 μm at a cutting speed of 2000 mm/min. there is a decrease in dross height when increasing cutting speed. this can be the effect of cutting speed inducing a lower ability to melt the cutting zone [22], [9]. the heat input of the laser in the cutting zone decreases as the cutting speed enhancement [18]. the loss of heat input affects the formation of melting area volume and fluidity [1]. heat inputs generally increase at a lower cutting speed, and it decreases at higher cutting speeds. the greater the volume of melting formed, the more difficult it is to be completely evaporated [18]. based on this outcomes, it is also confirmed by the kerf width formed as the kerf width decreased as the enhancement of cutting speed [19]. 73 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) fig. 5. average dross height value as a function of laser cutting speed. the formation of dross also depends on the viscosity, density, and surface tension of the workpiece material. in addition, it also relates to the flow type occurring during cutting where laminar flow takes place at the top zone while turbulent flow locates at the end of the bottom zone. during the cutting process, lower cutting speeds are shown to result in higher material removal. this is because the laser light absorbed by the material stays longer at lower cutting speeds. along the melting process with low cutting speed, the amount (volume) melting becomes greater than those at the high cutting speed which affects viscosity and fluidity. therefore, the melt carried out by gas pressure and surface tension material (melting) is lower because of the limited capabilities. the gas pressure not only evaporates the melt, but also generates the shear stress pushing melting area enlargement until the end of specimen bottom zone. when the greater melt pool is formed, the turbulent flow of gas results in ineffective and insufficient vaporization. thus, the melt solidification is entrapped within the bottom zone as the formation of solidified metal drops. that is why the dross height is higher at low cutting speed than higher cutting speed [18]. the results of this dross height research can be a reference for many automotive manufacturing industries, one of which is the train manufacturing industry. when the sidewall components of the railway train cut by laser cutting requires a low dross height (high quality cutting), a high cutting speed can be selected. it should be underlined that the height of the dross is important to note because it is a consideration for component assembly with other components. the higher the dross height value, the more disruptive the assembly of railway train sidewall components, thus sacrificing the precision of the products. therefore, it can be concluded that the higher the dross height, the effort of mechanical finishing by grinding process is needed and this consequently increase the cost and time for the train production. iv. conclusions the cutting speed study on the surface texture (surface roughness, kerf surface, and dross height) of sus 304 on the by nitrogen laser cutting has been successfully conducted. the use of higher cutting speed induced the increase of ra and the increase is severe at the bottom zone compared to those at the top one. the highest average ra value was 2.965 ± issn: 2580-0817 journal of mechanical engineering science and technology 74 vol. 7, no. 1, july 2023, pp. 66-75 pradana et al. (the effect of cutting speed of nitrogen laser cutting on the surface texture of sus 304) 0.05 μm at a cutting speed of 2000 mm/min and the lowest was 2.522 ± 0.16 μm at a cutting speed of 1400 mm/min. the ra highest bottom zone value is 3.555 μm at a cutting speed of 2000 mm/min and the lowest is 1.815 μm at a cutting speed of 1400 mm/min. on the other hand, the rise in cutting speed caused the distance between kerf lines to be widened. higher cutting speed indicated a lower heat energy and larger cutting force increasing shear deformation at the cutting zone. this characterized the formation of kerf surface from the top zone to the bottom zone. the top zone was dominated by the cutting zone while the middle and bottom zone were mainly dominated by the transition and deformation zone respectively. finally, increasing cutting speed also resulted in the decrease of dross height. the average value of dross height is highest 32.74 ± 3.68 μm obtained at cutting speed 1400 mm/min and lowest 9.86 ± 0.41 μm at cutting speed 2000 mm/min. references [1] c. wandera and v. kujanpää, “optimization of parameters for fibre laser cutting of a 10 mm stainless steel plate,” proc. inst. mech. eng. part b j. eng. manuf., vol. 225, no. 5, pp. 641–649, 2011, doi: 10.1177/2041297510394078. 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[22] e. haddadi, m. moradi, a. karimzad ghavidel, a. karimzad ghavidel, and s. meiabadi, “experimental and parametric evaluation of cut quality characteristics in co2 laser cutting of polystyrene,” optik (stuttg)., vol. 184, no. february, pp. 103–114, 2019, doi: 10.1016/j.ijleo.2019.03.040. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 28-38 28 doi: 10.17977/um016v7i12023p028 the combustion characteristics of calophyllum inophyllum fuel in the presence of magnetic field imam rudi sugara*, nasrul ilminnafik, salahuddin junus, muh nurkoyim kustanto, yuni hermawan department of mechanical engineering, university of jember, jl. kalimantan, jember, jawa timur, 68121, indonesia *corresponding author: nasrul.teknik@unej.ac.id article history: received: 9 january 2023 / received in revised form: 14 march 2023 / accepted: 27 march 2023 available online 11 may 2023 abstract the study objective is to investigate the combustion characteristics of callophyllum inophyllum fuel in presence of a magnetic fields. to conduct the experiment, a bunsen burner was utilized, with fuel and air being dispensed via a syringe pump and compressor, both regulated by a flowmeter. the fuel and air pipes were heated to 532.15 (k) to facilitate fuel evaporation. the equivalent ratio of 0.5, 1, and 1.5 was adjusted to control air discharge and fuel. an 11,000 gausses artificial magnet was used, with n-s, n-s, n-n, and ss being the various magnetic pole configurations. the study found that the magnetic field can enhance combustion quality by affecting the molecules involved in the combustion process. the magnetic field's force also intensifies the movement of o2, making it more energetic. as o2 travels from the north pole to the south pole through the combustion reaction zone, it quickens the oxidation-reduction process and curtails diffusion combustion. the red color's intensity diminishes with the magnetic field's effect, indicating this phenomenon. when a magnetic field is applied, the polarity of c.inophyllum biodiesel fuel becomes highly favorable. the triglyceride carbon chain bonds become unstable, and the van der walls dispersion forces are weakened, which facilitates easier o2 binding to the fuel, resulting in more efficient combustion. an increase in the laminar burning velocity value can be noticed when exposed to a magnetic field. copyright © 2023. journal of mechanical engineering science and technology. keywords: biodiesel, laminar burning velocity, magnetic field, premixed flame, rgb color i. introduction one of the problems facing the world today is the depletion of petroleum reserves and environmental pollution which has an impact on global warming. the industrial sector is heavily dependent on fossil energy, especially diesel fuel, which is mostly used in trains, ships, power plants, buses, trucks, and an increasing number of cars. several researchers have developed alternative energy as a substitute for fossil energy which is more environmentally friendly and has lower production costs. the second generation of biodiesel is a step forward in the development of sustainable fuels and does not conflict with food raw materials [1], [2]. the use of biodiesel in diesel engines produces lower carbon dioxide, hydrocarbon, and carbon monoxide emissions than fossil fuels [3], [4]. some of the raw materials that have been developed as second-generation biodiesel are crude jatropha curcas oil, crude sterculia foetida oil, crude ceiba pentandra oil, and crude c. inophyllum oil [5]. the plant of c. inophyllum, that grows abundantly in unproductive land and tropical/sub-tropical climates [6], has the potential to become an excellent material of mailto:nasrul.teknik@unej.ac.id 29 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) biodiesel production. the seeds contains a significant oil yield by 65.8%, surpassing even palm oil and jatropha, which typically yield only 40-60% [7]. promising results have emerged from tests conducted on engine performance and emissions using c. inophyllum biodiesel. researchers discovered that blending 10% c. inophyllum biodiesel with diesel oil augmented brake thermal efficiency by 2.3% and reduced fuel consumption by 3.06% compared to pure diesel oil [8]. furthermore, replacing pure diesel oil with a combination of diesel oil and c. inophyllum can result in decreased opacity of co and reduced production of smoke [9]. c. inophyllum biodiesel still has some drawbacks such as higher viscosity, density, and flash point when compared to diesel fuel [10]–[13]. when fuel viscosity is high, carbon buildup occurs on critical engine components such as the fuel filter, injectors, and piston ring[14]. additionally, high viscosity negatively impacts injector spray atomization, while also impeding the formation of a fuel-air mixture by slowing down evaporation [12]. moreover, fuel density plays a role in its combustibility, and high-density fuel is harder to burn, leading to reduced heat generation [15]. meanwhile, a higher flash point causes the fuel to require a longer burning time. fuel quality can also affect the ignition delay time which affects engine performance and the resulting emissions [16]. ignition delay is a condition where the first drop of fuel enters the combustion chamber until the slightest flash point is seen. ignition delay itself is affected by engine speed, load, and fuel temperature. the combustion process occurs with the presence of physical and chemical processes [17]. physical delivery delays are affected by the automation of fuel spray, evaporation, and fuelair mixing. meanwhile, chemically it is affected by fuel decomposition, aggregation, and oxidation-reduction processes. in addition, c. inophyllum biodiesel contains o2, which causes c. inophyllum biodiesel to produce higher nox emissions [9], [18]. several researchers have attempted to improve the combustion quality of c. inophyllum biodiesel fuel, including the addition of additives [19], mixing with fossil fuels [18], and the provision of a magnetic field in the fuel line [20]. by adding a catalyst to biodiesel, it can weaken the triglyceride atomic bonds, resulting in more efficient combustion [21]. the degree of polarity of the fuel can also affect the instability of the hydrocarbon chain bonds [22]. studies have shown that the magnetic field application into fuel pipes enhance combustion quality as well as minimize pollution [23]. magnetic field causes fuel ionization, making it easier to bind with oxygen molecules and burn efficiently [24]. one experiment saw the installation of 3000 gauss neodymium permanent magnets on fuel pipes, resulting in a 7% increase in efficiency, a 13% reduction in co2, and a 19% decrease in nox emissions [25]. this is due to the magnets' ability to alter fuel properties, aligning and orienting hydrocarbons for improved atomization [25]. the strength of the magnet used has a direct impact on reducing emissions and fuel consumption [26]. using a magnetic field as a means of improving engine performance is a highly efficient and cost-effective method. with its simple construction and easy-to-obtain raw materials, the initial installation cost is the only expense. however, while research on internal combustion engines typically focuses on performance and emissions, more in-depth analysis of flame behavior is necessary to truly optimize engine function. as such, the study sought to investigate the influence of a magnetic field on premixed flames when using c. inophyllum biodiesel fuel. to achieve optimal flame characteristics, various magnetic field pole variations (n-s, s-n, n-n, s-s) and equivalent ratio variations (0.5, 1, 1.5) were employed. issn: 2580-0817 journal of mechanical engineering science and technology 30 vol. 7, no. 1, july 2023, pp.28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) ii. material and methods 1. the production of c. inophyllum biodiesel the process of producing crude oil from c. inophyllum seeds involves crushing them into granules and then extracting the oil using a screw press. methanol, h3po4, h2so4, and distilled water are utilized to create biodiesel. the jember university energy conversion laboratory is where the process of making c. inophyllum biodiesel occurs. the combustion process can be disrupted by impurities and high ffa levels present in crude oil. hence, the transformation of crude oil into methyl ester requires the use of several processes such as degumming, esterification, and transesterification are required to get methyl ester from crude oil [27], [28]. the degumming process eliminates impurities and latex from crude oil, achieved by adding a 1% volume of h3po4 to c. inophyllum oil, and stirring it for 30 minutes at 60c. after stirring, it is left to stand for 4 hours. the esterification process is then employed to decrease the ffa levels in c.inophyllum oil. this is achieved by adding a 1% volume of h2so4 to the oil, followed by methanol at a ratio of 1:22 mol. the mixture is stirred for 2 hours at 60c before being left to stand for 8 hours for separation. the final step is transesterification, where fatty acids are converted to methyl esters. for this process, a 1% weight of naoh is added to c.inophyllum oil, followed by methanol at a ratio of 1 to 6 mol. the mixture is stirred for 3 hours using a magnetic stirrer. 2. composition of biodiesel c. inophyllum in order to analyze the fatty acid makeup of pure c. inophyllum biodiesel (b100), a gas chromatography mass spectrometry (gcms) test was carried out. table 1 illustrates the percentage composition of the biodiesel b100 molecules, which revealed that methyl oleate comprised the majority of the biodiesel b100 compound at 45.82%. this notable presence of methyl oleate is significant as it contributes to the improvement of low-temperature performance and also has a positive impact on the oxidation stability of biodiesel [29]. the methyl oleate content in this study was higher than the 38.108% castor oil biodiesel content [30] and palm oil 42.72% [31]. this shows that biodiesel b100 has good quality to be developed further. of all the chemical compounds contained in biodiesel, the stoichiometric combustion reaction can be seen as shown in equation (1). after obtaining the combustion reaction of chemical compounds, the stoichiometry afr of biodiesel b100 13.2 can be determined using equation (2). in contrast, diesel fuel has a higher afr of 14.59. this is because biodiesel compounds contain o2 compounds, so biodiesel requires less air in combustion while diesel fuel compounds do not contain o2. combustion reaction: 0.4582c19h36o2 + 0.4377c17h36o2 + 0.0297c15h30o2 + 0.0271c21h42o2 + 0.0225c19h34o2 + 0.0144c21h34o2 + 0.0062c13h26o2 + 0.0041c18h36o2 + 27.00685(o2 + 3.76n2) 18.0456co2 + 17.9225h2o + 101.545568n2 ........................................................... (1) afr stoichiometry = air mass fuel mass .......................................................................... (2) = 27.00685(o2+3,76n2) / 0.4582c19h36o2 + 0.4377c17h36o2 + 0.0297c15h30o2 + 0.0271c21h42o2 + 0.0225c19h34o2 + 0.0144c21h34o2 + 0.0062c13h26o2 + 0.0041c18h36o2 = 3,707.493504 / 280.75 = 13.2 mol 31 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) table 1. c. inophyllum biodiesel fatty acid composition no trivial name molecule formula volume (%) 1 methyl oleate c19h36o2 45.82 2 methyl palmitate c17h36o2 43.77 3 methyl myristate c15h30o2 2.97 4 methyl arachistate c21h42o2 2.71 5 methyl linoleate c19h34o2 2.25 6 methyl arachidonate c21h34o2 1.44 7 methyl laurate c13h26o2 0.62 8 methyl margarate c18h36o2 0.41 3. flame testing scheme figure 1 shows the scheme of the bunsen burner used to test the characteristics of the flame under the influence of a magnetic field. bunsen burners use stainless steel with an inner diameter of 0.6 cm and a y-junction geometry. the fuel is dispensed via syringe pump while the air discharge is managed by a compressor, regulated with a flow meter. a belt heater, operating at a temperature of 532.15 (k), evaporates the fuel in the pipe. to stabilize the temperature in the mixing chamber, the air is also heated to 532.15 (k). fuel and air debits are carefully controlled to maintain equivalent ratios of 0.5, 1, and 1.5. an artificial magnetic field with a strength of 11000 gausses is applied on both sides of the flame, with pole variations of n-s, s-n, n-n, and s-s, and a distance of 0.3 cm. a high-definition camera with 1080 and 64 megapixels specifications is positioned with a distance of 18 cm, parallel to the burner. video footage is captured in three trials for each variation, later converted to images using the software of dvdvideosoft free studio. fig. 1. bunsen burner research tool schematic 4. data analysis method data analysis of the laminar burning velocity and intensity of rgb color was conducted based on visual flame data. the rgb color analysis focused on the red color intensity, which is considered a diffusely burning fuel, and measured its level using the image-j program. the results, shown in figure 2a, were obtained through a series of steps, which included issn: 2580-0817 journal of mechanical engineering science and technology 32 vol. 7, no. 1, july 2023, pp.28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) opening the file, clicking on plugins, and analyzing the rgb measure. flame angle measurements were also carried out using the image-j program, as shown in figure 2b, on premixed flames. a. b. fig. 2. data analysis (a). intensity of rgb color, (b). flame angle equation (3) is essential to determine the reactant velocity at every equivalent ratio for computing the laminar burning velocity. once the reactant speed and flame angle are obtained, equation (4) can be applied to determine the laminar burning velocity. uo = qfuel+qair ab ……………………………………………………..(3) with: uo = reactants speed (cm³/s) 𝑄f𝑢𝑒l = fuel discharge (cm³/s) 𝑄a𝑖𝑟 = air discharge (cm³/s) sl = v. 1 2 sin α ………………………………………………………(4) with: sl = laminar burning velocity (cm/s); v = reactants velocity (cm/s); 1 2 sin α = half flame angle. iii. results and discussion 1. flame color intensity analysis in figure 3, the effect of magnetic field variations (n-s, s-n, n-n, and s-s) on the flame's visualization is depicted. the flame comprises two reaction zones: an internal premixed flame that converts fuel to co and h2, and an external diffuse flame that further oxidizes co and h2 to produce combustion [32]. the flame's structure varies at equivalent ratios of 0.5, 1, and 1.5, with the equivalent ratio having a significant influence on whether the combustion process succeeds or fails [15]. an equivalent ratio of 1.5 indicates a higher flame structure and some diffusion combustion at the tip of the flame. this happens because a less-than-ideal mixture of air and fuel tends to be richer in fuel so that some of the fuel is not premixed. at an equivalent ratio of 0.5, the flame structure is shorter due to the more air mixture and the less fuel mixture. whereas an ideal mixture of air and fuel close to stoichiometry will produce the most optimal combustion. α 33 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) fig. 3. b100 flame evolution, (a) ratio equivalent 0.5, (b) ratio equivalent 1, (c) ratio equivalent 1.5 the graph in figure 4 displays the red color intensity on b100 biodiesel flames. magnetic field variations from the s-s, n-n, s-n, and n-s poles sequentially decrease the red color intensity, with the most significant impact occurring at the n-s pole at 36.29 with an equivalent ratio of φ=0.5. in contrast, the non-magnetic flame shows the highest red intensity value, indicating that the magnetic field can impact molecules involved in the combustion reaction. molecular orbital theory suggests that o2 is paramagnetic due to its two unpaired free electrons, which the magnetic field can affect. as the magnetic field force leads from n to s poles, o2 outside the flame can experience attraction and repulsion between poles, allowing it to oxidize unburned fuel and minimize diffusion combustion. fig. 4. the intensity of the red color in b100 fuel 2. laminar burning velocity analysis researchers can gauge the quality of combustion by examining flame formation and laminar burning velocity. to this end, various parameters are used, including the latter [33]. in figure 5, the laminar burning velocity of b100 fuel is depicted with changes in equivalent 5 0 .5 4 8 4 2 .4 7 3 8 .0 7 3 6 .2 9 6 2 .5 1 5 0 .3 2 5 7 .2 1 5 0 .0 3 4 5 .7 7 7 0 .3 1 6 8 .7 9 6 5 .2 6 0 .3 4 5 8 .2 1 b 1 0 0 n o n m a g n e t b 1 0 0 s s b 1 0 0 n n b 1 0 0 s n b 1 0 0 n s r e d c o lo r i n t e n s it y 0,5 1 1,5 issn: 2580-0817 journal of mechanical engineering science and technology 34 vol. 7, no. 1, july 2023, pp.28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) ratio and magnetic field. the results indicate that the velocity increases under magnetic influence, regardless of the magnetic poles' variations. the most significant improvement occurred with n-s poles at 24 cm/s and equivalent ratio φ=1, followed by s-n at 22 cm/s, n-n at 16.17 cm/s, s-s at 15.68 cm/s, and non-magnetic at 14.7 cm/s. earlier research has also shown that the magnetic field plays a pivotal role in enhancing combustion quality [23], [25], [34], [35]. under the influence of the magnetic field, hydrocarbons undergo a transition from the para-state to the ortho-state, changing their orientation [20]. the carbon chain of triglycerides is primarily composed of carbon (c) and hydrogen (h) atoms. h atoms exist in two isomeric forms: para, predominant in fuels, and ortho, achieved by magnetic field application. these forms differ in the rotation of opposite nuclei. in the para molecule, h has an anti-parallel rotation, and the spin states of the atoms are in opposite directions, making them diamagnetic. conversely, in the ortho molecule, h has parallel degrees of rotation, and the spin states of atoms are in the same direction, making them paramagnetic [36]. by passing through a magnetic field, fuel molecules' orientation is altered from the para to the ortho state, resulting in a significant decrease in the intermolecular forces of the triglyceride and an increase in h atom spacing. as the hydrocarbons and o2 bond more strongly, combustion becomes increasingly efficient. research conducted by nanlohy et al., [21] stated that the addition of a catalyst to biodiesel of jatropha oil created polarization interactions that the molecular bonds of the triglyceride chain were weakened, allowing for easier rotation of bonds. this resulted in increased electron movement and energy, leading to heightened reactivity and efficient fuel combustion. according to nanlohy et al, [22] the composition of molecular mass and hydrocarbon chain bond instability are critical factors in the combustion process, with the polar properties of c. inophyllum biodiesel playing a significant role. magnetic fields are also important in this process. in the n-s magnetic field, the triglyceride chain bonds get a force of attraction from the magnetic field. this causes a weak van der waals dispersion force that it will make it easier for o2 to bind and the combustion becomes more optimal. fig. 5. laminar burning velocity (sl) fuel b100 the magnetic field's impact on the combustion process is depicted in figure 6. the sn magnetic field influences o2 movement, pulling it from the north pole to south pole and into a combustion reaction zone. conversely, h2o exhibits diamagnetic properties that propel it in the opposite direction, from the south pole towards north pole, and out of the 1 3 .5 1 4 .7 8 .9 8 1 4 .7 5 1 5 .6 8 9 .7 9 1 6 .5 1 6 .1 7 1 0 .2 2 1 2 2 1 4 .2 8 2 3 2 4 1 5 .5 1 0 , 5 1 1 , 5 s l (c m /s ) equivalent ratio φ b100 non magnet b100 s-s b100 n-n b100 s-n b100 n-s 35 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 28-38 sugara et al. (the effect of a magnetic field on the combustion characteristics of c.inophyllum fuel) flame. this distinctive behaviour results in a more proficient combustion process. the n-s pole proves more powerful, as its direction aligns with the earth's magnetic field during data collection. at n-n poles, the magnetic field pushes o2 towards the combustion reaction zone from both sides of the magnet, while drawing h2o out of the flame. conversely, the s-s pole's direction attracts o2 from the flame and pushes h2o into it as a heat source. this phenomenon does not significantly impact the combustion reaction. fig. 6. illustration of a flame influenced by magnetic field iv. conclusion an investigation was carried out into the impact of magnetic fields on premixed c.inophyllum fuel combustion. the results indicated that magnetic fields can influence molecular activity central to the combustion process. the force of the magnetic field causes increased energetic movement of o2, which travels from n to s poles through the combustion reaction zone. this, in turn, accelerates the oxidation-reduction process and reduces diffusion fires, as evidenced by the reduction in the red color intensity. additionally, the degree of polarity of c. inophyllum biodiesel fuel is enhanced by the influence of a magnetic field. this causes the triglyceride carbon chain bonds to become unstable, weakening van der walls dispersion forces and making it easier for o2 to bind to the fuel, ultimately improving combustion efficiency. this is supported by the increased laminar burning velocity observed as impact of a magnetic field. reference [1] a. e. atabani, a.s. silitonga, h.c. ong, t.m.i. mahlia, h.h. masjuki, i. a. badruddin, and h. fayaz., “non-edible vegetable oils: a critical evaluation of oil extraction, fatty acid compositions, biodiesel production, characteristics, engine performance and emissions production,” renew. sustain. energy rev., vol. 18, pp. 211–245, 2013, doi: 10.1016/j.rser.2012.10.013. 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[36] f. a. el fatih and g. m. saber, “effect of fuel magnetism on engine performance and emissions,” aust. j. basic appl. sci., vol. 4, no. 12, pp. 6354–6358, 2010. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 47-58 47 doi: 10.17977/um016v7i12023p047 lap joint on st.37 steel plate with friction welding clamping method widia setiawan1*, nugroho santoso1, wiyadi1, muhammad sulistiyo aji1, rachmat alamin1, achsan tarmudi2 1department of mechanical engineering, vocational college, gadjah mada university, bulaksumur, yogyakarta, indonesia. 2akademi perindustrian (akprind), kalisahak, yogyakarta, indonesia *corresponding author: widia_s@ugm.ac.id article history: received: 3 january 2023 / received in revised form: 27 march 2023 / accepted: 4 may 2023 available online 8 june 2023 abstract friction stir (fw) welding is a relatively fresh method that was created and has been continually refined and adapted to industrial applications due to its benefits. this approach for solid-state joining entails connecting the components at a temperature below their melting point and then heating them up. clamp joint applications are widely used using external heating and hitting with high strength, but the clamped joints with the fw method are rarely done. the research studied the characteristic of clamped joints at various plate thicknesses using the fw method. in this study, 30 specimens were used in the form of a st.37 low carbon steel plate with a size of 50 mm x 100 mm and a thickness of 3 mm, 5 mm, and 9 mm, and several holes were made with a diameter of 5 mm. the plate was connected by 2 clamps, and 4 clamps then the fw method was conducted in a milling machine. the results indicate that the plates were connected well. the highest hardness value was 256.4 vhn on the fw of 9 mm plate. the microstructure is dominated by ferrite and a little pearlite phase. the largest shear force is 66.54 kn obtained at 4 clamps with a plate thickness of 9 mm, and the lowest is 13.46 kn, obtained at 2 clamps with a plate thickness of 3 mm. copyright © 2023. journal of mechanical engineering science and technology. keywords: carbon steel, clamping, friction welding, microhardness, microstructure, shear force i. introduction the latest advancements and fundamental mechanisms of a variety of mechanical (formand force-closed) and metallurgical joining techniques have been presented and explored. it may be assumed that fundamental information is generally available, particularly in mechanical joining, which is frequently used in industrial applications [1]. the welding institute introduced friction welding (fw) as a novel welding technique in 1991 to develop a solid-state joining approach. this approach for solid-state joining involves attaching the components at a temperature below their melting point. to produce welded components with fewer residual stresses, defects, and distortion, issues with porosity, the creation of second phases, embrittlement, and cracking connected to the melting phase of the materials can be discussed. the fw approach has lately been widely applied in a variety of sectors, including aircraft, railroads, and automobiles [2]. fw utilizes atom movement in two directions toward the ductile iron-stainless steel interaction [3]. the addition of carbon atoms to stainless steel and chromium and nickel atoms to ductile iron. carbon enrichment in stainless steel causes the development of 48 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) chromium carbides, which are usually found along the grain boundaries. the addition of iron to cr and ni resulted in the formation of the alloy ferrite. during steady-state, the temperature in this area may be described thus that the heat generated by metal friction is [4]. the fw method is the welding joint that occurs in the solid phase, and then the joint process is divided into 4 phases, including: 1. the phase before connection; 2. the first contact phase, light load, and oscillation occur; 3. the axial phase is a full load, and oscillation occurs; 4. axial compression phase (a process of connection). inertia fw has been used for more than 30 years for joint problems using mechanical technology machines. heat is obtained from the rotation of the engine spindle, and the connection occurs due to the process of compressive force in the axial direction [5]. fw is a solid-state joining process that produces coalescence in materials, using the heat generated between surfaces through the combination of a mechanically induced rubbing motion and the applied load [6]. fw has a very strong bond because the fully bonded region is highly dependent on the pin geometry and the rotational speed of the machine [7]. described in detail as well as difficulties in intermetallic layers, welding processes, and interfacial stresses [8]. according to the fluctuation of axial force, the whole friction taper plug welding (ftpw) process consists of four stages: axial feeding, pressing, welding, and forging. the hole-filling process occurs mostly during the welding phase when burn-off is common. the welding duration, burn-off rate, and torque would be affected by changes in rotation speed and welding force [9]. at the conclusion of the welding joint, several furrow-shaped holes arise in the welding interface, and a smooth line appears in the center welding interface, resulting in a nice welding seam [10]. for example, the ultimate tensile strength measurements in all situations were more than the minimum value of 1000 mpa prescribed by the aerospace material specification for the base material in sta condition [11]. the rotational speed, pressure, and materials all impact the joint's mechanical strength. it might progressively develop as the parameter values improve [12],[13]. the clamped joints using the fw method are rarely done. this research aims to determine the characteristic of clamped joints at various plate thicknesses using the fw method. the thickness of the plate to be joined is 3 mm, 5 mm, and 9 mm, using 2 and 4 methods of fw clamping. macro photos, temperature measurements, micro photos, microhardness, and tensile strength of the joints will be evaluated. ii. material and methods 1. material the plates used for this study were low-carbon steel st.37 sheets with a length of 100 mm, a width of 50 mm, and a thickness of 3, 5, and 9 mm. for clamps, welding was used low carbon steel st.37 cylindrical, made in diameter of 4 mm, and a length of 7 mm. the joint was designed with milling cnc at 2000 rpm. issn: 2580-0817 journal of mechanical engineering science and technology 49 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) 2. methods 2.1. preparation before the clamping process, the low-carbon steel was cut to 200 mm for each plate and punched with an m6 hole at a distance of 25 cm from the edge for the top and bottom. meanwhile, the center of the plate was punched at a distance of 25 mm. for the detail, we illustrate it in figure 1. the top and bottom plates served as reinforcement, while the joining material was in the center. the clamping material was inserted into the hole for the fw process. (a) (b) fig. 1. the process of fw joint: a) two clamping methods; and b) four clamping methods. 2.2. friction welding process the fw process is shown in figure 2. it used a rotate fw method in a milling machine. the milling machine was switched on, and the top clamp was rotated in counter clock way at 2000 rpm while the bottom clamping was in state condition. the interface rubs against each other, and it took a few seconds to produce heat. then, the temperature will increase to reach a peak. after reaching the plastic condition, the milling machine was turned off. the upper clamp was pressed on the lower clamp, which was in line with a mechanical bond. this was done for the connection of 2 clamps or 4 clamps. it is expected that the results of the fw process are shown in figure 3, to consider the appearance and improve the mechanical strength. fig. 2. clamping used by the fw method. 50 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) (a) (b) fig. 3. fw joint design: a) two clamping methods, and b) four clamping methods 2.3. photo macro analysis the photo macro was used to describe how fw affects the deformation and shape change of the clamp joints. we used heatmap and plotting figures to highlight the areas with defects, especially in the clamp joint area. 2.4. temperature analysis the heat input must be considered to obtain a high connection strength in the process. heat input was detected using a thermocouple in three positions: top, center, and bottom of the clamp. after the temperature value was obtained, a graph was made to show the temperature changes that occur at each fw time. 2.5. microstructure analysis microstructure analysis was used to evaluate the phase after the fw method. microstructure photo observed under a metallurgical microscope with a magnification of 100 times to identify the resulting steel phase and comparison the weld, thermomechanically impacted zone (tmaz), and heat-affected zone (haz) area. 2.6. microhardness analysis vickers microhardness was measured at the clamps along a line. microhardness was determined by applying a load of 500 g for 10 seconds at a distance of 20 mm among indentations. six indentations were made on the same surface side of each specimen at various places, with a minimum interval of 1 mm between any two indentations. 2.7. shear stress analysis loading was done in the opposite direction of the interface plane. the shear and crosstension tests were performed in line with iso 14273. the tests were performed on a universal testing machine weighing 2000 kg and with a set cross-head speed of 10 mm/min. shear stress in the entire specimen may be calculated by averaging the strengths of three specimens. iii. results and discussions 1. macrostructure figure 4 shows the results of the joint with the fw clamping method. it is clear the success of this joint for plate thickness of 3 mm, 5 mm, and 9 mm, also for 2 clamps or 4 clamps. clamps that are deformed and show open and widened intersections should be avoided to achieve optimum connection strength. on the 3 mm thick plate, deformation occurs in the middle of the clamp. this is due to the meeting of the clamping nail in the top issn: 2580-0817 journal of mechanical engineering science and technology 51 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) position and the bottom position, not on the center point. several factors affect the deformation of the joint, one of which is the thickness of the joint [14]. the thickness affects the material to withstand a force from outside the material. in this study, the 3 mm plate's ability to withstand loads on plates with a thickness of 3 mm is not strong enough and causes deformation. fig. 4. a) joint of 2 clamps at 3 mm thick, b) joint of 4 clamps thick 3 mm, c) joints 2 clamps plate thickness 5 mm, d) joints 4 clams plate thickness 5 mm, e) joint 2 clamps on a plate thickness of 9 mm, f) joint 4 clamps on a plate thickness of 9 mm. the misalignment of the clamp nails in the upper and lower positions can also cause deformation because of uneven distribution of the fw twisting force received by the clamp, and ultimately causes deformation [15]. the clamp is also subject to deformation due to welding heating and clamping time [16]. clamping strongly affects the amplitude of weld distortion, possibly changing the distortion mode and enlarging into deformation [17]. the clamping distance significantly impacts the ultimate distortion; the closer the clamp is to the weld, the less distortion there will be. if the clamp is near the weld seam, the clamp's release time also affects the final distortion; as the release time increases, the distortion decreases [18]. 2. temperature distribution figure 5 shows the temperature distribution at the upper position of the clamp rotates at 2000 rpm, and the lower position of the clamp is stationary. the temperature after a few moments later rises. for the fw clamping process, the temperatures are below 300c. the maximum temperature during the welding process is 256.7c with a plate thickness of 3 mm and 5 mm. for 9 mm, the temperature is around 120c. after the joints melted, the rotation was stopped, clamping was done, and a mechanical joint occurred. the clamp joint was let cooled with air room to make grain growth on clamp joint materials [19] and can be analyzed with a microscope. the heat generated during welding is the combined effect of frictional and physical heating due to the plasticity of the stirred material [20],[21]. the difference in 52 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) the thermal rate is quite apparent in thermocouples 1, 2, and 3 are caused by the temperature is not distributed uniformly because of the resistance of the st.37 material [22]. rotation speed, friction pressure, and welding time are responsible for the speed of heat generation, while the dimensions of the joined materials influence heat generation and also the volume of material generated and stirred during welding [23],[24]. fig. 5. temperature distribution for plate thickness of 3 mm, 5 mm, and 9 mm 3. microstructure figure 6 shows the microstructure of 3mm, 5 mm, and 9 mm plates in the weld metal, tmaz, and haz areas with 100x magnification. the ferrite phase has white (light), while pearlite is black (dark), but the grain size of ferrite can also be smaller than pearlite [25]. for detail, the red arrow in figure 6 shows the pearlite phase formed, while the yellow arrow shows the ferrite phase. because it does not involve filler material, the microstructure in the weld metal region is ferrite and perlite, with greater ferrite content than perlite. fw merely includes grain refinement of atoms without phase change [26]. fig. 6. microstructure of joint clamps with thickness of 3 mm (a-c), 5 mm (d-f), and 9 mm (g-i) issn: 2580-0817 journal of mechanical engineering science and technology 53 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) the side of the stir zone (weld metal) deformation due to the heat of st.37 steel in the austenite region produce small austenite grains, and these grains turn into fine ferrite and pearlite during the cooling process of the material after the welding process [27]. as a result of the higher ferrite content, the material has ductile and soft properties. the fineness of the grains in the weld metal region (weld meta) increases the hardness value and tensile strength of the weld joint [28],[29]. the fine-grained microstructure is generated due to increased rotational speed and frictional pressure [24]. the tmaz is a transition zone between the stir zone (sz) and the haz with recrystallization similar to the stir zone. in this area, deformed grains have a fine size [30]. the microstructural characterization of the weld region revealed the formation of a fine structure consisting of a mixture of virgin martensite and some stable retained austenite in the cr region, whereas the microstructures of the haz and tmaz revealed the presence of virgin martensite plus δ-ferrite [31]. the microstructure of haz is identical to that of the parent metal as it is not subjected to stirring [32]. the difference in heat value is quite obvious in thermocouples 1, 2, and 3 because the temperature is not uniformly distributed due to the resistance of the st.37 material. this difference in heat can affect the length of the haz that occurs [22]. 4. microhardness tests the microhardness test used micro-vickers, carried out at 6 stepping points, including the clamping head, each given a distance of 500 µm, to assess the trend of hardness at the joint and to analyze the strength of the joint. from figure 7, vickers microhardness increases in friction area 5 of the interface of the specimen with plate 9 mm. the highest value of vickers microhardness occurs in area 5 in each sample, where the highest values are 191.63 vhn in specimens of 3 mm plates, 167.92 in specimens of 5 mm plates, and 256.4 vhn in specimens of 9 mm plates. fig. 7. vickers microhardness test of plate the specimen has the highest hardness in area 5 with a temperature of 120c rotation speed of 2000 rpm. it is caused by a change of microstructure in the interface area with a fine structure of ferrite [33]. a fine microstructure is obtained from increased stress during welding [34]. this result has the same as other research about stainless-steel pipes. their friction-welded microstructures and local mechanical characteristics (hardness, fracture toughness, and micro-tensile strength) were studied. formation of a delicate structure composed of virgin martensite and some stable austenite. the existence of virgin martensite 54 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) plus d-ferrite, on the other hand, was discovered in the microstructures of haz and tmaz [35]. the changes in the microstructure at various weld locations are closely related to variations in hardness; as the temperature rises, the grain size tends to become smaller and make the material become brittle characteristic [36]. the hardening of the material is affected by rotary friction, axial pressure, and becomes a force with the friction pressure and forging pressure that occurs during welding [37]. these forces cause increased friction and ultimately increase the hardness and young's modulus of each zone on the steel side [38], but the hardness was decreased caused by high heat energy on the joining interface will have oxide trapped in the nugget and finally reduce the mechanical properties, especially hardness [39]. 5. shear force tests in figure 8, the plate thickness and the number of clamps affect the resulting shear stress rate because the more clamps and plate thickness used, the resistance of the connection will be greater, and the force required to break will be even larger. the results of fw using 2 clamps with clamp thicknesses of 3, 5, and 9 which were carried out 3 times during the experiment, had an average shear force of 13.46 kn, 28.76 kn, and 32.33 kn, respectively. fw using 4 clamps with 3, 5, and 9 mm clamp thicknesses was carried out 3 times. it results in an average shear force of 50.87 kn, 58.32 kn, and 66.54 kn, respectively. fig. 8. maximum shear force of clamp joints a joint clamp with fw on a plate with a plate thickness of 3 mm has the lowest shear value. this occurs because the clamp with a thickness of 3 mm is deformed during welding so that the load distribution on the plate is uneven, ultimately decreasing its strength [14]. it is possible to extend the welding time and increase the heat input to increase the shear strength of the joint [40]. it will give the melting metals time and opportunity to bond with each other and create an interlocking mechanism that ultimately increases the material's mechanical strength [41]. iv. conclusions based on an analysis of the results of the study, the temperature distribution rapidly increases from the thin plate's thickness of 3 mm to 5 mm. the lowest temperature is 120°c on a 9 mm plate, while the highest is 250.70 °c on a thin plate. the microstructure in the issn: 2580-0817 journal of mechanical engineering science and technology 55 vol. 7, no. 1, july 2023, pp. 47-58 setiawan et al. (lap joint on st.37 steel plate with friction welding clamping method) weld metal and tmaz areas exhibits grain refinement with ferrite and pearlite phases dominating the friction and heating processes. the highest hardness value was shown in area 5 of each sample with hardness values of 191.63 vhn on 3 mm plate, 167.92 vhn on 5 mm plate, and 256.4 vhn on 9 mm plate. the average tensile test shows that the highest shear force is 4 clamp joints with a maximum shear force of 66.54 kn. acknowledgment this research was funded by damas vocational school, gadjah mada university. thank you to the mechanical engineering department for providing laboratory facilities and the ist akprind yogyakarta laboratory majoring in mechanical engineering. references [1] p. groche, s. wohletz, m. brenneis, c. pabst, and f. resch, “joining by forming a review on joint mechanisms, applications and future trends,” j. mater. process. technol., vol. 214, no. 10, pp. 1972–1994, 2014, doi: 10.1016/j.jmatprotec.2013.12.022. 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[41] z. wu, g. zhang, b. wang, and k. shih, “experimental investigation on solid state resistance spot welding,” in volume 2: advanced manufacturing, american society of mechanical engineers, nov. 2017. doi: 10.1115/imece2017-72581. journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 38-42 38 doi: 10.17977/um016v2i12018p038 the effect of rotational speed, friction duration, and pressure on tensile strength of aisi 6061 welding joints dewi puspitasari 1, poppy puspitasari 2*, m. rizka gita firmansyah 3 and solichin 1 1mechanical engineering department, faculty of engineering, university technology petronas, malaysia 2department of mechanical engineering, faculty of engineering, universitas negeri malang 2 center of nano research and advanced materials, universitas negeri malang *poppy@um.ac.id abstract electric arc welding with covered electrodes is ideally suited for flat plates. if this technique is employed for welding rigid bodies, the results would be of poor quality. one viable solution to weld rigid bodies is through friction welding. the study aimed to investigate the tensile strength of specimens subjected to friction welding with variations in rotational speed, friction time, and pressure and to examine the microstructure of friction welding joints. this research used the one-shot case study design and involved descriptive analysis. the descriptive analysis described the results of tensile testing and microstructure of welding joints. results showed that the specimen subjected to a 2850 rpm rotational speed, 60-second friction duration, and 8 mpa pressure had the highest tensile strength of 15.19 kgf, whereas that rotated at 2850 rpm under 8 mpa pressure for 80 seconds had the lowest tensile strength, i.e. 12.25 kgf. the photomicrographs showed that the friction welding joints underwent no phase change, but the refinement of mg2si particles occurred in the zpd and zpl zones. also, the zud zone consisted of the same form of mg2si particles as the untreated specimen. copyright © 2018journal of mechanical engineering science and technology all rights reserved keywords: friction welding, tensile strength, microstructure i. introduction welding is an integral part of the growth and improvement of the industry, as it plays a major role in metal engineering and manufacturing. welding with covered electrodes is widely used and more suitable for flat plates than rigid bodies. rigid bodies are much more difficult to weld, and thus friction welding is a more reliable technique to use. in friction welding, metal is welded without melting it first. instead, the joining process involves the rotating of one work piece against another at a constant pressure, which then generates heat caused by the friction between rubbing surfaces. rotational speed, friction duration, and pressure are the determining variables in the quality of friction welding joints. ii. methodology this study was a type of pre-experimental design called the one-shot case study, in which a group of subjects were given a treatment and then observed. the independent variables involved in this study were variations in rotational speed, friction duration, and pressure, while the dependent variables were tensile strength resulted from friction welding. data such as tensile test results and specimen microstructures after friction welding were analysed by descriptive data analysis. the standard for specimen tensile tesing used sni 07-0371-1998 shown in figure 1. fig. 1. specimen of tensile testing (sni 07-0371-1998) mailto:*poppy@um.ac.id issn: 2580-0817 journal of mechanical engineering science and technology 39 vol. 2, no 1, july 2018, pp. 38-42 dewi puspitasari et.al (the effect of rotational speed, friction duration, and pressure on tensile strength) table 1. size of tensile test specimen sni 07-0371-1998 diameter (d) gauge length (lo) parallel length (lc) radius shoulder (r) 12.5 50 approximately 60 maximum 15 table 2. results of elemental composition analysis (xrf) compound al mg si k ca ti cr fe br p k pr concentration (%) 64,5 20 5,3 0,23 2,10 0,2 1,6 3,7 0,5 0,47 0,23 0,4 table 3. results of tensile testing rotational speed tensile strength of al-mg-si at a friction pressure of 8 mpa 60 seconds 80 seconds 2850 rpm 12.80 12.81 15.47 8.98 17,31 14.96 mean 15.19 12.25 4000 rpm 13.32 12.62 15.14 17.45 11.25 12.87 mean 13.23 14.31 iii. results and discussion a. elemental composition analysis prior to friction welding, the composition of materials subjected to friction welding was determined using x-ray fluorescence (xrf) in table 2. b. tensile testing prior the tensile test results are presented in table 3. table 3 shows the tensile strength resulted from variations in treatment. the treatment with a rotational speed of 2850 rpm, friction duration of 60 seconds, and a pressure of 8 mpa produced a specimen with a tensile strength of 15.19 kgf. the specimen rotated at 2850 rpm for 80 seconds at 8 mpa had a tensile strength of 12.25 kgf shown in figure 2. the specimen subjected to a 4000 rpm rotational speed, 60-second friction duration, and 8 mpa pressure had a tensile strength of 13.23. the specimen rotated at a 4000 rpm speed under an 8 mpa friction pressure for 80 seconds had a tensile strength of 14.31 kgf. low rotational speeds and short friction durations produce high tensile strength. a specimen experiences a decrease in tensile strength when it rotates at a low speed for a longer time. it occurs because the maximum heat was generated during shorter friction duration. however, extending the duration of friction causes a decrease in temperature. in fact, these parameters affect significantly on the tensile strength of the friction welding joints [1]. fig. 2. average tensile strength resulted from friction welding 40 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 38-42 dewi puspitasari et.al (the effect of rotational speed, friction duration, and pressure on tensile strength) conversely, high rotation speeds coupled with longer friction durations tended to produce greater tensile strength. it happens by reason of the condition in which a specimen rotated at high speed for a short period of friction is unable to reach its peak temperature. on the other hand, a rotational motion set at high speed for a longer time is able to increase heat to the maximum temperature. however, a rise in friction duration may result in a decrease in tensile strength [2]. c. microstructure according to the asm handbook: metallography and microstructures, the aluminium matrix consists of dark particles, i.e. mg2si and grey particles, i.e. fe3sial12p [3]. the microstructureof the untreated specimen. figure 3 shows the great distances between mg2si particles whose shape was almost spherical. fig. 3. microstructure of untreated specimen fig. 4. microstructure of zud, zpd (haz) and zpl zones of the specimen rotated at 2850 rpm and 8 mpa for 60 s fig. 5. microstructure of zud, zpd (haz) and zpl zones of the specimen rotated at 2850 rpm and 8 mpa for 80 s fig. 6. microstructure of zud, zpd (haz) and zpl zones of the specimen rotated at 4000 rpm and 8 mpa for 60 s issn: 2580-0817 journal of mechanical engineering science and technology 41 vol. 2, no 1, july 2018, pp. 38-42 dewi puspitasari et.al (the effect of rotational speed, friction duration, and pressure on tensile strength) fig. 7. microstructure of zud, zpd (haz) and zpl zones of the specimen rotated at 4000 rpm and 8 mpa for 80 s friction welding only involves grain refinement of atoms without phase change because it does not use filler metal [4].variations in treatment during the welding process results in varying microstructures in zud, zpd and zpl zones [5]. as shown in figure 4, 5, 6 and 7, the zud zone had a large grain size while the grain size appeared in zpd and a zpl zone was small. it indicates that only grain refinement occurred (without phase change) in zpd and zpl zones because the welding process did not utilise filler metal [4]. differences in zud, zpd and zpl are owing to the heating process caused by friction and the forging process. the heating and forging processes lead to changes in microstructure [6]. the higher the temperature of the two rubbing surfaces is, the finer the grains will be. variations in particle shape are due to varying temperature during the friction welding. in fact, each welding parameter has a considerable influence on microstructure, micro hardness, and strength [7]. iv. conclusion findings in this research have led to the following conclusions:  the greatest tensile strength of 15.19 kgf was generated by the treatment involving a 2850 rpm rotational speed, 60-second friction duration, and 8 mpa pressure.  the specimen subjected to a rotational speed of 2850 rpm, a friction duration of 80 seconds, and a pressure of 8 mpa had the lowest tensile strength, i.e. 12.25 kgf.  the zud zone and untreated specimen had the same microstructure.  structure refinement of mg2si occurred in zpd and zpl zones.  the finer the mg2si particles was, the higher the tensile strength of friction welding joints would be.  a large number of mg2si particles led to an increase in tensile strength. v. references [1] r. kumar, r. singh, i. p. s. ahuja, a. amendola, and r. penna, “friction welding for the manufacturing of pa6 and abs structures reinforced with fe particles,” composites part b: engineering, vol. 132, pp. 244–257, 2018. [2] a. dawood, s. butt, g. hussain, m. siddiqui, a. maqsood, and f. zhang, “thermal model of rotary friction welding for similar and dissimilar metals,” metals, vol. 7, no. 6, p. 224, 2017. [3] s. f.w and d. dwilaksana, “analysis of mechanical properties and micro structures aluminum alloys al-mg-si results welding friction welding with variation speed play,” rotor, vol. 7, no. 2, 2014. [4] b. sugito, a. d. anggono, and d. prasetyana, “effect of depth pin (depth plung) against the strength of laser connection on welding strength al 5083,” in the 3rd universty research coloquium 2016, 2016. [5] s. prasetyono and h. subiyanto, “effect of friction duration, swipe pressure and forging pressure against impact strenght direct spindle weld connect on aisi 1045 carbon steel,” jurnal sains & seni pomits, vol. 1, no. 1, pp. 1–5, 2012. 42 journal of mechanical engineering science and technology issn: 2580-0817 vol. 2, no 1, july 2018, pp. 38-42 dewi puspitasari et.al (the effect of rotational speed, friction duration, and pressure on tensile strength) [6] b. l. sanyoto, n. husodo, s. b. setyawati, and m. murshid, “application of friction welding (friction welding) technology) in the process of connecting two low carbon steel steel pipes,” jurnal energi & manufaktur, vol. 5, 2012. [7] m. b. uday and m. n. a. fauzi, “joint properties of friction welded 6061 aluminum alloy/ysz–alumina composite at low rotational speed,” materials & design, vol. 59, pp. 76–83, 2014. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 73-78 73 doi: 10.17977/um016v5i22021p073 design of shielded metal arc welding parameters for optimum tensile strength using taguchi method moh. dedy indra setiawan, yanuar rohmat a. p., suprayitno* mechanical engineering department., universitas negeri malang, jl. semarang no 5, malang, 65145, indonesia *corresponding author: suprayitno@um.ac.id abstract shielded metal arc welding (smaw), an arc welding process, is widely used in applications. in practice, smaw is widely applied to the welding process on hollow square pipe. performance expected from this welding is the tensile strength of weld joint. the tensile strength is influenced by parameters process which have possibility for an optimization process to become ‘robust’. robust is a design which less sensitive to the effect of uncertain quantities or noise factors. taguchi method is the most efficient optimization method which accommodates the noise factors effect and requires less experiment. this study is focusing on optimizing the welding process on hollow square pipe. parameters process such as welding current (i), electrode angle (θ), root gap (d) and electrode type (e) are adopted as parameters design. taguchi method are chosen as a strategy and l9 fractional orthogonal array are chosen as the design experiment, which only 9 experiment samples needed from 81 experiments that should have been carried out for full factorial design. the objectivity is to maximize the tensile strength of weld joint. three replications of l9 fractional orthogonal array taguchi had been performed to generate the tensile strength and estimates the fluctuation of the output caused by noise factors. this study found that the welding current of 100a (i), electrode angle (θ) of 90o, root gap (d) of 2 mm, and electrode type (e) of e7018 produce the optimum results. tensile strength improved from this robust parameter design is about 98,39 mpa based on initial parameter design. copyright © 2021. journal of mechanical engineering science and technology. keywords: robust optimization, smaw, taguchi method, tensile strength i. introduction smaw is an essential welding process in the manufacturing and constructing field because of its efficiency, flexibility, and cheap cost welding process. in the construction field, this type of welding is widely used in application to welding on a hollow square pipe. to increase the welding output, improving the smaw parameters process is needed as part of the engineering process [1], [2]. smaw is the most used arc welding in indonesia due to its easier operating, flexibility and high efficiency [3]. astm a500 of the hollow square pipe is the most used material in the construction sector, widely used in the construction field. tensile strength is the expected performance of this welding process, which is generated as strains can be held by the workpiece before it goes to fractures[4]. smaw performance is affected by parameters processes. most of the parameters process is welding current, electrode angle, root gap, and electrode type. to find the optimum combination of the smaw parameters process, it is needed an optimization strategy to improve and optimize the tensile strength [5]. the taguchi method is the most efficient optimization strategy that is widely used. taguchi method objectivity is to improve a parameters process to become “robust”. robust is defined as a less sensitive design due to 74 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 73-78 setiawan et al. (design of shielded metal arc welding parameters using taguchi method) the effect of noise factors. these noise factors include inaccuracies during the manufacturing process, variations in loading, material properties, or variations in other operating conditions. taguchi s/n ratio compared between the signal (expected output) and the noise (unexpected error) to determine the robust design [6]. some of the previous studies were conducted by some authors. nair [4] used taguchi to improve the tensile strength of smaw welded joint of ss316l plates and found the optimum parameters are welding current of 100a, welding angle of 15o, and filler electrode of e316l. on the other hand, ahire [7] used the taguchi method supported by rsm and ga based techniques to optimize the tensile strength on ss304 and mild steel plates welded joint. they found that the optimum parameters are welding current of 91.4a, welding speed of 6.7 mm/s, electrode angle of 30o, and root gap of 1 mm. qazi [8], using the taguchi method to optimize the tensile strength on sa516, found the optimum parameters are welding current of 120a, welding speed of 4 mm/s, and root face of 2 mm. the previous studies do not fully adopt robust design optimization due to the effect of noise factors. it can be seen and indicated by a single measurement for each combination of parameters used in the experiment. for this work, three replications will be used in the experiment to estimate the fluctuation caused by the noise factor [9]. the main objectives of this study are to optimize the smaw parameters process to obtain the robust design parameter using three replications for each combination parameter to estimate the fluctuation caused by noise factors effect on the tensile strength. ii. material and methods a. material the material used in this research was a hollow square pipe of astm a500. dimensions of the hollow square pipe are 50 mm x 50 mm with a thickness of 2.8 mm. the material is cut into two parts with a length of 150 mm and will be welded together. then, the welded material was cut off into a specimen for tensile testing. the standard testing used in this study was the iacs weldments standard, as shown in figure 1. diameter electrodes of 2.6 mm are used in this study. tensile testing was conducted using a universal testing machine [7] to obtain the tensile strength of welded joints. fig. 1. specimen design b. experimental procedure this study begins with identifying the parameters process, optimization problem formulation, the experiment design, running the experiment, results analyze using anom and predicting the optimum parameter using an effect plot, experimental verification results, and analyzing the optimization improvement. the last was running anova to calculate the parameters effect in this study. issn: 2580-0817 journal of mechanical engineering science and technology 75 vol. 5, no. 2, november 2021, pp. 73-78 setiawan et al. (design of shielded metal arc welding parameters using taguchi method) c. optimization problem formulation objective max. (σu) parameters welding current; electrode angle; root gap; electrode type the objectivity of this study was to maximize the tensile strength (σu) of smaw welded joints affected by several parameters, including welding current (i), electrode angle (θ), root gap (d), electrode type (e). the practical parameters range was selected as the design parameters process and listed as shown in table 1. d. design of experiment (doe) this study used three levels of parameters as a design parameters process in this study with the lower range of parameter as level 1 and the upper range for parameter level 3, while level 2 is selected to be the middle range parameters as shown in table 1. table 1. parameter range parameters lower upper welding current (i) 60a 100a electrode angle () 30o 90o root gap (d) 0 mm 2 mm electrode type (e) e6013 e7018 l9 fractional orthogonal array taguchi is selected as a design of experiment with the smallest experiment needed from the total possible combinations of 81 experiments for four 3-level parameters, which is only needed for 9 samples of the experiment as shown in table 2 [10]. three replications were used in the tensile testing generating data [11] to estimate the fluctuation affected by the noise factors in this study. since maximizing the tensile strength is the objectivity of this optimization case, the larger the better s/n ratio will be selected as a robustness index in this study, as shown in equation 1.         −=  = n i i yn ns 1 210lt b 11 log10/ ……………… (1) iii. results and discussions a. tensile strength the data was generated from the field experiment using a designed experiment of l9 fractional orthogonal array with three replications for 4 three-level parameters. results of the experimental data are listed as shown in table 2. then from these three replications, the tensile strength average and the standard deviation are calculated. the larger the better s/n ratio formulation is used as a robustness index since the objectivity is to maximize the tensile strength [10]. the best design of l9 design experiment is number three experiment with 50.26 in s/n ratio, as shown in table 2. the initial design that is usually used in practice is number five experiment. 76 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 73-78 setiawan et al. (design of shielded metal arc welding parameters using taguchi method) table 2. l9 design of experiment parameter exp average tensile strength standard deviation s/n ratio i θ d e 1 1 1 1 1 174.67 15.53 44.74 1 2 2 2 2 261.61 49.86 47.90 1 3 3 3 3 328.02 22.20 50.26 2 1 2 3 4 312.38 52.31 49.54 2 2 3 1 5 259.45 10.14 48.26 2 3 1 2 6 253.18 24.78 47.95 3 1 3 2 7 305.61 35.23 49.53 3 2 1 3 8 276.81 36.23 48.63 3 3 2 1 9 312.20 29.80 49.77 b. optimum parameter analysis an analysis of mean (anom) is executed to calculate the effect of parameters process on the tensile strength response based on the experiment data from l9 design experiment. anom is executed for the s/n ratio, and the main effect of each parameter process then be plotted as shown in figure 2. fig. 2. effect plot for s/n ratio the s/n ratio gives the optimum response in the high level (level 3) of parameters process, as shown in figure 2. then, predicted from these effects plot as shown in figure 2 which the level of the parameter 3 of welding current (100a), level 3 of electrode angle (90o), level 3 of root gap (2 mm), and level 3 of electrode type (e7018) will give the optimum tensile strength for welded joint. since this optimum smaw parameter is still estimated, an experiment field is needed to verify this predicted optimum to clarify the prediction. -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 i1 i2 i3 θ1 θ2 θ3 d1 d2 d3 e1 e2 e3 issn: 2580-0817 journal of mechanical engineering science and technology 77 vol. 5, no. 2, november 2021, pp. 73-78 setiawan et al. (design of shielded metal arc welding parameters using taguchi method) c. verification optimal design an experimental field was performed to verify the predicted optimum parameter. the results of the experimental field verify that the average tensile strength is 357.84 mpa with a standard deviation of 22.05, and the value of s/n ratio is 51.02. this verified optimum parameters then compared with the initial design to evaluate the optimization results. d. optimization gain the gain of the robust parameter design compared to the initial design give an improvement of about 98.39 mpa in tensile strength and 2.76 of s/n ratio. the comparison results of the robust design and initial design shown in table 3. table 3. comparison results design parameters welding current electrode angle root gap electrode type s/n ratio initial design 80a 60o 2 mm e6013 48.26 robust design 100a 90o 2 mm e7018 51.02 gain 2.76 e. analysis of variance (anova) to evaluate contribution for each smaw parameter analysis of mean is performed [10]. the main effect for parameters process is calculated, but the parameters process interaction is not calculated. average tensile strength anova is presented as shown in table 4. table 4. anova ss dof ms f0 ft c i 8505.04 2 4252.52 3.78 3.55 11.70% θ 6433.86 2 3216.93 2.86 8.85% d 22833.98 2 11416.99 10.16 31.41% e 14686.47 2 7343.23 6.53 20.20% error 20230.06 18 1123.89 27.83% total 72689.41 26 100.00% based on table 4, root gap (d) is the most parameter contributing to the tensile strength response because it gives the optimum weld penetration. the electrode type (e) is the second parameter contribution because each type has a different composition, which is the level 3 gives the optimum tensile strength. the welding current (a) is also affected by the weld penetration given by the next parameter contributions after electrode type. while the electrode angle (θ) does not give a significant contribution to the tensile strength response. the contribution of interactions between parameters that can’t be calculated in this study is represented by the error in table 4. the taguchi method only considers the linear main effect of each variable, so the high pool error percentage in anova may be due to interaction effect between variables or higher-order main effect of each variable [10]. this anova has confirmed the taguchi analysis as presented in the previous sections, as shown in figure 2. 78 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 73-78 setiawan et al. (design of shielded metal arc welding parameters using taguchi method) iv. conclusions this optimization of smaw parameters can be concluded as follows: the welding current of 100a, electrode angle of 90, root gap of 2 mm, and electrode type of e7018 is selected as robust optimum parameter design. the gaining of optimization is 98.39 mpa in tensile strength and 2.76 in s/n ratio. the contribution of each parameters process is welding current of 11.70%, electrode angle of 8.85%, root gap of 31.41%, and electrode type of 20.20%. acknowledgment this research work was fully supported by the pnbp um 2020. references [1] shukla, joshi, and chel, “analysis of shielded metal arc welding parameter on depth of penetration on aisi 1020 plates using response surface methodology,” procedia manuf., vol. 20, pp. 239–246, 2018. [2] jasman, pebrian, and irzal, “the effect of strong welding flow on the violence of low carbon steel result of smaw weld using 7018 electroda type,” j. pendidik. tek. mesin, jur. tek. mesin, fak. tek. univ. negeri padang, no. october, 2018. [3] d. suherman, ridho, and c.p. marpaung,“effect of electric current on mechanical properties and microstructure of smaw welded joints of steel sa 516 gr.70,” j. ilm. “mekanik” tek. mesin itm, vol. 4(2), pp. 64–69, 2018. (in indonesia). [4] n.v. nair, “optimization of ss316l weldments using smaw by varying filler electrode,” int. res. j. eng. technol., vol. 03(12), pp. 351–356, 2016. [5] a.k. rude, and pimpalgaonkar, “optimization of process parameter in hardfacing by shield metal arc welding (smaw),” int. res. j. eng. technol., vol. 05(01), pp. 232– 236, 2018. [6] p.k. gupta, and a. kamboj, “smaw process parameters optimization using taguchi & fuzzy logic,” int. res. j. eng. technol., vol. 04(05), pp. 411–413, 2017. [7] p.g. ahire, u.s. patil, and m.s. kadam, “genetic algorithm based optimization of the process parameters for based manual metal arc welding of dissimilar metal joint,” procedia manuf., vol. 20, pp. 106–112, 2018. [8] m.i. qazi, and r. akhtar, “application of taguchi method for optimization of tensile strength of shielded metal arc welding (smaw) process for steel sa 516 grade 70,” int. j. progress. sci. technol., vol. 17(2), pp. 97–103, 2019. [9] a. arifin, “optimization of angular distortion on weld joints using taguchi approach,” j. kejuruter., vol. 31, pp. 19–23, 2019. [10] d. montgomery, "design and analysis of experiments", 8th ed. john wiley & sons, inc., 2012. [11] j. yu, c. chang, and s. suprayitno, “robust design optimization via surrogate network model and soft outer array design,” int. j. prod. res., vol. 4(56), pp. 1533– 1547, 2018. journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 100-106 100 doi: 10.17977/um016v1i22017p100 compositional and structural evolution during ball milling of ti-based metallic glass powder yanuar rohmat aji pradana1 1department of mechanical engineering, state university of malang, malang city, east java, indonesia yanuar.rohmat.ft@um.ac.id abstract ti42zr40ta3si7.5sn7.5metallic glass powder prepared for subsequent consolidation by hot pressing were produced by high energy ball milling from amorphous ribbon and both of the compositional and structural evolution on milled powders were studied using xrd and dsc analyses. by using wc vial and balls, the abrasion of milling media occurred causing wc contamination on < 105 µm milled powder after 2 cycles of milling. based on dsc analysis, the contamination clearly reduced theδtxof the alloy up to 48%. on the other hand, the contamination were overcome after milling using ss vial and balls, proved by no crystal peak observed on xrd pattern of all milling cycle levels. however, the thermal stability was noticed to be decreased implying the presence of nanocrystals on the amorphous powder after ball milling and the nanocrystal amount tend to be higher when more milling cycles were applied. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: ti-based mg powder, ball milling, contamination, structural evolution i. introduction the study of metallic glasses is recently important both in fundamental and application due to their unique and superior properties compared with the crystalline counterparts, which are high strength, high hardness,good corrosion and wear resistance, and excellent soft magnetic property[1]. titanium-based metallic glass (ti-based mg) is one of potential candidate materials applied in biomedical field due to its better corrosion and wear resistance, lower young’s modulus,and higher elastic strain limit modulus compared with ti and its alloys which are widely used as biomedical implant materials as their good implant requirement properties such as low densityand good biocompatibility[2], [3]. these properties of ti-based mg can be designed to solve large boneimplant young’s modulus mismatch resulting stress-shielding effects which can damage the surrounding tissue [2], [4], [5]. although ti-based mgs become the most attractive candidate of biomaterials among all metallic glasses, be, ni, and cu element need to be involved to improve their high gfa, therefore, they can be fabricated into bulk form. but, all of these elements are classified as toxic elements which harmful for human body after long period implantation[6].ti-zr-si-sn system of metallic glass had been successfully developed by jang’s group. however, this composition possess relatively low gfa due to the absence of toxic elements, so, amorphous structure could be only formed into ± 18 25 µm thick ribbon. one of the possible ways to obtain bulk and applicableti-basedmetallic glass is consolidation of its powder constituent by hot pressing process. usually, this process is isothermally conducted at supercooled liquid region for certain time depends on alloy incubation time for recrystallization. ball milling is a simple and flexible processing method to synthesize of metastable material such as amorphous, nanocrystals and solid solution [7], [8]. the main evolution of microstructure during milling generally initiateswith plastic deformation, followed by fracture and subsequent particle welding. milling parameters to convert ribbon into powder plays an important role to determine structure and properties of generated amorphous powder. the process feasibility and bulk product quality such as mechanical and chemical properties will be influenced by state of initial powder [8], [9].exceeds milling time and cycles can be the purpose of both powder contamination and crystallization due to the stress and temperature elevation during milling process. on the other hand, the interaction between powder and milling media (both of vial and balls) material also determines the powder composition obtained from milling process. it should be noted the spex mill could mailto:yanuar.rohmat.ft@um.ac.id issn: 2580-0817 journal of mechanical engineering science and technology 101 vol. 1, no. 2, november 2017, pp. 100-106 yanuar rohmat aji pradana (compositional and structural evolution during ball) possibly introduce contamination from the grinding media into the milled powders due to its high energetic efficiency.this can obstruct amorphous interface bonding between powders when powder consolidation by hot pressing, then, reducing the mechanical properties of hot pressed sample. in addition, low gfa ti-based mgs indicating low thermal and mechanical stabilization are susceptible to loss their amorphous nature as a result of thermal and mechanical working during powder milling. so, optimum milling condition and milling media selection must be reached to obtain high quality powder [9], [10]. nevertheless, the informations regarding milling parameters effect on ti-based mg powder structure and thermal properties have never been revealed by previous studies. in this study, the structure and thermal properties of non-toxic ti-based mgs powder obtained from high energy ball milling using different milling media and number of cycles were investigated due to the contamination and crystallization may occur during milling to provide an overview relating optimum condition and milling parameter selectionwhich can be applied for advance tibased mgs processing. ti42zr40ta3si7.5sn7.5mgwas selected as sample composition due to the absence of toxic elements andits highest gfa among all configuration of the alloy system. the structural and thermal evolution of as spun and powder mg after high energy ball milling were intensively discussed. ii. materials and method. alloy ingotswith composition of ti42zr40ta3si7.5sn7.5 (at.%) were firstly prepared by arc melting of representative elements having purity of 99.9% inside ti-gettered argon atmosphere. the process is repeated for 4 times by reversing and re-melting the ingot surface in each process to ensure their homogeneity. after the ingots had successfully evacuated from the chamber, they were re-melted and cast to be ± 18 25 µm mg ribbon by melt spinning method at temperature of 0oc. subsequently, amorphous ribbon were cut into a small size and put together with ball mill inside the milling vial under argon atmosphere to avoid oxidation during milling process. tungsten carbide (wc) and stainless steel (ss) ball and vial were utilized during powder milling using 8000m spex sample preparation machine.ball-to-powder ratio (bpr) of 10:1 was used to grind 10 g fine cut ribbon for each milling process. due to the low stability of ti-based mg, the milling procedure was set to grind for 5 min (very short milling time) followed by a break for 20 min until desired cycle was reached in order to hinder early crystallization. afterwards, the powder was evacuated from the vial and sieved to obtain only powder having particle size of <105 µm. this was chosen to be prepared as subsequent analytical sample. structural analysis was conducted on as spun ribbon and milled powder by using bruker d8a xray diffraction (xrd) with scanning rate of 4.861o min-1. meanwhile, the thermal properties of them were investigated by mettler toledo differential scanning calorimetry (dsc) instrument to obtain specific temperature (glass transition temperature, tg, and crystallization temperature, tx). supercooled liquid (scl) region (δtx = tx – tg) obtained from the dsc analysis was defined to be the thermal stability of alloys. iii. results and discussion. the alloy ingot of ti42zr40ta3si7.5sn7.5was successfully fabricated by arc melting and the crystal structure of combined compositions is confirmed by xrd shown on figure 1(a). due to the lower gfa of ti-based bmg compared with other based bmgs, the amorphous structure could only achieved at limited size, therefore, the ingot was cast by using melt spinning to produce ribbon. the xrd pattern of ± 18 25 µm as spun ribbon is shown on figure 1(b)exhibiting a broad diffraction peak of 2θ at 30-50o without any crystalline bragg peak indicating the structure is fully amorphous. 102 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 100-106 yanuar rohmat aji pradana (compositional and structural evolution during ball) fig. 1. xrd patterns of ti42zr40ta3si7.5sn7.5(a) ingot and (b) ribbon fig. 2. dsc curve of ti42zr40ta3si7.5sn7.5 mg ribbon fig. 3. dsc curves of ti42zr40ta3si7.5sn7.5 ribbon using different heating rates. to investigate the thermal properties of the alloy, dsc test ranging from 323 – 973 k was utilized and the curve of as spun ribbon is shown at figure 2. under the heating rate of 40 k min-1, both glass transition and crystallization temperatures (tgand tx) of ti-based mgwere determined to be 800 and 919 k, respectively, implying relatively wide scl region (119 k).δtx was suggested as the criteria to determine the thermal stability of bmgs. issn: 2580-0817 journal of mechanical engineering science and technology 103 vol. 1, no. 2, november 2017, pp. 100-106 yanuar rohmat aji pradana (compositional and structural evolution during ball) fig. 4. (a) ti42zr40ta3si7.5sn7.5 mg powder after ball milling and (b) xrd pattern of powder milled by different milling cycles. fig. 5. (a) dsc curves of wc-contaminated mg powder using different heating rates and (b) linearly plot of real tg and tx on wc-contaminated mg powder compared with the as-spun ribbon due to the isothermal condition is applied during subsequent hot pressing, it is necessary to find both of the real tg and tx by dsc analysis using different heating rates to predict the width scl regionwhen using heating rate of 0 k min-1 (isothermal). the results are shown on figure 3 and the real tg and t¬x of ribbon were linearly fit to be 777 and 893 k, thus,δtxwas calculated as 116 k. afterwards, high energy ball mill was used to produce the powder from small cut ribbon. tungsten carbide (wc) vial and ball were firstly utilized to grind the ribbon. different milling cycles was conducted to vary the powder result. from xrd pattern on figure 4 (b), no structural change is observed by 2 cycles of milling indicating the structure was still amorphous. by further milling cycles, the crystal peaks dominated by wc crystal are clearly appeared indicating the presence of crystal phase around the milled powders. in addition, the higher amount of crystal phases was generated by 12 cycles of milling with the presence of unknown crystal other than wc. to investigate the wc contamination on structural and thermal property of milled powders, the dsc analysis of contaminated powder were done using different heating rates. the dsc curves are shown on figure 5 (a). by using similar method to predict the real specific temperaturesof ribbon, the tg and tx of contaminated powders were determined to be 793 and 853 k resulting δtxof only 60 k (48% of reduction) (figure 5 (b)). this indicated the degradation of thermal stability of amorphous powder by the presence of certain amount of wc from vial and ball abrasion after high energy ball milling. the higher tg gives the higher opportunity for alloy to suffer oxidation during heating. in addition, lower tx generates rapid crystallization when alloys are put in practical usewithin scl region, i.e. superplastic forming. 104 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 100-106 yanuar rohmat aji pradana (compositional and structural evolution during ball) table 1. comparison of real glass transition temperature, crystallization temperature, and width of scl region between wc-contaminated mg powders and as spun ribbon sample tg[k] tx[k] δtx[k] ribbon 777 893 116 powder 793 853 60 fig. 6. (a) xrd patterns and (b) dcs curves of milled powder for different milling cycles by using ss vial and balls. on the other hand, stainless steel (ss) vial and balls were also used to produce the mg powder from small cut ribbons. the xrd pattern of 2, 4, 6, 8 cycles completed with its ribbon are delivered on figure 6 (a). it is clearly shown that the contamination of milling media on milled powders are hindered by using ss vial and balls proved by the absence of fe crystal peak. however, weak diffraction crystal peak at around main amorphous hump appeared at powder sample resulted by 4 cycles of milling, indicating the formation crystals with nanometer size(nanocrystals) in the amorphous. by the higher milling cycles, the more peaks are observed to be separated in other region. the limitation of xrd analysis to detect nanocrystals made the clear peaks on the pattern are not achieved, therefore, only weak signal could be performed[11]. due to relatively imprecise results of xrd to reveal the presence of nanocrystal, the subsequent dsc analysis was conducted to clarify the structural and thermal properties change after ball milling. as described on figure 6 (b), after ball milling for 2 cycles, bothof tg and txare lessvisible issn: 2580-0817 journal of mechanical engineering science and technology 105 vol. 1, no. 2, november 2017, pp. 100-106 yanuar rohmat aji pradana (compositional and structural evolution during ball) and the remain crystallization peak is slightly broadened. these phenomena are consistently observed at higher cycles of milling powders, moreover, the one additional crystallization peak rise after 8 cycles of milling. on the other hand, the δtxare gradually decreased with higher milling cycles. it indicates that the thermal stability remain reduced after high energy ball milling. the degradation of amorphous nature by minor crystallization of powder is considered to be occurred after the process, therefore, using high cycle parameter of ball milling remains disadvantage to produce powder for subsequent hot pressing. the change of alloy composition due to abrasion and contamination of milling media,direct crystallization and oxidation caused by rise of local temperature at collision region on powder trapped by milling balls or milling ball-vial, and stress induced crystallization from shear bands development which act as preferred site for nanocrystals precipitation are the possible reasons ofthe structural evolution on mg powder during ball milling[9], [12]. by using wc vial and balls, the contamination was possibly occurred due to the high strength of ti based mg powder damaging the wc particle bonding resulting abrasion on milling media wall and finally contaminate the powder. these phenomena are clearly proved by the presence of wc crystal peaks on xrd pattern. by using higher milling cycles, the contamination is observed to reach higher level consistent to the higher intensity of wc peaks. by the fact that the milling was done under ar atmosphere, the presence of oxygen in milling chamber could be neglected. increase of oxygen content related with the increase of powder surface-to-volume inducing oxidation when heat rise during milling process. however, this case was hindered due to the powder only milled for short time which is not sufficient to generate heat for oxidation. from the dsc test, the contamination clearly degrade the thermal stability of mg powder, therefore, reduce their properties for subsequent hot pressing. while ss vial and balls used, the abrasion and contamination of milling media on milled powders are not occurred by examining the xrd result. however the thermal stability change observed by dsc test indicates the structural evolution of milled powder compared with its ribbon counterpart. similar with the latest one, the oxidation could be neglected due to the presence of only very small amount of oxygen in ar atmosphere and the absence heat during short time milling process. on the other hand, the deformation of mg at temperature lower than tg is determined by the formation and movement of shear band which localized in weakest site of mg [13]. the strength of material inside the shear band is reduced during shear band formation, afterwards, deformation takes place along the shear bands [12], [14]. this suggest that during the mg deformation, viscous flow inside the shear bands is improved and structural changes may happen within the shearband.the rapid propagation of shear band induces the local temperature rise on shear band tip playing important role in the formation of nanocrystals on low gfa mg as shown by most of tibased mg without any toxic element composition[12], [15]. this possibly describes the presence of nanocrystals inside the amorphous powder, which reduce the thermal stability of the mg. by the higher cycles, the amount of nanocrystals are also improved. the presence of optimum amount of nanocrystals inside the amorphous phase may improve its mechanical properties, however, those on mg powder are not beneficial because it can deteriorate the thermal properties and impede the powder-to-powder interface during powder consolidation by hot pressing. iv. conclusion. ball milling has been progressively applied to produce ti42zr40ta3si7.5sn7.5metallic glass powder from amorphous ribbon using both of wc and ss milling media. from xrd analysis, wc particle contamination were clearly observed after 4 cycles of milling indicating deteriorate effect on mg powder after ball milling using wc vial and balls. the dsc test of contaminated powder revealed the reduction of their thermal stability compared with the ribbon. the contamination and its thermal stability degradation effect remained higher by using more cycles of milling. on the other hand, contamination of milling media was overcome when ss vial and balls were utilized during ball milling. however, the presence of nanocrystals were observed after ball milling as confirmed by xrd and dsc analysis. the amount of nanocrystals tend to be higher when the higher milling cycles were used. these phenomena may degrade the properties of mg powder for subsequent consolidation by hot pressing. 106 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 100-106 yanuar rohmat aji pradana (compositional and structural evolution during ball) references [1] a. inoue, “stabilization of metallic supercooled liquid,” acta mater., vol. 48, pp. 279–306, 2000. [2] m. calin et al., “designing biocompatible ti-based metallic glasses for implant applications,” mater. sci. eng. c, vol. 33, no. 2, pp. 875–883, 2013. [3] h. c. lin et al., “designing a toxic-element-free ti-based amorphous alloy with remarkable supercooled liquid region for biomedical application,” intermetallics, vol. 55, pp. 22–27, 2014. [4] j. j. oak and a. inoue, “attempt to develop ti-based amorphous alloys for biomaterials,” mater. sci. eng. a, vol. 448–451, pp. 220–224, 2007. [5] j.-j. oak, d. v. louzguine-luzgin, and a. inoue, “fabrication of ni-free ti-based bulk-metallic glassy alloy having potential for application as biomaterial, and investigation of its mechanical properties, corrosion, and crystallization behavior,” j. mater. res., vol. 22, no. 5, pp. 1346–1353, 2007. [6] [6] w. m. elshahawy, i. watanabe, and p. kramer, “in vitro cytotoxicity evaluation of elemental ions released from different prosthodontic materials,” dent. mater., vol. 25, no. 12, pp. 1551–1555, 2009. [7] p. ramasamy, r. n. shahid, s. scudino, j. eckert, and m. stoica, “influencing the crystallization of fe 80 nb 10 b 10 metallic glass by ball milling,” j. alloys compd., vol. 725, pp. 227–236, 2017. [8] j. bednar????k et al., “crystallization of cofesib metallic glass induced by long-time ball milling,” j. non. cryst. solids, vol. 337, no. 1, pp. 42–47, 2004. [9] c. l. chen and c. l. huang, “milling media and alloying effects on synthesis and characteristics of mechanically alloyed ods heavy tungsten alloys,” int. j. refract. met. hard mater., vol. 44, pp. 19–26, 2014. [10] m. cabeza et al., “effect of high energy ball milling on the morphology, microstructure and properties of nano-sized tic particle-reinforced 6005a aluminium alloy matrix composite,” powder technol., vol. 321, pp. 31–43, 2017. [11] a. inoue and c. suryanarayana, bulk metallic glasses. 2011. [12] c. a. schuh, t. c. hufnagel, and u. ramamurty, “mechanical behavior of amorphous alloys,” acta mater., vol. 55, no. 12, pp. 4067–4109, 2007. [13] a. s. argon, "plastic deformation in metallic glasses,"acta mater., vol. 27, issue 1, pp. 47-58, 1979. [14] p. s. steif, f. spaepen, and j. w. hutchinson, "strain localizationin amorphous metals," acta metal, vol. 30, issue 2, pp. 447-455, 1982. [15] j. j. lewandowski and a. l. greer, "temperature rise at shear bands in metallic glasses," nature mater, vol. 5, pp. 15-18, 2006. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 135-144 135 doi: 10.17977/um016v5i22021p135 spray characteristics at preheating temperatur of diesel-biodiesel (calophyllum inophyllum)-gasoline fuel blend moch. miftahul arifin1, nasrul ilminnafik 2*, muh. nurkoyim kustanto2, agus triono2 1postgraduate program, mechanical engineering department, university of jember, jember, 68121, indonesia 2mechanical engineering department, university of jember, jember, 68121, indonesia *corresponding author:nasrul.teknik@unej.ac.id abstract technological developments in diesel engines require improvements to the fuel injection system to meet the criteria for economical, high-power and efficient combustion and meet environmental regulatory standards. one method that has a lot of interest is changing the characteristics of the fuel, with the aim of producing optimal combustion. spray characteristics have a big role in determining the quality of combustion in diesel engines. a good spray can improve the quality of fuel atomization and the homogeneity of the air-fuel mixture in the combustion chamber so that it can produce good engine performance and low emissions. this study aims to determine the effect of a diesel-biodiesel (calophyllum inophyllum)-gasoline blend and fuel heating on the spray characteristics. the research was conducted with variations in composition (b0, b100, b30, b30g5 and b30g10) and fuel heating (40, 60, 80, and 100 °c). fuel injected at a pressure of 17 mpa in to a pressure chamber of 3 bar. the spray formed was recorded with a high-speed camera of 480 fps (resolution 224x168 pixel). in b100 biodiesel, the highest viscosity and density cause high spray tip penetration, small spray angle, and high spray velocity. the addition of diesel oil, gasoline, and heating fuel reduces the viscosity and density so that the spray tip penetration decreases, the spray angle increases and the velocity of spray decreases. copyright © 2021. journal of mechanical engineering science and technology keywords: biodiesel blend, gasoline and preheating fuel, spray characteristics i. introduction technological developments in diesel engines require improvements to the fuel injection system to meet the criteria for economical, high-power and efficient combustion and meet environmental regulatory standards [1]. viscosity has a major role in changing the characteristics of the spray. the research relationship between properties of physical liquid fuels and characteristics of the spray revealed that the characteristics of the spray are affected by the physical properties of liquid fuels [2-3]. spray characteristics with fuel nonconventional have different microstructures of conventional fuels, such as length of spray, spray angle, and spray speed that produces quality mixing of air and fuel [1]. as one alternative fuel, calophyllum inophylluma source of raw materials potential, contain oil that is high and can grow well in the tropics [4-6]. calophyllum inophyllum biodiesel has good oxidation stability [7], so it is classified as a high-quality fuel with stable combustion characteristics and is safe for transportation with a relatively high flash point and acidity [8]. but biodiesel fuel is identical with chemical properties that are non-volatile, more viscous, relatively large droplets, resulting in poor atomization [9]. mailto:nasrul.teknik@unej.ac.id 136 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. (spray characteristics at preheating temperatur of diesel-biodiesel-gasoline fuel blend) some of the solutions of which is the addition of gasoline and preheating fuel [10] in their research adding fuel and kerosene to biodiesel waste cooking oil, resulted in a decrease in density, cetane number and viscosity properties. examined the fumigation gasoline on fuel diesel oil and b20 [11], produced in a significant improvement in lowering emissions of uhc, exhaust gas temperature, smoke opacity, emissions of nox and co2. fuel heating up to 100°c does not have an adverse effect on the injection system [12]. preheating temperature of biodiesel effectively lowers kinematic viscosity, density and surface tension, wherein the physical properties of these fuels have a major impact on the process of atomization in the combustion chamber [13-14]. increased preheating temperatures of fuel affect spray tip penetration and spray angle, similar thing happened in the spray area and volume spray [15]. as for engine performance and emissions, heating of biodiesel and its blend can improve engine performance, reducing co emissions, although there is still an increase in nox emissions due to higher combustion temperature[13], [1617]. it is necessary to further research the characteristics of the spray on diesel-biodiesel and gasoline fuel blend with preheating temperature. the study aims to determine the effect of the fuel blend and preheating temperature on the spray characteristics, including spray tip penetration, spray angle and velocity of spray. ii. material and methods the fuel used in this study is a diesel (produced by pt pertamina indonesia), biodiesel made from calophyllum inophyllum seed oil obtained from bondowoso, east java, indonesia. calophyllum inophyllumextracted mechanically, followed by esterification and transesterification of calophyllum inophyllum oil triglycerides and gasoline (premium produced by pt pertamina indonesia with an octane number 88). the composition of the fuel blend is shown in table 1. table 1. composition of diesel-biodiesel-gasoline fuel blend no mixture code diesel biodiesel gasoline 1. b0 100 % 0 % 0 % 2. b30 70 % 30 % 0 % 3. b30g5 95%b30 5 % 4. b30g10 90% b30 10 % 5. b100 0 % 100 % 0 % mixing of the fuel use the dissolving method [18], which is conducted with a stirrer process for 10 minutes using magnetic stirrer (50-1000 rpm, max 2.5 liter, 25-110ºc) at a certain room temperature condition (40ºc) and a speed of 350 rpm constantly. that fuel is heated with variations temperature of 60°c, 80°c, and 100°c before being injected on test equipment. the testing process is conducted in 2 stages, testing the fuel propertiesby using pycnometer for density and viscometer ostwald for viscosity, then testing the spray on the nozzle tester. spray test using an injection pressure of 17 mpa with type nozzle r175 single hole and spray chamber at a pressure of 3 bar. this chamber has 2 transparent sides made of acrylic glass. one side is used to record the spray that occurs, and the other side is for lighting. the condition of the tester nozzles is shown in table 2. issn: 2580-0817 journal of mechanical engineering science and technology 137 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. (spray characteristics at preheating temperatur of diesel-biodiesel-gasoline fuel blend) the spray was recorded using a high-speed camera of 480 fps (frame per speed) with a resolution of 224x168 pixel. lighting use halogen lamps 1000 watts. the test scheme is shown in figure 1. table 2. experimental conditions fuel b0, b100, b30, b30g5, b30g10 temperatur fuel 60, 80, 100 injectors and injection conditions injector type number of nozzle holes nozzle diameter r175 type 1 0.8 mm injection pressure ambient pressure 17 mpa 3 bar chamberdimensions thick iron plate thick acrylic glass length x width x height = 30 x 30 x 30 cm 10 mm 10 mm the results of the spray in the form of video are converted into images which are then measured the spray tip penetration and the spray angle in each image. fig.1. test schemeof spray characteristics iii. result&discussion a. fuel properties fuel blend in the test characteristics and the results of its indicated on tabel 3. in this table, it appears that all of the fuel mix used has properties in accordance with standard fuel (diesel-b0). from the table, we also know that the higher the percentage of the gasoline mixture, the lower the density and viscosity of the fuel blend. peak combustion pressures of biodiesel/gasoline blend fuels increases lightly [19]. while ignition delays, peak heat release and thermal efficiency decrease but specific consumption increase [10]. 138 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. (spray characteristics at preheating temperatur of diesel-biodiesel-gasoline fuel blend) table 3. fuel blend characteristics composition of fuel blend density 40° (gr/ml) viscosity 40° (cst) b0 0.811 2.120 b30 0.828 2.842 b30g5 b30g10 0.818 0.798 2.397 2.219 b100 0.836 3.080 table 4 are shown the viscosity of the fuel blend and preheating temperature. from this table, it can be seen that the viscosity of the tested fuel decreased with increasing fuel temperature. fuel preheating cause hydrocarbon and carbon monoxide emissions increase at partial and medium loads and drop at high loads [20]. table 4. characteristics of fuel viscosity with preheating temperature fuel temperature ( o c) viscosity (cst) b0 b100 b30 b30g5 b30g10 60 1.897 2.978 2.777 2.342 2.013 80 1.642 2.933 2.623 2.269 1.961 100 1.498 2.865 2.359 2.190 1.903 b. spray tip penetration spray characteristics of the fuel blend in this study and preheating temperature of fuel are shown in figure 2, that is taken in the second spray or at the time 4.16 ms. each spray length is measured, and the results are displayed in graphical form so that it is easy to observe, and the measurement results are shown in figure 2. figure 3 shows the results of measuring the spray tip penetration of the fuel blend with fuel heating. the figure shows that 100% biodiesel (b100) has the longest spray tip penetration for all fuel temperature variations. this is caused by b100 having the viscosity and density of the highest that causes the spray easily through the air in the chamber so long spray tip penetration. the addition of 5% 10% gasoline (b30g5b30g10) and the addition of 30% diesel (b30) causes the viscosity and density to decrease so that the spray tip penetration also decreases but spray tip penetration of b30g10 is closest to b0. the addition of diesel also lowers the viscosity and density of the fuel blend, so that spray tip penetration is also declining. the diesel oil fuel 100% (b0) as the standard is commonly used in indonesia so that the viscosity and density are the lowest, which causes the spray tip penetration to be the lowest. while the increase in the percentage of gasoline in the fuel blend is able to reduce the density value of fuel blend [21]. the preheating temperature of the fuel also reduces the spray tip penetration of all fuel compositions because heating the fuel causes the viscosity and density to decrease as well. the lower viscosity value fuels reduce the grain size of spray so that the ability of the spray to pass through the air pressure in the chamber decreases [22]. this is because as the density of the fuel increases, the mass of the flow rate increases and causes the momentum to increase which allows the spray to move more easily [23-24]. increasing the percentage issn: 2580-0817 journal of mechanical engineering science and technology 139 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. (spray characteristics at preheating temperatur of diesel-biodiesel-gasoline fuel blend) value of the biodiesel blend increased the viscosity and density values but increasing the heating temperature of the fuel could decrease it [25]. the effect of preheating of fuel on viscosity can reduce spray tip penetration [15]. fig. 2. spray at different fuel blend and preheating temperature at the time 4.16 ms (second spray) fig. 3. spray tip penetration at different fuel blend and preheating temperature at the time 4.16 ms (second spray) 140 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. (spray characteristics at preheating temperatur of diesel-biodiesel-gasoline fuel blend) c. spray angle the spray angle of the fuel blend in this study with preheating temperature is shown in figure 4, which is taken in the third spray or at a time 6.24 ms. each spray angle is measured, and the results are displayed in graphical form so that it is easy to observe, and the measurement results are shown in figure 5. figure 5 is the average spray angle on the variation of the fuel blend and preheating temperature. in the figure, it can be seen that biodiesel fuel (b100) has the smallest spray angle. this is because b100 has the highest viscosity. the high viscosity and density of biodiesel cause poor atomization results [26], which causes deep penetration of the spray into the air in the chamber and large fuel momentum. fig. 4. spray at different fuel blend and preheating temperature at the time 6.24 ms (thirdspray) fig. 5. spray angle at different fuel blend and preheating temperature at the time 6.24 ms (third spray) issn: 2580-0817 journal of mechanical engineering science and technology 141 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. (spray characteristics at preheating temperatur of diesel-biodiesel-gasoline fuel blend) d. velocity fo spray velocity of spray with variations in fuel blend and preheating temperature is shown in figure 6 that taken at the third spray or at the time 6.24 ms. the effect of fuel blend composition shows that biodiesel fuel (b100) has the highest velocity of spray. the addition of diesel oil and gasoline reduces the velocity of spray due to its viscosity and density change. fig. 6. velocity of spray at different fuel blend and preheating temperature at the time 6.24 ms (third spray) the fuel heating also reduces the properties of the fuel so that it affects the velocity of spray, where the lowest spray occurs at the highest heating of 100 c, and the highest spray occurs at a temperature of 40°c. the decrease of velocity of spray affects the decrease in the momentum of the fuel to the air so that the homogeneity of the air and fuel blend decreases[21], [23-24]. spray tip penetrations are almost the same as each other, meaning that the velocity of spray and the momentum of the fuel are the same [30]. it needs a combination of treatment between the chamber condition and fuel composition so that the momentum, spray angle, and spray tip penetration remain high so that the homogeneity of the fuel and air mixture could be better. iv. conclusions research has been carried out on the effect of adding gasoline and heating fuel, and the results are the additions gasoline to the diesel and biodiesel fuel blend decrease spray tip penetration, increase spray angle, and decrease velocity of spray and preheating temperature of fuel causes a decrease in the viscosity and density of the fuel blend, which affects the spray characteristics. acknowledgment the author would like to thank pt. pertamina tanjung wangi who have helped provide material, characterize, and helped a lot in our research. 142 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 135-144 arifin et al. 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[30] r. mahmud, t. kurisu, n. ilminnafik, k. nishida, and y. ogata, “wall heat flux on impinging diesel spray flame : effect of hole size and rail pressure at similar injection rate condition,” vol. 5, no 32, pp. 1-10, 2020, doi: https://doi.org/10.4271/2020-32-2313. https://doi.org/10.4271/2020-32-2313 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 61-68 61 doi: 10.17977/um016v1i22017p061 development of a ferrite-based electromagnetic wave detector muhammad hanis bin zakariah1,*, poppy puspitasari2, nur azliza ahmad3 1department of electrical and electronic engineering, universiti teknologi petronas, bandar seri iskandar, 31750 tronoh, perak darul ridzuan, malaysia 2department of mechanical engineering, engineering faculty, universitas negeri malang, semarang st. no 5, malang, east java, indonesia, 65140 3faculty engineering, mahsa university, saujana putra campus, 46210 jenjarom, selangor *mhanisz@gmail.com abstract direct detection of hydrocarbon by an active source using electromagnetic (em) wave termed sea bed logging (sbl) has shown very promising results. however, currently available electromagnetic wave technology has a number of challenges including sensitivity and lapsed time. our initial response to this issue is to develop a ferrite-based em wave detector for sea bed logging (sbl). ferrite bar and copper rings in various diameters were used as detector 1 (d1). for detector 2 (d2), toroid added with copper wires in different lengths at the centre of it were used. the first experiment is to determine the inductance and resistance for both detectors by using lcr meter. we obtained the highest inductance value of 0.02530 mh at the ferrite bar when it was paired with a 15 cm diameter copper ring and 0.00526 mh for d2 using a 100 cm copper wire placed at the centre of the toroid. the highest resistivity for d1 was measured at ferrite bar paired with a 15 cm diameter copper ring and 1.099 ω when using 20 cm length of copper wire. the second interest deals with voltage peak-to-peak (vp-p) value for both detectors by using oscilloscope. the highest voltage value at the ferrite bar of d1 was 25.30 mv. while at d2, the highest voltage measured was 27.70 mv when using a 100 cm copper wire. the third premise is the comparison of sensitivity and lapsed time for both detectors. it was found that d1 was 61% more sensitive than d2 but had higher lapsed time than d2.. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: sea bed logging, detector, sensitivity,lapsed time i. introduction in sbl, a mobile horizontal electric dipole (hed) source and an array of seafloor electric field receivers are utilised. the transmitting dipole emits a low frequency electromagnetic signal that propagates into the seabed [1]. the array of sea floor receivers measures both the amplitude and the phase of the received signal directly from the transmitter, and waves reflected and guided from the seabed. the received signal depends on the resistivity structure beneath the seabed [2]. characterisation and detection of the reservoir using sbl are based on the electrical conductivity consisting in all geological media. the principle of conductivity differencein geological media is applied in this technology [3]. besides its advantage in segregating a resistivity in a non-conductive layer and conductive formation beneath the sea floor, the electromagnetic method has a robustness characteristic against bad operating conditions such as high temperature and high pressure [4]. many types of electromagnetic detectors have been developed for use in this type of hydrocarbon detection method. however, currently available detectors have a number of challenges and one of them is the reading instability that can result in a misinterpretation. this could lead to the loss of significant investments. this paper describes the initial work to develop an em detector with high sensitivity and short recovery time for sbl. the first part of this work is to compare the sensitivity for both detectors. sensitivity of detectors is an important aspect for sbl method. in the previous work, electromagnetic detector was used to geophysically detect layer boundaries [5]. this workhas been done because difficulties exist in magneto telluric and geomagnetic depth sounding method; these methods are geophysical methods sensitive to mantle melt. the selection of detectors plays a major role to gain good detection results. since sensitivity was taken into account, another aspect that needs to be considered is lapsed time or recovery time. mailto:*mhanisz@gmail.com 62 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) the second premise dealt in this work is the determination of recovery time. in detail, em detector for sbl needs a higher sensitivity with a shorter lapsed time that can prevent any error in sbl’s further data processing. em detection system used to detect buried metallic in the soil [6] found errors in the data caused by uncertainties in sensor height. as a result, a fluctuation in data occurred. ] these two parameters are important for sensitive em detectors because with the decreasing of recovery times, the efficiency of the detector will increase. output of the em wave detected was not affected by a pile-up caused by incoming em wave. now we can look thoroughly to the magnetic hysteresis element of the magnetic material used in this work. hysteresis is a phenomenon in which the magnetic field lags behind the electric field [7]. details about the hysteresis will be reviewed more comprehensively in the results and discussion section. ii. materials and methods a 20-turn toroidal transmitter with an aluminium rod placed in the centre of the toroid was used in this work. it was supplied by 5 mhz frequency of square wave from a wave generator (textronic ax493). the distance between the transmitter and the detector was fixed at one meter, as described in figure 1 and figure 2. the properties of the transmitter are summarised in table 1. two types of em detectors were investigated. the responses from the detectors were then determined by measuring the induced voltage with an oscilloscope. fig. 1. block diagram of transmitter-detector system fig. 2. block diagram of transmitter-detector system table 1. transmitter properties transmitter parameters propertieses aterial toroid with 20 turns and aluminium rod in the centre of the toroid frequency 5mhz distance from detector 1 meter waveform square-shaped issn: 2580-0817 journal of mechanical engineering science and technology 63 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) fig. 3. detector 1 (d1) set up consisting of a of a ferrite bar and copper wire fig. 4. schematic diagram of d1 fig. 5. detector (d2) set up consisting toroid and copper wire fig. 6. schematic diagram of d2 table 2. properties of ferrite material manufactured by acme ferrite products sdn bhd (source: www.acme.com.my) term symbol conditions value unit initial permeability µ i 10khz 25oc 800 ± 25% max. magnetic flux density bm 50oe 25oc 3100 gauss residual magnetic flux density br 25oc 1/00 gauss 25oc coercive force hc 0.65 relative loss factor tan ɗ/ µi 25oc 0.15 mhz 10-3 electrical resistivity p dc 25oc ≥108 ωcm temperature coefficient 20oc.80oc ≤5 10-6k-1 curie temperature tc >150 oc density ρ 5000 kg/m3 two types of em wave detectors were selected in the present work. figure 2 and figure 3 show the arrangements of the two types of detectors used..in addition, their schematic drawings are presented in figure 4 and figure 5. http://www.acme.com.my) 64 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) table 3. properties of detector (d1 and d2). detector 1 (d1) detector 2 (d2) copper wire shape ring-shaped with variable diameter wire thickness 0.8mm with variable diameter 0.8mm with variable length location placed vertically around the ferrite bar placed at the centre of toroid toroid none id 1.5mm od 2.5mm type type d28 with constant electric source applied ferrite bar type d28 with 20 wind by copper wire (thickness 0.8mm) none table 3. describes the properties of both detectors. the diameter of copper ring in d1 varies from 7.5mm, 8.0mm, 9.0mm, 11.0mm, 13.0mm, 15.0mm, to 20.0mm. measurements of parameters for both detectors have been performed by using oscilloscope and lcr meter (instex lcr-16). parameters that we have put into consideration for both detectors were voltage peak to peak (vp-p), inductance (l), resistance, (r) and recovery time (t). moreover, measurements of vp-p have been carried out by using two oscilloscopes at the ferrite bar and copper ring; single function and both function operations were performed. table 3 shows the clear method of operating oscilloscope during the measurement of vp-p for d1. measurements of inductance (l) and resistivity (r) during detection period have been performed by using lcr meter at each ferrite bar and copper ring. detector 2 consisted of a small toroid as a magnetic feeder with a copper wire in the centre of it. a constant magnetisation was supplied by connecting 9v dry-cell battery to the toroid. copper wires (0.8mm thickness) with different set of length varying from 10cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm to 100 cm were placed in turn at the centre of magnetic feeder. the measurement of v p-p for detector 2 have been taken by using oscilloscope at both ends of copper wire which had been placed at the centre of toroid during receiving an electromagnetic wave from the transmitter. by using the lcr meter, the inductance and resistance value have been determined during the detection period of em wave. lapsed time measurement was performed to determine hysteresis effect by the following methods. when the detectors were exposed to em wave, the signal detected at the oscilloscope showed a proportional response (due to the properties of the detector). time taken by a signal detected at oscilloscope at the peak value (when the em source transmitter was on) was dropped off to the base line when em wave source (transmitter) is off were measured. iii. results and discussion. measurements of sensitivity and lapsed time for the two detectors (d1 and d2) were carried out using a ferrite-core material [11]. table 4 shows the results of vp-p gained from d1 with the changing of diameter of the copper ring. the experiment conducted with oscilloscopes was divided into two sections, i.e. single function operation and both functions operation. during the single function operation of oscilloscope at the ferrite bar, the highest vp-p value recorded was 45.60mv, which was using a 15.0-cm-diameter copper ring. however, it was drastically decreased when both functions operation of oscilloscopes was operated. table 4. vp-p measurement method for d1using oscilloscope. oscilloscope function single operation both operation ferrite bar operated operated copper ring non-operated operated ferrite bar non-operated operated copper ring operated operated issn: 2580-0817 journal of mechanical engineering science and technology 65 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) table 5. vp-p values for d1 diameter of copper ring (cm) vp-p (mv) single function operation vp-p (mv) both function operation ferrite ring ferrite ring 20.0 31.80 19.40 23.40 5.04 15.0 45.60 17.10 7.79 7.79 12.0 37.60 19.60 36.00 6.41 11.0 24.40 19.60 25.30 14.50 9.0 36.20 11.60 34.00 11.20 8.0 37.80 9.43 10.70 10.70 7.5 31.20 11.30 31.20 11.30 fig. 7. graph pattern for vp-p values for ferrite bar and copper ring from d1 during single operation of oscilloscope fig. 8. graph pattern for vp-p values for ferrite bar and copper ring from d1 during both operations oscilloscope. table 6. l, r and vp-p values for d1 diameter of copper ring (cm) l (mh) x 10 -2 r (ω) vp-p (mv) ferrite ring ferrite ring ferrite ring 20.0 2.36 2.08 1.90 5.00 23.40 5.04 15.0 2.53 1.86 8.97 7.24 7.79 7.79 12.0 2.33 1.80 2.61 2.69 36.00 6.41 11.0 2.35 1.66 3.02 3.20 25.30 14.50 9.0 0.19 23.50 1.37 1.80 34.00 11.20 8.0 2.35 1.63 1.91 2.55 10.70 10.70 7.5 2.34 1.75 1.21 2.35 31.20 11.30 in another work done on em wave logging system for determining resistivity and dielectric constant of earth formations [8], it was proved that the resulting magnetic fields produced by electromagnetic induction from a high frequency alternating current in the earth formations surrounding the well bore were detected at the spaced receiver coil by sensing the induced currents or voltages in the receiver coil caused by the secondary currents flowing in the formations. another former research found that when the copper ring and ferrite bar were exposed to an em wave, their existing electric fields were found to be proportional with em field [7]. the electric fields from ferrite bar and copper ring are supposed to enhance each other and lead to a higher value of vp-p during both function operations than during single function operation of oscilloscope. however, when both function of oscilloscope test was conducted, there was a significant decrease in vp-p at ferrite bar and copper ring to 7.76 mv both. this result (figure 3 and 4) showed that during detection period, the magnetic field from copper ring and ferrite bar could not enhance each other. besides, the testing result of wider diameter of copper ring was expected to meet a threshold limit at 66 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) a certain diameter of copper ring. the achieved threshold limit led to a conclusion that magnetic field at the ferrite bar is not affected by magnetic field of the copper ring. generally, the results of inductance (l), resistivity (r), and vp-p values for d1 are presentedin table 4. the table shows the results obtained from measurements by using oscilloscope and lcr meter. figure 7 and figure 8 show the results of inductance and resistivity values obtained from d1. as shown in figure 7 and figure 8, the average value of the inductance (l) and resistance (r) at the ferrite was higher than the one of l and r at copper rings. in measurement of electromagnetic and electric field for d2, figure 5 shows that resistivity was increased when the length of copper wire was increased as well. from the resistivity value, we concluded that an electric field existed. one important difference between electromagnetic poles and electric charges is that electric charges can be isolated, but magnetic poles always exist in pairs [9]. this was proven by inductance values indicatingthe strength of the magnetic field in d2. figure 12 shows the inductance values gained from lcr meter when electromagnetic field was applied. inductance can be described as a measurement of how much magnetic energy stored in the detector [10]. the use of 100cm copper wire in the centre of toroid generated the highest value of inductance (0.00526 µh), resistivity (0.9001 ω), and vp-p (27.70mv) fig. 9. graph pattern for inductance values for ferrite bar and copper ring from d1 fig. 10. graph pattern for resistance values for ferrite bar and copper ring from d1 table 7. inductance, capacitance, resistance and voltage p-p (vp-p) values of detector 2 (d2). length of wire (cm) inductance (µh) resistance (r) voltage (mv) 0 2.53 0.00 0.0 10 3.95 0.00 4.0 20 4.00 1.10 11.2 30 4.11 1.05 17.3 40 4.50 0.88 13.2 50 4.48 0.78 18.3 60 4.80 0.58 22.4 70 4.97 0.67 23.8 80 5.15 0.70 24.6 90 5.18 0.78 25.7 100 5.26 0.90 27.7 issn: 2580-0817 journal of mechanical engineering science and technology 67 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) fig. 11. graph pattern resistivity values from d2 fig. 12. graph pattern vp-p values from d2 fig. 13. graph pattern for inductance values from d2 the results of magnetic after-effect lapsed time measurements conducted in this work shows that d1 had a higher lapsed time than d2. it took more than 15 minutes to have vp-p decreased to zero value when the em wave was switched off. it significantly affected the performance of the d1 even though it had a high sensitivity. d2 took 2 seconds to return to a zero voltage. one important mechanism to result in a short lapsed time for detector is to avoid incoming continuous electromagnetic wave to pile up. iv. conclusions we have constructed a novel ferrite-based em wave detector for sbl application. from the two experiments conducted, we found that the sensitivity of d1 was much higher than d2 by 61%. on the other hand, d2 had a lower lapsed time than d1, making it an important aspect for sbl application. acknowledgement the author wishes to thank the sbl group of universiti teknologi petronas for providing the facilities and all colleagues who have previously provided technical support. we appreciate acme ferrite products sdn. bhd who has given support in provideing ferrite products used in this experiment. references [1] t. eidesmo, s.ellingsrud, l.m.macgregor, s.constable, m.c sinha, s.johansen, h.westerdahl, and f.n kong. remote detection of hydrocarbon filled layers using marine controlled source electromagnetic sounding. eage 64th conference & exhibition, florence, italy (2002). [2] geo expro (june 2004) the same principle as in borehole logging (pp. 28-30). [3] x c.halfdan, geo expro proving the concept(june 2004). 68 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 61-68 muhammad hanis bin zakariah1et.al (development of a ferrite-based electromagnetic) [4] f. keisuke. high-responsive inductive electromagnetic sensor (sept 2003), ieee transactions on magnetic, vol. 39, no. 5. [5] a.t daniel & a.t james. electromagnetic detection of a 410-km-deep melt layer in the southwestern united states (pp. 991-994), nature (21 june 2007)). [6] h. huang and i.j. won electromagnetic detection of buried metallic objects using quad-quad conductivity. geophysics vol. 69. no 6. [7] m.n.o sadiku. elements of electromagnetic. (pp. 336) oxford university press, new york. (2001). [8] l.l adams, t.p cox, a.f james, a.m richard, l.w thompson. electromagnetic wave logging system for determining resistivity and dielectric constant of earth formations. u.s patent documents: 2900595, 3900879, 3944910, 3993944 and 4012689. [9] fawwaz t. ulaby electromagnetic for engineers. (pp.16). pearson international edition, new jersey. (2005) . [10] t. eidesmo, s.ellingsrud, l.m.macgregor, s.constable, m.c sinha, s.johansen, h.westerdahl, and f.n kong. sea bed logging (sbl), a new method for remote and direct identification of hydrocarbon filled layers in deepwater areas. (pp.144-152) first break vol.20.3 (2002). [11] noorhana y, a. salwani., m.z hasnah, d. hanita, a. a. azizuddin and h. hasnidar (2008) . fabrication and phase, morphology and magnetic characterisation of nickel zink ferrite as an electromagnetic detector. unpublished (2008). journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 1-8 1 doi: 10.17977/um016v6i12022p001 passive prosthetic ankle design based on indonesian anthropometry wahyu dwi lestari department of mechanical engineering, faculty of engineering, university of pembangunan nasional “veteran” jawa timur, jl. raya rungkut madya, gunung anyar, surabaya, 60294, indonesia *corresponding author:wahyu.dwi.tm@upnjatim.ac.id article history: received: 31 august 2021 / received in revised form: 8 march 2022 / accepted: 20 april 2022 abstract foot prosthesis is a replacement for the foot to overcome activity limitations due to disease, birth defects, accidents, or amputations. many foot prosthetics have been developed in recent years to treat patients. however, prostheses on the market today have drawbacks, including their high price, lack of comfort, stiff ankles, and low durability. the main objective of this study is to develop an existing ankle-foot prosthesis design that approximates the resemblance of a human foot according to the anthropometry of asians, especially indonesians. this study contains the design of a prosthetic foot with a skin design model and a support core. the prosthetic core supports the use of a compliance mechanism (cm) model that functions to connect the limb organs that have been amputated. the design process is carried out using the solidwork software. ankle foot prostheses are designed to be able to withstand a load of 100 kg and can be used for patients with a height range of 150 cm to 180 cm. based on the design results, it is found that the prosthesis mass is lower than the lowest mass of the user, so it feels light, ergonomic, and flexible when used. copyright © 2022. journal of mechanical engineering science and technology. keywords: ankle-foot, anthropometry, compliant mechanism, design i. introduction feet are very important lower limbs, where the majority of functional activities of the human body are carried out by the feet, such as walking, exercising, cycling, and praying for a muslim. however, some circumstances such as trauma, accidents, blockage of blood flow, and the presence of congenital diseases that result in amputation make humans have lower limbs that are not good and healthy. one way to restore normal motion for amputees is to use a prosthesis. one of the most important parts of the foot prosthesis in both belowknee and above-knee amputations is the ankle-foot. several researchers have designed ankle-foot prostheses, including prostheses with small and thin designs [1], prosthesis with control device and electric drive source [2], and also prosthetics with springs, clutches, and motors [3]. however, these models still have shortcomings, including models that are too complex, difficult to use, heavy, and expensive, so that they are still difficult to reach for people in developing countries such as indonesia. departing from these problems, it is still necessary to design a foot prosthesis that is lightweight, easy to use, and inexpensive. one of the keys to designing a new prosthesis is patient response analysis. this is important because if the design made does not provide functional, practical, and aesthetic characteristics, it will cause discomfort for the patient. the characteristics of the ankle-foot prosthesis that are considered important by patients to support natural activities include 2 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) dorsiflexion, eversion, energy return, impact absorption, and ankle torsion. lack of understanding of ankle-foot biomechanics and the dynamic interactions between the amputated body and the prosthesis are major obstacles in designing new prostheses that mimic natural function and form. there are two types of ankle-foot prosthesis that are common in the market, namely passive and active movement types. passive prosthesis is very affordable for amputee rehabilitation. the type of active prosthesis is currently growing rapidly, but it still requires power to produce energy. passive prostheses include springs to ensure storage and energy, as well as dampers to suppress vibration. previous studies have considered an ankle foot prosthesis with a solid ankle-based cushioned heel model [4]. there are several criteria that must be considered in designing a passive type of ankle-foot prosthesis. the first is related to portability capacity, where the priority criteria are the size and lightness of the prosthesis. the second is the design of the prosthesis, which is simple and affordable. some researchers make and develop passive ankle-foot designs to get the prosthesis function in accordance with the normal human body. pham et al. [5] made an ankle-foot design with type of multi-axis fully compliant prosthetic ankle (mapca) and its biomechanical behavior using the finite element method. as a result, the design characteristics are more flexible and can reduce impact forces on the residual limbs. koehler-mcnicholas et al.[6]compared the performance of passive, hydraulic and nonhydraulic ankle-foot prosthesis in minimizing individual socket reaction moments with transtibial amputation during sideways walking activities. dao & le chau [7] analyzed the design of a passive prosthetic ankle-foot made of glass fiber reinforced plastic with biomechanics, simulation, and optimization. in this study, a compliant mechanism (cm) is used or also known as a flexibility-based mechanism. this type of cm has friction-free, no backlash, and monolithic fabrication, which is a special kind of mechanical engineering [8]. therefore cm has lightweight. the study of compliant mechanisms is new research on design. but it has potential in use because of its advantages when compared to rigid-body mechanisms. one of the advantages is in its durability, which has flexible properties that can return to its original position after being moved or released. in addition, it is lighter but stronger and cheaper. some researchers are also considering the ankle-foot design using a suitable mechanism. miller & childress [9] investigated the influence of vertical compliance prosthetic foot for various activities when used by persons with amputation. scholarsarchive & wiersdorf [10] develop design approaches and models for prosthetic ankle joints using kinematic models of the human ankle and compliant mechanism technology. maykranz & seyfart [11] developed the spring-loaded inverted pendulum (slip) model by extending with a foot segment and a compliant ankle joint. the purpose is to extend foot contact and the displacement of the center of pressure during contact. this research is to design an ankle-foot prosthesis by combining currently available prosthetic design elements to be developed into a new prosthesis. the newly designed anklefoot prosthesis will exhibit a wider range of properties and characteristics than existing ones. thus, the new ankle-foot prosthesis will better represent the functionally normal human foot. the development of the ankle-foot prosthesis design in this study is a model that is adapted to the anthropometry of asian people, especially indonesians who have a height between 150 cm to 180 cm. the design consists of an outer shell and a support core. this prosthesis is expected to be able to replace the function of the ankle-foot as it should by paying attention to anthropometric aspects. issn: 2580-0817 journal of mechanical engineering science and technology 3 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) ii. material and methods the prosthesis design is a process that starts from the discovery of the need for the prosthesis until the final design for the manufacture of a prototype. the process of making the ankle-foot design in this study begins with observing the prosthesis products on the market. observations were made to obtain information about the advantages and disadvantages of the product so that further product development can be carried out. the need for repair of the prosthesis product that is needed based on the observations is related to the size, shape, and weight of the product. the solution to the problem taken in this study is to make an ankle-foot design based on anthropometry of asians, especially indonesians (table 1). the steps in making this ankle foot design are shown through the flow diagram in figure 1. start literature review design criteria design making does it fit the design criteria design finalization finish yes no fig. 1. research flow chart based on the flow chart in figure 1, it is necessary to select criteria for the development of the ankle-foot design. the selection of these criteria is based on pre-existing prosthesis problems. the list of ankle-foot design criteria used as the final goal in this study is presented in table 2. 4 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) table 1. anthropometry of indonesians [14] criteria minimum dimension maximum dimension height 150 cm 183 cm weight 39.8 cm 93.45 cm popliteal height 36 cm 50 cm knee height 42 cm 62 cm leg length 21 cm 29 cm feet width 7 cm 12 cm table 2. design criteria of ankle foot criteria description strength able to withstand weight up to 100 kg altitude setting ability the prosthesis can be used by both men and women with the provisions of a height between 150 cm 180 cm light has a lighter mass than the real leg, which is less than 2.2686 kg [13] convenience easy to return to a horizontal position when used in walking or standing conditions types of prosthesis compliant mechanism (the design of the fake sole almost resembles the sole of a human foot in general) durability has a safety factor of four times the maximum load received a. load analysis of ankle foot in making of the ankle-foot design, the maximum human weight is needed to determine the prosthetic foot strength. the prosthesis design is required to have a lower mass than the part of the amputated leg. according to rajput et al [8] the weight of the leg below the knee has a weight of 5.7% of the human body weight. meanwhile, according to chuan et al [12], the maximum human weight is calculated based on newton's 3rd law, namely: f = m x g (1) where f denotes the force in newtons (n), m is the mass (kg), and g is the gravitational force of the earth (m/s2). the maximum weight of the prosthesis in this study was calculated based on the formula below: maximum mass = 5.7% x lowest mass of indonesians (2) where the lowest mass is taken from the anthropometric data that has been obtained. the lowest value is taken because if the highest weight is taken, it will make users who have lower body weight have difficulty in using the prosthesis. based on the criteria in this study, the user's lowest mass is 39.8 kg, so the ankle-foot prosthesis product must have a maximum mass of 2.2686 kg. b. design specification the ankle foot design must have elastic properties that are easy to move to carry out daily activities like normal feet. the material used in the ankle foot skin design is silicon rubber. silicon rubber is a type of synthetic polymer that has several physical properties that issn: 2580-0817 journal of mechanical engineering science and technology 5 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) are not found in other types of polymers. these physical properties have very special functions and advantages including environmental resistance, extreme temperatures resistance, stability, and non-toxicity. these properties make silicon material suitable for artificial feet and can be shaped to mimic human feet. furthermore, the material used in the support core must strong, light, and flexible properties as a support, so it's easy to make intensive moves. in this study, we analyze three types of materials to be used in the support core, namely aisi 304, pom (polyoxymethylene), and abs (acrylonitrile butadiene styrene). from these three types of materials will be taken into consideration to choose the lightest material after going through assembly process with the outer skin of the ankle-foot. the properties of each material are shown in table 3. table 3. materials properties [14] material property density (kg/m 3 ) young’s modulus (mpa) poisson’s ratio yield strength (mpa) silicon rubber 2330 5000 0.28 120 abs 1020 2300-2750 0.37 26.84 pom 1560 2900-3500 0.42 75.8 aisi 304 8000 193000 0.29 241 c. design of ankle foot the ankle-foot design in this study was made by developing designs that have been circulating in the market before. the ankle-foot design is made to mimic the human foot in visual using predetermined dimensions. the ankle-foot design is made up of two types, namely the skin part and the core support, which are assembled into one. improvements made in the development of this ankle foot design are in the geometric dimensions. geometry measurements on the skin are obtained from the scan results using the creaform, ametex. the measurement results of the ankle-foot skin geometry from the scan process are shown in figure 2. the support core geometry is obtained from the design process using the solidwork 2017 software. this support core serves to strengthen the prosthesis when it is in a supporting condition and will provide encouragement when going to step. the design of the skin and supporting core in this study is presented in figure 3. and the design after assembly is shown in figure 4. fig. 2. foot scan measurement (unit length in mm) 6 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) a b fig. 3. the design of (a) skin part, and (b) supporting core of ankle foot fig. 4. assembly of ankle-foot design iii. results and discussion ankle foot prosthesis is very influential for a person with a disability or foot amputation patient in carrying out daily activities, such as walking normally, going up and downstairs, cycling, or performing prayer movements. the ankle-foot design in this study is a development of a pre-existing prosthesis. this development aims to improve the ergonomics of the product, so that it will support the comfort of prosthesis users in carrying out activities. the development is carried out on technical specifications, including geometric design and the type of material used. design development begins with an anthropometric study of prosthesis users to obtain information on improving technical specifications and obtaining products that meet the criteria through evaluation and design alternatives. based on literature studies, data were obtained from human body weight of 89.5 kg and the lowest human weight of 39.8 kg. human body weight is used as a consideration in designing the ankle-foot strength, where the artificial ankle-foot must be able to withstand the maximum weight of the user. in this study, it was determined that the design criteria of the ankle-foot must be able to withstand a human body weight of 100 kg, and have a maximum mass of 2.2686 kg. after modeling using cad software, the ankle-foot design was obtained that matched the criteria, as shown in figure 3(b). there are several changes when compared to the existing design, including the toe tip to the instep that is designed to be curved like the anklefoot of a human. it aims to smooth the movement when stepping from the midstance position to the toe-off. the curved shape can also provide additional thrust as the cycle moves from stance phase to swing phase. furthermore, the hollow design is an application of the compliant mechanism model, where its function is to provide flexibility when the walking issn: 2580-0817 journal of mechanical engineering science and technology 7 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) cycle movement is carried out. the ankle-foot design was made based on the lowest mass from the anthropometric data of the prosthesis user. the manufacture of this support core is useful as a helper for lifting power against the load from the top of the prosthetic foot. based on the design analysis, the lowest mass of the ankle-foot prosthesis made is owned by the pair of foot skin products and the supporting core made of abs. the mass measurement result of the ankle-foot prosthesis in each assembly is presented in table 4. table 4. ankle foot prosthesis mass ankle foot prosthesis mass (grams) silicon + abs 63.53 silicon + pom 97.17 silicon + aisi 304 498.29 v. conclusions the prosthesis should be lightweight, durable, and skin-friendly. the combination of intelligent design and materials with a good understanding of the patient's needs, will make the design of the prosthesis more similar to the function and shape of the normal body part. this study presents the ankle-foot design.the new ankle foot design adopts a compliant model mechanism with the aim of making the foot more flexible in walking movements. based on the research, the design is below the specified criteria, so it can be said that the model has a lightweight nature. the dimensions of the ankle foot prosthesis are based on anthropometric data, so this design is said to be more ergonomic and flexible when viewed from the mass of the prosthesis. the design innovations carried out show that the prosthesis can be used by asian people, especially indonesia with a height range of 150 cm to 180 cm and a weight of 39.8 kg to 100 kg. acknowledgment the authors would like to acknowledge for the financial support from the lppm university of pembangunan nasional veteran jawa timur under risda (riset dasar) grant. references [1] w. l. childers and k. z. takahashi, “increasing prosthetic foot energy return affects whole-body mechanics during walking on level ground and slopes,” sci. rep., vol. 8, no. 1, pp. 5354, 2018, doi: 10.1038/s41598-018-23705-8. [2] d. p. allen, r. little, j. laube, j. warren, w. voit, and r. d. gregg, “towards an ankle-foot orthosis powered by a dielectric elastomer actuator,” mechatronics, vol. 76, 2021, doi: 10.1016/j.mechatronics.2021.102551. [3] o. kirtas, y. savas, m. bayraker, f. baskaya, h. basturk, and e. samur, “design, implementation, and evaluation of a backstepping control algorithm for an active ankle–foot orthosis,” control eng. pract., vol. 106, 2021, doi: 10.1016/j.conengprac.2020.104667. [4] s. debta and k. kumar, “static structural analysis of a powered ankle foot prosthesis mechanism,” mater. today proc., vol. 5, no. 5, pp. 11616–11621, 2018, 8 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 1-8 lestari (passive prosthetic ankle design based on indonesian anthropometry) doi: 10.1016/j.matpr.2018.02.131. [5] h. t. pham, m. n. le, and v. t. mai, “a novel multi-axis compliant prosthetic ankle foot to support the rehabilitation of amputees,” proc. 3rd int. conf. green technol. sustain. dev. gtsd 2016, pp. 238–243, 2016, doi: 10.1109/gtsd.2016.61. [6] s. r. koehler-mcnicholas, e. a. nickel, j. medvec, k. barrons, s. mion, and a. h. hansen, “the influence of a hydraulic prosthetic ankle on residual limb loading during sloped walking,” plos one, vol. 12, no. 3, pp. 1–18, 2017, doi: 10.1371/journal.pone.0173423. [7] t.-p. dao and n. le chau, passive prosthetic ankle and foot with glass fiber reinforced plastic: biomechanical design, simulation, and optimization. springer singapore, 2019. doi: 10.1007/978-981-13-9977-0_6. [8] s. rajput, h. burde, u. s. singh, h. kajaria, and r. k. bhagchandani, “optimization of prosthetic leg using generative design and compliant mechanism,” in materials today: proceedings, 2021, vol. 46, pp. 8708–8715. doi: 10.1016/j.matpr.2021.04.026. [9] l. a. miller and d. s. childress, “analysis of a vertical compliance prosthetic foot,” j. rehabil. res. dev., vol. 34, no. 1, pp. 52–57, 1997. [10] b. scholarsarchive and j. m. wiersdorf, “preliminary design approach for prosthetic ankle joints using compliant mechanisms,” theses and dissertations, 2005. [11] d. maykranz and a. seyfarth, “compliant ankle function results in landing-take off asymmetry in legged locomotion,” j. theor. biol., vol. 349, pp. 44–49, 2014, doi: 10.1016/j.jtbi.2014.01.029. [12] t. k. chuan, m. hartono, and n. kumar, “anthropometry of the singaporean and indonesian populations,” int. j. ind. ergon., vol. 40, no. 6, pp. 757–766, 2010, doi: 10.1016/j.ergon.2010.05.001. [13] s. tayyari, “occupational ergonomics,” occup. ergon., vol. 3, p. 6221, 2017, doi: 10.4324/9780203484913. [14] g. kaur and s. pavia, “physical properties and microstructure of plastic aggregate mortars made with acrylonitrile-butadiene-styrene (abs), polycarbonate (pc), polyoxymethylene (pom) and abs/pc blend waste,” j. build. eng., vol. 31, 2020, doi: 10.1016/j.jobe.2020.101341. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 36-46 36 doi: 10.17977/um016v5i12021p037 effect of dcrp and dcsp polarity on the depth of penetration of smaw on low carbon steel astm a36 using e7018 electrode ma'mun hidayat1, helleni febnesia2, sulaeman deni ramdani3 1central for development of vocational serang, ministry of manpower, jl. raya pandeglang no. 3, 42118, serang, indonesia 2.3mechanical engineering education, sultan ageng tirtayasa university, jl. ciwaru raya no.25, 42117, serang, indonesia *corresponding author: s.deni.ramdani@untirta.ac.id abstract the study aims to determine the level of penetration depth using smaw (shielded metal arc welding) process based on the polarity type of dcrp (direct current reverse polarity) and dcsp (direct current straight polarity). this research used astm a36 low carbon steel plate with thickness of 6 mm and length of 200 mm, electrode e7018 lb-52-18 ∅ 3.2 mm, and with current parameters of 90 a, 100 a, 110 a, 120 a and 130 a and 70 ° welding arc angle. the method used the experimental research. data collection techniques applied direct observation techniques and descriptive statistical data analysis techniques. testing the penetration depth of the welds with a macrographic test was conducted by an optical microscope. the test results show that dcrp has more depth than dcsp when the current is 90 a with a difference of 0.38 mm. when the current is 100 a, dcrp is deeper with a difference of 0.312 mm compared to dcsp. the third experiment, with a current of 110 a dcrp, was deeper with a difference of 0.05 mm compared to dcsp. during the fourth and fifth experiments, dcrp was deeper with a difference of 0.21 mm compared to dcsp at 120 a and dcrp was 0.324 mm deeper than dcsp at 130 a. it can be concluded that the effect of dcrp and dcsp polarity on the depth of penetration using e7018 electrodes and astm low carbon steel a36, dcrp polarity has a deeper penetration depth compared to dcsp. copyright © 2021. journal of mechanical engineering science and technology. keywords: dcrp, dcsp, macrographic test, penetration depth, smaw i. introduction in current era, the development of the technology sector was accompanied by the development of the industrial and construction sectors [1]. the industrial and construction sectors certainly cannot be separated from the welding process. welding is a process of joining two materials permanently by melting two materials that will be joined with added material or not, which will cool together to become welding deposits [2]. the welding process belongs to a special process classification because the process and its manufacture are directly related to the quality of the final product. failure of the weld joint is fatal, meaning that if the weld joint is not suitable, it can be classified as a failure of the product itself [3]. one of the welding processes, namely shielded metal arc welding or commonly abbreviated as smaw, is a welding process that uses a heated metal arc to melt into molten metal as an added material and blend with the specimen material being welded [4]. the smaw welding process is a process that is often used because it is simple and has a relatively low cost in the preparation of workpieces, materials and personal protective 37 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) equipment (ppe) [5]. the welding process can occur due to obstacles that flow between the material and the added material, which causes heat so that the materials and added materials will melt and coalesce and cool together [2]. as a result of the process, the metal in the vicinity of the weld undergoes rapid thermal cycling and causes complex metallurgical changes, deformations, and thermal stresses [6][7]. therefore, it is closed to the problem of toughness, weld defects, cracks, and others, which generally have a fatal impact on the safety of construction welding. so, the deeper the penetration, the more the fusion between the material and the added material. it will also affect the strength of the weld [3]. the area affected by the thermal when the arc ignites from the welding process is called the penetration. penetration consists of a mixture of specimen metal and added material from the welding arc in the welding process [8]. to get the best welding results, it required careful preparation. the welding process starts from the preparation of materials and tools to cooling the material, which greatly determines the quality of the weld. preparation processes include creating welding process stages, and the quality of the tools and materials [1]. the welding process results in the emergence of residual stress in the form of stress in the fusion zone and haz (heat affected zone) and tensile stresses in the weld area [8]. the haz is an area of the specimen metal adjacent to the added material in the welding process, which undergoes a thermal cycle of heating and cooling with a certain time and speed [4]. the smaw welding process is at the top of the cluster in the fusion welding process due to its flexibility and cost-effectiveness. this process is needed to construct steel-framed buildings, shipbuilding, motor vehicle manufacturing, power plants, and other industries [6]. of course, welding in the shipbuilding construction sector has a very important role [1]. in the field of shipbuilding, welding functions as a process that connects ship parts that have been designed in such a way and connect when the repair process occurs on the ship [6]. the results of welding with the right methods and conditions will increase the results of the increasingly fused welds. astm a36 is a type of low carbon steel commonly applied in welding and power plant construction. astm a36 low carbon steel is one of the commonly applied as structural hotrolled steels. the type of carbon steel material has special characteristics which are relatively inexpensive and highly recommended for the welding process [9]. astm a36 carbon steel plate is included in the mild carbon steel category because it has good enough strength, and its shape can be changed easily by a machine or by the smaw welding process [9]. another advantage of astm a36 low carbon steel plate is that it can accept the galvanic coating process, leading to high-quality iron resistance from corrosion [4]. electric polarity is divided into 3 types, namely alternating current (ac) polarity, direct current polarity (dcrp & dcsp). in the current study, the welding process uses smaw using dcrp and dcsp polarity. dcsp (direct current straight polarity) is when the electrode handlebar is connected to the negative pole of the welding machine while the positive pole is connected to the material to be welded. dcrp (direct current reverse polarity) is when the electrode handlebar is connected to the positive pole of the welding machine while the negative pole is connected to the material to be welded [10]. several studies stated that dcrp and dcsp resulted in a temperature difference of 4200°c and 3800°c [8]. another factor that affects the polarity of dcrp results in deeper penetration of 2/3 compared to a dcsp of 1/3 due to the flow of electrons flowing from the positive pole of the welding machine to the negative pole while the negative ions coming from the negative pole to the positive pole welding machine. this process affects the heat distribution that occurs in the welding process [11]. issn: 2580-0817 journal of mechanical engineering science and technology 38 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) direct current has the characteristic of a stable electric flow so that it is easy to use in the smaw welding process, especially on thin metals. the temperature produced by the dcrp polarity and the dcsp polarity is 4200°c and 3800°c, respectively. the data indicates that the dcrp polarity will have deeper penetration than the dcsp polarity because the heat impact exerted by the dcrp polarity is greater than that of dcsp [8]. welding wire or electrodes is an added material in the smaw binder process. many welder use the type of electrode e7018 lb-5218 with a diameter of 3.2 mm. in accordance with the electrode code e7018, the electrode is included in the type of low hydrogen electrode. the number 70 in e7018 shows the minimum tensile strength of 70 ksi. number 1 on the e7018 indicates that electrode can be applied for various welding positions [12]. the last number on the e7018 shows the type of electrode as well as its composition and use of the welding current, meaning that the number 8 shows that the low-hydrogen electrode type is made of iron powder [12]. e7018 electrode storage in a dry and airtight place. it is recommended to use the oven at 300°c 350°c for 30-60 minutes [13]. the electrode with type e7018 consists of a layer of high calcium carbonate (limestone) and calcium fluoride (fluorspar). they can make the slag layer more fluid than rutile coating. this is the reason why the process of cooling and freezing welds in a vertical overhead position is faster. these electrodes are applied for welding fabricated parts where higher weld quality, good mechanical properties and resistance to cracking are required because of the high strain required [14]. the study aims to prove the effect of polarity on the depth of penetration in the smaw welding process using e7018 lb 52-18 electrodes ∅ 3.2 mm, and astm a36 low carbon steel with an electric current of 90 a, 100 a, 110 a, 120 a, and 130 a with a welding arc angle of 70°. ii. material and method the study used an experimental research method. the observation technique which is done is direct observation technique by descriptive data analysis technique. the direct observational observation technique means that the researcher observes the research process directly. while the technique of descriptive statistical data analysis means that the researcher describes the research results that have been tested. testing of speciment was conducted by macrographic testing or commonly known as macrostructure testing. the experiment study uses two astm a36 low carbon steel plates with a thickness of 6 mm with a length of 200 mm, and the type of electrode e7018 lb-52-18, which has a diameter of ∅3.2 mm. the tools in the welding process are welding helmets, hand gloves, safety wear packs and lincorn electric welding machines with the speedtec 405sp type. the tools and materials during the testing process are autosol liquid, etching solution, rags, cutting machines, grinding machines, and optical microscopes as instruments in macrostructure testing. the location of the data collection process uses the smaw welding process. which is carried out at the smaw workshop, bbplk serang. the testing process uses macro structure testing, which is carried out at the ndt testing building, bbplk serang. data collection techniques used direct observation techniques with descriptive statistical data analysis. the steps in the research process to determine the effect of dcrp and dcsp polarity in smaw welding on penetration depth of astm a36 low carbon steel plate using e7018 lb-52-18 electrodes is shown in figure 1. the initial stage of study was to determine the problem and the objectives that want to be achieved. this study was conducted to determine the effect of polarity on the depth of penetration in the smaw using electrode e7018 lb-52-12 ∅3.2 mm with a welding arc tilt 39 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) angle of 70° and the macrographic test used an optical microscope with a variation. the electric currents applied in welding were 90 a, 100 a, 110 a, 120 a, 130 a. start determine the problem topic and purpose preparation for literature studies, tools and materials welding process and data retrieval preparation for macrographic test macrographic test result of macrographic result data analysis conclusion finish fig. 1. flowchart of research design in the process of data collection, the tools and materials must meet the feasibility standard. the tools in this study were a set of smaw welding machines, wear packs, welding helmets, hand gloves, slag hammers, steel brushes, cloth wipes, automatic cutting machines, grinding machines, 2 drop pipettes and optical microscopes, which are carried out for macrostructure testing. the materials in the data collection and testing process were two astm a36 low carbon steel plates with a thickness of 6 mm and 200 mm, 1 box electrode e7018 lb-52-18, sandpaper with a roughness level of 100 400 grit, autosol, nitric acid, and alcohol. the data collection process was carried out by direct observation with a predetermined standard welding instrument. the standard of welding results determined, namely the length of the welding line must be straight with a length of 200 mm, interpass <200 °c, no visual issn: 2580-0817 journal of mechanical engineering science and technology 40 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) welding defects. collecting data applied the direct observation technique that the researcher directly observes and records all phenomena during the data collection process. data were collected by measured the depth of penetration of each specimen. specimen preparation applied a sandpaper and polishing machine that used sandpaper with various levels of fineness to 400 grit which functions to smooth the area of the specimen to be tested. testing the macrostructure itself is part of the metallographic process. macro or macrographic structure testing is a test that is carried out to study the structure of metals and their alloys directly by the eye or lenses that are magnified up to 20 times (20: 1) [15] [16]. the results of testing of macro or macrographic structure are called macrostructure. the function of metallographic test is to determine the main structure of the specimen metal, the haz area and the area of penetration or penetration. macrographic test puts more emphasis on the visual state of the specimen at a more detailed scale than with the naked eye [15]. in macrographic test process, initially, the specimen to be tested was cut according to the conditions and position of the specimen to be observed. then the sanding and polishing process with sandpaper up to 400 the polishing stage also the grits. in autosol metal polish then the final stage is polished with an etching solution consisting of 98% ethanol and 2% nitric acid, then cleaned with running water and cloth [17]. the etching solution serves to cause phase or grain boundaries in the specimen area. then, process use an optical microscope which has a magnification up to 15 times for observing the specimen structure more clearly. the data analysis technique in the study was the quantitative descriptive data analysis technique. the resulting data was a comparison of the value of the penetration depth between dcsp and dcrp for each of the current variations of 90 a, 100 a, 110 a, 120, and 130 a. iii. results and discussions the experimental was carried out in smaw welding process with two types of polarity, namely dcrp and dcsp, with electrodes of e7018 lb-52-18 ∅3.2 mm and a length of 200 mm, low carbon steel astm a36, a welding arc angle of 70°, and a large variation of current 90 a, 100 a, 110 a, 120 a, and 130 a. in the data collection process, the amount of voltage, travel speed and interpass temperature lower than 200°c were used as supporting data to measure the depth of penetration. the results of the welding process are shown in table 1 and table 2. table 1. data travel speed, interpass temperature and amount of voltage (dcrp) voltage welding current travel speed interpass temperature 22.2 v 90 a 126.32 mm/min 26.3 °c 24.1 v 100 a 133.33 mm/min 89.6 °c 24.5 v 110 a 155.84 mm/min 184.3 °c 24.6 v 120 a 150 mm/min 166.6 °c 25.6 v 130 a 171.43 mm/min 177.9 °c 41 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) table 1 and table 2 show the greater the current, the greater the voltage and travel speed and the resulting interpass temperature. for comparison, the travel speed dcsp has a speed which is greater than the polarity type dcrp, but for a large comparison the dcrp voltage has a large voltage compared to dcsp. table 2. data travel speed, interpass temperature and amount of voltage (dcsp) after collecting the data during the welding process, then the macrographic observation was carried out under an optical microscope to look at a depth of penetration of the welding process. observation results is ahown at table 3 and table 4. table 3. data of penetration depth dcrp table 3 shows the depth of penetration in the smaw welding process with various type of polarity dcrp. in experiment dcrp 1.1, the resulting penetration depth is 1.38 mm when the current is 90 a (figure 2), 1.46 mm when the current is 100 a (figure 3), 1.45 mm when the current is 110 a (figure 5), 1.57 mm when the current is 120 a (figure 5), and 3, 38 mm when the current is 130 a (figure 6). the test results tend to continue to experience an increase in penetration depth and the increase in current magnitude. but there was a decrease that was not too significant when the current was 110 a with a decrease in the depth level of 0.01 mm. it is indicated as a human error because the results are not significant. voltage welding current travel speed interpass temperature 22.5 v 90 a 153.85 mm/min 28.9 °c 22.7 v 100 a 136.36 mm/min 12.3 °c 22.9 v 110 a 160 mm/min 158.5 °c 23.7 v 120 a 176.47 mm/min 122.4 °c 23.9 v 130 a 196.72 mm/min 131.5 °c dcrp 90 a 100 a 110 a 120 a 130 a 1.1 1.38 1.46 1.45 1.57 3.38 1.2 1.66 1.82 1.82 2.02 2.57 1.3 1.62 1.71 1.71 2.21 2.18 1.4 1.46 1.64 1.64 1.97 2.06 1.5 1.47 1.56 1.59 2.11 2.06 total 7.59 8.19 8.21 9.88 12.25 average 1.518 1.638 1.642 1.976 2.45 *units in (mm) issn: 2580-0817 journal of mechanical engineering science and technology 42 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) fig. 2. penetration depth 1.1 when current 130 a fig. 3. penetration depth 1.2 when current 130 a fig. 4. penetration depth 1.3 when current 130 a fig. 5. penetration depth 1.4 when current 130 a fig. 6. penetration depth 1.5 when current 130 a in the second, third, fourth and fifth experiments, when the currents were 100 a, 110 a, 120 a and 130 a, it always had a deeper penetration depth as the current strength increased. the influence of these current is due to the fact that the welding process greatly affects the mechanical properties and the tensile strength of the welded steel tends to decrease, but the toughness of the material increases because it increases the percentage of the acicular ferrite phase. because if the greater the current given to the welding process, it will increase the angle of distortion that occurs in the welding results. 43 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) fig. 7. penetration depth 2.1 when current 130 a fig. 8. penetration depth 2.2 when current 130 a fig. 9. penetration depth 2.3 when current 130 a fig. 10. penetration depth 2.4 when current 130 a fig. 11. penetration depth 2.5 when current 130 a table 4 that shows the results of the depth of penetration in smaw welding process at various type of polarity dcsp. in experiment dcsp 2.1, the resulting penetration depth is 1.29 mm when the current is 90 a (figure 7), 1.3 mm when the current is 100 a (figure 8), 2.14 mm when the current is 110 a (figure 9), 1.93 mm when the current is 120 a (figure 10) and 2, 3 mm when the current is 130 a (figure 11). the test results tend to continue to experience an increase in penetration depth and the increase in current magnitude. but there was a decrease that was not too significant when the current was 120 a with a decrease in the depth level of 0.28 mm. it is indicated as a human error because the results are not significant. issn: 2580-0817 journal of mechanical engineering science and technology 44 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) in the second, third, fourth and fifth experiments in table 4, when the currents were 100 a, 110 a, 120 a and 130 a, it always had a deeper penetration depth as the current strength increased. the influence of these current is due to the fact that the welding process greatly affects the mechanical properties, and the tensile strength of the welded steel tends to decrease, but the toughness of the material increases because it increases the percentage of the acicular ferrite phase. because if the greater the current given to the welding process, it will increase the angle of distortion that occurs in the welding results. table 4. data of penetration depth dcsp * units in (mm) table 5 and figure 12 show that the depth of penetration is based on the type of polarity of dcrp and dcsp observed by a macrographic test with an optical microscope tool. the results show that the polarity of dcrp at 90 a has a depth of 1.518 mm and a difference of 0.38 mm is deeper than dcsp, which only has a depth of 1.138 mm, the polarity of dcrp at 100 a has a depth of 1.638 mm and a difference of 0.312 mm is deeper than dcsp which only has 1.326 mm depth. table 5. average penetration depth current dcrp dcsp difference in depth 90 a 1.518 1.138 0.380 100 a 1.638 1.326 0.312 110 a 1.642 1.592 0.050 120 a 1.976 1.766 0.210 130 a 2.450 2.126 0.324 * units in (mm) dcrp polarity at 110 a has a penetration depth of 1.642 mm and a difference of 0.05 mm deeper than the dcsp which only has a depth of 1.592 mm. the polarity of dcrp at 120 a has a depth of 1.976 mm and a difference of 0.21 mm is deeper than dcsp which only has a depth of 1.766 mm. dcrp polarity at 130 a has a depth of 2.45 mm and a difference of 0.324 mm is deeper than dcsp which only has a depth of 2.126 mm. dcsp 90 a 100 a 110 a 120 a 130 a 2.1 1.29 1.30 2.14 1.93 2.30 2.2 0.95 1.18 1.46 1.84 2.23 2.3 1.03 1.43 1.80 1.81 2.13 2.4 1.18 1.30 0.98 1.54 1.97 2.5 1.24 1.42 1.58 1.71 2.00 total 5.690 6.630 7.960 8.830 10.630 average 1.138 1.326 1.592 1.766 2.126 45 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) 1 .5 1 8 1 .6 3 8 1 .6 4 2 1 .9 7 6 2 .4 5 0 1 .1 3 8 1 .3 2 6 1 .5 9 2 1 .7 6 6 2 .1 2 6 0 500 1.000 1.500 2.000 2.500 3.000 9 0 a 1 0 0 a 1 1 0 a 1 2 0 a 1 3 0 a u n it s (m m ) ampere dcrp dcsp overall results show that the depth of penetration in the polarity type dcrp is deeper than the polarity of the dcsp type. it is in accordance with the previous explanation that the polarity of dcrp produces a temperature of 4200 °c compared to dcsp, which only produces a temperature of 3800 °c. fig. 12. comparison of depth penetration dcrp and dcsp iv. conclusions the effect of polarity dcrp (direct current reverse polarity) and dcsp (direct current straight polarity) on the penetration depth of smaw (shielded metal arc welding) welding using electrode e7018 lb-52-18 3.2 mm with an arc welding angle of 70° and the use of carbon steel astm a36 is low using dcrp is deeper at each current level. the influence of the current magnitude also affects the penetration results. if the current is higher, it will get a deep penetration result. the depth of deep penetration will make the value of the strength of the weld increase. references [1] putra, a., and wulandari, d., “effect of welding polarity and electrode type on tensile strength and toughness of smaw welding,” j. pendidik. tek. mesin unesa, vol. 6(01), 250958, 2017 (in indonesia). [2] santos, s., jaganathan, s., anantha, r., l, and balmurugan, m., “experimentation and comparative study of e6013 and e7018 weldments using shielded metal arc welding e7018 weldments using shielded metal arc welding,” int. j. mech. prod. eng. res. dev., vol. 8, pp. 174, 2018. [3] kumar, b.,s., p., and vijayakumar, y., “selection of optimum process parameters of shielded metal arc welding (smaw) to weld steel pipes by design of experiments,” intern. j. of engineering research and applications, vol. 2(5), pp. 377–381, 2012. [4] kahfi, a., “pengaruh kuat arus terhadap hasil pengelasan las gmaw pada baja issn: 2580-0817 journal of mechanical engineering science and technology 46 vol. 5, no. 1, july 2021, pp. 36-46 hidayat et al. (effect of dcrp and dcsp polarity on the depth of penetration of smaw) astm a36,” j. ilm. tek. mesin, vol. 7(1), pp. 1–53, 2016. [5] pathirana, s.d., weerasekralage, l. s. s. k, and karunaratne, m., “optimization of shielded metal arc welding (smaw) process for mild steel", transaction part b: technical paper. annual sessions of iesl, pp. 841 847, 2019. [6] sulaiman, s. a., abdullah, b., alias, s. k., ahmad, n. n., and aziz, m. n. a., “investigation of corrosion rate for different type of welding joints using shielded metal arc welding (smaw),” iop conf. ser. mater. sci. eng., vol. 834(1), 2020, doi: 10.1088/1757-899x/834/1/012055. [7] pagare, r., awati, d., mane, s., teli, v., and bhandare, a., “investigating the effects of welding parameters on mild steel by smaw technique,” iop conf. ser. mater. sci. eng., vol. 998(1), 7, 2020, doi: 10.1088/1757-899x/998/1/012052. [8] surasno, “analisa polaritas terhadap kedalaman penetrasi dan dilusi dari proses smaw pada baja karbon rendah astm a36.” berita teknologi bahan dan barang teknik, p. 10, 2005. [9] rahangmetan, k. a., wullur, c. w., and sariman, f., “effect variations and types of smaw welding electrodes on a36 steel to tensile test,” j. phys. conf. ser., vol. 1569 (3), 6, 2020, doi: 10.1088/1742-6596/1569/3/032052. [10] howard, h., and gerrish, “electricity and electronics,” good hear. co, inc., 1968. [11] ambiyari, teknik pembentukan plat, vol. 53(9), 2019. [12] american welding society, specification for carbon steel electrodes for shielded metal arc welding. american welding society i. 2004. [13] kobe-steel, “kobelco welding handbook, welding consumables and processes,” 2008. [14] suherman, s., muhammadiyah, u., utara, s., and mizhar, s. “effect of electrode on welding joint of steel sa106 grade a using smaw,” rotasi, vol. 22, p. 252, 2020, (in indonesia). doi: 10.14710/rotasi.22.4.246-252. [15] hatta, i., “aplication of micro analysis and fractograhy to determine the product quality and cause of damage of component,” pros. pertem. ilm. ilmu pengetah. dan teknol. bahan, vol. 30(c), pp. 175–180, 2012 (in indonesia). [16] sari a. l., and rusiyanto, r., “effect of thermal shock resistance and composition of refractory materials on impact strength and macro structure,” j.din. vokasional tek. mesin, vol. 4(2), pp. 105–110, 2019 (in indonesia). doi: 10.21831/dinamika.v4i2.27392. [17] asm handbook, “metallography and microstructures,” vol. 9, asm international, 2004. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 1-9 1 doi: 10.17977/um016v7i12023001 mechanical properties of biocomposite with various composition of caco3 and starch agris setiawan*, fransisca diana wahyuningsih, riria zendy mirahati department of metallurgical engineering, faculty of mineral technology, universitas pembangunan nasional veteran yogyakarta, yogyakarta, indonesia, 55281 *corresponding author:agrissetiawan@upnyk.ac.id article history: received: 20 september 2022 / received in revised form: 17 october 2022 / accepted: 17 december 2022 available online 21 april 2023 abstract calcium carbonate has the potential to be used in the development of medical materials, including biomaterials. biocomposite is composed of caco3 as matrix material and bioplastic from the combination of corn starch and cassava starch as reinforcement. this study aims to determine mechanical properties such as tensile strength and bending/flexural strength with varying compositions of caco3 and bioplastic. characterization of the biocomposite uses scanning electron microscope to observe the microstructure and composition elements of their structure. this study used 4 variations in the ratio of caco3 suspension: (corn starch + cassava starch). each sample was characterized using specimen code a for composition 30:70 (w/w)% and specimen b for composition 40:60 (w/w)%, specimen c for composition 50:50 (w/w)%, and specimen d for composition 60:40 (w/w)%. based on the results of shrinkage measurements on flexural strength specimens, specimen b has the lowest percentage value of 15±0.01%. the lowest tensile strength specimen is found in specimens c and d at 12±0.01%. the tensile test results also showed that specimen d had a higher ultimate strength value than the other specimens, which was 0.06±0.03 mpa. microstructure characterization was carried out using scanning electron microscopy with energy-dispersive x-ray spectroscopy, which revealed the presence of oxygen at approximately 48.39% mass, carbon at approximately 30.27% mass, nitrogen at approximately 11.77% mass, calcium at approximately 9.57% mass, with calcium being detected in the form of calcium carbonate (caco3). copyright © 2023. journal of mechanical engineering science and technology. keywords: bending strength, biocomposite, bioplastic, caco3, cassava starch, tensile strength i. introduction calcium phosphateand caco3–based ceramic materials have garnered significant attention in medical applications due to their similar mineral compositions and crystal structure with natural bone, excellent biocompatibility, osteoconductivity, and osteoinductivity [1]. calcium carbonate or caco3 has six polymorphs: vaterite, aragonite, calcite, amorphous, crystalline monohydrate, and hexahydrate. it has a typical biomineral that is abundant in both organisms and nature and has important industrial applications [2]. calcium carbonate is a derivative material from limestone that is processed with calcinate to extract calcium content. the industry has consumed limestone for many purposes and fields such as iron and steel fluxes, manufacturing industries for glass making, papermaking, and agricultural fields as soil conditioner [3]. calcium carbonate has the potential for development in biomedical applications [4]. bioceramics are ceramics that are used for the 2 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) health of the body and teeth in humans [5]. the material used in the manufacture of this bioceramic is calcium carbonate (caco3). bioplastics or often called biodegradable plastics have properties that are compatible with the body. bioplastics such as corn starch and cassava starch. cassava starch is a natural polymer. for plasticized purposes, we can add glycerol [6], even with low mechanical properties and hydrophilic [7]. citric acid-epoxidized soybean oil oligomers (ceso) were prepared and utilized to improve the properties of corn starch-based bioplastics [8]. the properties of cassava starch can be improved their properties and biocompatibility by using reinforcement from natural fiber and celluloses [9]. tontowi et al. developed biocomposite from the hydroxyapatite–bioplastic material [10]. biphasic calcium phosphate (bcp) development has been broadly performed in bone tissue engineering [11]. also, the combination of hydroxyapatite (ha) and biphasic calcium phosphate (bcp) has the potential to develop in application bone tissue engineering [12,13]. pure ha has poor biodegradability, which limits bone ingrowth and may lead to deformity after implantation in the long term [14]. a combination of calcium carbonate and natural bioplastics such as cassava and corn starch are an alternative to developing a biomaterial. this study was conducted to determine the composition variation of caco3 suspension as matrix and bioplastic from the combination of cassava starch and corn starch as reinforces that have tensile and bending strength values. they then characterized the highest bending and tensile value with scanning electron microscope (sem) to determine their microstructure. ii. material and methods 1. material the materials used in this research are caco3, corn starch, and cassava starch with other supporting ingredients, namely citric acid and glycerol. biocomposites are made by mixing bioceramics and bioplastics by varying their composition. caco3 suspension of 20% (w/v) was prepared by dispersing caco3 powder in aquadest with 10% (w/v) citric acid. the suspension caco3 was stirred using a hot plate magnetic stirrer to obtain a homogeneous suspension and become bioceramic. corn starch suspension of 60% (w/v) was prepared by dispersing corn starch in aquadest with the addition of 10% (w/w) citric acid, then 40% (v/w) glycerin, as well as making suspension of cassava starch with 40% (w/v) in aquadest. suspension of corn starch and cassava starch was converted into bioplastic by stirring at 500 rpm at 50ᵒ c until homogeneous. the biocomposite paste was created by mixing bioceramics and bioplastic suspensions in a weight percent variation (w/w) ratio, as shown in table 1. table 1. composition of biocomposite variations code of specimen composition ratio (% w/w) suspension of caco3 corn starch + cassava starch a 30 70 b 40 60 c 50 50 d 60 40 issn: 2580-0817 journal of mechanical engineering science and technology 3 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) 2. shrinkage shrinkage is done after the drying process. the shrinkage measurement aims to see the volume change in the specimen after the molding process. 3. tensile test the tensile test was carried out using the hung ta ht – 2402 universal testing machine made in china with a crosshead speed setting of 10 mm/min. specimen standard using astm d 638 type iv (116 mm x 22 mm x 4mm), as shown in figure 1, to determine the ultimate tensile strength and young modulus. fig. 1. specimen 𝜎uts astm d 638 type iv 4. flexural test the flexural test specimen using astm d 790 standard (50 mm x 25 mm x 4 mm), which can be seen in figure 2, to determine the value of flexural strength. fig. 2. specimen 𝜎fs astm d 790 microstructure characterization using scanning electron microscopy with energy dispersive x-ray spectroscopy (sem-edx) sem-edx was utilized to qualitatively and quantitatively determine the surface morphology and chemical composition of the specimens elements. iii. results and discussions 1. shrinkage analysis the average shrinkage value of the tensile test specimen is shown in figure 3, and the average shrinkage of the bending test is shown in figure 4. 4 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) fig. 3. average shrinkage percentage of uts specimen in figure 3, it is shown that specimen b has the highest average value of shrinkage tensile test specimen, which is 15±0.00%, compared to specimen a, 14±0.00%, and specimen c and specimen d, which has an average shrinkage value of 12±0.01%. fig. 4. average shrinkage percentage of the flexural test specimen figure 4 shows that specimen b has the lowest mean value of shrinkage flexural test specimen, which is 15±0.01%, compared to specimen a, 17±0.04%, and specimen c, 18±0.03%, and specimen d which has an average shrinkage value of 17±0.00%. biocomposite specimens undergo shrinkage due to the presence of gas molecules that cause porous. during the solidification process, porosity can inhibit solidification and affect the mechanical properties of the material. the level of porosity is influenced by the composition of the suspension of bioceramics and bioplastic. the optimum composition was found to be a suspension of 50% hydroxyapatite and 50% cassava starch (by weight), resulting in a shrinkage value of approximately 28% [15]. issn: 2580-0817 journal of mechanical engineering science and technology 5 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) 2. tensile test analysis (σuts) the mean ultimate tensile strength (σuts) value is shown in figure 5. it shows that specimen d has the highest mean ultimate tensile strength (σuts) of 0.06±0.03 mpa, while specimen a of 0.03±0.01 mpa, specimen b of 0.04±0.01 mpa, and specimen c of 0.04±0.03 mpa. fig. 5. average of ultimate tensile strength fig. 6. average young’s modulus the average young's modulus is shown in figure 6. it is shown that specimen d has the highest young's modulus average value of 0.33±0.031 mpa, while specimen a of 0.13±0.05 mpa, specimen b of 0.12±0.01 mpa, and specimen c of 0.12±0.04 mpa. it should also be noted that the composition of cassava starch/corn starch bioplastic as a reinforcement that functions as a binder in the specimen and its thermoplastic nature must also be considered. so, to get the maximum value of tensile strength, one must pay attention to the composition of caco3 and cassava starch/corn starch and the effect of glycerol as a plasticizer. in research conducted by li et al. on the composite composition with 60% corn starch content (w/w), the tensile strength can reach 10.95 mpa [16]. the value of ultimate tensile strength 6 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) (σuts) is directly proportional to the value of young's modulus, which means that the greater the resulting stress against the strain in the biocomposite specimen. 3. flexural test analysis (σfs) the mean value of flexural strength (σfs) is shown in figure 7. figure 7 shows that specimen a has the highest mean flexural strength (σfs) value of 0.02±0.006 mpa, while specimen b has 0.013±0.006 mpa. specimen c and specimen d has an average value of 0.02±0.006 mpa. fig. 7. average of flexural strength the percentage of bioplastics can have an impact on the flexural strength value of each composition, which is influenced by the level of hydrogen content in the bioplastics. during the evaporation process, which is also affected by temperature, the formation of pore sizes occurs, leading to increased porosity. the larger the porosity, the lower the density of the resulting biocomposites. the results of the low flexural test, when compared to the research conducted by yamaguchi et al., the value of the compressive test obtained a compressive test value of 270 mpa using a sintering process with a temperature of 200ºc-250ºc for 1 hour [17]. 4. microstructure analysis (σfs) microstructural testing was conducted to determine the microstructure on the surface of the sample and the composition of the elements on the surface of the sample. as shown in figures 8 (a) – 8 (d), the particles are solid and form a clump. at 5,000x magnification, as shown in figure 8(d), the bonds in the particles become denser and form flakes. the structure formed can be affected by the sulfur content and acidity of the composite [18], and also heating temperature affects the shape. the structure formation of cellulose/caco3 nanocomposite has been influenced by heating temperature. with the heating time of 2 hours and 4 hours, there is caco3 aggregation and induces the formation of a porous structure in caco3 agglomerates [19]. issn: 2580-0817 journal of mechanical engineering science and technology 7 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) fig. 8. microstructures at magnification; (a) 100x, (b) 300x, (c) 1,000x, (d) 5,000x table 2. edx data results element mass (%) atom (%) c k 30.27 38.04 n k 11.77 12.69 o k 48.39 45.66 ca k 9.57 3.61 total 100.00 100.0 table 2 shows the elemental content in the biocomposite specimen on sem – edx observations at 5,000x magnification. the element in the biocomposite analysis reveals that carbon (c) is the dominant element, accounting for approximately 30.275% of the mass in the k atom-shell. nitrogen (n) accounts for about 11.77% mass in the k atom shell, while oxygen (o) accounts for approximately 48.39% mass in the k atom-shell. calcium (ca) is detected in the k atom shell with approximately 9.57% mass. the study also shows that both carbon and oxygen are present in significant amounts in the biocomposite. in a previous study by siriprom et al., c-o bonds were detected in both caco3 and cellulose [20]. balzera et al. conducted a comparative study of the mineral element caco3 contained in shellfish, oysters, and artificial caco3 [21]. (a) (b) (c) (d) 8 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 1-9 setiawan et al. (mechanical properties of biocomposite with various composition of caco3 and starch) iv. conclusions biocomposite (caco3 suspension: bioplastic corn starch + cassava starch) has the potential to develop as soft material, regarding mechanical properties such as ultimate tensile strength (σuts) and flexural strength (σfs). the highest tensile strength and the lowest flexural strength are 0.06±0.03 mpa and 0.01±0.00 mpa, respectively. increasing the density of the material by considering the amount of aquades and the heating temperature can lead to an improvement in its mechanical properties. the microstructure of the material consists mainly of flake forms, with carbon and oxygen being the dominant elements present. acknowledgment the author would like to thank the department of metallurgical engineering upn "veteran" yogyakarta for completing this research. references [1] f.p. he, y. tian, x.b. fang, y.b. xu, and j.d. ye, “porous calcium phosphate composite bioceramic beads’, ceram. int. 44 (11), pp 13430–13433, 2018, doi: 10.1016/j.ceramint.2018.04.109 [2] m. g. ma, s. liu, and l. h. fu, “calcium carbonate and cellulose/calcium carbonate composites: synthesis, characterization, and biomedical applications”, materials science forum, vol. 875, pp 24-44, 2016, https://doi.org/10.4028/www.scientific.net/msf.875.24. 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[21] m. r. hamestera, p.s. balzera, and d. becker, “characterization of calcium carbonate obtained from oyster and mussel shells and incorporation in polypropylene,” materials research, vol. 15(2): pp. 204-208, 2012, https://doi.org/10.1590/s151614392012005000014. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 89-95 89 doi: 10.17977/um016v5i22021p089 effect of variations in pyrolysis reactor with glass wool equipped and without glass wool on the weight of the oil produced i gusti ngurah nitya santhiarsa department of mechanical engineering, university of udayana, jimbaran, bali, 80361, indonesia *corresponding author: nitya_santhiarsa@unud.ac.id abstract currently, plastic waste is a very serious threat because plastic waste pollution can harm all living things around and also harm the environment. the increasing volume of plastic waste is due to the lack of processing technology, so that the volume of plastic waste is increasing day by day. plastic is a material that is difficult to decompose because it is non-biodegradable. one application of plastic waste processing technology offered in this study is to use the pyrolysis principle. pyrolysis is a method of converting plastic into fuel oil through a thermal decomposition process without the use of oxygen. the pyrolysis process used with a variety of reactors equipped with glass wool and reactor variations without glass wool. the purpose of this study was to compare the yield of pyrolysis oil with a variety of reactors equipped with glass wool and reactors without glass wool. the plastic used is opp (oriented polypropylene), with a constant reactor heating temperature of 200° c. the pyrolysis process is carried out for 1 hour each test, and the condenser cooling temperature is 28° c. based on the results of the research, the reactor variation with glass wool got the highest oil weight of 175 grf, while the reactor variation without glass wool got the lowest oil weight of 17 grf. with a variety of reactors equipped with glass wool, the heat generated is more concentrated into the reactor core, resulting in higher oil weight and a more efficient pyrolysis process. copyright © 2021. journal of mechanical engineering science and technology. keywords: fuel, glass wool, opp plastic, plastic waste, pyrolysis i. introduction currently, plastic waste is the most abundant waste because every tool/ item can be made of plastic, such as transportation equipment, household, technology, and so on. plastic is a material that is cheap, light, flexible, and strong, but the increasing use of plastic materials also has an adverse impact on the environment, such as plastic waste pollution [1]– [3]. plastic is a type of material that is difficult to degrade by the environment, which is called non-biodegradable material. as much as 60-70% of the waste generated from human activities is organic waste, while the remaining 30-40% is classified as non-organic waste, 14% of the non-organic waste is a plastic waste [4], [5]. various efforts have been made by the community to eradicate the pile of plastic waste, which is increasing day by day, but the efforts made have triggered new problems such as blockage of flow and also combustion exhaust gases [6], [7]. increasing population growth causes energy consumption to increase as well. therefore, solutions are needed to find alternative energy sources. one of the methods offered is to utilize plastic waste to be used as fossil fuel through the pyrolysis process [8]–[10]. generally, plastic waste management techniques are only through open dumping, sanitary landfill, and composting. in this study, we introduce a plastic waste management technology with easy operation and feasible to develop called the pyrolysis technique. pyrolysis is the process of decomposition of a material at high temperatures that 90 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 89-95 santhiarsa (effect of variations in pyrolysis reactor on the weight of the oil produced) takes place in the absence of oxygen. the products produced by the pyrolysis can be used in various needs. the types of fuel phases produced from the conversion process of plastic waste into fuel include a solid/charcoal phase, a liquid/tar phase, and a gas flammable phase, where the fuel can be converted again into heat energy and electrical energy [11], [12]. handling plastic waste using the pyrolysis technique is expected to overcome the problem of environmental pollution caused by plastic waste. besides, the pyrolysis method is able to produce products in the form of fuel oil. previous research [13] carried out the pyrolysis process using plastic waste with the addition of twig waste. the pyrolysis temperature was maintained at 450° c for 10 min. based on the results of the study, the best liquid smoke was obtained from pp gr and guava 34.2 ml. the optimum charcoal was produced at 75 gr hdpe and 25 gr mango, which was 95.56%. previous research [14] carried out a pyrolysis technique using ldpe and pet plastic waste, which aims to determine the results of the comparison of oil volume and the quality of the fuel produced. the pyrolysis process was carried out within 2 hours with a constant temperature of 250° c. the results showed that the volume of oil produced from ldpe plastic was 525 ml, while pet plastic obtained 368.47 ml. the resulting density of these two types of plastic is close to the density value of kerosene. the calorific value of ldpe plastic is similar to the calorific value of diesel oil, while the calorific value of pet plastic is close to the calorific value of kerosene. research has been carried out [15], which aims to determine and compare the ability of plastic pyrolysis oil with kerosene and diesel in terms of density, duration of combustion, water temperature and volume of water lost (evaporated) when cooked using the oil. based on the results of the study showed that the density of the pyrolysis oil was 0.8 g/ml. cooking water using pyrolysis fuel oil produces a temperature of 75°c at a cooking time of 4 minutes with a volume of water lost (evaporating) of 12.6 ml. the time it takes to burn down an object is 4.02 minutes. from the 4 parameters observed, the quality of pyrolysis oil is below kerosene but above diesel oil. based on the description above, the pyrolysis technique is determined as a method of processing plastic waste. it is expected to be a solution to the problem of plastic waste and an alternative fuel source in the form of oil as a substitute for fossil fuels. this study aims to determine the ratio of the weight of the pyrolysis oil in a variety of reactors equipped with glass wool and reactors without glass wool. ii. material and methods the tools used in this study include 3 kg lpg gas cylinders, gas stoves, digital thermometers, digital lpg scales, digital scales, pyrolysis equipment, as shown in figure 1. the material used in this research is opp (oriented polypropylene) type plastic, as shown in figure 2. the research procedure included preparing tools and materials by cleaning plastic, weighing it to 500 grams, and designing a pyrolysis device with glass wool and without glass wool. the pyrolysis reactor equipped with glass wool is made of stainless steel with a diameter of 20 cm and a height of 30 cm, consisting of three main components: a heating reactor, a condenser, and a filter equipped with activated carbon. a bimetal thermometer is attached to the pyrolysis reactor component to determine the temperature during heating. the reactor was covered with glass wool so that not much heat was wasted, and the reactor was connected by 80 cm long connecting pipes to the condenser. the condenser is made of an iron plate with a capacity of 10 liters. next for the design of the pyrolysis device without issn: 2580-0817 journal of mechanical engineering science and technology 91 vol. 5, no. 2, november 2021, pp. 89-95 santhiarsa (effect of variations in pyrolysis reactor on the weight of the oil produced) glass wool has the same design, but it is not covered with glass wool. after completion of the device design process, 500 grams of opp plastic is inserted into the pyrolysis reactor, which will experience a heating process when the burner is turned on with a fuel source of 3 kg lpg gas, and a process of change of state in the reactor from solid to gas occurs. the condenser tube has previously been filled with water as a cooling medium, which is called the liquification process, which is the process of changing the form of gas to liquid. in this condensation stage, a distillation process occurs to produce pure pyrolysis oil. the temperature of the cooling water in the condenser was found to be 28°c. the pyrolysis process was carried out within 1 hour of each test, with a reactor temperature of 200°c. after the testing process is complete, the results of the weight of the pyrolysis oil are compared to the reactor variations equipped with glass wool and without glass wool. fig. 1. pyrolysis device fig. 2. opp (oriented polypropylene plastic) iii. results and discussions from the retrieval of test data, namely the pyrolysis process using opp type plastic at a constant reactor temperature of 200°c, the results obtained by weight of pyrolysis oil for each variation of the pyrolysis reactor equipped with glass wool and without glass wool as described in figure 3. the pyrolysis process is a conversion process, in this case, plastic 92 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 89-95 santhiarsa (effect of variations in pyrolysis reactor on the weight of the oil produced) material into fuel oil with high temperatures and without the use of oxygen. incomplete combustion of opp plastic causes complex carbon compounds not to be oxidized to carbon dioxide, and this is called pyrolysis [15]. fig. 3. oil weight of each reactor variation the increase in condenser temperature every 10 minutes in the variation of the pyrolysis reactor can be seen in figure 4. fig. 4. temperature increase in condenser 0 20 40 60 80 100 120 140 160 180 200 reactor is equipped with glasswool reactor without glasswool p y ro ly si s o il w e ig h t (g rf ) reactor variations 26 27 28 29 30 31 32 30 mnt 40 mnt 50 mnt 60 mnt in cr e a si n g c o n d e n se r te m p e ra tu re ° c time (mnt) reactor with glass wool reactor without glass wool issn: 2580-0817 journal of mechanical engineering science and technology 93 vol. 5, no. 2, november 2021, pp. 89-95 santhiarsa (effect of variations in pyrolysis reactor on the weight of the oil produced) the phenomenon that occurs in pyrolysis is that when opp plastic is heated in a pyrolysis reactor with temperatures reaching 200°c, the plastic will melt by changing its state from solid to gas. in the heating process, heat energy encourages oxidation which causes complex carbon molecules to decompose, most of which will become carbon or charcoal. hot gas from the plastic conversion process in the reactor will be flowed into the condenser tube through the connecting pipe between the reactor and the condenser. in the condenser tube, the hot gas will be cooled by the water in the condenser. the phenomenon that occurs in the condensation process is the change of gas into a liquid. in this case, the hot gas is cooled so that the gas will melt into fuel oil. figure 3 describes the results of the pyrolysis oil weight test in each reactor variation. reactor equipped with glass wool produces oil with the highest weight of 175 grf, while the reactor variation without glass wool produces the lowest oil with a weight of 17 grf. this is because the reactor equipped with glass wool produces heat that is more concentrated in the reactor core so that the heat that is wasted out is not so much, and the reactor reaches a temperature of 200°c faster. meanwhile, the reactor without glass wool takes a longer time to reach a temperature of 200°c, because the heat generated is not concentrated in the reactor core, so it takes a longer time to reach a temperature of 200°c than a reactor equipped with glass wool. previous studies have carried out the pyrolysis process using plastic waste with a stainless steel-based reactor, with a reactor heating temperature of 606.9°c and a condensation temperature of 17°c. from the results obtained, the weight of the oil produced is 460 grf [16]. in the pyrolysis process, in addition to the low condensation temperature, the parameter to produce high oil is the reactor heating temperature. the higher reactor temperature, the higher and faster the process of converting solid to gas. figure 4 describes the increase temperature in the variation of the reactor equipped with glass wool and reactor without glass wool. in reactor with glass wool, it can be seen that at the 40th minute, the temperature increased to 29.8°c, while at the 50th minute, the temperature increased by 30.4°c. at the final minute of 60 minutes, the temperature was found to be 31.4°c. meanwhile in reactor without glass wool, it can be seen that at the 40th minute the temperature increased to 29.6°c, while at the 50th minute, the temperature became 30.4°c. at the 60th minute, the temperature increased to 31.2°c. the increase in temperature in the condenser is caused by hot steam originating from the solid to the gas conversion process in the pyrolysis reactor. this hot steam flows through the connecting pipe to the condenser to be cooled so that the hot steam is converted into liquid fuel oil. as the condensation process progresses, the coolant temperature in the condenser increases. the limitation of this research is that the maximum reactor temperature only reaches a temperature of 200°c. in the pyrolysis process, it is suggested that the reactor temperature can reach temperatures above 200°c. at the condensation temperature, it reaches below 20°c so that the pyrolysis process becomes more efficient and produces a higher weight of pyrolysis oil. iv. conclusions based on the research, it can be concluded that the variation of the reactor equipped with glass wool produces the highest oil weight of 175 grf, while the variation of the reactor without glass wool produces the weight of oil the lowest is 17 grf. the addition of glass wool material to coat the reactor can cause the heat generated to concentrate to the reactor core so as to produce more fuel oil and the pyrolysis process becomes more efficient. 94 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 89-95 santhiarsa (effect of variations in pyrolysis reactor on the weight of the oil produced) acknowledgment i would like to express my gratitude to i gede artha negara st mt, i wayan putra adnyana st mt, and all parties who have helped in this research process, so that this research can be completed properly. references [1] s. suminto, “ecobrick: solusi cerdas dan kreatif untuk mengatasi sampah plastik,” prod. j. desain prod. (pengetahuan dan peranc. produk), vol. 3, no. 1, p. 26, 2017. [2] n. nasrun, e. kurniawan, and i. sari, “pengolahan limbah kantong plastik jenis kresek menjadi bahan bakar menggunakan proses pirolisis,” j. energi elektr., vol. 4, no. 1, pp. 1–5, 2017. [3] b. a. septiani, d. m. arianie, v. f. a. a. risman, w. handayani, and i. s. s. kawuryan, “pengelolaan sampah plastik di salatiga: praktik, dan tantangan,” j. ilmu lingkung., vol. 17, no. 1, p. 90, 2019. [4] b. t. andriastuti, a. arifin, and l. fitria, “potensi ecobrick dalam mengurangi sampah plastik rumah tangga di kecamatan pontianak barat,” j. teknol. lingkung. lahan basah, vol. 7, no. 2, p. 055, 2019. [5] p. purwaningrum, “upaya mengurangi timbulan sampah plastik di lingkungan,” jtl, vol. 8, no. 2, pp. 141–147, 2019. [6] a. apriyani, m. m. putri, and s. y. wibowo, “pemanfaatan sampah plastik menjadi ecobrick,” j. masy. berdaya dan inov., vol. 1, no. 1, pp. 48–50, 2020. 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[16] d. amalia ardianti, “rancang bangun alat pengkonversi sampah plastik menggunakan metode pirolisis menjadi bahan bakar minyak dalam upaya penanganan masalah lingkungan,” j. ilmu dan inov. fis., vol. 3, no. 2, pp. 91–96, 2019. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 47 doi: 10.17977/um016v5i12021p047 camshaft failure simulation with static structural approach riduwan prasetya, andoko*, suprayitno mechanical engineering department, universitas negeri malang, jl. semarang 5, 65145, indonesia *corresponding author:andoko.ft@um.ac.id abstract a failure happens within the camshaft of the minibus when the vehicle is in utilize. the camshaft was a fracture within the bearing between the primary cylinder exhaust valve and the second cylinder suction. this simulation aims to find the causes of camshaft failure utilizing the finite element method with a static structural approach, including simulations of deformation, strain, stress, fatigue life (stress-life and strainlife), and cracks. the method used in this paper is the finite element method with a static structural approach by ansys software. the camshaft material is a gray cast iron designed using solidworks. pre-processing includes meshing with a size of 3 mm. the value of loading force (1348.28 n) and torque (113400 nmm) are fixed, and the boundary conditions are varied. processing includes the process of computation and postprocessing into a part that displays the results. the simulation results show that for all the deformation and strain values that are in the elasticity area of the material, the maximum and minimum stress which is below the strength of the material, the location of the maximum values of deformation, strain, and stress is not at the fault location. the simulation of fatigue life both in stress-life and strain-life results in infinite cycles, which is above 106 cycles, while the simulation of cracks results in a decrease in the cycle. based on the simulation results with the above parameters to the camshaft, it was found that a failure was caused by a defect characterized by reduced fatigue life at the same loading conditions. copyright © 2021. journal of mechanical engineering science and technology. keywords: ansys, camshaft, failure analysis, simulation, static structural i. introduction a combustion engine is a power producer whose complex structure plays an important role today [1]. composed of essential components that support each other in generating power, one of the critical components is the camshaft. the camshaft is a shaft with a cam that functions to open and close the suction and exhaust valves so that the combustion process can occur [2]. when a failure occurs, the engine cannot run properly and causes problems that impact losses [3]. for example, the owner of a toyota minibus who suffered a damaged camshaft in a broken car was used. a break occurred between the exhaust valve of the first cylinder and the inlet cylinder of the second. repair is the right step to resolve these problems, but preventive action is also much more critical so that similar failures do not occur. taking preventative measures would have to know the causes of an object that fails, one of them with failure analysis [4]. static structural failure analysis is an approach to analyze the causes of the failure of a structure [5]. there are various methods used to analyze the failures using experiments and simulations. experiments include macroscopic examination, microscopic examination, material characterization (metallographic analysis, mechanical testing, chemical analysis), 48 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) and residual stress measurement. simulation using the finite element method consists of stress analysis and fracture mechanics. a finite element method is a numerical approach to engineering problems that have been developed since 1950 [6]. this method has more advantages compared to experimental testing [7]. the finite element method gives a lot of variation in the test to provide a broader picture to the researchers. this simulation aims to find the causes of camshaft failure using the finite element method with a static structural approach, including simulations of deformation, strain, stress, fatigue life (stress-life and strain-life), and cracks. the previous simulation by patil et al. regarding the camshaft failure analysis is the one that analyzes the camshaft using the modal and camshaft fatigue on the pump [8]. wang et al. predicts camshaft fatigue fracture under bending and torsional loads and provides cracks [9]. suhas et al., in 2011, conducted a contact fatigue analysis of the camshaft [10]. ii. material and methods a. material the camshaft material was determined by a chemical composition test using the hilger e-9 oa701 spectrometer (table 1) and compared with the standard to obtain a gray cast iron material [11]. the mechanical properties of gray cast iron are shown in table 2. table 1. chemical composition of gray cast iron [11] chemical composition wt.% c 3.10 – 3.60 si 1.95 – 2.40 mn 0.60 – 0.90 p max. 0.10 s max. 0.15 cr 0.85 – 1.25 mo 0.40 – 0.60 ni 0.20 – 0.45 table 2. mechanical properties of gray cast iron [11] tensile strength 220 mpa compression strength 669 mpa torsional shear strength 220 mpa maximum deflection 4.3 mm b. methods the method used was the finite element method or simulated with the help of ansys. stages on the finite element method with static structural approaches include pre-processing, processing, and post-processing. issn: 2580-0817 journal of mechanical engineering science and technology 49 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) 1. pre-processing pre-processing was the initial step in the simulation. the step was first designing the camshaft according to actual conditions using solidworks and export using .sat format (figure 1). then imported into the ansys software and added gray cast iron as camshaft's material. after that, generate mesh with size of 3 mm for accurate results. meshing produced 339,270 nodes and 226,400 elements for simulating deformation, strain, stress, stress-life, and strain-life. for crack simulation, it used meshing with default size and tetrahedron meshing for more stable results. fig. 1. camshaft's design deformation, strain, and stress simulations were carried out with a fixed value loading force (1348.3 n) at the ends of cam 2 and 3 and torque (113400 nmm). the support in these conditions is fixed, and cylindrical support is varied and shown in table 1 appendix. this variation aimed to find the value and location of the highest deformation, strain, and stress. the location of load (force and torsion) and support is shown in figure 1. fatigue life simulation was done by applying load and boundary conditions which give the highest stress to the camshaft (obtained from previous simulations). in the fatigue life approach that uses stress-life and strain-life, defects were ignored, while defects were applied to the crack simulation approach. the location of the defect in the form of a crack is shown in figure 2 with 6 points. 2. processing processing was a calculation step performed by a computer. the calculation was based on the load and boundary conditions that have been entered in the previous process. 3. post-processing after the calculation process was completed, the post-processing would display the results of the calculations. in deformation, strain, and stress simulation, the captured data was the minimum and maximum value of each condition and their distribution indicated by the color bar on the camshaft (visually). in the life simulation (stress-life, strain-life, and cracks), the results taken were the fatigue life of the components. data values (maximum, minimum, and life) were taken from tabular data generated by ansys. 50 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) fig. 2. crack location iii. results and discussions a. deformation the deformation simulation results for the maximum values of various conditions are shown in figure 3. at conditions 1 to 42, the deformation values are below 0.02 mm. this condition occurs when all bearings are held both by cylindrical support and a fixed support. the deformation value then increases at condition 43 and moves up and down in the range 0.02 mm to 0.10727 mm (except 46th condition), which support in 43rd to 51st condition is fixed support on the second bearing. the force exerted in the y-axis direction results in lower deformation than the force in the yz-axis direction and the torque. the added torque makes the maximum deformation value increase to 0.005 mm. fig. 3. maximum deformation of various conditions issn: 2580-0817 journal of mechanical engineering science and technology 51 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) the location of the maximum deformation under which all bearings held and applied is at the cam end where the force applied (figure 4 (a)). when torque is used, the location of the maximum deformation shifts to an area close to the site of the given torque (figure 4 (b)). however, this does not apply to torque loading with force in the yz direction. the maximum deformation is at the end of the cam. different things are shown in the condition of 43 to 51. when the load is given to 3rd cam, the maximum deformation is located at the left end of the camshaft. at the same time, the force applied to the second cam and the load torque of maximum deformation is at the right end of the camshaft. the location of maximum deformation has never been in part a fracture camshaft. (a) (b) (c) fig. 4. location of maximum deformation at (a) 4th (b) 46th (c) 50th condition 52 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) the maximum deformation value for various conditions is 0.10727 mm, which occurs in 50th condition (figure 4 (c)). 50th condition is the loading in the form of a force on 2nd cam and torque and 2nd bearing being held. compared with the maximum deflection value of the material (4.3 mm), the resulting deformation is far below this value, therefore did not lead to plastic deformation. the change is unable to reverse and fails [11]. b. strain the maximum strain for each condition is shown in the graph in figure 5. the value of the strain varies from 0.02% to 0.12%. as with the deformation simulation results, when all the bearings are held, the result is lower than one bearing. the highest strain was 0.12406% which occurred at 50th condition (the same as the maximum deformation) (figure 6 (c)). fig. 5. maximum strain in various conditions the location of the maximum strain when only the force is applying with all the bearings held is on the side cam (figure 6 (b)). meanwhile, if the load is torsional, then the location of the maximum strain is located on the side of the camshaft’s gear (figure 6 (a)). both occur in areas undergoing geometric changes. in the fault area, it has never experienced the highest strain. strain and deformation have a relationship in explaining the changes in shape in objects [12]. the various loading conditions given indicate that these conditions do not lead to failure. the strain simulation results confirm it. the resulting strain is below 1%, which means that the camshaft is deforming elastically [13]. according to hooke's law, further evidence shown in the graph of stress and strain in figure 7 forms a linear line. in terms of the location where the maximum value is, both deformation and strain show that the maximum value never occurs in the fracture area. issn: 2580-0817 journal of mechanical engineering science and technology 53 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) (a) (b) (c) fig. 6. location of maximum strain at (a) 11th (b) 19th (c) 50th condition 54 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) fig. 7. stress vs. strain c. stress figure 8 shows the maximum and minimum stress results for various conditions. the stress approach used includes von misses, maximum principal stress, and minimum principal stress. under conditions when all bearings are held, resulting in lower stress than one bearing held. maximum stress on von misses, and principal stress is 136.4 mpa and 79.814 mpa, respectively. both occur at the 50th condition. meanwhile, minimum principal stress is -84.392 mpa that occur at the 51st condition. based on mohr's modification theory, the failure approach for brittle materials can be done by comparing the maximum stress with the ultimate tensile strength (uts) and the minimum stress with the ultimate compressive strength (ucs) [14]. the von misses stress simulation yields a higher value than the principal stress, and when compared to the tensile strength of the material (220 mpa), the value is below it. the same thing is also shown by the minimum principal stress, which is far below the value of the compression material strength (669 mpa). both indicate that the stress applied to the camshaft does not result in failure. fig. 8. maximum and minimum stress in various conditions -100 -50 0 50 100 150 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51s tr e ss ( m p a ) condition maximum principal stress von misses minimum principal stress issn: 2580-0817 journal of mechanical engineering science and technology 55 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) the location of the maximum stress (von misses and maximum principal) has the same position as the maximum strain. the location of the maximum von misses stress, and principal stress is shown in figure 19 (a) and (b), while the minimum principal stress is in figure 19 (c). fracture areas tend to be subjected to lower or even lowest stresses when these conditions are applied. this show that the fault location has never experienced the highest stress as long as the load is applied. (a) (b) (c) fig. 9. location of (a) maximum von misses stress at 50th condition (b) maximum principal stress at 50th condition (c) minimum principal stress at 51st condition (b) (a) 56 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) deformation, strain, and stress simulation results are similar. the result is a load applied to various conditions in the region show elasticity and below the strength of the material. in terms of location, the highest value has never occurred in a fractured area. in relation to the failure, the load applied is not the cause of a fracture in the camshaft. d. stress – life dan strain life the stress life and strain life simulations results are shown in table 3. simulation of material fatigue life using stress-life and strain-life approaches is a fatigue approach in which the camshaft is considering no defects [15] [16]. the applied loading is the condition with the highest maximum stress and strain in the previous simulation. the results show that for stress-life, the fatigue life is 2 x 107 cycles. at the same time, the strain life approach is 109 cycles. based on the fatigue theory, when the number of cycles reaches 106 without damage, it can be mentioned that the components can last indefinitely / infinite cycles [17]. this shows that the stress applied to the camshaft will not break the camshaft or within the endurance limit of the material. table 3. stress-life and strain-life result stress-life (𝜎 − 𝑁) 2 × 107 cycles strain-life (𝜀 − 𝑁) 1 × 109 cycles e. crack simulations with defects to determine the camshaft life are carried out by providing cracks with shape like in figure 10 in part shown in figure 2. points 1 and 2 are the areas with the highest stress, and points 3 to 6 are the fracture locations. fig. 10. crack shape figure 11 shows the crack simulation results. the size of the cracks varied from 0.05 mm to 0.5 mm at points 1 and 2. cracks placed in position 1 gave a lower lifespan than cracks placed in position 2 (figure 11 (a)). with a crack size of 0.5 mm, position 2 requires issn: 2580-0817 journal of mechanical engineering science and technology 57 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) 88 cycles to break, while position 1 requires 594 cycles. the more minor cracks were 0.05 mm, 39775 cycles, and 302950 cycles at positions 1 and 2 for fracture. figure 11(b) shows the simulation results when the crack is placed at points 3 to 6 (fault area) with a crack size of 0.5 mm to 2 mm. it is seen that the life of crack growth is greater than that of the cracks placed in positions 1 and 2. given a crack of 0.5 mm, all four show an age of more than 1010 cycles. when compared with the simulation without defect, it is seen that giving a defect shortens the life of the camshaft with the same load. although the age values in the stresslife and strain-life simulations are smaller than the crack simulations at a specific defect size, this is influenced by the age limits included in the stress-life and strain-life tests. the crack simulation shows that when the component reaches its maximum value, it indicates that it is a failure. thus, camshaft failure results from a defect characterized by reduced fatigue life under the same loading conditions, and experimental testing is needed to further review the defects that occur. (a) (b) fig. 11. fatigue life with variation in crack size (a) locations 1 and 2 (b) locations 3-6 58 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) iv. conclusions based on the simulated parameters (deformation, strain, stress, life, and cracks), camshaft fracture is not caused by the load applied but by defects. deformation and strain simulations show that the resulting value is in the area of elasticity of the material. the stress-strain graph, which produces a linear line, also reinforces this result. the stress simulation shows that the highest location of stress does not occur in the fault area, and the value is below the strength of the material. in the crack simulation, it is seen that giving a defect shortens the life of the camshaft with the same load as the stress-life and strain-life simulations. this simulation indicates that the defect results in camshaft failure, characterized by reduced fatigue life under the same loading conditions. references [1] lubis, d.z., and andoko, “elastic linear analysis of connecting rods for single cylinder four stroke petrol engines using finite element method,” j. mech. eng. sci. technol., vol. 3(1), pp. 42–50, 2019. [2] lin, d.-y., hou, b.-j., and lan, c.-c., “a balancing cam mechanism for minimizing the torque fluctuation of engine camshafts,” mech. mach. theory, vol. 108, pp. 160–175, 2017. [3] andoko and amin, w. r., “investigation of stress, deformation, and cracks in the brakes of car using finite element method,” iop conf. ser. mater. sci. eng., vol. 515(1), 2019. [4] altinisik, a., and hugul, o., “the seven-step failure diagnosis in automotive industry,” eng. fail. anal., vol. 116, p. 104702, 2020. [5] jamili and andoko, “stress and deformation simulation in 6 hole steel rim using finite element method,” iop conf. ser. mater. sci. eng., vol. 494(1), 2019. [6] andoko et al., “simulation of cnc milling 5 axis with finite element method,” in aip conference proceedings, p. 040013, 2020. [7] andoko, paryono, prasetya, r., jeadi, r. p., kurniawan, p., and pradica, d. r., “simulation of the effect of energy absorption on crashbox with full crash initiator and without crash initiator,” in aip conference proceedings, vol. 2262, 2020. [8] patil, s. and karuppanan, s., “modal and fatigue analysis of a camshaft using fea,” int. j. appl. eng. res., vol. 8(14), pp. 1685–1694, 2013. [9] wang, g., taylor, d., bouquin, b., devlukia, j., and ciepalowicz, a., “prediction of fatigue failure in a camshaft using the crack modelling method,” eng. fail. anal., vol. 7(3), pp. 189–197, 2000. [10] suhas, k.s., and haneef, d.m., “contact fatigue analysis using finite element analysis for 6 station 2 lobe cam shaft,” indian j. appl. res., vol. 4(7), pp. 185– 187, 2011. [11] astm, “standard specification for automotive gray iron castings,” vol. 03, no. reapproved, pp. 1–5, 2000. [12] wang, h., fu, c., cui, w., zhao, w., and qie, s., “numerical simulation and experimental study on stress deformation of braided wire rope,” j. strain anal. eng. des., vol. 52(2), pp. 69–76, oct. 2016. issn: 2580-0817 journal of mechanical engineering science and technology 59 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) [13] chen, t.-c., chen, s.-t., tsay, l.-w., and shiue, r.-k., “correlation between fatigue crack growth behavior and fracture surface roughness on cold-rolled austenitic stainless steels in gaseous hydrogen,” metals (basel)., vol. 8(4), p. 221, 2018. [14] norton, r. l., machine design: an integrated approach (4th edition). 2011. [15] vukelic, g., and brcic, m., “failure analysis of a motor vehicle coil spring,” procedia struct. integr., vol. 2, pp. 2944–2950, 2016. [16] doshi, k., roy, t., and parihar, y. s., “reliability based inspection planning using fracture mechanics based fatigue evaluations for ship structural details,” mar. struct., vol. 54, pp. 1–22, 2017. [17] xin, q., “2 durability and reliability in diesel engine system design,” woodhead publishing, pp. 113–202, 2013. 60 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) appendix table 1. boundary condition condition cam support force (n) torsi (nmm) 1 3 fixed 1348.28 (-y) 2 3 fixed 1348.28 (z) 3 2 fixed 1348.28 (-y) 4 2 fixed 1348.28 (z) 5 3 cylindrical support 1348.28 (-y) 6 3 cylindrical support 1348.28 (z) 7 2 cylindrical support 1348.28 (-y) 8 2 cylindrical support 1348.28 (z) 9 3 cylindrical support 113400 10 3 cylindrical support 1348.28 (-y) 113400 11 3 cylindrical support 1348.28 (z) 113400 12 2 cylindrical support 1348.28 (-y) 113400 13 2 cylindrical support 1348.28 (z) 113400 14 3 cylindrical support + gear fixed 1348.28 (-y) 15 3 cylindrical support + gear fixed 1348.28 (z) 16 2 cylindrical support + gear fixed 1348.28 (-y) 17 2 cylindrical support + gear fixed 1348.28 (z) 18 3 cylindrical support + 1st bearing fixed 1348.28 (-y) 19 3 cylindrical support + 1st bearing fixed 1348.28 (z) 20 2 cylindrical support + 1st bearing fixed 1348.28 (-y) 21 2 cylindrical support + 1st bearing fixed 1348.28 (z) 22 3 cylindrical support + 2nd bearing fixed 113400 23 3 cylindrical support + 2nd bearing fixed 1348.28 (-y) 24 3 cylindrical support + 2nd bearing fixed 1348.28 (z) 25 2 cylindrical support + 2nd bearing fixed 1348.28 (-y) 26 2 cylindrical support + 2nd bearing fixed 1348.28 (z) 27 3 cylindrical support + 2nd bearing fixed 1348.28 (-y) 113400 28 3 cylindrical support + 2nd bearing fixed 1348.28 (z) 113400 29 2 cylindrical support + 2nd bearing fixed 1348.28 (-y) 113400 30 2 cylindrical support + 2nd bearing fixed 1348.28 (z) 113400 31 3 cylindrical support + 3rd bearing fixed 1348.28 (-y) 32 3 cylindrical support + 3rd bearing fixed 1348.28 (z) 33 2 cylindrical support + 3rd bearing fixed 1348.28 (-y) 34 2 cylindrical support + 3rd bearing fixed 1348.28 (z) 35 3 cylindrical support + 4th bearing fixed 1348.28 (-y) 36 3 cylindrical support + 4th bearing fixed 1348.28 (z) 37 2 cylindrical support + 4th bearing fixed 1348.28 (-y) 38 2 cylindrical support + 4th bearing fixed 1348.28 (z) 39 3 cylindrical support + 5th bearing fixed 1348.28 (-y) 40 3 cylindrical support + 5th bearing fixed 1348.28 (z) issn: 2580-0817 journal of mechanical engineering science and technology 61 vol. 5, no. 1, july 2021, pp. 47-61 prasetya et al. (camshaft failure simulation with static structural approach) 41 2 cylindrical support + 5th bearing fixed 1348.28 (-y) 42 2 cylindrical support + 5th bearing fixed 1348.28 (z) 43 3 2nd bearing fixed 113400 44 3 2nd bearing fixed 1348.28 (-y) 45 3 2nd bearing fixed 1348.28 (z) 46 2 2nd bearing fixed 1348.28 (-y) 47 2 2nd bearing fixed 1348.28 (z) 48 3 2nd bearing fixed 1348.28 (-y) 113400 49 3 2nd bearing fixed 1348.28 (z) 113400 50 2 2nd bearing fixed 1348.28 (-y) 113400 51 2 2nd bearing fixed 1348.28 (z) 113400 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 66-73 66 doi: 10.17977/um016v6i22022p066 investigate the potential renewable energy of microalgae spirulina sp using proximate analyzer, sem-edx, and thermogravimetry yahya zakaria1, sukarni sukarni1,2,*, poppy puspitasari1,2, nandang mufti2, samsudin anis3, anwar johari4 1department of mechanical engineering, universitas negeri malang, jl. semarang no 5, malang, 65145, indonesia 2center of advanced materials for renewable energy (camry), universitas negeri malang, jl. semarang no 5, malang, 65145, indonesia 3agro energy research center, department of mechanical engineering, universitas negeri semarang, indonesia 4center of hydrogen energy, institute of future energy, universiti teknologi malaysia, johor baru, 81310, malaysia *corresponding author: sukarni.ft@um.ac.id article history: received: 18 april 2022 / received in revised form: 30 june 2022 / accepted: 4 july 2022 abstract microalgae spirulina sp which has been cultivated by the brackishwater aquaculture development center, situbondo indonesia were tested for their potential energy performance using proximate analyzer, semedx, and thermogravimetry. the proximate analyzer showed volatile matter (vm), fixed carbon (fc), moisture, ash content (ac), total sulfur of microalgae spirulina sp 68.15, 12.57, 11.22, 8.06, and 0.67 (wt%, ar), respectively, and the gross calorific value (gcv) is 4971 kcal/kg (dry basis). sem-edx test showed the morphology and chemical content of spirulina sp. the content of microalgae spirulina sp is dominated by carbon (c) and oxygen (o), then followed by chlorine (cl), sodium (na), potassium (k), sulfur (s), magnesium (mg), and phosphorus (p). thermogravimetry pyrolysis test of microalgae spirulina sp resulted thermogravimetry (tg) analysis and derivative thermogravimetry (dtg) analysis curve, which is divided into three different steps. the moisture of microalga spirulina sp was vaporized at the first step, started at 27 °c, and finished at 173 °c with a decomposed mass of about 13.81% of the total initial mass. the second step began at the end of vaporize moisture at about 173 °c and ended at around 618 °c. the gasification process occurred in volatile matter content and resulted mass loss of about 57.9% of spirulina sp total mass. the last step showed the process of gasification of residual substances, started at the end of the volatile matter step, 618 °c, and stopped at 995 °c with a decomposed mass of 24.6% from total mass. copyright © 2022. journal of mechanical engineering science and technology. keywords: microalgae, proximate, renewable energy, sem-edx, spirulina sp., thermogravimetry i. introduction russia's invasion of ukraine not only caused damage to infrastructure but also caused an energy crisis in europe union (eu) and even the world. as is well known, russia has become a global power in terms of providing energy sources [1]. russia controls exports of energy sources to asia 55.8% and 42% to the eu in 2020. russia is now starting to limit exports of its energy sources to the western world as a form of retaliation for sanctions imposed on the country led by vladimir putin [2]. mailto:sukarni.ft@um.ac.id 67 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 66-73 zakaria et al. (investigate the potential renewable energy of microalgae spirulina sp) the export restrictions resulted in a high price dispute. oil prices on tuesday, march 22, 2022, at 07:46 (jakarta time) showed brent oil at us$ 117.49/barrel, up 1.62% from the previous day's closing position. meanwhile, the light sweet type or west texas intermediate (wti) costs us$ 114.16/barrel, an increase of 1.82%. in london, the fuel increase was over two euros or the equivalent of $2.2 per liter at each gas station. the price of brent oil, the main international benchmark for oil, jumped past $130 on tuesday, march 8, 2022, as joe biden banned russian oil and gas from the united states. while sweden faces the highest price increase in europe, exceeding 25 kronor or 2.31 euros per liter. in addition, the average price of gasoline in germany also rose to 1.83 euros per liter [3],[4],[5]. the energy crisis occurs shows that the world still relies on fossil energy sources and comes from certain countries. indonesia, as the g20 presidency, must take decisive steps in an effort to overcome the global energy crisis. one of the efforts that can be done is optimizing new renewable alternative energy sources that can reduce dependence on fossil energy sources. biomass is one of the promising new renewable energy sources to be converted as a substitute for fossil energy sources. biomass has the character of being easily renewable, environmentally friendly, and has a high enough calorific value to be substituted into fossil fuels [6]. one type of biomass that can be used is the microalgae spirulina sp. microalgae have the characteristics not requiring a large area for the cultivation process and requiring a relatively short time for the harvesting process compared to other biomass [7]. before being used as fuel, microalgae spirulina sp needs to be characterized for its physical and chemical properties [8]. characterization in this research using a proximate analyzer, a scanning electron microscope-energy dispersive x-ray (sem-edx), and thermogravimetric analysis (tg). a proximate analyzer is used to determine the physical properties and calorific value of the sample. sem-edx test was used to show the topography, morphology, and chemical composition of spirulina sp., while the thermogravimetric test was used to determine changes in weight loss associated with changes in temperature. the data from this research is expected to be able to provide an overview of the character of microalgae spirulina sp. therefore, the resulting fuel product will be more optimal. ii. material and methods material. the sample of microalgae spirulina sp was cultivated, harvested, dried, and powdered by balai besar pengembangan budidaya air payau, situbondo, indonesia. then the sample was crushed using a mortar and filtered through a size 60 mesh. finally, the sample was put into a tightly closed bottle. procedure. the sample was tested using a proximate analyzer to find out the value of moisture, volatile matter (vm), ash content (ac), fixed carbon (fc), total sulfur, and gross calorific value (gcv). the proximate analysis method according to american standard testing and material (astm) with different procedures on each parameter is shown in table 1. another physical and chemical analysis was characterized using sem-edx fei inspects50 type. sem was used to show the topography and morphology of the sample, while the chemical content was investigated using edx test. a thermogravimetric differential scanning calorimetry (dsc) analyzer, mettler toledo tg/dsc 1, was used to show the graph of tg analysis and derivative thermogravimetry dtg analysis of the sample with heating rate and nitrogen flow rate is 10°c/min and 100 ml/min, respectively. issn: 2580-0817 journal of mechanical engineering science and technology 68 vol. 6, no. 2, november 2022, pp. 66-73 zakaria et al. (investigate the potential renewable energy of microalgae spirulina sp) iii. results and discussions proximate analysis results and test methods are shown in table 1. the result shows that the most dominant content of microalgae spirulina sp is vm, 68.15 wt% ar or 76.76 wt% db. it indicates that spirulina sp is reactive during reaction process, and this condition is suitable for biomass combustion. vm value shows the convenience degree of biomass to be burned. the higher content of vm indicates that biomass is more sensitized to burn as a consequence of higher reactivity. on the other hand, a lower vm content makes the biomass hard to burn [9]. table 1. the result proximate analysis of spirulina sp parameters unit ar* db** test method total moisture %wt 11.22 -astm d 2961 17 ash content %wt 8.06 9.08 astm d 3174 – 12(2018)el volatile matter %wt 68.15 76.76 astm d 3175 – 20 fixed carbon %wt 12.57 14.16 astm d 3172 – 13 total sulfur %wt 0.67 0.75 astm d 4239 – 18el b gross calorific value kcal/kg 4413 4971 astm d 5865 – 19 *ar: as received, **db: dry basis fc becomes the second dominant content in spirulina sp, about 12.57 wt% for ar and 14.16 wt% for db. fc is the remaining part of the evaporation process of volatile substances ends. carbon in spirulina sp is an organic substance that comes from the co2 fixation process during the photosynthesis process. some organic carbon will turn into pyrolytic carbon during the photosynthesis evaporation process [10]. fc values can be used to determine the reactivity of solid fuels through a comparison of vm, vm/fc [11]. the comparison value of vm/fc on biomass is usually greater than 4.0, vm/fc > 4.0. the greater ratio value indicates that the solid fuel is more flammable and vice versa [12]. in this case, the ratio of vm/fc of spirulina sp is 5.42. (a) (b) fig.1. a) sem surface image and b) topography of microalgae spirulina sp 69 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 66-73 zakaria et al. (investigate the potential renewable energy of microalgae spirulina sp) moisture and ash content on the third and fourth position of spirulina sp content with 11.22 and 8.06 wt% ar, respectively. both of the values are lower compared to vm. the lower moisture value has an effect on the energy requirements used for the evaporation process on a smaller solid fuel [13]. while the low value of ash content will give the advantage of a low solid residual. ash content in spirulina sp is relatively small but contains alkali metals such as sodium and potassium, which can cause clumping and corrosion in a combustion system [14]. visual analyses of microalga spirulina sp surface via the micrograph is shown in figure 1a. in this figure, the surface roughness of spirulina sp is shown in two dimensions (2d) with width of 20 μm. then imaged in 3d using the originpro 2017 software, as shown in fig. 1b. the red graphs in fig. 1b show the maximum peak, while the blue graphs show the lowest peak of the sample surface. dominate red graph compare to the blue graphs indicates that the surface of spirulina sp is rough. the level of surface roughness is proportional to the effective surface area, which causes an increase in the rate of intermolecular reactions [15]. it can shorten the reaction time. the higher surface area makes the evaporation process of vm on spirulina sp faster [16]. fig. 2. chemical content of microalgae spirulina sp figure 2 shows the chemical content of microalgae spirulina sp characterized by the edx test. the content of microalgae spirulina sp is dominated by carbon (c) and oxygen (o), then followed by chlorine (cl), sodium (na), potassium (k), sulfur (s), magnesium (mg), and phosphorus (p). element c leads the composition with 62,2 wt%. it is considered good condition because element c contributes positively to the formation of calorific value. the higher value of c makes the gcv value in microalgae spirulina sp higher too [17]. the second dominant is element o with 30.02 wt%. it contributes negatively to the formation of the calorific value of microalgae spirulina sp. this condition is caused by the character of the element o, which can cause the oxidation of carbon so that it obstructs the reaction [18]. the high oxygen content can be reduced using a metallic platinum (pt) or issn: 2580-0817 journal of mechanical engineering science and technology 70 vol. 6, no. 2, november 2022, pp. 66-73 zakaria et al. (investigate the potential renewable energy of microalgae spirulina sp) palladium (pd) catalyst [19]. element cl content in spirulina sp is about 3.11 wt%. in combustion process, it will vaporize and react become hydrochloride (hcl), chlorine (cl2), and alkaline chloride compounds. the alkaline chloride will condense and bond to fly-ash particles when the temperature decreases [20]. other chemical contents of microalgae spirulina sp contribute to the formation of the ash content. elements of calcium and magnesium can increase the melting temperature of the ash, while elements of potassium and sodium can decrease the melting temperature at the ashes [16]. fig. 3. the tg and dtg curve of pyrolysis spirulina sp at heating rate of 10 °c/min figure 3 shows the curve of tg and dtg pyrolysis spirulina sp at heating rate of 10 °c/min. the pyrolysis process occurs between an initial temperature of 27 °c until 995 °c for the final temperature. the decomposed process of spirulina sp is divided into three different steps. the first step started at 27 °c and finished at 173 °c. the moisture of spirulina sp was vaporized at this stage. in the first step, the mass of spirulina sp was decomposed at about 1.44 mg or 13.81% of the total initial mass, and the dtg peak at 62.04 °c. the second step began at the end of vaporized moisture at about 173 °c and ended at around 618 °c. in this step, a gasification process occurred in the volatile matter content of spirulina sp. the dominant elements gasified in this stage are carbon and oxygen. the gasification process resulted in mass loss of about 6.06 mg or 57.9 % of spirulina sp total mass. there are two peaks of dtg curves at this step. the first peak, at 286.47 °c, is degradation and combustion between carbohydrates and protein of spirulina sp. while the second peak, at 311.6 °c, shows the further decomposition and combustion between protein 71 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 66-73 zakaria et al. (investigate the potential renewable energy of microalgae spirulina sp) and lipid [21]. this observation is considered by the fact that the temperature degradation of lipids is higher than others [22]. spirulina sp at the last step shows the process of gasification of residual substances. in this process, the remaining carbon in spirulina sp will continue to react together with the formation of charcoal from the remaining chemical elements that did not react in the two previous steps. this process occurred at the end of the volatile matter step, 618 °c, and stopped at 995 °c with a decomposed mass of 2.57 mg or 24.6%. table 2. compare the physical properties of biodiesel spirulina sp and diesel fuel [21] properties spirulina sp diesel density (kg/m3) 860 830 viscosity (mm2/s) at 40 oc 5.6 2.6 calorific value (mj/kg) 41.36 43.8 flashpoint (oc) 130 50 regarding the potential of spirulina as a biofuel, table 2 display the comparison physical properties between biodiesel spirulina sp and diesel fuel by rajak. the comparative value of the two fuels is not far apart. it's just that the flash point value of spirulina sp is higher. a higher flash point value indicates that the fuel is more difficult to ignite. the difficulty level is due to the carbon bonds in the fuel, which are difficult to decompose [22]. spirulina sp has more complex carbon bonds than diesel fuel, c6h10o5, so it will be more difficult to decompose than diesel fuel, c16h34 [23],[24]. furthermore, the lower calorific value and kinematic viscosity value of fatty acids increased proportionally with chain length and decreased as the level of fatty acid alkyl chain saturation decreased. figure 3 in step 2 also confirms that there is a low-temperature reactivity due to the increased carbon-tohydrogen ratio present in the fatty acid alkyl chains [22]. iv. conclusions based on the test results, the microalgae spirulina sp has great potential to be converted as fuel. the chemical content and physical properties of microalgae spirulina sp have the characteristics needed to be used as fuel to substitute fossil fuels. the main component that must be optimized in spirulina sp microalgae is lipid because it plays a large role in the biofuel formation process, as shown in the thermal decomposition of volatile matter. potential fuel products from microalgae spirulina sp could be optimized more by researching better cultivation methods. acknowledgment i would like to acknowledge that this research was successfully carried out with the full support of prof. sukarni through research funding from penerimaan negara bukan pajak (pnbp) universitas negeri malang. reference [1] t. lancet and r. health, “editorial the regional and global impact of the russian issn: 2580-0817 journal of mechanical engineering science and technology 72 vol. 6, no. 2, november 2022, pp. 66-73 zakaria et al. 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[21] u. rajak and t. n. verma, “spirulina microalgae biodiesel – a novel renewable alternative energy source for compression ignition engine,” j. clean. prod., vol. 201, no. x, pp. 343–357, 2018, doi: 10.1016/j.jclepro.2018.08.057. [22] h. y. nanlohy, i. n. g. wardana, n. hamidi, l. yuliati, and t. ueda, “the effect of rh3+ catalyst on the combustion characteristics of crude vegetable oil droplets,” fuel, vol. 220, no. december 2017, pp. 220–232, 2018, doi: 10.1016/j.fuel.2018.02.001. [23] u. rajak, p. nashine, and t. n. verma, “characteristics of microalgae spirulina biodiesel with the impact of n-butanol addition on a ci engine,” energy, vol. 189, no. x, p. 116311, 2019, doi: 10.1016/j.energy.2019.116311. [24] y. hu, m. gong, s. feng, c. (charles) xu, and a. bassi, “a review of recent developments of pre-treatment technologies and hydrothermal liquefaction of microalgae for bio-crude oil production,” renew. sustain. energy rev., vol. 101, no. november 2018, pp. 476–492, 2019, doi: 10.1016/j.rser.2018.11.037. journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 69-77 69 doi: 10.17977/um016v1i22017p069 thermogravimetric and kinetic analysis of cassava starch based bioplastic nanang eko wahyuningtiyas 1,2, heru suryanto 3*, eddy rudiyanto4, sukarni sukarni 5, and poppy puspitasari 6 1 environmentalist, samarinda, east borneo, indonesia 2,3,4,5,6 department of mechanical engineering, faculty of engineering, universitas negeri malang * heru.suryanto.ft@um.ac.id abstract cassava starch based bioplasticfor packaging application has great potency because of the various starchproducing plants in indonesia.bioplasticcan contribute to reduce the dependence on fossil fuels andpetroleumthat can solve the environmentalproblem.thepurpose of this research is to find out the thermal decomposition and the activation energy of cassava starch based bioplastic. the methods weresynthesis bioplastic with cassava starch as main component and glycerol as plasticizer. the thermogravimetry analysis was conducted to obtain the decomposition process mechanism of bioplastic and the heating valueof bioplasticwas measured using theadiabatic bomb calorimetric. data analysis was conducted using a fitting model approach with an acikalin method to determine the activation energy. the result of thethermogravimetricanalysis showed thatbioplasticisgraduallydecomposedto the moisture, volatilematter, fixed carbon, andash in four stages mechanism. totally decomposition of bioplastic was 530°c, then all of bioplastic was become the ash. the activation energy in the early and primary thermal decomposition stages are 1.27 kj/moland 22.62 kj/mol, respectively and heating valueof bioplastic is 15.16 mj/kg. copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: ctivation energy, bioplastic, cassava starch, decomposition, kinetic analysis, thermogravimetric i. introduction the synthetic plastic is made of petroleum, coal and natural gas [1]. plastic waste poses a risk to the human health and the environment [2]. indonesia is one of the second largest plastic waste donors in the world after china [3]. waste plastichas become an environmental problem around the world [4] because it takes a long time to be degraded[5][6] and take 50 years to be degraded it in nature [7]. bioplastic can help to reduce the problem of plastic waste, because of easy to make it, abundant and affordable raw materials [8][9][10]). itiscategorized to environmental friendly [11]and able to be degraded by the activity of microorganisms by 10 to 20 times faster than the conventional plastic resulting in carbon dioxide, methane, water, biomass, humus and other natural substances from the sources of compounds in plants, such as starch, cellulose, and lignin [5][12][13]. the number of bioplastics produced in a worldwide is less than 200.000 tons per year, a smaller number when compared to 30 million tons of petroleum-based plastic[1]. however, in 2020, the utilization of bioplastic is predicted to reach at least 10%-30% of the global plastics industry [14].the potential of cassava starch as bioplastic material is great since indonesia has high cassava production, the third largest in the world [15]. the potential of cassava starch as an environmentally friendly plastic materials is very large because indonesia is the third largest producer of cassava in the world with cassava products reached 26 million tons in 2014 [16]. the use of fossil fuels will lead to global warming [17][18] because of the fossil-made plastic release about 2900 kg/tons of co2 [19]. imperfect process in the incineration also produces the harmful gases, such as so2, co, nox, no,n2o, hcl, and hf [20]. bioplastic offers a solution in reducing the dependence on fossil fuels that have an adverse impact on the sustainable environment [2]. the incineration of bioplastic will produce co2[21], but lower than synthetic plastic because of the raw material (starch) is more environmental friendly. thus, this paper explores the thermal decomposition of cassava starchbased bioplastic using the thermogravimetric and kinetic analysis mailto:heru.suryanto.ft@um.ac.id 70 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 69-77 nanang eko wahyuningtiyas et.al (thermogravimetric and kinetic analysis of cassava) ii. material and method a. material the research material wasthe cassava starch from malang, east java, indonesia. the glycerol in technical grade with concentration of 98% used as the plasticizer,provided by cv. makmur sejati, malang, indonesia. b. synthesis of bioplastic the synthesis of bioplastic refers to wahyuningyas and suryanto[6], through the process of mixing the cassava starch with glycerol.the cassava starch 5% (b/v) was mixedwithwater/aquadestof 98.5 ml,then were stirred on a magnetic stirrer at 900 rpm for 5 min. next, glycerol at concentrations of 1.5%(v/v), was added to each solution, and then the solutions were re-stirred for 5 min at 900 rpm. the solutions were heated on a magnetic stirrer at 80°c while being stirred with a magnetic stirrer at 900 rpm for 45 min. each stirred solutions werecasted into a mold 88 mmin diameter, then dried in an oven for 24 hat70°c, and finally placed at ambient temperature (27-30°c) then kept in adesiccator. c. thermogravimetry analysis the thermogravimetryanalysis refers to astme1131 [22].thermal decomposition of bioplastic was analyzed using a thermogravimetry(mettler toledo tga/dsc1 simultaneous analyzer). the 10 mg sample was heated from 30°c to 800°cwith a heating rate of 10oc/min inthepresence air with a flow rate of 50 ml/min. the thermogravimetric(tg), derivative thermogravimetric (dtg) can identify the thermal decomposition that occurs in bioplastic through the loss of weight. d. kinetic reaction the kinetic reaction of thermal decomposition of bioplastic can can be analyzed using the thermogravimetric method. the kinetic reaction behavior was obtained from the loss of mass towards the temperature.the activation energy (e) of bioplastic was calculated by using the kinetic calculation of arrhenius method according to acikalin. the following reaction scheme can illustrate the combustion of biomass: the fraction of biomass combustion (or conversion) α, is defined as follows: α = (1) where mo,mt and mf refer to the initial mass of biomass, the final value of time t and mass m at the end of the combustion, respectively. the degree of combustion, dα/dt, is a linear function of constantly determined temperature (k), and reaction model (sample temperature conversion function), f (α): (2) replace the constant rate (k) using the arrhenius equation, and enter the heating rate (β = dt/dt) in the non-isothermal case, so that equation2 will be: (3) where a is the pre-exponential factor, r is constant gas (8.314 j ok mol-1), e is activation energy, , and t is aconstant temperature. determine the value of n to derive equation 3, so that equation4 will be: (4) equation 4 is the expression used as the basic model in the calculation method for kinetic analyses of tg data. the activation energy and the pre-exponential factor of each active combustion stage are calculated from the corresponding slope (-e/r) and the interception of each final plot(ln (a /b)), respectively. issn: 2580-0817 journal of mechanical engineering science and technology 71 vol. 1, no. 2, november 2017, pp. 69-77 nanang eko wahyuningtiyas et.al (thermogravimetric and kinetic analysis of cassava) e. heating value the heating value of bioplastic was conducted by using ika type c2000 basic adiabatic bomb calorimetric. the sample about 0.25 g was heated from a temperature of 25°c to 270°cwas applied for 15 min with 75% moisture and anoxygen pressure of ± 30 bars. the heating value obtained from the process of the device is j/g unit, by the standard ofastm d 240. the heating value is calculated by using the measurement of the temperature of the water which increases due to heat. the bioplastic samples were wrapped in paper and burned in the bomb calorimetric. the heating value of the paper wrap without bioplastic was also measured to subtract the heat value of the paper-wrapped bioplastic sample so that the heating value of the bioplasticwas obtained from the substraction. the heating value of solid bioplastic can be determined by using bomb calorimetric. iii. results and discussion. a. thermogravimetryanalysis thermogravimetric analysis is a method used to study the reaction of thermal decomposition [24] between weight change and temperature[25] which are lost due to the effect of temperature on the material. the result of thethermal analysis is in the form of a curve called a thermogram. thermal decomposition is a process of changing the form of a sample into a simpler form [26] which is influenced by many factors such as temperature,heating rate, pressure, moisture, residence time, particle size, and material composition [27]. thermal decomposition involves changes in the weight of the polymer [28]. the thermal decomposition of the polymer refers to an increase in temperature that either has or has not experienced any chemical changes and also serves to find out various chemical mechanisms which experience the underlying structural changes, polymer morphology effect, additive reaction path and filler interaction[29]. the mechanism of the thermal decomposition of starch based bioplastic is shown in fig.1. stage 1 is the reduction weightcaused bythe release of moisture or water until 10.7% b/bthat occurred at 30°-130°c for 12 min.in this stage, the very light volatile matter compounds also lost [26] and the initial stage of the thermal decomposition process occurs due to evaporation of the water[30]. fig. 1. tg-dtg curve of bioplastic 72 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 69-77 nanang eko wahyuningtiyas et.al (thermogravimetric and kinetic analysis of cassava) stage 2 is the process of releasing volatile matter that occurred at 130°c-380°c for 25 min. this stage is the main thermal decomposition stagebecause a high level ofmaterial lost (69.10% b/b) since cassava starch contains amylose particles which can form carbohydrate lipids: carbon, hydrogen, and oxygen in the volatile cassava starch [31][32]. cassava starch starts to decomposed thermally at the temperature of 300°c [33]. the process of this stage triggers the rapid thermal decomposition with a large mass loss [34] and runs rapidly due to the considerable amount of oxygen. stage 3 is the stage after the release of volatile matter in the samples occurred at the temperature of 380°c–530°c for 16 min. the fixed carbon content of bioplastic was relatively low, i.e.,20.17% (b/b). in this stage, the charcoal is flammable as it is surrounded by volatile matter and oxygen diffused on the surface of the charcoal, which burn the charcoal and volatile matter simultaneously. this stage occurs after the release of volatile matter which leaves or forms carbon [35]. stage 4 is the last stage of the thermal decomposition process in bioplastic that occurred at 530°c-800°c for 23 min. this process does not produce ash, since it has been fully decomposed in the thermal decomposition process shown in the tg-dtg graphic of the low thermal decomposition reaction, since the residue of the charcoal is surrounded by the combustion ash marked by the flat tg graph in fig. 1, thus indicating the slowly confined mass. acikalinmethod this research used a fitting model approach. the fitting model is a kinetic method which involves a single heating rate[36]. the acikalin method is used for determining the activation energy in this study. the final equation of the arrhenius method can be obtained by using the logarithm of eq. 4 and makes some rearrangement as follows [37]: (5) where: (6) fig. 2. curve of stage i plot ln (dα / dt) n ln (1 α) vs (1 / t) issn: 2580-0817 journal of mechanical engineering science and technology 73 vol. 1, no. 2, november 2017, pp. 69-77 nanang eko wahyuningtiyas et.al (thermogravimetric and kinetic analysis of cassava) fig. 3. curve of stage 2 plot ln (dα/dt) n ln (1 α) vs (1/t) table 1. the parameter values in arrhenius acikalin formula stage β /oc mine/kj mol-1 r2 n plot equation 1 10 1.26954 0.982 1.0 -152.7x 1.429 2 10 22.62239 0.768 1.5 -2721.x + 6.027 according to eq. 5, plot ln (dα/dt) n ln (1 a) vs (1/t) results in a straight line (slope) to determine the value of reaction order (n) (fig. 3 and fig. 2). in order to determine the suited n value in the active combustion stage, several n values were selected, the plot was drawn, and the related correlation coefficient (r2) was calculated to generate the r2 curves vs. n. the highest r2 value ensures the most appropriate n value to determine the curve of all decomposition levels studied from the n value and had the final plot drawn. the activation energy and the pre-exponential factor of each active combustion stage were calculated from the related slope (-e/r) and interceptions(ln (a/β)) of each final plot. the results obtained by the arrhenius method on the final plot are shown in table1. e = slope x r (7) kinetics is a science that discusses the rate and reaction mechanism[38]. according to arrhenius, activation energy is the minimum energy required to start a chemical reaction (combustion). there are two ways to convert bioplastic into energy (heat), thermochemically and biochemically or biologically[17]. the conversion of bioplastic into thermochemical energy can be performed by pyrolysis, gasification, and combustion [39]. this research used combustion method. the combustion process is the process in which the combustion process occurs due to a reaction of bioplastic and oxygen to convert the solid bioplastic into the energy [38]. the activation energy determination using flynn-wall-ozawa (fwo) method for cassava starch, banana starch, and potato starch was 188.0 kj/mol, 199.3 kj/mol, and 203.60 kj/mol, respectively.the activation energy determination usingcoats–redfern methods for cassava starch, banana starch, and potato starch is 188.3 kj/mol, 200.2 kj/mol, and 204.8 kj/mol, respectively[40].it shows that the activation energy of cassava starch is low.it possibly caused by the long polymer chains and the increased polymerization, because amylose content [40] can form carbohydrate lipids: carbon, hydrogen, and oxygen in the volatile starch [41][32] in the volatile matter process. the amylose content in cassava starch is higher for 24.3% ([42] than in banana starch for 18.33% and potato starch for 16.88%[43]. the cassava starch has the lowest activation energy compared to banana and potato starch. the higher activation energy will reduce the reaction rate[44] as it will be harder to start the combustion 74 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 69-77 nanang eko wahyuningtiyas et.al (thermogravimetric and kinetic analysis of cassava) reactionprocess. the low activation energy of 1.27kj/molon stage 1indicates the weak bonds between volatile materials and polymers (bioplastic) [45]. in stage 2, it takes a higher energy of 22.62 kj/mol and a long time for 25 min to thermally decompose the carbohydrate particles. table 3 indicate that the bioplastic is easy to decompose with activation energy of 22.62 kj/mol.this activation energy is higher than the activation energyof plastic poly-lactic acid (pla) (11.2 kj/mol)[46][47] but lower than an inorganic plastic waste such as pe (248.0 kj/mol), pp (183.8 kj/mol), ps (172.0 kj/mol), hdpe (233.2 kj/mol), ldpe (206.4 kj/mol), pvc (190 kj/mol)[48] and the types of coallike brown coal (39.15 kj/mol), low coal (73.96 kj/mol)[49], anthracite (40.43 kj/mol), lignite (28.60 kj/mol)[50],and bituminous (36.18 kj/mol) [51].the higher activation energy value cause the slow and harder to initiate the combustion reaction [44][52]. the heating value the heating valueis the energy released per unit mass of a material or when the material is fully combusted or burned. the heating valueobtained using the calorimetric bomb experiment [23]. the heating valueof bioplasticis indicated by hhv (higher heating value) [53] and the someof the heating value of materials arelisted in the table 2. the heating value of a substance is influenced by the composition of the substance contained in the sample[60]. as shown in the thermogravimetric test result (fig. 1), it shows that almost bioplastic is fully combusted in the volatile matter process that contains a high level of carbohydrates results the higher the heating value or energy contained [61]. the samples with low ash content are perfectspecimens because they reduce the exhaust emissions [62]. the heating value test ofbioplastic sample is 15.16 mj/kg (table 2). the heating value ofbioplasticis relative sama with the polyvinyl chloride (pvc) with hhv of 18.00 mj/kg [54]. the heating value of bioplastic is also higher than four types of coal:bituminous coal spanish,lignite coal germany,anthracite spanish,and peatswedish with hhv of 7.55 mj/kg, 9.00 mj/kg, 7.97 mj/kg, and 12.66 mj/kg, respectively[56]. the heating value of bioplastic is also higher than of food waste,husk, textiles, and paper with hhv of 4.00 mj/kg,15.00 mj/kg [55], 15.02 mj/kg [63], 15.02 mj/kg [57], respectively. table 2. heating valuefrom a variety of materials sample heating value(mj/kg) references bioplastic cassava starch 15.16 this study polyvinyl chloride (pvc) 18.00 [54] polypropylene (pp) 46.40 [54] polyethelene (pe) 46.30 [54] polystyrene (ps) 41.40 [54] food waste 4.00 [55] rice husk 15.00 [55] textiles 15.02 [56] bituminous coal spanish 7.55 [56] lignite coal germany 9.00 [56] anthracite spanish 7.97 [56] peat swedish 12.66 [56] corn stalks 18.48 [57] wood 18.42 [58] straw 15.61 [59] issn: 2580-0817 journal of mechanical engineering science and technology 75 vol. 1, no. 2, november 2017, pp. 69-77 nanang eko wahyuningtiyas et.al (thermogravimetric and kinetic analysis of cassava) iv. conclusion. the cassava starch based bioplasticwasthermally decomposed in four stages mechanism and, has an activation energy at the initial and main thermal decomposition stages of 1.27kj/mol and 22.62 kj/mol, respectively. thus, theheating value of bioplastic obtained in the heat test for 15.16 mj/kg. the bioplastic can be thermally degraded as easy as the synthetic plastic. acknowledgements greatly appreciate to the ministry of research and technology and higher education, republic indonesia through pupt program 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[63] islam k. m. nazmul, “municipal solid waste to energy generation in bangladesh : possible scenarios to generate renewable electricity in dhaka and chittagong city,” j. renew. energy, vol. 2016, pp. 1– 16, 2016. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 48-55 48 doi: 10.17977/um016v6i12022p048 gasohol engine performance with various ignition timing hendry y. nanlohy1*, suyatno1, helen riupassa1, marthina mini1, trismawati2, mebin panithasan3 1department of mechanical engineering, jayapura university of science and technology, jayapura, 99351, indonesia 2department of industrial engineering, panca marga university, probolinggo, 67271, indonesia 3department of mechanical engineering, king abdullah university of science and technology, 23955, saudi arabia *corresponding author:hynanlohy@gmail.com article history: received: 11 june 2022 / received in revised form: 25 june 2022 / accepted: 29 june 2022 abstract experimental research has been conducted on the effect of ignition timings on the characteristics and performance of gasohol engines such as power, torque, specific fuel consumption, and thermal efficiency. the fuel used in this research is pure gasoline and a mixture of 50% bioethanol (be50). the results show that the ignition timing that gives the maximum effect occurs at the top and bottom dead points of 9 degrees for gasoline and 12 degrees for be50 fuel. furthermore, the maximum power is obtained at 6,500 rpm, and at an ignition time of 12 degrees btdc the maximum power generated is 4.63 hp, while for an ignition time of 9 degrees btdc the power generated is 3.38 hp which occurs at 6500 rpm. these results indicate that there is an increase in power of 6.4%. moreover, the results also show that for optimal gasoline conditions, the amount of energy consumed at an engine speed of 7000 rpm is around 15705.78 kcal/hour, and for be50 it is around 12582.03 kcal/hour, where there is a reduction of about 25.44 %. however, in general, it can be seen that during optimal ignition, there is a saving in fuel consumption in the gasoline-be50 mixture, while at the same time producing a fairly large thermal efficiency. these results indicate that be50 has the potential to be used as an alternative fuel in small gasoline engines. copyright © 2022. journal of mechanical engineering science and technology. keywords: bioethanol, engine power, fuel consumption, ignition timing, thermal efficiency, torque i. introduction the increase in industrial activity and the increasing world population cause fuel consumption to increase so that it interferes with air quality and causes an energy crisis [1], [2]–[4]. this makes the need for environmentally friendly alternative fuels very crucial [3], [5]. therefore, the researchers conducted many studies and found that bioethanol is one type of alternative fuel that can be applied to internal combustion engines (icdise) and at the same time to overcome the fuel energy crisis [4], [6], [7]. the raw material for bioethanol used in this study is sourced from coconut sap water which is processed through natural fermentation and fractional distillation [8], [9]. furthermore, the production cost is relatively cheap because it only requires distillation equipment, unlike the transesterification or esterification process which is more expensive and need more equipment. moreover, it requires a long process with a lot of equipment.bioethanol is one type of alternative fuel that is converted from bioenergy plants and biomass [10], and with a high octane number, it has the opportunity to be used as an alternative to gasoline [11]. in addition, bioethanol has 49 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 48-55 nanlohy et al. (gasohol engine performance with various ignition timing) greenhouse gas emissions and lower production costs, as well as a more profitable future evolution that makes bioethanol and its mixtures have great potential to be used as renewable fuels, especially in ice [12]. on the other hand, a lot of research has been done on the production of bioethanol and its application to machinery [13], [14] and it was found that ethanol fuel is suitable for internal combustion engines but is more focused on diesel engines [15]–[17]. in addition, a recent study on the effect of a mixture of ethanol and gasoline on nox emissions [18] and their effect on fuel properties and fuel efficiency for blending ethanol and gasoline have also been applied to the ice and resulted in very good performance improvements [8], [19]. on the other hand, studies on the application of bioethanol (be5, be10, be15, and be20) by modifying the ignition timing constant on the ice have been carried out [20]. from the results of the study, it was found that there was an increase in the octane number for all variations of gasoline bioethanol mixtures and reduced carbon monoxide and unburned hydrocarbon gas emissions. furthermore, for be30 with different ignition timing variations, it was also found that emission reduction achieved by increasing the ignition timing further advanced the ignition timing resulting in a significant reduction in nox emissions [21], [22]. however, it is unfortunate because there are no results from the above research that have revealed the effect of the use of a mixture of bioethanol and gasoline on a stationary si engine including combustion characteristics, performance, and exhaust emissions. therefore, this study aims to reveal scientific information about the performance of bioethanol fuel and its mixture with gasoline on the performance of stationary ice, including power, torque, sfc, and thermal efficiency (ηth). ii. material and methods this study uses pure gasoline and a mixture of gasoline with 50% bioethanol (be50). the results of testing the fuel properties can be seen in table 1. table 1. comparison of the main properties of fuel properties gasoline be-50 molecular formula c7h18 c2h5oh molecular weight 100-105 46.07 research octane number (ron) 95.5 120-135 auto-ignition temperature (oc) 257 423 specific heat (kj/kg k) 2.4 2.0 density at 15 oc (g/ml ) 0.739 0.79 viskosity at 20 oc (mpa) 1.19 0.37-0.44 in addition, this experiment used a variable speed test with a wide-open throttle accompanied by a load setting on the water brake dynamometer to get the expected engine speed [10]. the research scheme can be seen in figure 1. the test begins with checking the engine performance on the ignition timing btdc 9 degrees, 12 degrees, and 15 degrees. the engine is operated with an engine speed of 4000 rpm to 7500 rpm accompanied by cooling from the fan to avoid overheating. the next step is to increase the engine speed until a half-open throttle condition is achieved accompanied by loading by adjusting the water issn: 2580-0817 journal of mechanical engineering science and technology 50 vol. 6, no. 1, july 2022, pp. 48-55 nanlohy et al. (gasohol engine performance with various ignition timing) flow opening through the water brake dynamometer to 7500 rpm and then observing the load (n) and time (s). the first test used pure gasoline and after that, it used a be50 mixture where the combustion time was increased every 3 degrees. fig 1. experimental scheme iii. results and discussions a study on the comparison of the effect of gasoline-be50 mixture and variations in ignition timing on the performance of the ice has been carried out. the results showed that there were changes in engine performance parameters, including; torque, effective engine power, thermal efficiency (ηth), specific fuel consumption, and energy consumption. fig 2. comparison of torque (left) and engine power (right) figure 2 shows the maximum torque achieved at 12 degrees btdc ignition time is 6.05 n.m and for 9 degrees btdc ignition timing is 5.93 n.m, and these results indicate that there is an increase in torque of 1.97%. meanwhile, when compared to gasoline, there was a decrease in torque from 6.93 n.m to 6.05 n.m, or an average decrease of 7.54%. these results indicate that more bioethanol content in gasoline causes a decrease in power. this analysis is possible because the specific energy and heat (see table 1) contained in the be50 fuel mixture are very low. furthermore, the large hydrogen mass content in bioethanol has 51 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 48-55 nanlohy et al. (gasohol engine performance with various ignition timing) the potential to increase the strong attractive force with oxygen so that it has the potential to produce h2o molecules and become a coolant in the combustion chamber. this is very reasonable because from figure 2 it can be seen that the maximum power is obtained at 6,500 rpm, and at an ignition time of 12 degrees btdc the maximum power generated is 4.63 hp, while for an ignition time of 9 degrees btdc the power generated is 3.38 hp which occurs at 6500 rpm. these results indicate that there is an increase in power of 6.4%. on the other hand, when compared to the power produced by gasoline under standard conditions, there is a decrease in power from 4.86 hp to 4.63 hp, or an average decrease of 7.55%. fig 3. variations in thermal efficiency (left) and specific fuel consumption (right) at different engine speeds on the other hand, thermal efficiency is a parameter of the amount of energy used in the converted fuel to produce optimal work (n). figure 3 shows that the highest thermal efficiency is obtained at 9 degrees, while the smallest is at 15 degrees. this result proves a phenomenon where the spraying of fuel into the combustion chamber at an ignition time of 9 degrees btdc becomes more effective for generating power. this is very possible because, during the compression process and the ignition timing just before reaching the top dead point, the mass of material that can react in the combustion stage becomes less. this result is confirmed and indicated by the amount of specific fuel consumption with a low ignition timing of 9 degrees. in addition, figure 3 (right) also shows that the lowest sfc occurs at the ignition timing of 9 degrees when compared to fuel consumption at other positions. this is what causes the thermal efficiency to be greater. in addition, the results of the study also found that the maximum thermal efficiency was achieved at an ignition timing of 12 degrees btdc accompanied by the maximum power generated (see figure 4). while the minimum thermal efficiency is at 9 degrees btdc ignition time. on the other hand, it can be seen that although the ignition time of 9 degrees btdc is less than that of gasoline, the be-50 has the highest thermal efficiency. this phenomenon is influenced by the lower calorific value of be50 which is around 8427.86 kcal/kg so that energy consumption with be50 is reduced. moreover, this indicates that at the correct ignition timing, the air-fuel ratio is achieved, and this is triggered by the increased reactivity of the many hydrogen atoms in bioethanol. this analysis is very possible and is by previous research which states that atomic reactivity has the potential to increase the reaction speed of the fuel molecules to increase the energy contained in the fuel [23], [24]. 19 20 21 22 23 24 25 26 27 3500 4500 5500 6500 7500 8500 t h e rm a l e ff ic ie n cy ( % ) engine speed (rpm) 09 btdc 12 btdc 15 btdc 0.240 0.260 0.280 0.300 0.320 0.340 0.360 3500 4500 5500 6500 7500 8500 s fc ( kg /h p ja m ) engine speed (rpm) 09 btdc 12 btdc 15 btdc issn: 2580-0817 journal of mechanical engineering science and technology 52 vol. 6, no. 1, july 2022, pp. 48-55 nanlohy et al. (gasohol engine performance with various ignition timing) on the other hand, from figure 4 it can be seen the impact of changing the ignition timing on the amount of energy consumed (ec). for optimal gasoline conditions, the amount of energy consumed at engine speed of 7000 rpm is around 15705.78 kcal/hour, and for be50 it is around 12582.03 kcal/hour, where there is a reduction of about 25.44%. fig 4. comparison of thermal efficiency (left) and energy consumption (right) at different engine speeds iv. conclusions an analysis of the effect of ignition timing of various degrees on the performance of gasoline-bioethanol-fueled gasoline engines has been carried out, and there are some very important practical findings. the optimal ignition timing for gasoline engines is 9 degrees, while for bioethanol the optimal ignition timing is 12 degrees btdc. furthermore, the improved performance of the be50-petrol mixed fuel engine proves that the be50 can be used as an alternative fuel by changing the ignition timing. as for the be-50, the ignition timing must be changed to 12 degrees btdc where the skepticism needle in the carburetor is in position one from the bottom to produce an optimal power of 4.63 hp at 6500 rpm, and an optimal torque of 6.05 nm at 4000 rpm. to get the maximum benefit from bioethanol, further research is needed using bioethanol with a higher blend content of 80 to 95% bioethanol (be80-be95) or 100% bioethanol (be100) on si engines with engine speeds of around 5000 to 8000 rpm. several studies have found that without modification [25], the bioethanol-fueled si engine produces different performance [26], so it can be tried to modify the engine with different loading and compression ratio variations. acknowledgment a big thank you to lppm jayapura university of science and technology for their financial assistance and support so that this research can be completed properly. in addition, thanks also to the fuel and combustion laboratory, department of mechanical engineering, jayapura university of science and technology for the support of research materials and equipment. 53 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 48-55 nanlohy et al. 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(gasohol engine performance with various ignition timing) [26] j. r. varma, s. k. r. katepalli, m. sreeja, and b. hadagali, “comprehensive studies on alcohol using port fuel injection facilitated with spark plug engine,” mater. today proc., vol. 45, pp. 3219–3225, 2021, doi: 10.1016/j.matpr.2020.12.379. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 40-47 40 doi: 10.17977/um016v6i12022p040 machine vision for the various road surface type classification based on texture feature susi marianingsih1*, widodo1, marla sheilamita s. pieter1, evanita veronica manullang1, hendry y. nanlohy2 1faculty of computer science and management, jayapura university of science and technology, 99351, indonesia 2department of mechanical engineering jayapura university of science and technology, 99351, indonesia *corresponding author:ssmarianingsih@gmail.com article history: received: 9 april 2022 / received in revised form: 10 mei 2022 / accepted: 10 june 2022 abstract the mechanized ability to specify the way surface type is a piece of key enlightenment for autonomous transportation machine navigation like wheelchairs and smart cars. in the present work, the extracted features from the object are getting based on structure and surface evidence using gray level co-occurrence matrix (glcm). furthermore, k-nearest neighbor (k-nn) classifier was built to classify the road surface image into three classes, asphalt, gravel, and pavement. a comparison of knn and naïve bayes (nb) was used in present study. we have constructed a road image dataset of 450 samples from real-world road images in the asphalt, gravel, and pavement. experiment result that the classification accuracy using the k-nn classifier is 78%, which is better as compared to naïve bayes classifier which has a classification accuracy of 72%. the paving class has the smallest accuracy in both classifier methods. the two classifiers have nearly the same computing time, 3.459 seconds for the knn classifier and 3.464 seconds for the naive bayes classifier. copyright © 2022. journal of mechanical engineering science and technology. keywords: co-occurrence matrix, image data set, k-nearest neighbor, naïve bayes, road surface types i. introduction for now, several studies about the use of machine learning are very useful in developing the automotive industry [1], [2], and this fact shows that the development of the automotive industry does not always depend on the field of mechanical engineering i.e. fuel and engine performance [3-5], but also on the field of machine learning of computer vision. through computer vision, a machine vision is created to detect the way surface object, which is the crucial piece of information for automated machine technologies users [6]. determination of road surface type is crucial, especially to develop security aspects for transportation users and minimize congestion and accidents [7]. image classification is one way that can be used to solve problems that have the potential to arise in automatic driving technologies. information about the feature texture of road surface types is one part of image classification that can be applied to analyze the type of road surface [8], [9]. however, these different road models have the potential to cause problem, therefore, a better and more accurate method is needed to classify road surface conditions [10]. 41 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 40-47 marianingsih et al. (machine vision for the various road surface type classification) some researchers use the glcm classification method for describing texture details into spatial domain and edge images [9], [11]. moreover, glcm is also used to detect rock images in the road type classification based on visual data, the glcm method is also used to characterize way surfaces by several aspects such as texture [12], color [13], and border features of riders’ sight image to coach a neural network of objects. in addition to glcm, there is also the use of several classification methods such as convolutional neural networks [14] and support vector machine [15] to detect, but, the accuracy was low [16] and the sample size is too small with an accuracy below 60% [8]. furthermore, other classifiers have also been used, such as k-nn [9],[17] and nb [18],[19]. however, the use of this classification method only focuses on determining the location, classifying images, and combining the k-nn [20] and nb methods to characterize numeral and total attributes [21]. based on the brief description above, it can be seen that the use of classification methods to detect and provide detailed information on an object is very important. but with the low accuracy of results and a small number of samples, not much scientific information has been revealed. the application for detecting road surface types has not even been seen yet based on feature textures. therefore, further research on this matter is needed to produce scientific information about the detection of three road types (asphalt, gravel, and pavement) based on feature texture using the glcm, knn and nb methods. ii. material and methods a. road image dataset figure 1 and figure 3 shows a sample image of each class from the dataset. the dataset was constructed from 90 road images with good illumination from google street view and divided into 3 classes and each object is 30 pieces. fig. 1. sampling images from each class. furthermore, we extract 50 x 50 part-images from the obtained images to create our set of data (see figure 2). in total of data collection, there are 450 road surface images, 300 for practice and 150 for verifying. fig. 2. extraction of part-images from the road image issn: 2580-0817 journal of mechanical engineering science and technology 42 vol. 6, no. 1, july 2022, pp. 40-47 marianingsih et al. (machine vision for the various road surface type classification) (a) (b) (c) fig. 3. the typical surface image b. glcm texture features glcm is an approach for extracting texture features from an image. glcm identifies the relationship between 2 neighboring pixels. each pixel has a gray level, distance, and angle attribute. this study uses a gray level range of 0-255, the distance in glcm is calculated by the number of pixels between the reference pixel and neighboring pixels, and 8 angles can be used in glcm, including angles 0°, 45°, 90°, 135°, 180°, 225°, 270°, or 315°. this study uses 4 angles, namely 0°, 45°, 90°, and 135°, because the glcm value at an angle of 0° is equal to a value of 180°, as well as the values of 45°, 90°, and 135° are equal to 225°, 270°, and 315°. furthermore, the glcm technique begins with the creation of a matrix with sizes according to the range of gray levels. the second step is to create a co-occurrence matrix, which means filling the matrix with several pixel pairs for a certain brightness level, with a certain combination of distance and angle. the third step is to create a symmetric matrix by adding the co-occurrence matrix to the transpose matrix. finally, normalize the value of the co-occurrence matrix by dividing each matrix element by the sum of all the matrix element values. fig. 4. the example calculation of the glcm matrix. the texture features of an image are obtained by calculating the second-order statistical features [22]. furthermore, several attributes are used to shorten computation time i.e. angular second-moment (asm), entropy, contrast, and correlation. the angular secondmoment (asm) feature is a measure of image homogeneity. the entropy feature is a measure of gray-level irregularities in the image. high value if glcm elements have relatively equal value and low value if glcm elements close to zero or one. c. classification of road surface types image furthermore, to classify the type of road surface, two methods are used, namely knn and nb. knn classifier is a supervised machine-learning algorithm that can be used to solve 43 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 40-47 marianingsih et al. (machine vision for the various road surface type classification) classification and uses ‘similarity measure’ for an estimate and compare the identical values of the actual data with the data in the training set. however, knn has four-step i.e. (1) load the data training and test data; (2) select the k value; (3) compute the distance between test data. furthermore, every line of training data with the euclidean distance is based on the distance value, and sort them in ascending order. (4) choose the top k rows from the selected range and specify a class to the test point based on the majority class of these lines. on the other hand, the nb classifier is an approach method for achieving the best prediction and increasing accuracy levels. iii. results and discussions this study uses achievement measurements of confusion matrix. the confusion matrix consists of four basic characteristics (value) that are used to define the measurement metrics of the classifier. these four values are recall, precision, f-measure, and accuracy [23]. an example of a confusion matrix is shown in table 1. the number of negative examples classified accurately is denoted true negative value and the number of positive examples classified accurately is denoted true positive value. the number of actual negative examples classified as positive is false positive value and the number of actual positive examples classified as negative is false negative value. moreover, this phenomenon is the same as the results of previous studies that discussed vehicle safety systems to minimize accidents [23]. table 1. confusion matrix predicted negative positive actual negative true negative false positive positive false negative true positive percentage of related sides that are properly intelligible recall. the predicted proportion of interrelated sheets thus precision occurs. f-measure comes from precision and recall amount. the part of the total sum of the true forecast is called accuracy. the equation we are considering is: 𝑅𝑒𝑐𝑎𝑙𝑙 = 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 𝐹𝑎𝑙𝑠𝑒 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒+𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 ............................................................................. (1) 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 = 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 𝐹𝑎𝑙𝑠𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 + 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 ................................................................................ (2) 𝐹 − 𝑀𝑒𝑎𝑠𝑢𝑟𝑒 = 2 𝑥 𝑅𝑒𝑐𝑎𝑙𝑙 𝑥 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 𝑅𝑒𝑐𝑎𝑙𝑙 + 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 ................................................................................. (3) 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦 = 𝑇𝑟𝑢𝑒 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒+𝐹𝑎𝑙𝑠𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 𝑇𝑟𝑢𝑒 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒 + 𝐹𝑎𝑙𝑠𝑒 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒+𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒+𝐹𝑎𝑙𝑠𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒 ................................... (4) the road image dataset (see figure 3) consists of 450 images which are divided into 300 training images (100 objects per grade) and a test set of 150 (50 objects per grade). the glcm program is well-used to select texture features (entropy, contrast, correlation, and asm) from each image data. issn: 2580-0817 journal of mechanical engineering science and technology 44 vol. 6, no. 1, july 2022, pp. 40-47 marianingsih et al. (machine vision for the various road surface type classification) the features of each image are stored in a vector, and these features are inputs for the knn classifier and naïve bayes classifier. figure 5 showed the system of the block diagram. furthermore, the early examination is to complete the value of k with the top categorization, and the output on several k values (see fig. 6). moreover, the results show that the k=2 gives the best performance with an accuracy of about 78%. we use this accuracy to compare naïve bayes classifiers. this phenomenon indicates that the classification method used gives positive results and has the opportunity to be used in identifying road surfaces. this analysis is very possible because it is in alignment with the results of previous studies [19]. furthermore, with an accuracy above 70%, it has the potential to improve automatic driving technologies, which are beneficial in reducing congestion and accidents. this finding is very important because it provides additional scientific information on the impact received by a car or driver as a result of vibrations [24], [25] caused by changes in the road surface. figure 5. block diagram of the system figure 6. effect of k value on experiment classification accuracy the confusion matrix and the performance measurements result for knn classifier with k value is 2 (see table 2), and naïve bayes classifier are shown in table 3. the result indicates that the knn classifier have the best performance on asphalt class and naïve bayes classifier has the best performance on gravel class. in final, the knn classifier produces better accuracy around 78% than the naïve bayes classifier around 72%. this result is following previous research regarding road surface conditions, which were discussed with a different perspective [6], [23], where they stated that the knn classifier is 62 64 66 68 70 72 74 76 78 80 0 2 4 6 8 10 12 14 16 18 20 22 a c c u ra c y ( % ) value (k) the highest acuration the lowest acuration 45 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 40-47 marianingsih et al. (machine vision for the various road surface type classification) more recommended for detecting slippery road surface conditions during the rainy season because it is able to produce a better level of accuracy than the naïve bayes classifier. furthermore, we tested the classification ten times with the same type of data (training and test). the computational time of the knn classifier and the naive bayes classifier, tend to be the same, and the average computation time of knn is 3.459 seconds and naive bayes is 3.464 seconds with a standard deviation of about 1.4. table 2. confusion matrix of knn classifier with value of k = 2 class asphalt gravel pavement knn nb knn nb knn nb asphalt 49 38 1 8 0 4 gravel 8 3 36 46 6 1 pavement 5 2 13 39 32 9 table 3. performance measurements result of knn classifier with the value of k = 2 class precision recall f1-score knn nb knn nb knn nb asphalt 0.79 0.88 0.98 0.76 0.88 0.82 gravel 0.72 0.49 0.72 0.92 0,72 0.64 pavement 0,84 0.64 0.64 0,18 0.73 0.28 iv. conclusions in this study, we proposed the feature from texture information and used knn classifier to classify road surface types such as asphalt, gravel, and pavement. the knn classifier with a k value is 2 has the best performance with an accuracy of 78% and the gravel class has the highest accuracy. as a comparison, the same dataset is classified using naive bayes classifier and yields an accuracy of 72% and the gravel class has the highest accuracy. the paving class has the smallest accuracy in both classifier methods. the two classifiers have nearly the same computing time, 3.459 seconds for the knn classifier and 3.464 seconds for the naive bayes classifier. furthermore, to get comprehensive scientific information about road surface detection and classification, thus future studies can use features of colour and texture for improved accuracy results up to 80% and even 90%, and besides that, they can use or compare with other classifiers. acknowledgment the authors are very grateful to the faculty of computer science and management of jayapura university of science and technology through the computer vision research group, which has supported the funding of research and equipment so that this research can be completed properly. references [1] g. mao, c. zhang, k. shi, w. ping, “prediction of the performance and exhaust emissions of ethanol-diesel engine using different neural network,” energy sources, issn: 2580-0817 journal of mechanical engineering science and technology 46 vol. 6, no. 1, july 2022, pp. 40-47 marianingsih et al. 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[25] g. doğan, b. ergen, “a new mobile convolutional neural network-based approach for pixel-wise road surface crack detection,” measurement, vol. 195, may 2022, 111119. https://www.sciencedirect.com/science/article/abs/pii/s0263224122003815#! journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 74-84 74 doi: 10.17977/um016v6i22022p074 the effect of nozzle temperature, infill geometry, layer height and fan speed on roughness surface in petg filament doohan taqdissillah, aris zainul mutaqqin, mahros darsin*, dedi dwilaksana, nasrul ilminnafik department of mechanical engineering, faculty of engineering, university of jember, jl. kalimantan 37, jember, 68121, indonesia *corresponding author: mahros.teknik@unej.ac.id article history: received: 28 july 2022 / received in revised form: 13 september 2022 / accepted: 24 september 2022 abstract 3d printing is a process of making three-dimensional solid objects from a digital file process created by laying down successive layers of material until the object is created. many filaments can be used in 3d printing, one of which is petg (polyethylene terephthalate glycol). petg is a modification of pet (polyethylene terephthalate) with added glycol at a molecular level to offer different chemical properties that provide significant chemical resistance, durability, and excellent formability for manufacturing. this study aims to find the most optimal parameter of surface roughness of petg with different parameters of nozzle temperature, infill geometry, layer height and fan speed. taguchi l16 (44), with four levels for each parameter, was used to determine the effect of each parameter. each experiment was repeated five times to minimize the occurrence of errors. based on the result, the effect of each parameter is nozzle temperature at 4.9%, infill geometry at 5.9%, layer height at 82.3%, and fan speed at 4.6%. layer height has the highest effect on surface roughness, and other parameters have a low effect, under 7%. research shows that the optimal combination of parameters is a nozzle temperature of 220 °c, infill geometry zig-zag, layer height of 0.12 mm, and a fan speed of 80 %. copyright © 2022. journal of mechanical engineering science and technology. keywords: 3d printing, petg filament, printing parameter, taguchi, surface roughness i. introduction in this massive industry era, many industries try to satisfy the customer with their product, and one factor that can satisfy the customer is customization. customization can make the customer choose the design based on what they want, and because of that customer will satisfy with the product [1]-[3]. one of the manufacturing techniques for customization is 3d printing because 3d printing uses a building system so the product can be built up to the design the customer desires. many filaments can be used as a base material for 3d printing, such as abs, pla, pc, pekk, dan petg, etc. [4], [5]. petg is a kind of filament in 3d printing with the market name polyester plastic with the addition of glycol modification [6]. the advantage of petg material is its excellent chemical resistance, high impact resistance, low shrinkage, and good interlayer bonding [7][9]. the popularity of petg is in the food industry (food-safe plastic containers), the medical sector can be created for medical use (rigid structures that withstand rigorous sterilization processes, implants) and body accessories customization [10]-[13]. in body accessories customization, one product is a necklace. in body accessories customization, mailto:mahros.teknik@unej.ac.id 75 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) surface roughness is the factor that affects in quality of petg because the smooth surface of accessories can provide comfort to the user. because of that, smoother surface roughness can improve the material's quality [14]-[16]. che mat et al. [17] studied that layer height affects surface roughness; the smoothest surface roughness was ra 4.2, with a parameter layer thickness of 0.1 mm and infill density of 50%. pramanik et al. [18] conclude that the parameter that has the most effect on surface roughness is printing speed (58.15%), followed by extruder temperature (23.79%), infill density (15.64%), layer height (7.11%) and bed temperature (0.924%). in this research, printing speed has the most extensive domination, above 50%, while other parameters are under 25%. priyadarsini et al. [19] conclude that surface roughness has a linear relationship with a layer thickness parameter. as the layer thickness increase, the surface roughness can be rougher. barrios et al. [20] conclude that the parameter with the most decisive influence on surface roughness is printing acceleration (pa) and flow rate (f). pa contributes to a surface roughness of 23.00 %, and f contributes to a surface roughness of 43.74 %. from the previous research, there is no research on the surface roughness of petg with the parameter of infill geometry, and this research wants to use the parameter of infill geometry to find out the effect of this parameter on the surface roughness of 3d printing specimens. this research aimed to obtain the most affected combination of surface roughness parameters from 4 parameters (nozzle temperature, infill geometry, layer height and fan speed). ii. material and methods in this study, the material used is petg filament (esun brand), and the tools used are 3d printing creality 3 v2 and surface roughness tester tr220. table 1. petg filament specification material petg filament diameter (mm) 1.75 printing temperature (°c) 200-220 tolerance (mm) 0.02 printing speed (mm/s) 50-100 bed temperature (°c) 60-80 net weight (kg) 1 bruto (kg) 1.3 filament length (m) 320 melting process speed (gr/min) 61 certificate rohs, reach the process parameter used in this study is independent parameters and control parameters. independent parameters are nozzle temperature, infill geometry, layer height and fan speed. furthermore, every parameter has four levels. the control parameters are infill density 50%, bed temperature 80 °c and printing speed 50 mm/s. table 2 shows the independent parameters and the levels in this study. issn: 2580-0817 journal of mechanical engineering science and technology 76 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) table 2. research independent parameters parameter level 1 2 3 4 layer height (mm) 0.12 0.16 0.20 0.24 infill geometry grid zig-zag gyroid triangles nozzle temperature (°c) 220 230 240 250 fan speed (%) 20 40 60 80 in this study, taguchi oa l16 (44) was used to minimize the number of experiments from 256 to 16 without reducing the data accuracy. in layer height, the reason for selecting the four levels is because 0.12 mm is the smoothest layer height, 0.24 mm is the roughest layer height, 0.16 mm and 0.20 mm are used as proof of the difference value between the smoothest and roughest. in infill geometry, the reason for selecting that four levels is because every level has a different foundation pattern and to prove which pattern has the best effect on surface roughness. nozzle temperature is the reason for selecting those four levels because 220°c to 250°c are the temperature required for petg filament. in fan speed, the reason for selecting that four levels is because every level has a different effect in hardening petg filament. each experiment was repeated five times to reduce data error. the taguchi oa l16 table is obtained from the minitab application. table 3 shows the combination of each parameter and level in every experiment. table 3. orthogonal array experiment layer height infill geometry nozzle temperature fan speed 1 1 1 1 1 2 1 2 2 2 3 1 3 3 3 4 1 4 4 4 5 2 1 2 3 6 2 2 1 4 7 2 3 4 1 8 2 4 3 2 9 3 1 3 4 10 3 2 4 3 11 3 3 1 2 12 3 4 2 1 13 4 1 4 2 14 4 2 3 1 15 4 3 2 4 16 4 4 1 3 the design of the specimen used in this study is a cube with an arch-shape on one side, the dimension of the cube is 25 mm, and the diameter of the arch-shape side is 25 mm. five sides will be points of surface roughness measurement. there are 1 point on the right side, 1 point on the front side, 1 point on the left side, 1 point on the left side arch, and 1 point on the right side arch for measuring direction if toward the front from behind in every side of specimens. figure 1(a) shows the specimen's design, and figure 1(b) shows the specimen after being printed. figure 2 shows the specimen with 16 different parameters. 77 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) fig. 1. design of specimen (left) and specimen after printing (right) fig. 2. specimens of this research iii. results and discussions this study measured surface roughness in 16 specimens with surface roughness tester tr220. table 4 shows the result of the surface roughness of 16 specimens in ra score. based on the table 4, the specimen with the lowest surface roughness point is experiment 2 with a surface roughness point (ra) 8.308, and the specimen with the highest surface roughness point is experiment 16 with a surface roughness point (ra) 17.144. based on this data specimen with the smoothest surface is in experiment 2, and the specimen with the roughest surface is in experiment 16. each experiment was repeated five times to calculate the signal-to-noise ratio or snr. snr is used to determine the parameters that affect the response. in this study is the surface roughness. minitab application is used to analyze experimental data. the parameters are sorted from most to least influential and written in the main effect graph and response table. the surface roughness response of the specimen was analyzed using the smaller is better snr method, or the lower the response value, the better result will be. the results of the snr value is shown at table 5. the formula for the smaller is better snr method is below: issn: 2580-0817 journal of mechanical engineering science and technology 78 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) table 4. surface roughness result exp surface roughness score (µm) standard deviation a b c d e average 1 9.828 8.342 8.437 8.357 7.566 8.506 0.819 2 8.163 7.962 9.996 8.010 7.407 8.308 0.986 3 10.289 7.964 10.210 9.560 8.588 9.322 1.020 4 10.340 8.121 8.843 8.079 9.928 9.062 1.034 5 12.259 11.359 12.270 11.569 10.970 11.685 0.570 6 8.923 9.317 8.826 7.900 9.145 8.822 0.549 7 17.389 16.780 15.909 15.079 15.470 16.126 0.948 8 12.590 11.329 10.960 11.260 12.140 11.656 0.680 9 13.710 13.449 14.560 13.210 12.899 13.565 0.631 10 14.970 13.199 13.779 14.189 13.220 13.871 0.740 11 14.460 13.109 13.850 13.539 13.439 13.679 0.510 12 14.579 13.050 16.139 15.170 14.140 14.615 1.151 13 17.469 16.229 17.829 15.579 16.569 16.735 0.915 14 17.299 16.709 17.329 16.219 16.450 16.801 0.499 15 17.549 16.819 17.129 15.979 16.520 16.799 0.596 16 18.250 16.829 17.579 15.470 17.590 17.144 1.062 table 5. snr parameter response level layer height (mm) infill geometry nozzle temperature (˚c) fan speed 1 -18.92 -21.78 -21.24 -22.65 2 -21.45 -21.18 -21.91 -21.75 3 -22.89 -22.14 -21.99 -22.09 4 -24.55 -22.71 -22.67 -21.32 delta 5.63 1.53 1.43 1.33 rank 1 2 3 4 based on table 5, the level that affects the best score in surface roughness are layer height of 0.12 mm, infill geometry zig-zag, nozzle temperature 220˚c and the fan speed of 80%. analysis of variance for the snr table shows every parameter's contribution to the surface roughness response. the contribution can be determined by dividing the sequel sum of square (seq ss) by total ss and multiplying by 100%. table 6 shows an analysis of parameter variance. 79 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) based on table 6, the confidence level used as a standard is α = 0.05. if p-value has a lower score than α mean, the parameter gives more effect in surface roughness, and if pvalue has a higher score than α mean, the parameter gives less effect in surface roughness. the data show that only layer height has a p-value lower than α and the rest of the parameters have a p-value higher than α. the p-value of the three parameters is higher than 0.20 because the three-parameter supports layer height and affects layer height. they have a common effect on surface roughness because they are indirectly related. the parameter with the highest contribution is layer height at 82.3 %, followed by infill geometry, nozzle temperature and fan speed under 7%. bintara et al. [9] conclude that increasing layer height affected the distance between the valley and the peak. the higher the distance between the valley and the peak, the rougher the surface will be. based on this, a lower layer height is used, and then a smoother surface of the specimen is made. mayank et al.[19] conclude that layer height was the parameter with the highest contribution due to layer height being the score index (value) of the score of each layer. it may be because the lower layer height printing process can reduce the space or gap, making printing results perfect and spread evenly. table 6. analysis of parameter variance source df seq ss adj adj ms f p contribution (%) layer height (mm) 3 68.24 68.24 22.75 36.17 0.01 82.3 infill geometry 3 4.91 4.91 1.64 2.60 0.23 5.9 nozzle temperature (˚c) 3 4.09 4.09 1.36 2.17 0.27 4.9 fan speed (%) 3 3.81 3.80 1.27 2.02 0.29 4.6 residual error 3 1.89 1.89 0.62 total 15 82.94 in this study, analysis of variance (anova) was used to prove the relationship between independent and dependent variables. there are two treatments in anova, normality test and homogeneity test. figure 3 shows the normality test results, and table 7 shows the decision of the normality test. figure 4 shows the homogeneity test results, and table 8 shows the decision of the homogeneity test. based on figures 3-4 and tables 7-8, the result of anova is h0 rejected in the normality and homogeneity tests, meaning the data was normally distributed and homogenous. soejanto [16] indicates that the normality test determines whether the data spread on a variable has been normally distributed. the homogeneity test is used to prove whether the data that has been used has variations in two or more distributions was the same or not. table 7. the decision of normality test response p-value test results surface roughness 0.076 h0 rejected issn: 2580-0817 journal of mechanical engineering science and technology 80 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) fig. 3. result of the normality test fig. 4. result of the homogeneity test 81 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) table 8. the decision of the homogeneity test parameter p-value test results layer height 0.168 h0 rejected infill geometry 0.871 h0 rejected nozzle temperature 0.863 h0 rejected fan speed 0.966 h0 rejected in this study, the most optimal parameters for surface roughness are layer height of 0.12 mm, infill geometry zig-zag, nozzle temperature 220˚c and a fan speed of 80%. figure 5 shows the graph of the confirmation test of the most optimal parameter combination for surface roughness (symbolized with ct), and table 9 shows a comparison between the confirmation test and the specimen with the smoothest surface (experiment 2). fig. 5. confirmation test graph table 9. comparison of confirmation test and experiment 2 exp surface roughness score (µm) standard deviation a b c d e average ct 8.4049 7.919 8.489 7.242 7.650 7.941 0.522 2 8.163 7.962 9.996 8.010 7.407 8.308 0.986 issn: 2580-0817 journal of mechanical engineering science and technology 82 vol. 6, no. 2, november 2022, pp. 74-84 taqdissillah et al. (the effect of nozzle, infill, layer height and fan speed on roughness petg filament) based on table 9, the confirmation test result is smoother than experiment 2, with a different point of 0.367. the combination parameter of the confirmation test is proven to be the most optimum combination parameter for surface roughness. the difference between this research and previous research is the parameter used. infill geometry is a parameter that is rarely used in surface roughness research. in this research, infill geometry is used as a parameter to find out the effect of this parameter on surface roughness. infill geometry functions as the foundation of an outer layer, so infill geometry can help the outer layer stabilize its form. different patterns of infill geometry can have different effects on the stability of the outer layer. iv. conclusions two conclusions can be drawn from this research. first, the layer height parameter contributes to the surface roughness by as much as 82.3 %, which is the most considerable contribution to the surface roughness value. the infill geometry, the nozzle temperature, and the fan speed contribute to the surface roughness by 5.9%, 4.9 %, and 4.6 %, respectively. second, the parameters that produce the smoothest surface roughness values are a layer height of 0.12 mm, infill geometry zig-zag, nozzle temperature of 220˚c and fan speed of 80%. for future research, the author has recommended research. application of some parameters that are rarely used in surface roughness can be used to find another effect of the parameter in surface roughness. some parameters are rarely used in surface roughness because those parameters have little effect on surface roughness. however, if those parameters are combined, that can have a more significant effect on surface roughness. acknowledgement the authors would like to appreciate the universitas jember, which provides the facilities to conduct the research. we also thank mas abduh, the technician of the material test laboratory. references [1] m. attaran, “the rise of 3-d printing: the advantages of additive manufacturing over traditional manufacturing,” bus horiz, vol. 60, no. 5, pp. 677–688, sep. 2017, doi: 10.1016/j.bushor.2017.05.011. 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(the effect of nozzle, infill, layer height and fan speed on roughness petg filament) [17] m.a. che mat, f. r. ramli, m. r. alkahari et al., “influence of layer thickness and infill design on the surface roughness of pla, petg and metal copper materials,” proceedings of mechanical engineering research day 2020, pp. 64-66, december 2020. [18] d. pramanik, a. mandal, and a. s. kuar, “an experimental investigation on improvement of surface roughness of abs on fused deposition modelling process,” in materials today: proceedings, 2019, vol. 26, pp. 860–863. doi: 10.1016/j.matpr.2020.01.054. [19] b. mayank and v. r.o., “parameters affecting surface roughness of fused deposition modeling,” i-manager’s journal on mechanical engineering, vol. 6, no. 1, p. 34, 2016, doi: 10.26634/jme.6.1.3739. [20] j. m. barrios and p. e. romero, “improvement of surface roughness and hydrophobicity in petg parts manufactured via fused deposition modeling (fdm): an application in 3d printed self-cleaning parts,” materials, vol. 12, no. 15, aug. 2019, doi: 10.3390/ma12152499. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 79-88 79 doi: 10.17977/um016v5i22021p079 comparative studies on combustion characteristics of blended crude jatropha oil with magnetic liquid catalyst and dex under normal gravity condition hendry y. nanlohy department of mechanical engineering, jayapura university of science and technology, jayapura, 99351, indonesia corresponding author:hynanlohy@gmail.com abstract a comparative study on the combustion characteristics of a single droplet fueled by dex, crude jatropha oil (cjo), and a mixture of cjo with a magnetic liquid catalyst of rhodium trisulfate has been carried out under normal gravity conditions. the high viscosity of crude jatropha oil makes it difficult to burn under normal conditions (room temperature and atmospheric pressure), therefore the addition of a magnetic liquid catalyst rhodium trisulfate is needed to improve the properties of crude jatropha oil. as a catalyst, rhodium trisulfate has the potential to improve combustion performance while improving the physical properties of crude jatropha oil as an alternative fuel for the better. furthermore, performance tests were also carried out with dex fuel with a cetane number (cns) 53. the results showed that compared to dex, it was seen that the liquid metal catalyst rhodium trisulfate succeeded in making crude jatropha oil more charged so that the combustion process was better. this is evidenced by a significant change in the dimensions of the flame and an increase in the combustion temperature. moreover, it is also seen that the burning rate increases and the ignition delay become faster. copyright © 2021. journal of mechanical engineering science and technology. keywords: combustion characteristics, crude jatropha oil, dex, rhodium trisulfate, single droplet i. introduction with the depletion of petroleum reserves, the increasing world population and energy consumption have a direct impact on the decreasing availability of fuel [1], [2]. therefore, the need for alternative fuels (non-fossil fuel) is very important [3], and crude jatropha oil is one of the natural resources that can be converted into alternative fuels (biodiesel) to replace diesel oil [4]. unfortunately, the sustainability of biodiesel use is hampered when it is found that the combustion products still contribute to greenhouse gases [5], and it is even worse with the addition of production equipment and the need for large costs to convert crude vegetable oil into biodiesel [6]. however, the crude jatropha oil compound, which is unsaturated, shows that there are c=c double bonds in the carbon chain [7], [8]. the presence of these double bonds has the potential to harm fuel combustion performance [9], where each double bond can reduce ignition properties such as cns and others by a significant amount [10]. due to the unfavorable effect of double bonds on ignition properties and fuel performance, some researchers use several catalysts such as fe2o3, al2o3, naoh, and cobalt [11]–[15] including rhodium liquid catalyst [8], [16]–[20], which are used to reduce or even eliminate the negative impact of double bonds present in the fuel. on the other hand, the results of previous studies have found that the presence of c=c double bonds in the geometric 80 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) structure of the carbon chain of unsaturated oil does not reduce the ignition performance of vegetable oil fuels [18]. therefore, this research is very important to produce new scientific information about the role of liquid metal catalysts on the combustion performance of vegetable oil (crude jatropha oil). in addition, the use of dex to obtain other scientific information on the performance comparison of fuels containing catalysts. on the other hand, the use of magnetic liquid catalyst rhodium trisulfate in crude jatropha oil also aims to determine the working principle of the catalyst in the fuel combustion process. in addition, with the complexity of the fuel combustion process that includes compression of combustion air, fuel injection, evaporation, mixing, ignition and chemical combustion reactions between fuel vapors and air, the role of catalysts in combustion is difficult to know through the applied research method. therefore, the suspended single droplet method was chosen to reveal the role of metal-based catalysts and their impact on the combustion characteristics of crude jatropha oil. ii. material and methods there are three types of fuel used in this study, i.e. dex, crude jatropha oil, and a mixture of crude jatropha oil with a magnetic liquid catalyst of rhodium trisulfate rh2(so4)3. the composition of the catalyst in blended cjo is 0.00% (pure cjo), 0.01% (cjor 0.01 %), and 0.02% (cjor 0.02 %). the test results on the main properties of the fuels are shown in table 1. dex, often called pertamina dex, is a fuel that has a cetane number 53 with a sulphur content of about 300 ppm or equivalent to euro 3 to make the engine more durable and produce lower emissions and environmentally friendly [21]. while the magnetic liquid catalyst of rhodium trisulfate rh2(so4)3 is a catalyst that has a 12 hydrogen acceptor, which results in a difference in electronegativity between the catalyst and the carbon chain. this difference causes the dipole-dipole interactions of the hydrocarbon chains to be pulled and attached to the catalyst surface. this causes the geometric structure of the carbon chain to change so that the viscosity and flashpoint of the cjo decrease, and it is easy to ignite [22]. table 1. the main properties of fuels properties dex pure cjo cjor 0.01% cjor 0.02% flash point (oc) 56 243 203 207 viscosity at 40 oc (cst) 5.181 35.52 32.38 34.29 density at 15 oc (gr/ml ) 0.827 0.917 0.916 0.936 caloric value (cal/gr) 10600 9400 8939 8896 the research scheme can be seen in figure 1. droplets of crude jatropha oil are attached to the junction of a 13% wt. pt/rh type thermocouple with a diameter of 0.1 mm. this thermocouple is type r, is a precious metal thermocouple, and has a temperature range that can measure up to 1600 c. its has low sensitivity around 10 v/c and high accuracy with an error tolerance of less than one-celsius degree [23]. the distance between the droplet and the electric heating coil is about 0.5 mm to 0.7 mm. the droplets are ignited using an electric heating coil with a diameter of 0.7 mm and a wire length of 40 mm with a resistance of 1ω. temperature data is obtained from the thermocouple signal that is connected to the data logger, and ignition delay data is obtained from the recording of the high-speed camera. the testing process was carried out five times for each type of fuel. issn: 2580-0817 journal of mechanical engineering science and technology 81 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) fig. 1. experimental scheme iii. results and discussions the suspended single droplet combustion performance is known from four parameters, i.e. the dimension of the flame (height and width), ignition delay, burning rate, and combustion temperature. figure 2 shows a comparison of the shape of the flame of the four types of fuel. the results show that with (see figure 2b and 2c) and without rhodium trisulfate (see figure 2a), the flame of crude jatropha oil appears to have the same shape, which is slightly wide and round, and for the dex flame (see figure 2d) looks more oval. the results also show that without a catalyst, the cjo flame evolutions look longer, while with a catalyst are shorter. this phenomenon indicates that the catalyst can absorb more heat energy so that the droplets heat up faster, evaporate and burn. furthermore, it is also seen that the flame of cjo droplets with and without a catalyst is more volatile than dex that looks calmer. this phenomenon shows that saturated cjo compounds produce an imbalance in atomic composition and mass so that the droplet flame looks more reactive so that the viscosity and flash-point (see table 1) decrease and the droplets ignite easily. this analysis makes a lot of sense because saturated oil has a c=c double bond which creates an imbalance of bonding electron pairs. where in that section, the cjo carbon chain lacks two hydrogen atoms so that the bonding electron pairs are not evenly distributed among the atoms carbon chain compounds. on the other hand, it appears that dex has low volatility, and the flame looks calmer. this phenomenon indicates that the dex constituent compounds are in a balanced state. 82 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) fig. 2. flame evolution comparison (a). pure cjo, (b). cjor 0.01%, (c). cjor 0.02%, (d). dex furthermore, figure 3 shows the variation of the flame height of the four fuels. it can be seen that successively dex has the highest flame, which is around 19.15 mm and is followed by pure cjo around 15.51 mm, then cjor 0.02% is around 15.28, and the lowest is cjor 0.01%, which is around 12.84 mm. the high flame indicates that dex fuel has a faster evaporation rate than the three types of cjo fuel with and without a catalyst. fig. 3. flame height evolution of fuels droplet on the other hand, these results indicate that cjo droplets with and without a catalyst have a faster combustion rate than dex, and this is because the addition of a rhodium trisulfate catalyst makes the mass of the fuel increase so that the distance between the fuel molecules gets closer, thus accelerating the interaction between the fuel molecules causing an effective collision have the potential to occur. this analysis is consistent with previous studies, which stated that the flame height was inversely related to the molecular diffusivity [24]. moreover, it is also seen that the cjor flame height of 0.02% exceeds the pure cjo and 0.01% cjor flame height. this is due to the increase in the catalyst mass in the fuel causes the cjo molecules to be more charged, resulting in a potential difference between issn: 2580-0817 journal of mechanical engineering science and technology 83 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) the cjo molecules and the catalyst molecules, and this causes attractive interactions between atoms. the interaction between the fuel atoms makes the fuel molecules more reactive, so they are flammable and have the potential to facilitate microexplosion, which creates bulge geometry, and suddenly the height of the flame will increase like a needle [25]. fig. 4. flame width evolution of fuels droplet as for the flame width (see figure 4), it can be seen that cjor 0.02% of the catalyst was achieved, which was around 9.111 mm, dex was around 7.97 mm, followed by cjor 0.01% of 6.51 mm, and the smallest flame width was produced by pure cjo about 6.52 mm. these results indicate that the addition of rhodium trisulfate catalyst can produce faster combustion than evaporation. this is possible because of the cjo carbon chain structure, which is not balanced bonding electron pairs. it is made electrons have a larger space to move, and this is supported by the increase in atomic volume due to expansion due to atoms absorbing heat energy from the electric coil heater. this phenomenon also confirms the shape of the cjo flame with the catalyst, which looks more volatile and highly reactive (see figure 2.). furthermore, figure 3 and 4 also show the duration of the droplet flame of the four fuels and it can be seen that the longest flame time was produced by pure cjo, while the fastest flame was produced by cjor 0.01%, followed by dex and the next was cjor 0.02%. a fast flame time indicates that the fuel produces more power or vice versa because power is inversely proportional to time. moreover, figure 3 and 4 show a change in the shape of the fire accompanied by a sudden increase in the height and width of the fire, indicating that there is a release of energy as evidenced by the occurrence of micro-explosion (see figure 5). this result is in accordance with previous studies, which stated that the sudden change in the shape of the fire indicated that the satellite particles contained in the droplet were thrown out, resulting in micro-explosions [23], [26]. 84 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) fig. 5. microexplosion phenomena. (a) pure cjo, (b) cjor 0.01 %, (c) cjor 0.02 %, and (d) dex fig. 6. ignition delay time of cjo droplet with and without catalyst vs dex figure 6 shows the ignition delay of the four types of fuel. it can be seen successively that cjor 0.02% has the longest ignition delay time, which is around 2.31 seconds, the next is cjor 0.01%, then dex 1.37 seconds and the fastest is pure cjo which is around 1.03 seconds. these results indicate that the magnetic liquid catalyst rhodium trisulfate has not been able to produce a faster ignition delay time. this is very reasonable because the working principle of rhodium catalyst is to lower its high activation energy in addition reactions by converting double bonds into single bonds. this has the potential to reduce the dissociation energy value of the cjo fuel molecules so that the fuel is easy to heat and ignite. moreover, from figure 6, it can also be seen that when compared to dex fuel, the ignition delay time of cjor 0.01% and cjor 0.02% is longer. this phenomenon is very possible because, with the increase in the mass of the fuel molecules due to the addition of rhodium trisulfate, the fuel molecules need a longer time to absorb heat energy from the electric coil heater. another reason is that the operating temperature of the rhodium trisulfate liquid catalyst is at 400-500 °c, so with the addition of a catalyst, the time needed to reach the working temperature is longer. this causes the value of heat of evaporation of cjo to increase, where the heat of evaporation of cjo is 210 kj/kg, and rhodium is 4564.81 kj/kg. figure 7 shows the effect of variations in the addition of catalysts on the burning rate of cjo droplet combustion compared to dex. sequentially, it can be seen that the highest burning rate was achieved by cjor 0.02%, then cjor 0.01%, dex, and pure cjo had the issn: 2580-0817 journal of mechanical engineering science and technology 85 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) lowest burning rate. this result proves that the catalyst can make the fuel molecules more charged, making it easier for them to interact with oxygen. this analysis is very reasonable because with the number of protons greater than the protons of the atoms of the cjo compounds (carbon, hydrogen, and oxygen), the catalyst becomes more positive, causing a potential difference with the cjo carbon chain. fig. 7. burning rate comparison of cjo droplet with and without catalyst vs dex furthermore, the unbalance of bonding electron pairs in the c=c double bond makes it a weak point in the arrangement of the carbon chain. this causes the catalyst to be able to attract electrons in the phi orbitals from the carbon atoms in the c=c double bond so that the cjo has the potential to lose electrons and is positively charged. because the cjo is positively charged while the oxygen around the droplet is negatively charged, there is an attractive interaction that generates the reactivity of the fuel molecules. this is what causes the burning rate of the cjo fuel mixture with a catalyst to be higher than pure cjo and dex, where the attraction between the fuel molecules increases the reactivity of the molecules so that the fuel easily absorbs heat and burns fast. fig. 8. temperature evolution of fuel droplet 86 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 79-88 nanlohy (comparative studies on combustion characteristics of blended crude jatropha oil and dex) figure 8 shows the temperature evolution of the four fuel types. especially for cjo, it can be seen that the highest temperature was achieved by cjor 0.01% at 606.70 °c, followed by cjor 0.02% at around 590.92 °c, and pure cjo at 578.87 °c. these results indicate that the catalyst can increase the enthalpy of the fuel, which is a function of the effective collisions between charged molecules and the random motion of the atoms. on the other hand, it can be seen that there is a decrease in the temperature value at cjor 0.02%, and this phenomenon indicates that at certain compositions, the catalyst work is not optimal [14]. this is because the presence of an excessive amount of catalyst mass has the potential to reduce the calorific value of cjo (see table 1) fuel which has a heating value of 39662.48 kj/kg, while rhodium is 5148.14815 kj/kg. in addition, with more mass, the time required for cjor0.02 fuel molecules to absorb heat and burn becomes longer, resulting in a longer burning lifetime compared to cjor 0.01%. iv. conclusions a study of the combustion characteristics of pure cjo with a blended cjo with magnetic liquid catalyst and a comparison with dex has been carried out. the results showed that the catalyst was able to increase the reactivity of the fuel molecules to increase the performance of cjo combustion. the catalyst increases the mass of fuel molecules and the distance between atoms, thereby facilitating attractive interactions between the fuel molecules. this makes cjor 0.01% capable of producing good performance, as indicated by a high combustion temperature and burning rate, as well as a shorter burning lifetime. determination of the correct composition of the catalyst volume is very important to produce good fuel performance because the excessive amount of catalyst mass reduces the calorific value of cjor 0.02%. to reveal the role of platinum group metal catalysts in improving the performance of crude vegetable oil fuels, further research is needed using the same or different magnetic liquid catalysts such as ruthenium or platinum. moreover, an in-depth study is also needed of the role of catalysts on the performance of crude vegetable oil fuels composed of saturated or polyunsaturated compounds. acknowledgment the authors express grateful thanks to the institute for research and community service, jayapura university of science and technology 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[26] k. meng, w. fu, y. lei, d. zhao, q. lin, and g. wang, “study on micro-explosion intensity characteristics of biodiesel, rp-3 and ethanol mixed droplets,” fuel, vol. 256, 2019, doi: 10.1016/j.fuel.2019.115942. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 20-27 20 doi: 10.17977/um016v7i12023p020 synthesis and characterization of nitrogen-doped activated carbon for lithium battery anode applications prihanto trihutomo, poppy puspitasari, muhammad bustomi radja*, milzam rahmat busono mechanical egineering, universitas negeri malang, malang, 65114, indonesia *corresponding authors: radjabustomi22@gmail.com article history: received: 4 november 2022 / received in revised form: 27 january 2023 / accepted: 8 april 2023 available online 30 april 2023 abstract nitrogen-dopped activated carbon was synthesized to see its effect on the characterization of the nitrogen surface functional groups, crystal size, and morphology of the resulting sample. synthesis of nitrogen-doped activated carbon was carried out by varying the addition of urea as a nitrogen doping source. activated carbon compared its characteristics with variations in the concentration of added urea to activated carbon, at 1:3 and 1:5. the ftir results obtained were the presence of functional groups indicating the presence of nitrogen bonds in each sample. the crystallinity results showed that the samples were classified as crystalline and nitrogen doping influenced the size of the crystallinity of each sample. the morphology of nitrogen-doped activated carbon shows differences in the grain size of nitrogen-doped activated carbon. crystallinity and morphology have been shown to affect battery anode performance. the more crystalline of anode material, the electrochemical properties are better. the smaller the grain size of the sample morphology, the stability of the battery cycle is to be great. copyright © 2023. journal of mechanical engineering science and technology. keywords: activated carbon, characterization, nitrogen concentration, nitrogen doping, surface i. introduction new and renewable natural resources are needed, especially due to increasing global warming and limited fossil resources [1]. the utilization of renewable energy, such as wind, solar, ocean waves, and biomass, has shown a positive trend in the last few decades [2]. one of the most important aspects of utilizing new and renewable energy sources is access to energy transmission and storage technology. currently, the limitations of renewable energy development are hindered by storage and transmission technologies due to environmental impacts [3]. the environment consisting of thousands of islands makes it difficult for energy, such as electricity, to reach remote areas [4]. alternative solutions for downstream renewable energy development are through superior storage technology. lithium battery is an excellent energy storage device that can easily convert chemical energy and electrical energy, which is also popularly used as a portable electronic device [5]. however, making these batteries with high energy and power density through an economical and environmentally friendly process is still a big challenge. existing anode materials exhibit high specific capacities, cycle stability, and safety, but their high cost and relatively small current densities limit their practical applications [6]. mailto:radjabustomi22@gmail.com 21 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) activated carbon with a large surface area, high absorption capacity, and minimal charging time is suitable for application in several materials, including the anode material in batteries [6]. during maximizing the potential of activated carbon in the form of its capacity properties, nitrogen doping can be utilized to increase the capacity of activated carbon. nitrogen, with an atomic size almost the same as the carbon atom, can be an electron donor for n-doping substitution. after nitrogen is doped, the interaction between electrons and ions becomes relatively negative [7]. silicon (si) is also used as an anode material for lithium-ion batteries due to its high theoretical capacity (~4200 mah/g). however, a large volume expansion occurs during the charge-discharge process, which significantly affects the stability of the silicon anode. silicon also tends to be expensive, increasing the cost of producing anodes. therefore, it is necessary to develop a new carbon-based anode material that has a high energy storage capacity and low volume expansion during the charge-discharge process [2] the focus of this research is the synthesis and modification of activated carbon. urea is added as a nitrogen source to form nitrogen functional groups. nitrogen atom doping was chosen because it is relatively stable, easy to obtain, and affordable. the next process is chemical activation with koh as an activator agent. the synthesized material was analyzed for surface functional groups, crystallinity, and morphology in its application as a lithium battery anode. ii. material and methods 1. material the main materials are activated carbon, pore diameter on activated carbon, mesoporous carbon (2 nm to 50 nm), urea as a doping source, and koh as an activator. in addition, other materials needed include distilled water and hcl acid. activated carbon, demineralized water, urea, and koh were obtained from cv makmur sejati, malang, indonesia. the chemical activation method was used to increase the surface area of nitrogen-doped activated carbon. the pore diameter of activated carbon decreases, and the surface area increases. this mechanism is through adding koh and reacting to form co and co2 gases that evaporate into the air. synthesis results from nitrogen-doped activated carbon samples were tested for their fourrier transform infrared/ftir functional groups using the shimazu ir prestige 21, x-ray diffraction/xrd using pan-analytical expert pro, and their morphology with sem using fei inspect-s50. 2. methods activated carbon is impregnated in a solution of urea and koh activator. the ratio of the mass of activated carbon: koh: urea (nh2)2co is 1:2:x (x = 3 or 5). the solution was then homogenized using a stirrer for 2 hours at 750 rpm and then sonicated for 30 minutes. after sonication, the solution was heated in an oven at 200 c for 4 hours, then the material became solid and then crushed for 1 hour until it became powder. the resulting powder is then soaked in hcl for 24 hours to neutralize the ph. the solution was then titrated and dried in an oven. the resulting solid is then crushed for 1 hour. each sample was named according to the ratio of urea doping as a nitrogen source (ndac 3 and ndac 5). in addition, the pure sample of activated carbon without doping and treatment was also given the name ndac 0 for comparison. the resulting sample was then characterized as a lithium battery anode potential material. issn: 2580-0817 journal of mechanical engineering science and technology 22 vol. 7, no. 1, july 2023, pp.20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) iii. results and discussions 1. surface functional group the nitrogen doping process and chemical activation gave changes in the chemical structure of ndac 0, ndac 3, and ndac 5. the ftir spectrum of each sample is shown in figure 1. the figure shows the stretching of chemical bonds in the aromatization reaction and heteroatom doping. oxygen functional groups are seen in the c-o, c=o, and o-h bonds [8]. nitrogen functional groups are seen in the c-n and n-h bonds [9]. at the same time, the bonds between c atoms are seen in the c-h, c=c, and c=ch bonds [10]. the addition of nitrogen doping can increase electrochemical properties due to the presence of nitrogen donors from doping [11]. the table of bond types with respect to absorbed wavelengths is shown in table 1. table 1. bonding type based on ftir result no wave number bonding type 1 670-900 c-h 2 1020-1220 c-n 3 1250-1300 c-o 4 1560-1640 o-h 5 1640-1680 c=c 6 1710 c=o 7 3020 c=ch 8 2400-3000 n-h 9 3200-3400 o-h source : withrow, (2013) the intensity of the c-h bond at ndac 0, ndac 3, and ndac 5 seems to be increasing, which can be seen in the range of 900-670 cm-1. the intensity of the c-n bond itself increases. this increase in absorption occurred in the range of 1020-1220, indicating that nitrogen doping occurs effectively [13]. fig. 1. the ftir spectrum 23 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) the intensity of the c-o bond occurring in the range of 1300-1250 cm-1 also increases as the nitrogen doping concentration in the sample increases. in addition, the o-h bond that occurs in the range of 1640-1560 cm-1 also tends to increase. the bond between c=c at 1680-1640 cm-1 also tends to increase in absorption. at wave number 1700, it is seen that the double bond between c and o atoms also increases with the addition of nitrogen doping [12]. the double bond between c and ch atoms increased in intensity in the ndac 3 sample but decreased again in the ndac 5 sample. in addition, the absorption intensity of the n-h bond was also clearly seen to increase as the nitrogen doping concentration increased [13]. 2. crystallization synthesis of nitrogen-doped activated carbon was prepared in several stages. nitrogen doping on activated carbon is synthesized by impregnation in urea solution [13]. activation uses a chemical activation method through koh as an activator agent to increase the surface area of nitrogen-doped activated carbon [14][15]. this impregnation and activation process affects the lattice structure of activated carbon [16]. the xrd patterns on the ndac 0, ndac 3, and ndac 5 samples are shown in figure 2. in the observed patterns, all samples showed the highest diffraction pattern centered at 2 = 24, 28, and 40 [17]. the ndac 3 and ndac 5 samples showed increased diffraction intensity than ndac 0. the highest diffraction peaks among the 3 samples occurred in ndac 3 samples. the degree of crystallization was used to calculate the crystal size of each sample using equation 1 [1], d= k . λ β cosθ , ……………………..…………………........................................................ (1) where k is the material constant of 0.9, λ is the wavelength of the x-ray (nm), β is the maximum half-peak width (rad), θ is the bragg angle of the diffraction peak, and d is the crystal size (nm) [4]. fig. 2. the xrd pattern of samples issn: 2580-0817 journal of mechanical engineering science and technology 24 vol. 7, no. 1, july 2023, pp.20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) based on equation 1, the crystal size was obtained in the ndac 0 sample of 72.65 nm, the ndac 3 sample of 48.338 nm, and the ndac 5 sample of 43.490 nm. diffraction intensity and peak shift are affected by the concentration of nitrogen doping on activated carbon [18]. figure 2 shows that the higher the nitrogen doping concentration, the diffraction intensity will increase. however, at a certain point, the intensity reaches a peak, and the intensity will decrease as the nitrogen doping increases. this is due to the relationship between crystallinity and nitrogen doping in activated carbon [5]. activated carbon modified with heteroatoms will improve its electrochemical properties as an application in lithium battery anodes [7]. this is very useful for modifying the electrochemical properties of carbon which is a type of porous carbon. the tendency of carbon to lose capacity after several cycles can be solved by modification with heteroatoms, one of which is the nitrogen atom [19]. 3. morphology the results of the sem (scanning electron microscope) test showed that pure activated carbon (1:0) had the largest size among the three samples, followed by nitrogen-doped activated carbon with a ratio of 1:3 and 1:5 (figure 3). this is because pure activated carbon does not go through the synthesis process, while samples that get nitrogen doping have a reduction in particle size [13]. the addition of nitrogen doping on activated carbon also increases surface area due to more potassium hydroxide (koh), which reacts with c atoms to produce co and co2 gases, which will then evaporate and form a pore structure. the pores function as access and pathways for ions or adsorbents to bind nitrogen to activated carbon. the results show that the nitrogen functional group in carbon serves as an ideal functional group to improve energy storage properties [20] according to han (2020), activated carbon, without adding koh, shows a dense and smooth surface with small pores. upon activation by koh, many large pores (2 µm) can be found in carbon materials. koh is a good chemical activator on carbon because it can increase its surface area up to 3000 m2/g and release co2 during n-ac activation [22]. the released co2 passes through the carbon material at high temperatures, creating many large pores. these results are consistent with other studies using koh as a pore-forming agent in manufacturing activated carbon. a b c fig. 3. sem morphology (a) ndac 1:0 (b) ndac 1:3 (c) ndac 1:5 25 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) iv. conclusions nitrogen-doped activated carbon can be a solution to replace graphite in lithium batteries due to their low capacity. modification of nitrogen doping in ratios (1:3 and 1:5) using the chemical activation method has an ideal function to increase energy storage. nitrogen can bond with carbon atoms if the atomic structure has many pores. the small pore size will increase the surface area and improve the cycle stability of the battery. the smaller grain size in the sem test shows a large surface area. nitrogen functional groups in the ftir and xrd results showed the most optimal performance at a ratio of 1:3 and decreased at a ratio of 1:5. this was due to the increasing number of nitrogen atoms, which would inhibit the formation of pores. research on the application of nitrogen-doped activated carbon in lithium battery anodes should be carried out to determine its effect on lithium battery performance. acknowledgment this research was funded by the universitas negeri malang grant through a student innovation scheme in 2022. references [1] s. zong, “preparation of n-doped porous carbon materials and their supercapacitor performance dissertation submitted for the degree of mtech : engineering : chemical prepared by,” no. january, 2021. [2] j. yan, c. e. ren, k. maleski, c. b. hatter, b. anasori, p. urbankowski, a. sarycheva, and y. gogotsi, “flexible mxene/graphene films for ultrafast supercapacitors with outstanding volumetric capacitance,” adv. funct. mater., vol. 27, no. 30, pp. 1–10, 2017, doi: 10.1002/adfm.201701264. [3] a. d. roberts, x. li, and h. zhang, “porous carbon spheres and monoliths: morphology control, pore size tuning and their applications as li-ion battery anode materials,” chem. soc. rev., vol. 43, no. 13, pp. 4341–4356, 2014, doi: 10.1039/c4cs00071d. [4] h. susana and astuti, “pengaruh konsentrasi lioh terhadap sifat listrik anoda baterai litium berbasis karbon aktif tempurung kemiri,” j. fis. unand, vol. 5, no. 2, pp. 136–141, 2016. 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[8] a.n.a. el-hendawy, “variation in the ftir spectra of a biomass under impregnation, carbonization and oxidation conditions,” j. anal. appl. pyrolysis, vol. 75, no. 2, pp. issn: 2580-0817 journal of mechanical engineering science and technology 26 vol. 7, no. 1, july 2023, pp.20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) 159–166, 2006, doi: 10.1016/j.jaap.2005.05.004. [9] s. shi and y. liu, “nitrogen-doped activated carbons derived from microalgae pyrolysis by-products by microwave/koh activation for co2 adsorption,” fuel, vol. 306, no. january, p. 121762, 2021, doi: 10.1016/j.fuel.2021.121762. [10] s. timur, i. c. kantarli, s. onenc, and j. yanik, “characterization and application of activated carbon produced from oak cups pulp,” j. anal. appl. pyrolysis, vol. 89, no. 1, pp. 129–136, 2010, doi: 10.1016/j.jaap.2010.07.002. [11] r. mishra, p. r. prasad, p. panda, and s. barman, “highly porous activated n-doped carbon as an ideal electrode material for capacitive energy storage and physisorption of h2, co2, and ch4,” energy and fuels, vol. 35, no. 17, pp. 14177– 14187, 2021, doi: 10.1021/acs.energyfuels.1c02051. [12] j. withrow, infrared spectroscopy. new york: research, 2016. [13] y. f. ferawati and r. f. susanti, “peran n-doping terhadap karakteristik pori karbon aktif yang dihasilkan dari limbah destilasi akar wangi,” metalurgi, vol. 36, no. 2, pp. 59–68, 2021, doi: 10.14203/metalurgi.v36i2.595. [14] n. khoirina, a. f. nugraheni, a. a. alfian, and w. d. p. rengga, “preparation and characterization of activated carbon derived from the bovine bone doped urea as an electrode material,” iop conf. ser. earth environ. sci., vol. 969, no. 1, 2022, doi: 10.1088/1755-1315/969/1/012040. [15] h. marsh and f. rodríguez-reinoso, activated carbon. elsevier ltd. 2006. [16] s. ahmed, a. ahmed, and m. rafat, “nitrogen doped activated carbon from pea skin for high performance supercapacitor,” mater. res. express, vol. 5, no. 4, 2018, doi: 10.1088/2053-1591/aabbe7. [17] y. y. garcía-guel, e. m. múzquiz-ramos, j. c. ríos-hurtado, a. moreno-santos, s. e. flores-villaseñor, and g. b. escalante-ibarra, “surface modification of activated carbon cloth with calcium silicate and hydroxyapatite: bioactive composite material,” heliyon, vol. 8, no. december 2021, p. e11586, 2022, doi: 10.1016/j.heliyon.2022.e11586. [18] q. li, m. yuan, y. wang, x. gao, x. li, m. yao, h. he, q. tan, z. zhong, and f. su, “designing and preparing carbon anode materials modified with n and fenanoparticle: creating the interior electric field to improve their electrochemical performance,” electrochim. acta, vol. 383, p. 138367, 2021, doi: 10.1016/j.electacta.2021.138367. [19] r. naraprawatphong, c. chokradjaroen, and s. thiangtham, “nanoscale advanced carbons as an anode for lithium-ion battery,” mater. today adv., vol. 16, p. 100290, 2022, doi: 10.1016/j.mtadv.2022.100290. [20] x. xue, y. weng, z. jiang, s. yang, and y. wu, “journal of analytical and applied pyrolysis naturally nitrogen-doped porous carbon derived from waste crab shell as anode material for high performance sodium-ion battery,” j. anal. appl. pyrolysis, vol. 157, no. january, p. 105215, 2021, doi: 10.1016/j.jaap.2021.105215. [21] w. hana, h. wanga, k. xi, s. chen, p. yan, t. deng, and w. zhu, “superior nitrogen-doped activated carbon materials for water cleaning and energy storing prepared from renewable leather wastes,” environ. int., vol. 142, no. may, p. 105846, 27 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 20-27 trihutomo et al. (synthesis and characterization of nitrogen-doped activated carbon for lithium battery) 2020, doi: 10.1016/j.envint.2020.105846. [22] n. nurfitria, k. febriyantiningrum, w. p. utomo, z. v. nugraheni, d. d. pangastuti, h. maulida, and f. n. ariyanti, “pengaruh konsentrasi aktivator kalium hidroksida (koh) pada karbon aktif dan waktu kontak terhadap daya adsorpsi logam pb dalam sampel air kawasan mangrove wonorejo, surabaya,” akta kim. indones., vol. 4, no. 1, p. 75, 2019, doi: 10.12962/j25493736.v4i1.5071. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 123-134 123 doi: 10.17977/um016v5i22021p123 study of methanol and ethanol absorption on vacuum temperature of adsorption cooling machine adsorption cycle jhon sufriadi purba, jandri fan ht. saragi* department of mechanical engineering, faculty of engineering, universitas hkbp nommensen pematangsiantar, pematangsiantar indonesia *corresponding author:jandrifan@gmail.com abstract cooling machines are currently being used more and more in accordance with technological advances and increasing living standards. common uses are for preserving food, air conditioning, cooling beverages, for making ice cubes, and others. the need for cooling systems in remote areas for various needs such as preservation or storage of food ingredients is felt to be increasing, while the existing conventional cooling systems cannot necessarily be used because not all remote areas have electricity networks, so a simple adsorption cooling system is an alternative for solving problems. a cooling system needs in remote areas like this. the purpose of this study was to obtain the optimum vacuum temperature in an adsorption cooler using activated carbon as adsorbent and methanol and ethanol as adsorbate. this study used the experimental method by analyzing the testing and data processing of methanol and ethanol. the results of this study indicate that the vacuum absorber temperature of the refrigerant (methanol) gets the maximum temperature: 123.53c on a thermostat with a temperature of 200c, it can absorb methanol as much as 6.35 ml/kg and produce a water temperature of 9.12c. meanwhile, the absorber vacuum temperature for refrigerant (ethanol) has a maximum temperature of: 123.26c, on a thermostat with a temperature of 200c, it can absorb ethanol as much as 6.35 ml/kg and produce a water temperature of 11,79c. copyright © 2021. journal of mechanical engineering science and technology. keywords: adsorption cycle, ethanol, methanol, refrigeration machine, vacuum temperature i. introduction the cooling process is an attempt to lower the temperature in the room or on the material. in other words, to get the desired conditions for the product or material, in this case, a low temperature so that the product or material can be stored for a relatively long time, both for consumption, production as well as trade [1]. food storage and transportation, food and beverage processing, and ice making are some activities requiring cooling and freezing processes. the cooling process takes heat from a room or object to reduce its temperature by transferring the heat contained in the room or object. so the cooling process is a series of heat transfer processes [2-3]. the heat transfer process can occur by convection, conduction or radiation. the development of the refrigeration system is very rapid, along with advances in technology. the type of collector used is a flat plate. the area of the adsorber is 0.25 m2 with a plate thickness of 1 mm. this adsorber is filled with 8 kg of activated carbon. the collector angle limit used is 0. the adsorber uses this heat to generate the system by absorbing the methanol/ethanol that evaporates from the evaporator. the water temperature will decrease along with the decrease in the methanol/ethanol temperature in the evaporator. during the day, the desorption process occurs, namely the adsorber receives heat from the lamp, and the issn: 2580-0817 journal of mechanical engineering science and technology 124 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) methanol/ethanol will flow into the condenser and melt in the evaporator. at night the adsorber is cooled by the outside environment so that an adsorption process occurs. the methanol/ethanol will evaporate from the evaporator to the condenser and will be absorbed adsorber [4]. refrigeration machines are now increasingly being used in accordance with technological advances and increasing living standards. a common use is to preserve food [5]. at ordinary temperatures (room temperature), food spoils quickly (because at normal temperatures, bacteria will grow quickly). meanwhile, at a temperature of 4.4oc or 40of (the usual temperature for cooling food), bacteria grow very slowly, so the food will last longer. so here, food can be preserved by cooling it [6-7]. other uses of refrigeration machines are air conditioners, beverage coolers, to make ice cubes, and others. for preservation in larger quantities, for example, found in slaughterhouses, for storing shrimp, and others. also in vehicles transporting meat/vegetables/fish to faraway places are equipped with refrigeration machines, so they don't rot until they reach their destination [8]. for a cooling process to occur, a refrigerant is needed that is easily changed from gas to liquid or from liquid to gas to take heat from the evaporator and throw it into the condenser. the need for cooling systems in remote areas for various needs such as preservation or storage of food ingredients is felt to be increasing, while the existing conventional cooling systems cannot necessarily be used because not all remote areas have electricity networks, so a simple adsorption cooling system is an alternative for solving problems. the cooling system needs in remote areas like this [9]. in recent years, research on methanol as a refrigerant and activated carbon as an adsorbent has been carried out to make a simple adsorption cooler that is inexpensive but can produce a refrigerant without pollution. sitorus et al. showed that the experimental results showed that the adsorption pair system could produce an evaporator temperature of around 9.92°c, and the cooling load could be achieved by a heat source with a temperature range of 83.95°c and 95.39oc [10]. the level of technology readiness in this research has been developed and allows it to be applied theoretically and empirically, so the characterization of the technology components to be developed can be determined properly. the performance of the elements developed will be useful for maximizing the use of solar energy, which is a renewable natural resource. ii. material and methods the tools used in this study are as follows: 1) vacuum pump to vacuum and remove particles/dirt and remove water from the generator, condenser and evaporator. 2) thermocouple is a cable connected to the device whose temperature is to be measured and connected directly to agilent. the thermocouple used in this study is a type j thermocouple, which is a cable that is resistant to heat; 3) agilent; 4) station data log hobo micro station. hobo micro station is a data recording device from 3 multi-channel microclimates recording sensors (solar radiation intensity, speed, wind, and relative humidity); 5) manometer function to determine the pressure that occurs during the desorption and adsorption processes; 6) the lamp serves to heat the adsorber. 125 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) table 1. physical properties of refrigerant [11] refrigerant chemical formula normal boiling point (c) molecular weight (mol) latent heat of vaporization l(kj/kgk) density (kg/m3)  x l (ml/m3) ammonia water methanol ethanol nh3 h2o ch3oh c2h5oh -34 100 65 79 17 18 32 46 1368 2258 1102 842 681 958 791 789 932 2163 872 665 table 2. specification of methanol specification value purity 99.9 % molar mass 32.04 g/mol density 0.7910.793 g/cm3 boiling point 64-65 oc melting point -97.8oc viscosity 0.59 mpa at 20oc the materials used are made of stainless steel. the lamp was designed which be coated with rockwall to reduce heat loss to the outside environment. the design of the lightbox was adjusted to the height of the lamp on the surface of the adsorber. in this case, the lamp only functions to heat the adsorber, and then the lamp was removed so that there was a decrease in the temperature of the adsorber. the adsorption cycle cooling machine to be designed is shown in figure 1. fig. 1. the adsorption cycle cooling system model to be designed issn: 2580-0817 journal of mechanical engineering science and technology 126 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) after making the components of the adsorption cycle cooling machine, it looks like in figure 2. this adsorption cycle refrigeration schematic clearly illustrates the processes that occur in the refrigeration machine. there are 2 main processes that occur, namely the desorption process and the adsorption process. the desorption process takes place during the day, and the adsorption process takes place at night. both of these processes occur naturally as a result of heat transfer by natural convection. furthermore, research on the adsorption cycle cooling machine was carried out. a. assembling assembling was carried out before testing because, previously, all components were still separate. the components of the refrigeration machine were connected/assembled between the collector, condenser and evaporator. in the connection pipe, the manometer valve and the bolts on the methanol/ethanol glass were glued properly to avoid leakage. methanol/2 liters of ethanol is put into the evaporator. after that, the methanol inlet valve was tightly closed and glued firmly, so it didn't leak. as much as 2.5 liters of water was put in a water container, then it was well insulated to reduce heat loss. the water container is affixed under the methanol, then tightly wrapped with an insulating box. b. vacuum vacuuming was done to find out if the cooling machine was no longer leaking. because the condition for the adsorption cycle to take place properly was at a vacuum pressure (-76 cmhg = -1 atm = -101.325 kpa). after the vacuum reaches the vacuum pressure (usually it never reaches -76 cmhg), the device is left for 2 × 24 hours. next, see how much the pressure drops to find out whether the tool is leaking or not. if there was a leak (the pressure reaches 0 atm), then re-examine to find out where the leak was. after that, gluing is done so that it doesn't leak. if it doesn't leak anymore, then proceed to the next stage. c. adsorber vacuum process after all components were connected perfectly, and there were no leaks. preheating was carried out using an electric lamp of 300 w and 500 w. during heating, the adsorber valve was opened, and the evaporator valve was closed. starting at 9.00 am. until 5.00 pm. heating the adsorber for ± 8 hours was conducted until the temperature of the bottom of the collector reached 120oc. the temperature of the thermostat was kept constant at 200oc. after the bottom temperature of the collector was constant at 120oc, the adsorber was vacuumed for 30 minutes (the lamp remains on) which functions to remove the gas and water vapor contained in the activated carbon. before the vacuum ended, the evaporator valve was opened slowly. the methanol/ethanol appeared to be boiling, and the vacuum could be stopped. after vacuuming, the adsorber valve was closed, and the process was allowed to proceed naturally. d. adsorption cycle the adsorption process (at night), allowed the temperature of the adsorbent to decrease along with the decrease in the ambient temperature. at night when the adsorber temperature decreases, the activated carbon will absorb methanol/ethanol so that the refrigerant will evaporate in the evaporator and rise to activated carbon. with the evaporation of this refrigerant, the temperature of the evaporator will decrease which causes the temperature of the surrounding water to decrease. pressure measurements were carried out at the beginning of the adsorption cycle. 127 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) fig. 2. schematic of adsorption cycle refrigeration machine e. desorption cycle in the desorption process (during the day), a heater with electric lamp radiation was installed and isolated perfectly so that there is no air flowing in the adsorption. the isolation box is ensured to be well insulated from all sides. then vacuum the adsorbent starting from a vacuum temperature of 100oc to 200oc. with the increase in the temperature of the adsorber, it was expected that a desorption process would occur. the refrigerant (methanol/ethanol) would evaporate and flow to the condenser and condenser. the methanol/ethanol vapor melts and returns to the evaporator. the adsorber pressure was recorded at the beginning of the desorption cycle. f. heat transfer 1) conduction the equation for the conduction heat transfer rate is generally expressed in the form of the differential equation (1)-(4) [12-14]: dx dt kq −= ................................................................................................................. (1) l tt ak dindingcond q 21 , − = .......................................................................................... (2) where, q = energy flow rate (w) issn: 2580-0817 journal of mechanical engineering science and technology 128 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) a = cross-sectional area (m2) t = temperature difference (k) l = length (m) k = thermal conductivity (conductivity) (w/m.k) dx dt = the rate of change of temperature t with distance in the direction of heat flow x fig. 3. adsorption cycle cooling machine 2) convection )( −= tstsahconvq ............................................................................................ (3) where, h = convection coefficient (w/m2k) ts = surface temperature (k) t∞ = fluid temperature (k) 3) radiation 4 taq = .............................................................................................................. (4) where, σ = stephan–boltzman coefficient (5,67 x 10-8w/m2k4) 129 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) iii. results and discussions analysis of testing and data processing of methanol. vacuum adsorber with vacuum temperature of 100oc. in this section, which is to determine the absorption of the adsorber on methanol, the test on the desorption process is carried out in the morning until the afternoon which produces the maximum adsorber temperature on the first day, which is 80.27oc, then vacuum is carried out every hour for 15 minutes during the test and produces an adsorber pressure of -40 cmhg, condenser and evaporator pressure -36 cmhg. the test on the second day of vacuuming the adsorber with a vacuuming temperature of 120oc resulted in maximum adsorber temperature of 89.55oc, adsorber pressure -40 cmhg, condenser pressure and evaporator -36 cmhg. the test on the third day of vacuuming the adsorber with vacuum temperature of 140oc resulted in a maximum adsorber temperature of 95.82oc, adsorber pressure -40 cmhg, condenser pressure and evaporator -36 cmhg. fig. 4. graph of evaporator temperature and time for 100oc vacuum temperature with refrigerant (methanol) fig. 5. graph of evaporator temperature and time for 120oc vacuum temperature with refrigerant (methanol) the test on the fourth day of vacuuming the adsorber with a vacuum temperature of 160oc resulted in maximum adsorber temperature of 103.82oc, adsorber pressure -40 cmhg, condenser pressure and evaporator -36 cmhg. the test on the fifth day of vacuuming the adsorber with vacuum temperature of 180oc resulted in maximum adsorber temperature of 119.64oc, adsorber pressure -40 cmhg, condenser pressure and evaporator -36 cmhg. the test on the sixth day of vacuuming the adsorber with vacuum temperature of 200oc resulted in maximum adsorber temperature of 123.53oc, adsorber pressure -40 cmhg, condenser and evaporator pressure -36 cmhg. tests during the adsorption process with a vacuum temperature of 160oc on the fourth day resulted in a minimum water temperature of 16.34oc and methanol absorbed as much as 2.5 ml/kg after the adsorber was heated, the methanol absorbed would return as much as 2.5 ml/kg (figure 7). testing during the adsorption process with a vacuum temperature of 180oc on the fifth day resulted in a minimum water temperature of 15.09oc and 3.75 ml/kg of methanol absorbed after the adsorber was heated, the methanol absorbed would return to 3.75 ml/kg (figure 8). tests during the adsorption process with a vacuum temperature of 200oc on the sixth day resulted in a minimum water temperature of 9.12oc and 6.35 ml/kg of methanol absorbed after the adsorber was heated, the methanol absorbed would return as much as 6.35 ml/kg (figure 9). issn: 2580-0817 journal of mechanical engineering science and technology 130 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) fig. 6. graph of evaporator temperature and time for 140oc vacuum temperature with refrigerant (methanol) fig. 8. graph of evaporator temperature and time for 180oc vacuum temperature with refrigerant (methanol) fig. 7. graph of evaporator temperature and time for 160oc vacuum temperature with refrigerant (methanol) fig. 9. graph of evaporator temperature and time for 200oc vacuum temperature with refrigerant (methanol) analysis of tests and data processing on ethanol. vacuum adsorber with vacuum temperature of 100oc. in this section, which is to determine the absorption of the adsorber on ethanol, the test on the desorption process is carried out in the morning until the afternoon which produces the maximum adsorber temperature on the first day, which is 79.98oc, then vacuum is carried out every hour for 15 minutes and produces an adsorber pressure of -36 cmhg, condenser pressure and evaporator -34 cmhg. the test on the second day of vacuuming the adsorber with vacuuming temperature of 120oc resulted in maximum adsorber temperature of 87.98oc, adsorber pressure -36 cmhg, condenser pressure and evaporator -34 cmhg. the test on the third day of vacuuming the adsorber with vacuuming temperature of 140oc resulted in a maximum adsorber temperature of 93.99oc, adsorber pressure -36 cmhg, condenser pressure and evaporator -34 cmhg. the test on the fourth day of vacuuming the adsorber with vacuum temperature of 160oc resulted in maximum adsorber temperature of 103.75oc, adsorber pressure -36 cmhg, condenser pressure and evaporator -34 cmhg. the test on the fifth day of vacuuming the adsorber with vacuum temperature of 180oc resulted in maximum adsorber temperature of 118.88oc, adsorber pressure -36 cmhg, condenser pressure and evaporator -34 cmhg. 131 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) fig. 10. graph of evaporator temperature and time for 100oc vacuum temperature with refrigerant (ethanol) fig. 12. graph of evaporator temperature and time for 140oc vacuum temperature with refrigerant (ethanol) fig. 11. graph of evaporator temperature and time for 120oc vacuum temperature with refrigerant (ethanol) fig. 13. graph of evaporator temperature and time for 160oc vacuum temperature with refrigerant (ethanol) the test on the sixth day of vacuuming the adsorber with vacuum temperature of 200oc resulted in maximum adsorber temperature of 123.26oc, adsorber pressure -36 cmhg, condenser pressure and evaporator -34 cmhg. tests during the adsorption process with a vacuum temperature of 100oc were carried out at night and resulted in a minimum water temperature of 24.50oc ethanol absorbed as much as 1.25 ml/kg after the adsorber was heated, the absorbed ethanol would return as much as 1.25 ml/kg (figure 10). tests during the adsorption process with a vacuum temperature of 120oc on the second day resulted in a minimum water temperature of 23.88oc and ethanol absorbed as much as 2.5 ml/kg after the adsorber was heated, the ethanol absorbed would return as much as 2.5 ml/kg (figure 11). tests during the adsorption process with a vacuum temperature of 140oc on the third day resulted in a minimum water temperature of 23.56oc and 2.5 ml/kg of ethanol absorbed after the adsorber was heated, the ethanol absorbed would return as much as 2.5 ml/kg (figure 12). testing during the adsorption process with a vacuum temperature of 160oc on the fourth day resulted in a minimum water temperature of 22.23oc and 2.5 ml/kg of ethanol absorbed after the adsorber was heated, the ethanol absorbed would return as much as 2.5 ml/kg issn: 2580-0817 journal of mechanical engineering science and technology 132 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) (figure 13). testing during the adsorption process with a vacuum temperature of 180oc on the fifth day resulted in a minimum water temperature of 16.37oc and 3.75 ml/kg of ethanol absorbed after the adsorber was heated, the ethanol absorbed would return 3.75 ml/kg (figure 14). testing during the adsorption process with a vacuum temperature of 200oc on the sixth day resulted in a minimum water temperature of 11.79oc and ethanol absorbed as much as 6.35 ml/kg after the adsorber was heated, the ethanol absorbed would return as much as 6.35 ml/kg (figure 15). fig. 14. graph of evaporator temperature and time for 180oc vacuum temperature with refrigerant (ethanol) fig. 15. graph of evaporator temperature and time for 200oc vacuum temperature with refrigerant (ethanol) sitorus et al. [10] showed that the experimental results showed that the adsorption pair system could produce an evaporator temperature of around 9.92°c and the cooling load could be achieved by a heat source with a temperature range of 83.95°c and 95.39oc, while in this study, data analysis was carried out, it can be concluded that the temperature of the vacuum adsorber to the refrigerant (methanol) gets the maximum temperature: 123.43oc on a thermostat with a temperature of 200oc can absorb methanol as much as 6.25 ml/kg and produce a water temperature of 9.02oc , that this research is better than previous studies, it can be seen from the previous evaporator temperature of 9.92oc while this study obtained the evaporator temperature of 9.02oc. iv. conclusions from the results of the study, more methanol was absorbed by the absorber to cool water than ethanol. based on the research and data analysis carried out, it can be concluded that the temperature of the vacuum adsorber to the refrigerant (methanol) gets the maximum temperature: 123,43oc on a thermostat with a temperature of 200oc, it can absorb methanol as much as 6.25 ml/kg and produce a water temperature of 9.02oc. meanwhile, the absorber vacuum temperature for refrigerant (ethanol) gets the maximum temperature: 123.16oc on a thermostat with a temperature of 200oc. it can absorb ethanol as much as 6.25 ml/kg and produce a water temperature of 11.69oc. to get the fluid to be absorbed more, it is better to use a thermostat above a temperature of 200oc. vacuuming is carried out with the correct method so that the water vapor content in the activated carbon and the system as a whole can be removed so that the adsorption cycle cooling machine works well, and to get a better 133 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) water temperature. the evaporator fins should be modified again because they drink 2.5 liters of cooled water. acknowledgment the authors would like to thank the directorate of research and community service, deputy for strengthening research and development, ministry of research, technology / national research and innovation agency of the republic of indonesia for providing financial support to carry out this research. references [1] m. a. oluleye and r. boukhanouf, “development trend of solar-powered adsorption refrigeration systems : a review of technologies, cycles, applications, challenges and future research directions,” vol. 6, no. 8, pp. 10491–10504, 2019. [2] e. wolak, “the cooling effect by adsorption-desorption cycles,” e3s web conf., vol. 14, 2017, doi: 10.1051/e3sconf/20171401052. [3] t. b. sitorus, f. h. napitupulu, and h. ambarita, “study on adsorption refrigerator driven by solar collector using indonesian activated carbon,” j. eng. technol. sci., vol. 49, no. 5, pp. 657–670, 2017, doi: 10.5614/j.eng.technol.sci.2017.49.5.7. [4] k. r. ullah, r. saidur, h. w. ping, r. k. akikur, and n. h. shuvo, “a review of solar thermal refrigeration and cooling methods,” renew. sustain. energy rev., vol. 24, pp. 499–513, 2013, doi: 10.1016/j.rser.2013.03.024. [5] i. f. odesola and j. adebayo, “solar adsorption technologies for ice-making and recent developments in solar technologies: a review,” int. j. adv. eng. technol., vol. 1, no. iii, pp. 284–303, 2010. [6] n. vi cao, x. q. duong, w. s. lee, m. y. park, s. s. lee, and j. d. chung, “exergy analysis of advanced adsorption cooling cycles,” entropy, vol. 22, no. 10, pp. 1–13, 2020, doi: 10.3390/e22101082. [7] s. singh and s. dhingra, “thermal performance of a vapour adsorption refrigeration system: an overview,” j. phys. conf. ser., vol. 1240, no. 1, 2019, doi: 10.1088/17426596/1240/1/012024. [8] m. li, h. b. huang, r. z. wang, l. l. wang, w. m. yang, and w. d. cai, “study on intermittent refrigeration phenomenon for solar solid adsorption refrigeration,” appl. therm. eng., vol. 25, no. 11–12, pp. 1614–1622, 2005, doi: 10.1016/j.applthermaleng.2004.11.010. [9] m. m. younes, i. i. el-sharkawy, a. e. kabeel, and b. b. saha, “a review on adsorbent-adsorbate pairs for cooling applications,” appl. therm. eng., vol. 114, pp. 394–414, 2017, doi: 10.1016/j.applthermaleng.2016.11.138. [10] t. b. sitorus, f. h. napitupulu, and h. ambarita, “experimental study of solar refrigerator system using activated alumina and methanol adsorption pair,” int. j. technol., vol. 7, no. 5, pp. 910–922, 2016, doi: 10.14716/ijtech.v7i5.1484. [11] l. w. wang, r. z. wang, and r. g. oliveira, “a review on adsorption working pairs for refrigeration,” renew. sustain. energy rev., vol. 13, no. 3, pp. 518–534, 2009, doi: 10.1016/j.rser.2007.12.002. issn: 2580-0817 journal of mechanical engineering science and technology 134 vol. 5, no. 2, november 2021, pp. 123-134 purba & saragi (study of methanol and ethanol absorption on cooling machine adsorption cycle) [12] f.p. incropera, d.p. dewitt, t.l. bergman, a.s.lavinne. "fundamentals of heat and mass transfer 6th edition ". 2007. john wiley & sons, inc. [13] a.cengel, yunus. "heat transfer a practicial aproach 2nd edition" 2003. mcgraw hill. [14] m. a. hadj ammar, b. benhaoua, and f. bouras, “thermodynamic analysis and performance of an adsorption refrigeration system driven by solar collector,” appl. therm. eng., vol. 112, pp. 1289–1296, 2017, doi: 10.1016/j.applthermaleng.2016.09.119. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 17-28 17 doi: 10.17977/um016v5i12021p017 evaluating storage and effective moduli of in situ polymerised and melt extruded pa6 graphite (g) composites muneer umar1, michael ikpi ofem2*, auwal sani anwar1, muhammad murtala usman3 1chemical engineering department, kaduna polytechnic, nigeria 2mechanical engineering department, cross river university of technology calabar, nigeria 3chemical engineering department, federal polytechnic, nasarawa, nigeria *corresponding author: michaeliofem@crutech.edu.ng abstract four pa6/graphite (g) composites systems were made. two using in situ polymerisation equivalent in mixing strain and two systems melt extrusion of equivalent processing strain. the effective modulus of the carbons, room temperature storage modulus and storage modulus at 80 ⁰c were evaluated. the composite/unfilled pa6 ratios at e25 and that at e80 for the in situ polymerised system ig 40/10 are 1.37 and 1.63, respectively. for the in situ polymerised system ig 20/20, the same were 1.96 and 2.28, respectively. for the melt-extruded systems, g 100/6 had the best e25 ratio of 1.67 and e80 of 2.03, whereas the same for g 200/3 system were respectively 1.87 and 2.64. while the better storage modulus properties exhibited by ig 20/20 in the in situ polymerised system is associated with a better filler connectivity network that enhanced heat dissipation. the better values shown in the g 200/3 melt-extruded system is associated with the lesser extrusion, which significantly reduced the tendency to thermal decay. effective modulus for the in situ polymerised systems ig 40/10 and ig 20/20 were 7.5gpa and 8.9gpa while that of melt-extruded systems g200/3 and g100/6 tallied at 8.2 gpa. copyright © 2021. journal of mechanical engineering science and technology. keywords: effective-modulus, in situ-polymerisation, melt-extrusion, storage-modulus i. introduction research on polymer nano-composites was followed to add extra value to the properties of pure polymer, without losing its processability or adding unnecessary weight to the composite. carbon centred nano-particles offered the prospective of combining numerous properties, such as thermal stability, mechanical strength, and electrical conductivity [1]. these excellent properties ascend from the outstanding assets of nanotubes, whose structure is based on graphene. the copiousness of graphene has made it possible for the production of efficient nano-composites. flaw free graphene offers exceptional physical properties, such as the visual transmission of almost 98%, large specific surface area, high intrinsic mobility and ballistic transport, high thermal conductivity and young’s modulus, among others [2, 3]. the ability of a material to elastically store deformation energy and bounce back when the load is released describes its storage energy. the effective modulus of the filler describes the maximum modulus reinforcement it can possibly have in a given composite if it were to maintain the interfacial strength it manifests within the composite. composites’ storage modulus generally increases beyond the matrix value upon addition of fillers, reflecting the polymer-filler interaction, modulus of the filler, its aspect ratio, shape and size-scale. the 18 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) intimate polymer-filler interaction that arises from in situ polymerisation is expected to produce significant increases in modulus with loading [4]. processing plays an energetic part in the production of polymer/carbon composites, and if cautiously manipulated, the inherent properties of polymers may be maintained. additionally, the good mechanical properties and electrical conductivity of fillers such as particulate carbons can be gained by the composites/nano-composites. the anticipated gains are normally dependent on a number of factors, among which are chosen production process and the processing conditions. these two play vital roles in determining the state of the filler in a composite following compounding, including dispersion how well the filler is reduced down to its primary particles and distribution the distance between neighbouring filler particles within the composite and how well the positions of the particles are randomised. poor compounding frequently leads to filler agglomeration, and the filler shows a lower aspect ratio and surface area to volume ratio. in this research, two graphitic platelet-structured carbon fillers were used; graphite (g), an example of a micro-scale filler, and graphite nano-platelets (gnp), a comparative nanoscale filler. the size scale of the fillers is considered in fixing the level of loading with that of the gnp-based nano-composites being an order of magnitude lower than that of the gbased micro-composites. this is considered to be a better basis for comparison against the traditional [5] same-weight comparison. from an industrial position, melt blending is the favoured compounding method for the preparation of composites as it is cost-effective and environmental friendly [6]. mixing equipment such as an extruder, and an internal mixer, can be adopted during melt blending operations. melt processing, which still maintains a lead in the commercial production of polymeric composites [7], was employed to make pa6/carbon composite systems over a range of loadings of g and gnp fillers. comparing the acquired properties between melt-extruded and in situ polymerised polymer/filler composites is not new [8], but here the comparisons are more extensive. melt extrusion was carried out using either 100/6 processing condition, which indicates an extrusion screw rotation frequency of 100 rpm applied for 6 minutes (min) or 200/3 processing conditions of 200 rpm for 3 min. similarly, in the in situ polymerised systems g and gnp dispersion was made using two similar conditions designated as 40/10 and 20/20. here, 40/10 indicates that sonication amplitude of 40% was applied for 10 min, whereas in the 20/20 conditions, the amplitude of 20% was applied for 20 min. ii. material and methods details experimental procedure for making the composites can be found elsewhere [9]. since storage modulus is obtained using dynamic mechanical and thermal analysis (dmta). dmta is used to investigate the viscoelastic behaviour of polymers and composites by subjecting the test specimens to dynamic sinusoidal stress or strain within a temperature range, a time frame or a frequency range [10]. for viscoelastic polymers, dmta provides useful information related to their molecular structure and relaxations [11]. a ta instruments q800 dynamic mechanical analyser was used to determine the thermomechanical responses. specimens (approximately 5.00 x 1.55 x 17.50 mm) were cut from within the gauge length of injection moulded dog-bones made using haake minilab injection moulding machine. at least 3 specimens were tested for each material. the specimens were tested using a single cantilever mode and applying a poisson’s ratio of 0.35 for pa6 [12] and its composites. the tests were carried out using a temperature ramp/frequency sweep issn: 2580-0817 journal of mechanical engineering science and technology 19 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) in multi-frequencystrain operation mode, at a strain rate of 0.2 %, and a temperature ramp of 3° c/min within the region of 0-200 °c. iii. results and discussions a. storage modulus of ig 40/10 and ig 20/20 systems the glass transition (tg), storage modulus at 25 °c (e25) and storage modulus at 80 °c (e80) are presented in table 1. figure 1a and b is the e25 data plotted for the in situ polymerised systems, ig 40/10 and ig 20/20. e25 has more significant practical applications since amorphous and semi-crystalline composites are mainly subjected to loadings at temperatures below their tg. table 1. dmta derived storage modulus for composites in ig 40/10 (labelled-1) and ig 20/20 (labelled-2) systems g based in situ polymerised systems e’ at 25 °c /mpa e at 80 °c /mpa tg/°c (dmta) tan δ at tg x 10−3 pa6 2,224±179 440±36 49.3±1.5 148±1 5g-1 2,355±393 520±130 56.7±4.0 142±6 10g-1 2,728±137 585±34 46.7±2.5 146±1 15g-1 3,052±1 750±23 53.5±2.1 143±5 20g-1 3,213±96 861±15 54.8±0.8 142±5 25g-1 2,106 ±297 695±35 32.7±5.8 136±6 5g-2 2,650±203 592±42 56.2± .1 138±2 10g-2 2,951±117 738±11 59.2±1.0 138±2 15g-2 3,213±247 837±85 57.8±2.3 134±2 20g-2 3,580±204 1001±80 59.3±1.5 138±6 25g-2 3,642±103 997±65 55.5±2.3 135±3 fig. 1. storage modulus (e’) versus temperature data for (a) ig 40/10 (40% amplitude of sonication for 10 min) and (b) ig 20/20 (20% amplitude for 10 min) systems. 20 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) the storage modulus increase below tg can be noticed from table 1 to be more significant compared to the e80, which lays ahead of tgbut below the melting temperature (tm) of pa6. this behaviour concurs both with the weak interaction between g and the pa6 matrix as well as the fact that g particles are micron in size. similar behaviour was observed when modified and unmodified montmorillonite clays were used to reinforce pa6 [13] using melt processing. the unmodified micron-sized clay composite behaved in a similar manner as observed with g.the modified nano-sized clay gave higher storage modulus at temperatures in between tg and tm. relative to the unfilled pa6 forms. the table 1 comparison shows that the highest e25 values are obtained with the modified nano-sized (5t) clay. this is most likely attributed to the nano-scale size of the 5t modified clay and the stronger polymer/filler interaction, which is aided its ability to form h-bonds. there is a possibility that a limited h-bonding occurred with the unmodified clay (5p). notwithstanding, all the four g based micro-composites have better e25 reinforcement compared to 5p, the unmodified clay at 5 wt. % loading. 5gs-1 has a modulus ratio of 1.06, whereas for 5gs-2 the highest went up to 1.19. this in all indicates that at 5g wt. % loading, the highest reinforcement occurs with the in situ polymerised ig 20/20 processing stream. this validates its better g dispersed state and relatively strong pa6/g interaction arising having the g fillers coated by pa6 as shown in the sem micrograph presented in figure 3. it may be observed from figure 2-a that composites in ig 40/10 system generally portray lower e25 compared to those in ig 20/20 system, and the traces have cross-overs, thereby delineating with g loading at the pre-tg stage. delineation resumes above 100 °c with the modulus traces correlating with g loading. the occurrence of the initial crossover at lower modulus reflects the difference in g dispersion between ig 20/20 and ig 40/10 systems. it is also very likely that upon softening additional particles generated in ig 40/10 migrated to form connected g aggregates which add to the modulus of the composite at higher temperatures. previously, a loss in modulus in pa6/g systems at higher loadings was observed, and it was blamed on factors such as decreased crystallinity, reduction in spherulite dimensions and the presence of unconverted ec and of oligomers [14]. fig. 2. sem micrographs of pa6/g composites at 25 gwt. % loading. a showing exposed g particulates with b showing mainly pa6 coated g particles. issn: 2580-0817 journal of mechanical engineering science and technology 21 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) b. room temperature storage moduli (e25) of the ig 40/10 and ig 20/20 systems figure 3 a and b is e25 in g synthesised systems for ig 40/10 and ig 20/20 systems. in both systems, the modulus of the composites did not improve above unfilled pa6 at the lowest loading level (5g wt. %), probably because at low g loading an effective rigidity and filler connectivity [15] is yet to be met. although in both systems, e25 generally increases with filler loading, the diverging pattern observed is interesting. in ig 40/10 the observed steep drop in modulus at the highest loading is assigned to plasticisation due to unconverted ec and low molecular weight species [16]. in the 20/20 system too, with the exception of the highest g loading (25 gwt. %), a linear rise in modulus occurs. these observations show that at higher g loading, inhibition of the anionic polymerisation occurs. the significant fall in e25 seen in 25gwt.% of the g 40/10 system, probably results from g inhibiting the rate of reaction arising from the increased volume of g particles generated with 40 % sonication amplitude. this increases the amount of diluents remaining with a resultant negative effect that compromises the modulus value. the inhibition of the anionic polymerisation is preventable by increasing the mole % of catalysing species [17]. the fact that the effect is so much less at the same 25 gwt. % loading in the ig 20/20 system upholds the suggestion that a bigger fragmentation of g occurs whilst the 40/10 sonication stream is used, and this increases with g loading. fig. 3. a and b: e25 in g synthesised systems. ig 40/10 indicates 40% amplitude of sonication for 10 min and ig 20/20 indicates 20% amplitude for 10 min. the effective moduli of g in both systems are estimated by linearly extrapolating to 100 wt. % g loading. in both cases, the composites’ modulus value at 25 gwt. % was excluded due to significant deviation from linearity. excluding 25gs-1 in the ig 40/10 system, the effective modulus of g is 7.5 gpa. excluding 25gs-2 in the ig 20/20 system, an effective modulus value of g of 8.9 gpa is obtained. the values obtained support the notion that g not only gets better dispersed in the ig 20/20 system but it also remains less fragmented, thereby giving a more effective reinforcement. when the data from [18] with g loading up 20 gwt. % was subjected to the same extrapolation, an effective g modulus of 4.1 gpa was obtained. 22 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) to further assess the whether or not improvements in modulus are attained figure 4-a and b compares normalised modulus values for the composites systems presented with some in literature. in figure 4-a, the systems g 40/10 and g 20/20 are compared with two similar g-based synthesised systems. horsky et al. [14] used graphite (g) as well as molybdenum disulphate (mos2) and oil (o) in one system (described in legend as mos2/g/o) and another system with carbon fibre (cf), g and oil described in the legend as (cf/g/o) to synthesise pa6 composites with the wt. % based on g alone. the overall best modulus enhancement is obtained in the ig 20/20 system, where steady enhancement is obtained up to 25g wt. % loading whereas, in the other systems, modulus declined at higher loadings. but at equivalent g wt. %, even ig 40/10 system did better than the literature systems. the steep drop in modulus in the cf/g/o system was blamed on the reaction inhibiting effect of cf. however, the fact that twice the amount of catalysing species were used by horsky et al. [14] (1.2 mole % as against 0.6 mole %) and the fact that the reaction was initiated within the temperature region for maximum crystal formation (140 °c) [19, 20] and decreased side reactions [21], their products ought to have shown higher modulus since their synthesis conditions favour higher doc [22]. although the presence of oil as lubricant might contribute to lower the modulus, the authors assigned the decrease in modulus to weaker interactions as filler loading gets higher. the presence of low molecular weight species equally caused plasticisation, which generated voids within the composites. in the synthesised systems reported here, sonication breaks down g particles and improve its dispersion just as it also increases the tendency for g to inhibit the reaction as the loading levels becomes high. so, the drop in modulus at 25 g wt.% is not surprising and has a precedence [14]. it is important to note that this drop in modulus at 25 g wt. % concurs well with the drop in tg. however, this is not always what obtains in literature and may be considered to be a discrepancy [5]. fig. 4. a-b: comparison of storage moduli of systems ig 40/10 (40% amplitude of sonication for 10 min) and ig 20/20 (20% amplitude for 10 min) systems) with ref.[25]. b present study with system g 200/3 and g 100/6 where(g 200/3 indicates screw speed of 200 rpm for 3 min and g 100/6 indicates screw speed of 100 rpm for 6 min ), with storage moduli taken from references [5, 26] figure 4-b compares data for the g-based melt-processed systems presented here with literature data [23, 24]. in both g 200/3 and g 100/6 systems, modulus increases with g loading up to 25 g wt. %. the data of ramanathan et al. [5] shows a steep increase in modulus (between 1 and 3g wt.%), followed by a levelling-off at 5 g wt.% loading, which probably indicates an onset for agglomeration. he et al. [26] observed a linear increase in issn: 2580-0817 journal of mechanical engineering science and technology 23 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) modulus without reduction up to 10 g wt. %. in both cases [5, 26], the higher modulus obtained at low g loading can be attributed to the superior filler dispersion provided by solution blending processing [6]. due to stronger interaction, higher normalised modulus values are obtained in modified clay nano-composites, especially above tg, where the modulus seems to collapse in the micro-composites due to the weaker and limited polymer/filler interaction. for instance, a 340% increase was obtained in a pa6/nano-clay nano-composite at 100 °c using 10 gwt. % of modified clay while the increase at room temperature was only 86% [13]. c. damping behaviour of the ig 40/10 and ig 20/20 systems dynamic mechanical behaviour of synthesised and melt-processed systems based on pa6 and pa6/g composites were studied. data from the dmta tests are given for all the systems in table 1. table 1 shows that greater increases in storage modulus (both at 25 and 80 °c) occur in the ig 20/20 system in comparison with ig 40/10. high storage modulus results from a good dispersion of filler in a composite, whereas increases in damping result from weak interfacial bonding [27]. therefore, exceptional variations are not expected in the damping behaviour of these composites. not only due to weak interaction at the fillerpolymer interface but also because of the limitation in the interfacial area due to the micron size-scale of g. however, in situ polymerisation improves matrix-filler contact on the molecular scale, which in turn improves interaction [6]. fig. 5. tan δ versus temperature for (a) ig 40/10 (40% amplitude of sonication for 10 min) and (b) ig 20/20 (20% amplitude for 10 min) systems. figure 5-a and b shows the damping behaviour of the two g-based in situ polymerised systems. in both systems, relative to the unfilled pa6, considerable damping occurs below tg, but more damping also occurs at and above tg in g 40/10 while in the same region, damping is only slightly greater than the unfilled in the g 20/20 system. this damping behaviour may indicate the presence of unconverted ec, low molecular weight species [14], remnants of catalysing species and even hydrogen-bonded water molecules in the composites [16]. all of these can plasticise and cause molecular motions below tg. in a related study [14], similar damping behaviour was observed, in which damping below tg increased with g loading (due to increased amounts of plasticising diluents), which subsequently led to reduced strength properties. this significant damping effect has to do not just with the inclusion of g but also with its loading level and dispersion. it can be observed that the unfilled pa6 has a more intense tan δ peak at tg and narrower tan δ curves. 24 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) the composites in turn have peaks with reduced intensities which did not proportionately correspond with the increase in g loading even though, with additional g loading, more segmental chain constraint is expected. however, the relatively broader curves of the composites describe the damping behaviour resulting from the constraining effect of g on the amorphous phase. in figure 5-a, the ig 40/10 system has a relatively broader and less intense tan δ versus temperature traces reflecting the intensity of the amplitude of sonication used compared to ig 20/20 system. the tan δ peaks are more scattered for the ig 40/10 system, and 25gs-1, which has the highest g loading but also has the lowest tg (32.7±5.8 °c) as well as the lowest tan δ peak value of 136 ± 6 x 10^(-3) (table 1). it is expected not only because it has the highest g loading but also because it has the highest doc. having the highest doc and at the same time having the highest g loading shows the nucleating effect of g. in addition, the low tg and high pre-tg damping suggests that it is a low molecular weight product with high proportion of low molecular weight species [28]. horsky et al. [14] got tg values of not more than 21°c for similar composite systems and even for the unfilled pa6. these tg values were recovered to 55 °c by washing the product. in the g 40/10 system, further support of the effect of sonication amplitude is the appearance of broad shoulders on the tan δ peaks between 90-145 °c for the composites. the intensity of these shoulders seems to decrease with g loading, and therefore the shoulder appears most faintly in 25gs-1. more clearly defined peaks (shoulders) were observed in clay-based composites of pa6, which were assigned to the merger of associating constrained amorphous phases [13, 29]. therefore, these shoulders may indicate softening of this constrained amorphous phase [28, 30] at higher temperatures, similar to the interpretation of tsagaropoulous and eisenberg [31]. in the ig 20/20system, the composites’ tan δ responses are close together, although relative to unfilled pa6 the peaks are less intense and are relatively broader indicating limited interfacial interaction. the order in terms of the height of the tan δ peak, the lowest of which describes the most restrained composite, is 15gs-2 followed by 25gs-2. whereas 20gs-2, 10gs-2 and 5gs-2 have practically the same tan δ height (values in table 1). therefore, taking g loading the order in tan δ peak value within the system’s composites’ is consistent and suggests that g is better distributed in pa6. this correlates well with the rise in tg of 10 °c between pa6 and 20gs-2. furthermore, the rise in the composites’ tg, e25 and modulus at 80 °c between composites of parallel loading in ig 40/10 and ig 20/20 systems confirm the same. changes in the damping behaviour of polymers upon adding foreign particles occur with diverse effects on tg, which is sometimes taken as an indicator for good interaction [5]. for example, milliman et al. [32] co-blended pa6 with polyhedral oligomeric silsesquioxane (poss) up to 10 wt. % loading. increased damping occurred above 1wt. % poss loading. however, the best improvements in modulus occurred at 2.5 wt. % loading, and at the same time, tg rose by 15 °c due to strong interactions. no further improvements occur with further loadings due to phase separation. however, increased damping followed by a reduction in tg implied good interaction in the case of modified clays [13] due to the release of organic diluents intercalated within the clay galleries upon exfoliation. again, anionic polymerisation of ec with mwcnt led to reduced tg, and increased damping though higher modulus values were obtained with loading due to good dispersion [33]. issn: 2580-0817 journal of mechanical engineering science and technology 25 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. (evaluating storage and effective moduli of pa6 graphite (g) composites) iv. conclusions the storage and effective moduli of four pa6/g composite systems were investigated and compared. two, which are g 40/10 and g 20/20 systems, were in situ polymerisation based where theoretically equivalent g dispersion strain of 400 was used. in the other two systems, g 100/6 and g 200/3, melt extrusion was used. an extrusion strain theoretically equivalent to 600 was used to disperse g in molten pa6. the storage moduli were evaluated at 25 ⁰c (e25) and 80⁰c (e80). the composite/unfilled pa6 ratios of e25 and e80 for the in situ polymerised system ig 40/10 are 1.37 and 1.63, respectively. for the in situ polymerised system ig 20/20, the e25 and e80 ratios were respectively 1.96 and 2.28. this gave the ig 20/20 system superior thermo-mechanical property amongst the in situ polymerised systems. for the melt-extruded systems, g 100/6 had lower e25 and e80 ratios of 1.67 and 2.03 as against the g 200/3 system, where the ratios were respectively 1.87 and 2.64. while the better storage modulus values shown in the g 200/3 melt-extruded system is associated with the lesser extrusion duration, which significantly reduced any tendency to thermal decay, the better storage modulus properties exhibited by g 20/20 in the in situ polymerised system is associated with the enhanced filler connectivity network that improved heat dissipation the effective modulus for the in situ polymerised systems ig 40/10 and ig 20/20 were 7.5 gpa and 8.9 gpa while that of melt-extruded systems g200/3 and g100/6 tallied at 8.2 gpa. all the results indicate that the g 20/20 processing conditions produced composites with the best thermo-mechanical properties. nomenclature pa6 : nylon 6 g : graphite ig : in situ polymerised graphite e25 : storage modulus at 25οc e80 : storage modulus at 80οc ig 40/10 : sonication amplitude of 40% applied for 10 min. ig 20/20 : sonication amplitude of 20% applied for 20 min. g 100/6 : melt extrusion screw rotation frequency of 100 rpm applied for 6 min. g 200/3 : melt extrusion screw rotation frequency of 200 rpm applied for 3 min. gnp : graphite nano-platelets dmta : dynamic mechanical and thermal analysis ec : epsilon caprolactam doc : degree of conversion poss : polyhedral oligomericsil sesquioxane tan δ : storage modulus tg : glass transition temperature tm : melting temperature mos2/g/o : molybdenum disulphate (mos2), graphite (g) and oil (o) cf/g/o : carbon fibre (cf), graphite (g) and oil (o) 5g-1 : 5 % weight of g relative to ec for ig 40/10 system 10g-1 : 10 % weight of g relative to ec for ig 40/10 system 15g-1 : 15 % weight of g relative to ec for ig 40/10 system 20g-1 : 20 % weight of g relative to ec for ig 40/10 system 25g-1 : 25 % weight of g relative to ec for ig 40/10 system 5g-2 : 5 % weight of g relative to ec for ig 20/20 system 10g-2 : 10 % weight of g relative to ec for ig 20/20 system 26 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 17-28 umar et al. 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[33] kelar, k., and jurkowski b. “properties of anionic polymerised ε-caprolactam in the presence of carbon nanotubes”, journal of applied polymer science, vol. 104(5), pp. 3010-3017, 2007. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 57-65 57 doi: 10.17977/um016v6i22022p057 backpack effects on two-dimensional gait spatiotemporal and kinematic parameters nardo rizaldy1, alvin alvin1, wirawan lingga1, ethan b.w. goeij1, f. ferryanto2* 1mechanical engineering study program, faculty of mechanical and aerospace engineering, institut teknologi bandung, jalan ganesha 10, bandung 40132, indonesia 2mechanical design research group, faculty of mechanical and aerospace engineering, institut teknologi bandung, jalan ganesha 10, bandung 40132, indonesia *corresponding author: ferryanto@ftmd.itb.ac.id article history: received: 1 july 2022 / received in revised form: 30 august 2022 / accepted: 11 september 2022 abstract loads could affect the body gait in various ways. backpacks, sling bags, suitcases, and even trolleys could hugely affect human gait without us realizing it. the effects of these loads have been scientifically researched in biomechanics and sports science for the past few years. for instance, the comparison of walking with and without a backpack could easily reveal significant differences in body segments, which could be utilized for therapy and medicine development. the aim of this research is to determine the differences of the spatiotemporal kinematic parameters between a conventional human gait and a backpackloaded gait. some parameters to be highlighted are stride lengths, stride duration, joint angles, linear and angular segment positions, velocities, and accelerations. the method used for marker data acquisition is based on the 2-dimensional direct linear transformation. the results demonstrate that the backpack increases stride lengths and reduces stride duration, contrast to the expected where backpacks would reduce stride lengths. it was observed that the angle between the bag and the body posterior affects the abdomen relative angle, which directly translates to stride lengths as well. during unloaded walking, increases in pelvic rotation contribute to increases in stride length with increasing walking speed. however, in loaded walking, the back angle is also a factor in determining kinematic parameters. copyright © 2022. journal of mechanical engineering science and technology. keywords: comparison, direct linear transformation, gait, kinematic parameters, loads, spatiotemporal, stride i. introduction the smallest difference in the body behavior, external or internal, could be observed from the human gait. studies in psychophysics reveal that humans are capable of recognizing people from impoverished displays of gait, indicating the presence of identity information in the gait signature [1]. carriage of backpacks applies a substantial load to the spine [2],[3]. backpack weights carried by students are at least 10% of their body weight [2]. according to paez-moguer et al., their experimental study showed that increased backpack loads alter gait parameters [4]. the stance load response and swing phases had a significantly greater duration for the 15 and 20% weight children than those with baseline weight. adding weight to the body using a backpack will shift the centre of gravity toward the rear of the base of support (feet). this combination of increased load and postural change can alter gait patterns. paez-moguer et al. found increased value in both double limb support and stance phase, single support, swing, and contact phase, from baseline to loads of 15% and 20% 58 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) body weight. their results indicated that carrying a backpack requires children to increase the time spent on both feet to manage this load during gait. some children walked more slowly to manage the weight, yet secondly, and by way of contrast, other children increased their speed in response to loading. in contrast, pau et al. found that spatiotemporal parameters were unaffected by backpack carriage from two hundred-eighteen school children’s gait. however, they also reported that there are significant increases (up to 25%) in plantar pressures found during both static standing and walking, especially in the forefoot by carrying a mean mass in their backpacks of 5.2 kg (at least 10% of their weight) [5]. based on the results of dames and smith [6] on the effects of load carriage on human gait, it mentioned that lower limb kinematic differences were noted in response to both loading and footwear. changes in spatiotemporal parameters observed when walking barefoot were not exacerbated by the addition of a backpack load. dembia et al., which studied walking with a heavily loaded carriage, show significant effects of loading in joints that influenced subjects’ walking kinematic parameters [7]. zaheer et al. also found a significant association between heavy bag lifting and poor posture with related pain in regions of the cervical followed by upper back in secondary school students [8]. dockrell et al. stated that the recommended load limit for schoolchildren to carry varies from 5% to 20% of their body weight, and the evidence linking backpack weight and back pain is inconclusive [9]. the present study focused on the gait of a 20-year-old student as a subject. the gait being examined are subject’s gait while carrying a bag containing the general needs of lectures, such as books, laptops, stationery, and drinks, or while not carrying a bag. the present study aims to determine the difference in spatiotemporal kinematic parameters between a natural conventional gait and a natural backpack-loaded gait. camera calibration is based on markers and 2-dimension direct linear transformation. parameters to be observed are stride lengths, stride duration, joint angles, linear and angular segment positions, velocities, and accelerations. therefore, this study will help develop studies on biomechanics, sports science, medicine, or therapies in developing their own specialties for a backpack-loaded gait. ii. material and methods the tools utilized were led lights as markers, a video camera, a tight black suit, and software capable of tracking objects in a video. there are 5 led lights needed to mark the subject’s joints while the subject wore a tight black suit. these joints were: right shoulder (1), torso (2), right hip (3), right knee (4), and right foot ankle (5), as shown in fig. 1. with these markers, the observation was made at the sagittal plane because the author expects that the significant influence due to backpack usage on the subject’s movement would occur in this plane. using the led lights as markers, the experiment was conducted inside a dark room and recorded by a 60-frame-per-second video camera. figure 2 illustrates the schematic of the recording. the experiment was done within 2 conditions. for the first condition, the subject walked for 3 meters straight wearing a backpack of 4.76 kilograms, and then for the next condition, the subject walked straight for 3 meters without wearing the backpack. before recording the movement, the subject was asked to practice walking following the path for a few moments until he got used to it. the purpose of these methods was to get the result as similar as a issn: 2580-0817 journal of mechanical engineering science and technology 59 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) normal walking movement. but, prior to the data collection, camera calibration needs to be performed first. first, measure the length of objects in real life and then compare it to what is detected in the image that being captured by the camera. the quality and the shutter speed for calibration’s video recording must be the same as in the data’s video recording. the calibration’s recorded video will be extracted into frames (pictures), and then select one of the pictures to detect points as a camera calibration reference. figure 3 shows the camera calibration reference. fig. 1. marker placement fig. 2. schematic of motion capture data acquisition fig. 3. camera calibration reference 60 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) the rest of the process was done in matlab. the first step was to calibrate the reference picture from camera’s pixel to obtain a metric scale. calibration was done using the dlt method [10, 11]. the process in recording images using a camera is equivalent to mapping object point o in the object space to image point i' in the film plane, as shown in figure 4 (a). this recorded image would be projected again to image i in the projection plane for digitization, as shown in figure 4 (b). dlt method has a collinearity condition basis. the optical system of the camera/projector maps point o in the object space to image i in the image plane. [x, y, z] was the object-space coordinates of point o, while [u, v] was the image-plane coordinates of the image point i. points i, n & o thus are collinear, as shown in figure 4(c) [12]. fig. 4. (a) mapping object point o in the object space to image point i' in the film plane, (b) projection from i’ in the film plane to image i in the projection plane, and (c) illustration of the relation projected image and the object [12]. after using dlt methods, the root mean square function [13] was used to calculate the error in image detection of points in figure 3 that have been measured before. 𝑅𝑀𝑆𝐸 = √ ∑ (𝑋𝑖−𝑋𝑖 ′) 2𝑛 𝑖=1 𝑛 ……………….................................................................... (1) where xi refers to the point that we measure, 𝑋𝑖 ′ refers to the point detected using the dlt method, and n is the number of data. after performing the calculation, we obtained the errors of the image processing in the x direction was 5.148 mm and in the y direction was 4.9 mm. the next step was video extraction and processing. the recorded video was extracted into frames, then the frames were converted into black and white pictures with a 0.7 threshold level so that there would be no other light source in the frame other than the led marker lights. the function region properties were then used to detect the position of the white points (light) centroid for every frame. these centroid data then would be named based on their position from top to bottom. however, some frames had one or more markers blocked by the subject’s limb while recording the movement. therefore, to acquire the issn: 2580-0817 journal of mechanical engineering science and technology 61 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) missing data, the regression method was used. since the coordinates obtained in the previous step were pixelated, these coordinates were converted into gcs (global coordinate system) coordinate by using the scale calculated from the calibration frame. from this point, the position coordinates were obtained. the next step was to calculate the velocity data smoothing. data smoothing utilizing the spline method was used to smooth the position coordinates so it would be easier to differentiate the position of the coordinates numerically. the method was done as such in order to obtain the velocity and acceleration when the velocity data was smoothed and differentiated numerically again. the linear velocity and acceleration were calculated using a finite difference equation [14]. this method was selected because of its simplicity. the requirements of linearity were already satisfied due to small time step between each data point. 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 = (𝐶ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑑𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡) (𝐶ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒) …………............................................................ (2) 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 = (𝐶ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦) (𝐶ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒) …....................................................................... (3) spatiotemporal parameters, such as stride duration and stride length, are obtained from the gcs coordinate data. segment angles were defined as the angle of the segment with respect to a righthorizontal line originating form proximal end of the segment [15]. the illustration in segment angles is shown in figure 5. fig. 5. angular kinematics parameter modeling angular velocity (ω) and acceleration (α) were calculated using a finite difference equation [15]. 𝜔𝑖 = 𝜃𝑖+1−𝜃𝑖−1 2 (∆𝑡) ……………………………............................................................... (4) 𝛼𝑖 = 𝜔𝑖+1−𝜔𝑖−1 2 (∆𝑡) ………………...…………................................................................ (5) or 𝜔𝑖 = 𝜃𝑖+1 − 2 𝜃𝑖 + 𝜃𝑖−1 2 (∆𝑡) …...………………................................................................ (6) 62 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) where θ represents the angular position and ∆t represents the time duration between adjacent data points which in this case one over frame per second used in the camera during recording. iii. results and discussions from the data processing that has been done, the results such as right shoulder (m1), torso (m2), right hip (m3), right knee (m4), and the right foot ankle (m5) markers’ linear kinematics have been found. the results then plotted into graphs such as markers’ position which plotted x coordinate in mm respected to y coordinate in mm, then markers’ velocity and acceleration which plotted respected to time domain (seconds). the graph example is shown in figure 6. there are two lines in figure 6 (a), (b), and (c) for knee linear kinematic parameters, where the red line represents data when the subject did not carry backpack and blue line represents data when the subject carried backpack. phase shift noticed in figure 6 (a) was x-directional differences between “with bag” and “without bag” subject’s initial contact due to overground walking movement that was not captured at the same time. fig. 6. ankle marker (m5) (a) position, (b) velocity, (c) acceleration the result also shows angular kinematics of back, hip and knee condition. it shows an angular position in degree, velocity and acceleration graphs which plot respected to the time domain (seconds). the graph example is shown in figure 7. there are two lines in figure 7 (a), (b), and (c) for knee angle angular kinematics parameters, where the red line represents data when the subject did not carry backpack, and the blue line represents data when the subject carried backpack. issn: 2580-0817 journal of mechanical engineering science and technology 63 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) fig. 7. knee angle (a) position, (b) velocity, (c) acceleration fig. 8. angle (a) back, (b) hip, and (c) knee 64 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) from data in figure 6, the spatiotemporal parameters for the walking condition while using backpack or not are also obtained. the subject while walking without using backpack has 1347 mm step length, 673.5 mm stride length, 1.17 seconds period, and 0.86 seconds cadence. while walking using a backpack, the subject has a longer step length, which is 1365 mm, and a longer stride length, which is 682.5 mm, but a shorter period and cadence, which are 1.15 seconds and 0.87 seconds. those differences were about 1.34% relative difference for step length and stride length, 1.74% relative difference for period, respectively. subject back angle, hip angle, and knee angle are plotted in a graph with respect to time is shown in figure 8 (a), (b), and (c), where the red line represents the data while the subject was not using backpack and the blue line where the subject was using a backpack. it appears in figure 8 (a), (b), and (c). the trends are the same, although the values are different for “with bag” and “without bag”. subject’s upper body posture while using backpack is pulled backward compared to the posture without a backpack. it can be seen in the negative value of the angle and the illustration figure from data processing that is shown in figure 9. fig. 9. subject illustration (a) without using a backpack and (b) using a backpack iv. conclusions based on the results that have been obtained, loaded walking increases stride frequency and stride length. in most cases, stride length would decrease. the project found out that the back angle is also a determining factor in spatiotemporal kinematic parameters. the subject with the bag tightened up to the body, which minimizes the angle between the bag and the body posterior, increasing pelvis rotation and directly translates to the increment of the stride length. references [1] t.-w. p. huang, k. a. shorter, p. g. adamczyk, and a. d. kuo, "mechanical and energetic consequences of reduced ankle plantar-flexion in human walking," journal of experimental biology, vol. 218, no. 22, pp. 3541-3550, november 2015. issn: 2580-0817 journal of mechanical engineering science and technology 65 vol. 6, no. 2, november 2022, pp. 57-65 rizaldy et al. (backpack effects on two-dimensional gait spatiotemporal and kinematic parameters) [2] t.-w. p. huang and a. d. kuo, "mechanics and energetics of load carriage during human walking," journal of experimental biology, vol. 217, no. 4, pp. 605-613, february 2014. [3] b. liew, s. morris, and k. netto, "the effect of backpack carriage on the biomechanics of walking: a systematic review and preliminary meta-analysis," journal of applied biomechanics, vol. 32, no. 6, pp. 614-629, december 2016. [4] j. paez-moguer, j. montes-alguacil, i. garcia-paya, m. medina-alcantara, a. m. evans, and g. gijon-nogueron, "variation of spatiotemporal parameters in school children carrying different backpack loads: a cross-sectional study," scientific reports, vol. 9, no. 1, pp. 1-8, august 2019. [5] m. pau, s. mandaresu, b. leban, and m. a. nussbaum, "short-term effects of backpack carriage on plantar pressure and gait in schoolchildren," journal of electromyography and kinesiology, vol. 25, no. 2, pp. 406-412, april 2015. [6] k. d. dames and j. d. smith, "effects of load carriage and footwear on lower extremity kinetics and kinematics during overground walking," gait & posture, vol. 50, pp. 207-211, october 2016. [7] c. l. dembia, a. silder, t. k. uchida, j. l. hicks, and s. l. delp, "simulating ideal assistive devices to reduce the metabolic cost of walking with heavy loads," plos one, vol. 12, no. 7, pp. e0180320, july 2017. [8] m. zaheer, n. fatima, u. riaz, and n. haseeb, "association of heavy bag lifting time with postural pain in secondary school students," pakistan biomedical journal, vol. 5, no. 2, pp. 64-67, february 2022. [9] s. dockrell, c. simms, and c. blake, "schoolbag weight limit: can it be defined?," journal of school health, vol. 83, no. 5, pp. 368-377, march 2013. [10] k. l. el-ashmawy, "using direct linear transformation (dlt) method for aerial photogrammetry applications," geodesy and cartography, vol. 44, no. 3, pp. 71-79, october 2018. [11] y. xue, s. zhang, m. zhou, and h. zhu, "novel sfm-dlt method for metro tunnel 3d reconstruction and visualization," underground space, vol. 6, no. 2, pp. 134-141, april 2021. [12] y.-h. kwon, "dlt method", 1998. [online]. available: http://kwon3d.com/theory/dlt/dlt.html [accessed may 20, 2022] [13] m. ćalasan, s. h. a. aleem, and a. f. zobaa, "on the root mean square error (rmse) calculation for parameter estimation of photovoltaic models: a novel exact analytical solution based on lambert w function," energy conversion and management, vol. 210, pp. 112716, april 2020. [14] j. o. robertsson and j. o. blanch, "numerical methods, finite difference," in: gupta, h.k. (eds) encyclopedia of solid earth geophysics, springer, dordrecht, 1-9, february 2020. [15] d. g. e. robertson, g. e. caldwell, j. hamill, g. kamen, and s. whittlesey, research methods in biomechanics, champaign: human kinetics, 2013. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 96 doi: 10.17977/um016v5i22021p096 implementation of internet of things (iot) in a plastic blow moulding machine and its performance measurement muhammad f. faqih, mahros darsin*, aris z. muttaqin, danang yudistiro department of mechanical engineering, jember university, jl. kalimantan, tegalboto no.37, krajan timur, jember, 68121, indonesia *corresponding author: mahros.teknik@unej.ac.id abstract efficiency and effectiveness are indispensable things in the production process. accurate use of existing resources and the shorter cycle time of production are of particular concern to optimize the production process. this research aims to implement automation to a conventional blow molding. an advanced attempt was carried out to use the internet of things (iot) to increase its efficiency while maintaining the quality of the products. the use of the nodemcu microcontroller and the blynk application allows the operator to operate the machine without having to come into or having direct contact with the machine. the performance of automation and iot were tested by examining the products using taguchi design using quality criteria of nominal the best. the efficiency of the system was also considered by comparing the cycle production time. s/n ratio of taguchi analysis showed that the optimum volume of the bottle would be achieved when applying the temperature, injection time, and holding time of 190 oc, 14 minutes, and 5 minutes respectively. the error or deviation is only 0.41%. the application of the iot system takes 34.45 seconds for a cycle time production, which is 3.76 seconds faster than a conventional system. copyright © 2021. journal of mechanical engineering science and technology keywords: blow moulding, blynk, internet of things, plastic, taguchi. i. introduction human life cannot be separated from the use of plastic. the application is very wide, ranging from household needs to industrial scale. the increasing use of plastics is also a consequence of the development of plastic processing technology. another reason that has led to the increasing number use of plastics is the characteristic of plastics that are strong but lightweight, rust-free, and some are recycled [1]. a blow molding machine is a plastic processing machine that prints hollow plastic workpieces by blowing air into the material (usually called as parison) using a mold consisting of two parts of a mold without a core. items such as drinking bottles, liquid gallons, and other packaging bottles are examples of products produced by blow molding machines. drinking water and other packaging bottles are examples of products produced by blow molding machines. efficiency and effectiveness are two things that must be considered in every production process. the application of an automation system for control can increase the effectiveness and accuracy of operator movements [2]. one of the automation systems that currently being widely used is the iot (internet of things). iot is a conceptual network that will affect the relationship between heterogeneous devices in which exchange information on a large scale to be able to work together and reach the same level, both humans and the presence of objects [3]. iot can also be interpreted as technology that usually allows communication between physical and virtual objects [4]. the 97 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) application of the iot system to industrial machines has several advantages, including reducing the need for space, resources and reducing physical contact [5]. the application of the iot system to a blow molding machine can increase efficiency and reduce the cycle times required by the machine. this research aimed to implement automation in a conventional blow molding machine. further, it also attempts to use iot to the newly automated machine. to examine the performance of the automation and iot to the machine, a set of experiments was carried out using taguchi design. in addition to taguchi analysis, working time measurements are also carried out and then compared between iot systems and conventional systems. the measurement of working time is very important because it can make a significant contribution to high efficiency and productivity [7]. ii. material and methods a. wireless control system a blynk application was used to input the command via a mobile phone. a nodemcu microcontroller was used as the interpreter from to operator’s command to the machine. it was chosen because this controller to the internet without any additional components. a schematic of the blow molding machine work process flow is shown in figure 1. fig. 1. blow moulding machine workflow following the automation implementation, a set of experiments was carried out to check their performance. the taguchi design was used for experimentations and analysis. material of ldpe would be used for experiments. when the best combination that resulting in the optimum product achieved, the error will be calculated and compared to the conventional system. issn: 2580-0817 journal of mechanical engineering science and technology 98 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) b. automatic control system three automation would be implementer to the machine, i.e. the temperature, injection time, and the holding time. for temperature control, a combination between thermocouple, max6675, nodemcu, and relay were used to govern the heater. there are three temperature setting points: 190c, 200c and 210c. injection time was controlled by series of nodemcu, relay, and contactor relay. the contactor relay was connecting both 3 phase driver motor and 3 phase motor. when the contactor relay closed, the motor was running, and then the driving screw injected the melted plastic into the barrel. holding time control system consists of nodemcu, relay and solenoid valve. the solenoid valve will govern the flow of air from the compressor. c. taguchi analysis taguchi analysis is used to confirm whether the application of the iot system to the appliance is successful or not seen from the error that the volume of the product produced does not exceed 5%, by finding the most optimum parameter level. in this study, there are three parameters with each of the three observed levels, namely temperature, injection time and holding time. based on the number of parameters and parameter levels, the orthogonal array l9 (33) was used with 9 (nine) trials, and each experiment was repeated 3 (three) times so that there were a total of 27 data retrieval times. d. signal to noise ratio (s/n ratio) analysis s/n ratio is a measure that compares the level of a desired signal to the level of background noise [9]. there are three types of s/n ratio, namely smaller the better, which means that the smaller the desired number will better the result; the bigger the better, which means that the bigger the number generated means the better; and the nominal is the best, which means that the closer the number to the intended value will be better. in this study, nominal is the best would be used. at the end, a confirmation test was carried out by doing 10 experiments with the best parameters. e. working time measurement measurement of working time is needed to determine the standard time required to complete a production cycle time. in this study, one cycle time is calculated starting from the operator giving the injection command from the smartphone until the product is removed from the mold. measurement of working time is carried out in two ways, directly and indirectly. direct working time measurement is where the researcher is at the place where the production process occurs, while the indirect method of working time measurement the researcher does not have to be in the place where the work takes place but by reading the available table as long as he knows the movements used during the production process. both methods of measuring working time are used in this study. direct working time measurement is used to calculate the working time of the iot automation system, while indirect working time measurement is used to calculate the working time of conventional systems based on the sop (standard operational procedure) of the blow moulding machine. the time obtained from measurement is the cycle time. the cycle time needs to be adjusted to get the normal time. adjustment is a factor used to normalize working speed. the adjustment method used is the shumard method, where the points are given based on the performance of the operator. 99 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) in this study, operator performance is considered excellent or has a value of 80. the adjustment is obtained by dividing the operator's performance value by the operator’s normal performance value or has a value of 60. then the normal time needs to be allowed to get the standard time. allowance is added to reduce fatigue, personal necessity and inevitable delays [10]. in this study, the allowance given was 19%. iii. results and discussions from the observed results, it was found that the automation system applied to the blow molding machine was able to control the machine well. machines work more efficiently yet still maintain good product quality. the image of the blow molding machine after the automation system is applied shown in figure 2. fig. 2. blow moulding machine with automatic system a. temperature control system from the observations, it was found that the device was able to control the temperature automatically based on the predetermined temperature setting point. the machine will automatically control machine temperature without any human intervention. the temperature point setting command is first given by the operator via a smartphone via an internet connection and then accepted by the nodemcu. nodemcu will drive the relay that connects the voltage source with the appliance heater. when the temperature of the machine is below the setting point, the mcu node will order the relay to close so that electricity flows to the heater and heating occurs and vice versa. a schematic of a temperature automation system is shown in figure 3. issn: 2580-0817 journal of mechanical engineering science and technology 100 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) fig. 3. temperature control system figure 4 shows the results of the temperature measurement for a few minutes. the blynk application allows its users to perform data collection or data logging. the x-axis shows the observed time, and the y-axis shows the measured temperature, the blue line shows the current setting point (190 c), and the yellow line shows the measured temperature. from the observations, it was found that the highest temperature read can reach more than 3 c from the predetermined setting point, and the lowest can also reach 3 c lower than the setting point. fig. 4. temperature data logging b. injection control system after machine temperature reaches the specified setting point, nodemcu will order the relay to close so that electricity flows from the voltage source to the relay contactor. consequently, the relay contactor will also be closed so that 3-phase electricity from the 3phase motor driver will flow to the 3-phase motor. the motor that is electrified will turn on and move the screw that is in the barrel. this loop will push molten plastic towards the 101 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) nozzle end of the machine. when the injection time has been fulfilled, nodemcu will automatically open the relay so that no electricity flows from the motor driver to the electric motor. the schematic of the injection time control system is shown in figure 5. fig. 5. injection control system c. holding time control system the holding time control system allows the operator to control how long compressed air is blown into the parison within the mold. a certain holding time was inputted by the operator via a smartphone and translated by the modemcu. then, the nodemcu will close the relay, electric current flows through the solenoid valve, open the valve and let the compressed flow from the compressor to the parison. the expanded parison will fill up the inner mold wall. a schematic of the holding time control system is shown in figure 6. fig. 6. holding time control system issn: 2580-0817 journal of mechanical engineering science and technology 102 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) d. wireless control system commands given by the operator via the smartphone will be forwarded to nodemcu via the wi-fi network. in this study, the application used on the smartphone is blynk. the blynk application was chosen because it is free and easy to use (no additional coding required), also capable of data logging. before connection, this app will be red blinked (figure 7a) and no blink after connected (figure 7b). (a) (b) fig. 7. blynk interface, (a) before connection, (b) after connection e. taguchi analysis to determine the successful implementation of the iot automation system on the device, taguchi analysis is used to find the optimum level of the parameters for each parameter studied. there are several parameters that are considered to have an effect on the tool, including temperature, injection time, holding time and air pressure. in this study, the parameters studied were temperature, injection time and holding time. each parameter has 3 (three) levels. table 1 shows the experimental data obtained. to avoid bias in the experimental data, data collection was randomized at each level repetition. table 1. experiment result trial num bers control factor obtained volume average volume variation s/n ratio temperature (c) injection time (s) holding time (s) i ii iii 1 190 14 3 210.3 210.9 211.0 210.7 0.1 2 190 15 4 214.7 211.0 215.0 213.6 5.0 39.6329 3 190 16 5 216.2 216.8 217.9 217.0 0.7 48.0160 4 200 14 4 214.8 215.8 219.1 216.6 5.1 39.6675 5 200 15 5 209.9 212.0 219.2 213.7 23.8 32.8321 6 200 16 3 207.2 212.5 211.8 210.5 8.3 37.2795 7 210 14 5 212.9 213.1 213.6 213.2 0.1 55.4363 8 210 15 3 210.4 211.1 213.1 211.5 2.0 43.5776 9 210 16 4 213.8 213.2 216.8 214.6 3.7 40.9272 average 43.6 ( a ) 103 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) f. s/n ratio calculation as shown in table 2, it can be seen the most optimum level of each observed parameter. the most optimum level for the temperature parameters is at level 1 (one) of 190 c. for injection time parameters, the optimum level is at level 1 (one) for 14 seconds and for the optimum holding time parameter is at level 3 (three) for 5 seconds. this result is an experimental design which will then be used in the confirmation test. the s/n ratio is calculated using the eq. 1 : 𝑆 𝑁⁄ = 10𝐿𝑜𝑔 𝑌2 𝑆2 ………………………………………………………………..…(1) where: y2 = mean s2 = variation an example of calculating the s/n ratio is as follows: level 1 temperature: = (54.91 + 39.63 + 48.01) ÷ 3 = 47.5 table 2. s/n ratio calculation parameter level 1 level 2 level 3 delta (min-max) temperature 47.5 36.6 46.6 10.9 injection time 50.0 38.7 42.1 11.3 holding time 45.3 40.1 45.4 5.3 average 43.6 g. confirmation test table 3 shows the confirmation experiments. confirmation experiments are carried out by doing 10 (ten) experiments with the most optimum parameter design from the s/n ratio analysis that had been calculated before. table 3. confirmation test repetition volume (ml) 𝑋2 1 214.6 46053.16 2 214.6 46053.16 3 215 46225 4 216 46656 5 214.9 46182.01 6 215.7 46526.49 7 215.4 46397.16 8 214.7 46096.09 9 215.9 46612.81 10 214.1 45710.44 ∑ 𝑋 2150.9 σ 0.65 issn: 2580-0817 journal of mechanical engineering science and technology 104 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) the control test is carried out by seeing whether all the data is between the upper and lower control limits, the upper and lower control limits calculated using eq. 2 and eq. 3, respecyively: upper limits control: x + 2(𝜎)……………………………………………………………………………(2) where : 𝜎 = sandard deviation = 215.09 + (2 × 0.65) = 216.39 upper limits control: x − 2(𝜎)....................................................................................................................(3) = 215.09 (2 × 0.65) = 213.79 the control test graph can be seen in figure 8. fig. 8. control chart s confirmation test from figure 8, it is known that each data is between the upper and lower limits, so it can be said that the data is uniform. then the data sufficiency test was carried out by using eq. 4: 𝑁′ = [ 𝑘 𝑠⁄ × √𝑁 ∑ 𝑋 2−(∑ 𝑋)2 ∑ 𝑋 ]2 …………………………………………………………(4) where: k = eligibility degree (using 95% eligibility = 2) s = degree of accuracy (10%) n = number of observation x = observation data 105 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) 𝑁′ = [ 20 × √𝑁 ∑ 𝑋2−(∑ 𝑋)2 ∑ 𝑋 ]2 = (130/2150.6)2 = 0.003 because the value of n (number of experiments) is greater than the value of n '(data sufficiency), it can be said that the data is sufficient. from the average number of confirmation experiment data, it was found that the volume of bottled products obtained was 215.09 ml or had an error of 0.41%. h. effect of temperature on the product the higher the temperature of the barrel used, the higher the preform (parison) temperature that occurs. as a result of the higher the parison temperature, the parison is getting softer and the easier it expands when it is blown by compressed air so that the product walls expand easier and faster. as a result, the walls the bottle becomes thinner, seen from the more transparent the walls of the resulting product. this is in line with research conducted by damirel, which states that preform temperature has a significant effect on the product [11]. this can be seen from the resulting product at setting point temperatures of 190 c and 210 c, as shown in figure 9. (a) (b) fig. 9. products comparison, (a) at 190c, and (b) at 210c i. effect of holding time to the product from the research, it was found that the longer the compressed air is blown into the parison, the longer the parison will experience development. this will result in the thinning of the walls of the resulting product. as a result of the thinning of the bottle product walls, the measured volume becomes larger. this can be seen at the setting point 190 c, where the holding time of 5 seconds has a volume greater than 4 and 3 seconds. however, it is not happening at temperatures of 200 c and 210 c, where shrinkage defects occur at a holding time of 5 seconds, as shown in figure 10. issn: 2580-0817 journal of mechanical engineering science and technology 106 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) (a) (b) fig. 10. shrinkage defect at temperature 210 c, (a) 5 seconds, and (b) 4 seconds j. effect of injection time to the product observations showed that the longer the injection process, the thinner the bottle it be. the volume of the molten injected parison is aligned with the injection time. in such a volume, the passion will be self-separated due to its weight. the result of this arcing will make the parison wall thinner so that the measured volume of the filled bottle becomes larger. in simple terms, the effect of injection time on the product is that the longer the injection time is carried out, the less empty weight of the product or the thinner the walls of the resulting bottle [10]. a comparison of bottled products with an injection time of 14 seconds and 16 seconds at a temperature of 190 c is shown in figure 11. fig. 11. products comparison at 190 c temperature, (a) 14 seconds, and (b) 16 seconds 107 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) k. direct working time measurement direct measurement of working time is carried out using a stopwatch when the operator is carrying out the production process. table 4 shows the cycle time measurement data directly. table 4. direct measurement of working time data sub group work time measurement repetition value total 1 22.23 22.05 22.03 22.05 88.36 2 22.10 22.30 22.25 22.31 88.96 3 21.92 22.47 22.38 22.24 89.01 4 22.39 22.63 22.38 22.52 89.95 total 35.,28 deviation standard 0.194 𝑁′ = [ 20 × √𝑁 ∑ 𝑋2−(∑ 𝑋)2 ∑ 𝑋 ]2 = [20 × (13.12) ÷ 356.28]2 = 0.54 upper limits control = 22.27 + (2 × 0.194) = 22.658 lower limits control = 22.272 – (2 × 0.194) = 21.884 because the value of n (number of repetitions) is greater than the value of n '(sufficient amount of data), it can be said that the data is sufficient. the control chart for working time calculations can be seen in figure 12. fig. 12. control chart s from the calculation of the average working time, the cycle time is 22.27 seconds. then finding the normal time using formula: issn: 2580-0817 journal of mechanical engineering science and technology 108 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) p = 80 ÷ 60 = 1.3 wn = 22.27 × 1.3 = 28.95 seconds then finding the standard time: wb = 28.95 + (28.95 × 19%) = 34.45 seconds l. indirect working time measurement table 5 shows the work elements used in a conventional system production process in one cycle: table 5. work element in conventional system no description of motion motion analysis time (min.) 1 reach for a 3 phase motor driver as far as 40 cm a 16 d 0.0105 2 pressing the run button on the 3 phase 10 cm motor driver in front of the finger f 4 dw 0.0042 3 fingers return to their original position as far as 10 cm f 4 d 0.0033 4 hands return to their original position as far as 50 cm a 20 d 0.0080 5 walk 90 cm to the right l 35 u 0.0118 6 walk 80 cm to the left and stop l 30 ud 0.0137 7 grabbing the handle of the mold 36 cm away a 14 d 0.0069 8 holding the handle of the mold, the fingers move as far as 10 cm h 4 d 0.0033 9 closing the mold, the hand moves 40 cm a 16 wsd 0.0115 10 opening the mold, the hand moved as far as 40 cm a 16 wsd 0.0115 11 removing the mold handle, the finger moves 10 cm h 4 d 0.0033 the total time used was 0.0949 minutes, equivalent to 5.7 seconds. after adding the adjustment and allowance using eq. 5: wn = ws × p……………………………………………………………………….(5) where : wn = normal time ws = cycle time p = adjustment wn = 24.7 × 1.3 = 32.11 wb = wn + (wn x allowance)………………………………………………………(6) where : wb = standard time wb = 32.11 + (32.11 × 19%) = 38.21 seconds from the calculation of the working time of the automation system and conventional systems, it is found that the automation system has a faster cycle time of 3.76 seconds. 109 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 96-109 faqih et al. (implementation of internet of things (iot) in a plastic blow moulding machine) iv. conclusions based on the taguchi analysis, the best level of temperature parameters is at level 1 (one) or a temperature of 190 oc, injection time parameters at level 1 or for 14 seconds and holding time parameters at level 3 or for 5 seconds. based on the best experimental design, the best bottle product was obtained with a volume of 215.09 ml or had an error of 0.41%. calculation of working time found that the automation system requires a cycle time of 34.45 seconds, while the conventional system for 38.21 seconds, or in other words, the automation system has a cycle time of 3.76 seconds faster than conventional systems. references [1] g. gourmelon, “global plastic production rises, recycling lags | worldwatch institute,” worldwatch inst., pp. 1–7, 2015. 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[10] m. a. m. amran, n. idayu, k. m. faizal, m. sanusi, r. izamshah, and m. shahir, “part weight verification between simulation and experiment of plastic part in injection moulding process,” iop conf. ser. mater. sci. eng., vol. 160, no. 1, pp. 0– 7, 2016, doi: 10.1088/1757-899x/160/1/012016. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 10-19 10 doi: 10.17977/um016v7i12023p010 effect of grafting nano-tio2 on sansevieria cylindrica fiber properties chrisrulita sekaradi wiguna1, heru suryanto1,2*, aminuddin1, jibril maulana1, joseph selvi binoj3, and alamry ali4 1master program of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang 5, malang 65145, indonesia 2center of excellence for cellulose composite (ceccom), departement of mechanical engineering, universitas negeri malang, jl. semarang 5, malang 65145, indonesia 3institute of mechanical engineering, saveetha school of engineering, saveetha institute of medical and technical sciences (simats), chennai, india 4department of mechanical engineering, college of engineering in al-kharj, prince sattam bin abdulaziz university, al-kharj 11942, saudi arabia *corresponding author:heru.suryanto.ft@um.ac.id article history: received: 11 october 2022 / received in revised form: 2 december 2022 / accepted: 2 december 2022 available online 21 april 2023 abstract natural fibers, which are abundant, environmentally friendly, and biodegradable, are used as a replacement for synthetic fibers. the composite strength can be increased by treating the surfaces of natural fibers with suitable chemicals, which can also improve the interface interaction between fiber and matrix. application of a coupling agent in chemical treatment is utilized to reinforce the bonding between fiber and matrix. the objective of the study is to determine the influence of silane concentration on the sansevieria cylindrica fiber properties. the methods included fibers treatment using ethanol and coupling agent as dissolving and tio2 with concentrations of 0%, 0.25%, 0.5%, 0.75%, and 1%. the mechanical strength testing was conducted through a single fiber test. fiber morphology was observed using an electron microscope. ftir analyzes the change in fiber chemical composition caused by tio2 addition. as a result, the morphology of s. cylindrica fibers became rougher and showed a rougher surface after a silane concentration of 1%, but with the proper concentration, some fiber surfaces provided a good interface. ti-o bonds are formed at a wavelength of 475 cm-1. the shift in a peak at 400–500 cm-1 indicates ti-o-ti group stretching vibrations believed to have originated from tio2 particles. the mechanical strength increases as the concentration of tio2 increases, with the highest fiber strength of 284.66 mpa observed at a tio2 concentration of 1%. this represents a 26% higher tensile strength compared to the control specimen. copyright © 2023. journal of mechanical engineering science and technology. keywords: coupling agent, nano-tio2, sansevieria cylindrica, silane, tensile strength i. introduction the past year has witnessed a significant surge in technological advancements in the field of materials, with increased demands for materials that are strong, lightweight, environmentally friendly, and cost-effective. when searching for materials with these characteristics, scientists, engineers, and researchers look for materials based on existing materials, such as composites made from natural fibers. natural fibers are preferred because they are less expensive, healthy for the environment and people, and strong enough to compete with other synthetic materials. because they can be compared to synthetic materials in terms of characteristics, new natural fibers are being explored more frequently in this 11 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) industry. the automotive industry is considering switching to synthetic fiber composites from natural fibers [1]. fiber has the potential to reduce vehicle weight by up to 80% [2]. in recent years, natural fibers have provided numerous benefits. in contrast to composites reinforced with synthetic fibers, natural fiber composites offer numerous benefits such as being low-cost, lightweight, easily separable, abundantly available, renewable, biodegradable, and posing no health risks [3]. wheat straw is one of a number of substitutes for crop fiber sources as agricultural by-products [4], and the other is pineapple peel waste [5], switch grass [6], banana tree [7], napier grass [8], mendong grass [9], and some of these fibers have been utilized as reinforcement in composites. fiber from s.cylindrica is potential as fiber reinforcement in polymer composite due to showing a high modulus of about 7.0 gpa, a tensile strength of about 658.0 mpa, and total elongation in a range from 10% to 12%. the composition of sansevieria fiber consists of a high water content of 84%, along with 5% fiber, 1% cuticle, and 10% dry matter, resulting in a structurally layered and robust fiber [10]. many ways have been developed to engineer interfaces in composite materials. natural fiber functionalization is used to increase matrix reactivity and achieve better psychochemical bonding. the a coupling agent is capable of enhancing the interfacial bond and improving the composite properties by converting the natural fibers from their initial hydrophilic state to a hydrophobic [11]. coupling agents are used to change the surface to be hydrophobic so that it can bind the polymer well. it has an impact on increasing strength [12]. mechanical interlocks can be improved by controlling the roughness and texture of the fiber surface. previous research on s. cylindrica fiber only used alkaline treatment[10]. in this study, additional treatment on s. cylindrica using a coupling agent varied by tio2. the coupling agents improve the adhesion between the matrix and reinforcement. it also influences surface roughness to reduce the hydrophilicity of natural fibers. adding a coupling agent in fiber composites will increase the mechanical properties of the fiber up to 61% when compared to without a coupling agent because the coupling agent can increase the bond between organic and inorganic materials [13]. the fiber is processed with addition material using a tio2 to increase the mechanical strength. the influence of tio2 treatment can increase the tensile strength of natural fibers up to 61% [12] when compared with natural fibers without treatment. the tio2 addition can improve fiber's inter-organic and inorganic bonding [4]. the effect of the concentration tio2 will determine the mechanical properties of the fibers. objective of this study is to determine the influence of variations in the concentration of tio2 on the properties of s. cylindrica. ii. material and methods 1. materials the study used material chemical reagents, including silane coupling agent (merck, germany), ethanol (merck, germany), naoh (technical grade, indonesia), and tio2 (sigma aldrich). the s. cylindrica fiber used in the study was sourced from a homestead in malang, east java, indonesia (figure 1). the leaf length was about 80 to 100 cm, and samples were chosen when the plants were 6 to 8 months old. the s. cylindrica fiber consists of 72.14% cellulose, 20.22% hemicellulose, 3.44% lignin, 4.22% t extractive compounds, and 4.22 to 5.22% moisture [9]. issn: 2580-0817 journal of mechanical engineering science and technology 12 vol. 7, no. 1, july 2023, pp.10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) fig. 1. sansevieria cylindrica plant 2. fiber extraction the fiber was extracted mechanically by beating the stems of s. cylindrica while still wet, then cleaning them in an aqueous medium until the fibers were separated from the connective tissue. the fiber is then soaked in water for a week. s. cylindrica fiber was collected, cleaned, and allowed to air dry. 3. alkali pretreatment alkali pretreatment was carried out by immersing the fiber in alkali (naoh 5%) for two hours and then rinsing it with distilled water up to five times. after being dried at room temperature until they were completely dry, the fibers were wrapped in plastic wrap and stored in a dry box with a humidity level of 40% [15]. 4. nanoparticles grafting mixing the silane coupling agent in alcohol with concentration of 10% and nanoparticles tio2 with a stirring process for 30 minutes. nano tio2 with a concentration of 0.1% shows good hydrophilic characteristics when compared to a higher concentration of nano tio2 1%[16]. the tio2 concentrations used were 0%, 0.25%, 0.5%, 0.75%, 1% since a higher concentration can degrade the fibers' mechanical qualities. the fibers were soaked in each solution using an ultrasonic homogenizer for 15 minutes, washed with distilled water for 1 hour, then dried using an oven at 75°c for two hours. 5. morphology analysis surface morphology observations were conducted 1000 times magnification with scanning electron microscope (sem), fei type inspect s50, with a voltage range of 10.00 to 15.00 kv. the surface of the nanocomposite was coated with a sputter coater to enhance the surface conductivity and investigate the morphology of the nanocomposite surface. 6. functional group analysis the ftir test in this study was to see the characterization of the chemical properties of the functional groups of s. cylindrica fiber with tio2 grafting process compared to sansevieria fiber without tio2 grafting using ftir merk shimadzu, type: ir-prestige21. the spectrum was scanned at a range of 400-4000 cm-1. 13 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) 7. tensile strength analysis the tensile strength of s.cylindrica fibers was measured at fiber length of 30 mm, using five specimens at ambient temperature. the fiber tensile tester had a maximum load of 50n, and a loading rate of 3.5 mm/min. the fiber cross-section area was determined by horizontal photographic observation using an optical microscope. it was assumed that the fiber had a circular cross-section, and the imagej software was used to measure its diameter at five different points along the photograph. after the area measurements were recorded, the average cross-sectional area of fiber was calculated. figure 2 depicts the single fiber tensile test specimen. fig. 2. single fiber tensile test specimen iii. results and discussions 1. morphology analysis the morphology was analyzed using sem with 1000 times magnification to observe fiber morphology. morphological results of s. cylindrica fibers without tio2 from the sem observation are shown in figure 3a, addition 0.25% tio2 in figure 3b, addition 0.25% tio2 in figure 3b, addition 0.50% tio2 in figure 3c, addition 0.75% tio2 in figure 3d, and addition 1% tio2 in figure 3e. as shown in figure 3a, 3b, and 3c, the surface of the fiber becomes more evenly tight and smoother. the higher concentration of tio2, the rougher surface of s. cylindrica fibers. the addition of 1% tio2 resulted in a rougher surface morphology. by incorporating additional materials and subjecting fibers to chemical treatments, the surface of the fibers can become rougher. this is because the silane coupling agent causes the hydrolysis of the lignin content in the fiber, resulting in a rougher interface on the fiber [17]. the nano-tio2 particles agglomerated on the fiber surfaces, with the quantity increasing as the nano-tio2 content increased [18]. issn: 2580-0817 journal of mechanical engineering science and technology 14 vol. 7, no. 1, july 2023, pp.10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) fig. 3. morphology of s. cylindrica fibers with tio2 concentration of (a) control; (b) 0.25%, (c) 0.50%; (d) 0.75%, and (e) 1%. 2. functional group analysis the fibers were a type of heterogeneous lignocellulosic substrate, displaying a spectral pattern containing absorption bands that were relatively distinct in nature. the addition of tio2 to the cellulosic fiber caused it to swell, removing lignin, hemicellulose, and other impurities from the fiber surface. ftir was used to analyze the change in the fiber functional group caused by tio2 addition. chemical treatments involving coupling agents can (a) (b) (c) (d) (e) 15 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) strengthen the interactions at the interface by reinforcing chemical bonds through the presence of chemical functional groups and an acid-base interaction mechanism. this, in turn, can improve the overall effectiveness of the treatment [19]. as shown in figure 4, the broadband ranging from 3000 to 4000 cm-1 indicates the oh stretching present in hemicellulose, cellulose, and lignin. changes at the peak around the value of o-h undergo strain, and peak shift at the stretch number 3100-3600 is seen in fibers. this is due to the surface hydrolysis reaction of the silane coupling agent in s.cylindrica fibers [20]. the c-h bond, frequently seen in alkane groups, was thought to be responsible for the wide band of 2850-3000 cm-1. at 1765-1715 cm-1, the hemicellulose compound exhibits sharp peaks for carbonyl and ketone c=c groups. at 1730 cm-1, peak was disappeared after fibers were treated with 5% naoh. it is evidence that hemicellulose decreased following alkalization process. the alcohol compounds and aromatic lignin structure (c=o bond) present in the fiber were referenced by the peaks at 1450 and 1650 cm-1. the observed peak at 890-900 cm-1 indicated the -glycosidic linkage of fiber, which is contributed by both hemicellulose and cellulose [21]. fig. 4. ftir test results of s. cylindrica fibers with variations in tio2 concentrations of 0%, 0.25%, 0.5%, 0.75% and 1%. the reduction of hydroxyl groups in these fibers is due to the hydrolysis of the silane coupling agent, resulting in a new peak formed in fiber around the peak value of 1157cm-1 (si–o–si), where the fiber without silane coupling agent treatment does not have such a peak. si–o–si indicates the condensation reaction of a silane coupling agent that reacts between fiber and silane [11]. the addition of tio2 to the other silanes constructs a valley that represents each molecular bond between the ca-tio2 fibers. the valleys that are visible in detail indicate the presence of o-h bonds at 3600 cm-1. c-o bonds exist at wavelengths ranging from 1500 to 1600 cm-1. ti-o bonds are formed at a wavelength of 475 cm-1. the shift in the peak at 400–500 cm-1 indicates ti-o-ti group stretching vibrations believed to have originated from tio2 particles [23]. stretching of c-o and carbonyl (c=o) is the result of the decomposition of ch2oh groups in cellulose with the help of tio2 as a catalyst [24]. 4000 3500 3000 2500 2000 1500 1000 500 t ra n s m it ta n c e ( % ) wavenumber (cm-1) ca tio 1% ca tio 0.75% ca tio 0.5% ca tio 0.25% ca tio 0% o-h c-h c=c si-o-sic-o ti-o issn: 2580-0817 journal of mechanical engineering science and technology 16 vol. 7, no. 1, july 2023, pp.10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) 3. tensile strength analysis figure 5 represents the tensile strength of s. cylindrica fiber with variation addition tio2. the strength of control fiber and treated fiber using silane are differrent because control fibers have hydrophilic properties, they cannot bond well with hydrophobic polymers like epoxy. fibers treated with silane coupling agents can acquire hydrophobic surfaces, allowing them to adhere to active groups in hydrophobic polymers. silane converts hydroxyl groups (-oh) in the fiber into silanol groups (si o si), increasing the bonding between the fiber and matrix and thus increasing the interfacial shear strength of the composite with the silane bridging material [12]. fig. 5. tensile strength s. cylindrica fiber with variation concentration of tio2. the fiber surface has an intrinsically high surface atomic energy so that adhesion to rough surfaces can be effective. when expressed per unit nominal area, the increase in the area due to various factors also increases the surface energy. when stress is applied to a roughened surface, the stress is redistributed, and the resulting interface is strengthened because roughness can change the fracture mechanism from a small one to a more energetic mode. when two incompatible polymers come into contact, the mechanism shifts from chain to other types of plastic deformation. an extended single fiber will undergo configuration deformation of the macromolecular chain as an elastic response because the macromolecular chains in the cell wall of the fiber are not oriented to the length of the fiber axis [18]. the addition of tio2 to a single fiber of s. cylindrica fiber can influence the interface shear stress, increasing the fiber strength. the tensile test results showed that the highest value was 284.66 mpa at 1% tio2 concentration. at 0% tio2 concentration, the lowest tensile strength value is 208.27 mpa. overall, the addition of tio2 increases the s.cylindrica strength. tensile strength increased to 210.62 mpa, 248.56 mpa, and 256.36 mpa with a tio2 addition of 0.25%, 0.5%, and 0.75%, respectively. the influence of nano-tio2 on the fiber surface after silane treatment can be attributed to the increase in fiber strength and breaking strain. the silane coupling agent layer filled with nano-tio2 can improve the fiber tensile strength and reduce the stress concentration on 17 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 10-19 wiguna et al. (effect of grafting nano-tio2 on sansevieria cylindrica fiber properties) the fiber surface. the effect of grafting nano-tio2 on the strength of s. cylindrica fiber was restricted when compared to the treatment that involved solely the addition of a coupling agent. furthermore, the concentration of nano-tio2 grafted on sansevieria fiber can increase its tensile strength. iv. conclusion the treatment of s. cylindrica fiber was carried out to obtain the characteristics of the fiber. fiber specimens with a 5% concentration of silane coupling agent with the addition of tio2 with a concentration of 1% have a coarser structure so as to improve mechanical properties. surface variation in fiber on 1% tio2 surface additive has the highest tensile strength value of 284.66 mpa. ftir results indicate that adding tio2 to the other silanes constructs a molecular bond between the fiber-silane-tio2. incorporating tio2 nanoparticles can enhance the bonding properties and tensile strength of the material. it is suggested to modify the surface of natural fibers through nanoparticle grafting to attain optimal mechanical properties for natural fibers. acknowledgement the authors thank the indonesian ministry of research, technology, and higher education for funding this project through the penelitian tesis magister 2022, contract no. 18.3.24/un32.20.1/lt/2022. references [1] h. suryanto, e. marsyahyo, y. s. irawan, and r. soenoko, “effect of alkali treatment on crystalline structure of cellulose fiber from mendong (fimbristylis globulosa) straw,” key eng. mater., vol. 594–595, pp. 720–724, 2015, https://doi.org/10.4028/www.scientific.net/kem.594-595.720. 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[24] t. parangi, and m. k. mishra, “titanium dioxide as energy storage material: a review on recent advancement,” in titanium dioxide, intechopen, 2021. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 145-154 145 doi: 10.17977/um016v5i22021p145 characterization of bacterial nanocellulose graphite nanoplatelets composite films bili darnanto susilo1, heru suryanto2, 3,*, aminnudin2 1master program of mechanical engineering, universitas negeri malang, jl. semarang 5, malang 65145, indonesia 2center of excellence for cellulose composite (ceccom), department of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang 5, malang 65145, indonesia 3centre of advanced material for renewable energy (camry), universitas negeri malang, jl. semarang 5, malang 65145, indonesia *corresponding author: heru.suryanto.ft@um.ac.id abstract bacterial cellulose (bc) was synthesized from pineapple peel extract media with addition of fermentation agent bacteria acetobacter xylinum. bc was disintegrated from the pellicle into bacterial nanocellulose (bnc) by using a high-pressure homogenizer (hph) machine, which has a three-dimensional woven nanofibrous network. the synthesis of composite films started when bnc, graphite nanoplatelets, and cetyltrimethylammonium bromide (ctab) were homogenized using an ultrasonic homogenizer then baked on a glass mold at a temperature of 80 degrees celcius for 14h. a scanning electron microscope (sem) was used to analyze its morphology. x-ray diffraction spectra were used to analyze the composite films structure. the functional groups of the composite films were analyzed using the ftir spectrum. sem micrograph shows that gnp was evenly distributed into bnc matrix after ctab addition. gnps are shown as flat and smooth flakes with sharp corners. some peak corresponds o-h, c-h, c≡c, and ch3 stretching was identified by using ftir spectroscopy at wavenumber 3379, 2893, 2135, and 1340 cm-1, respectively. xrd analysis shows that crystalline index (c.i) of bnc increases after 2.5 wt% addition of gnp. the presence of ctab decreases c.i value of composite films. bnc/gnp composite films have the best mechanical properties with young’s modulus about 77.01 ± 8.564. copyright © 2021. journal of mechanical engineering science and technology. keywords: bacterial nanocellulose, ctab, ftir, graphite nanoplatelet, morphology, xrd i. introduction bacterial cellulose (bc) is one type of cellulose available in this world. bc seems like a hydrogel with three-dimensional tangled network of white cellulose nanofiber [1] linked by hydrogen bond [2]. several applications of bc have been developed, the main ones being bioengineering, cosmetics, pharmaceutical, and biomedical. bc is widely known as natural polymers [3]. bc synthesized by gram-negative bacteria. the most common bacteria used in bc synthesis were pseudomonas aeruginosa or acetobacter xylinum [4-5]. bc is naturally synthesized from the bottom-up process by those bacteria [6], which beneficial physical properties of the resulted cellulose [7]. the extract of pineapple peel waste is used as the medium of bacterial fermentation [8]. the interesting properties of bc are chemical and thermal stability, biodegradable, mechanical strength, hydrophilicity and high crystallinity [9]. bc is the only kind of cellulose with the highest cellulose content compared to other natural cellulose, almost 100% [4]. 146 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. (characterization of bacterial nanocellulose graphite nanoplatelets composite films) bacterial nanocellulose (bnc) is bc that has been disintegrated using a high-pressure homogenizer, resulting in nanosized cellulose, approximately 35-55 nm [10]. bnc was used for basic material in carbon nanofibers (cnf) manufacture. previous supercapacitors and alkali metal batteries have used this cnf as the electrode materials [1]. several applications of bc utilization as a binder, reinforcement agent, and to form transparent film [11]. as a result, there are many possibilities for using bnc as a basic matrix material for binder agents in energy storage device manufacture like li-ion battery electrodes [12-13].[13]. the physical and chemical properties of nanostructured carbons could be attractive. they are specially designed with the ability in chemical resistance, strength, good thermal and electrical conductivity and high surface area. several previous studies have used nano carbons, hydrogen storage, nanocomposites, and catalysts for energy generation and storage. graphite nanoplatelets (gnp) are a form of nanocarbon [14]. it is composed of graphene sheets in the form of 2d nano-sized carbon material [15]. several properties of composite films that have been studied and proven that are affected by the presence of gnp are thermal properties, electrical, mechanical, and electrochemical [16-19]. gnp’s morphology seems in the form of flat, sharp edge pieces separated from the graphite lumps at 1000 °c. these pieces have a thickness of 10-100 nm [17]. several studies have explored the potential of gnp for composite formation purposes [21-26].[19][20][21][22][23] surfactants are molecules that are both hydrophilic and hydrophobic in the same molecule. the type of surfactant was used in this work, namely cetyltrimethylammonium bromide (ctab). ctab is used to dissolve gnp in aqueous solvents [15, 21, 27-28]. ctab is included in cationic surfactants. ammonium (n+) group becomes the head part, which is hydrophilic, and cetyl groups become its tail part, a hydrocarbon chain that consists of hydrophobic. the polar compound would interact with the head part of ctab, while the non-polar compound interacts with ctab. gnp is a non-polar compound, so to disperse into a solvent, a polar compound, surfactant like ctab is needed. the study of bacterial cellulose-based composite films explored in several previous studies use surfactant but does not use disintegrated and homogenized bnc. the novelty of this research is using the high-pressure homogenized bnc as matrix reinforced by gnp. this study uses gnp as a reinforcement agent of the bnc matrix to produce bnc/gnp composite film with ctab addition. bc was synthesized using pineapple peel extract media. bnc was produced through the disintegration process and then processed with highpressure homogenizer (hph) and filtered by a vacuum filter to remove the excess water. bnc, ctab, and gnp were mixed into distillation water media then stirred and sonicated. the presence of gnp into bnc/gnp composites film was analyzed whether its morphology, functional groups, and crystallinity of composites were measured by sem, ftir spectroscopy and x-ray diffraction, respectively. ii. material and methods a. materials acetobacter xylinum bacteria supplied from laboratorium teknologi terapan, universitas muhammadiah malang, indonesia. bc is synthesized in a pineapple peel extract medium. graphite nanoplatelets were supplied from cv.gamma scientific biolab, malang.urea, sodium hydroxide and glucose (c6h12o6) were obtained from cv.makmur sejati, malang, indonesia. issn: 2580-0817 journal of mechanical engineering science and technology 147 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. (characterization of bacterial nanocellulose graphite nanoplatelets composite films) b. synthesis of bc referring to previously published methods by suryanto et al. [24], bc synthesis starts with making juice from 300 gr of pineapple peel (rotten) plus water up to a volume of 2 l. the juice was then filtered. the pineapple peel extract is boiled. after boiling, add 7.5% (w/v) glucose and 0.5% (w/v) urea. put 1 l on a tray with more than 1 l capacity, then chilled. once cool, add a 1% (v/v) fermentation bacterial. incubated for 14 days. the harvested bc pellicle was then washed using water, boiled using a solution of naoh 1% at 90oc for 2 hours, and washed again until neutral. c. synthesis of bnc 50 grams of bc pellicle and 300 milliliters of aquades disintegrated by a high-powered blender for 1.5 min. add more 700 ml of purified water and blend again for 2 min. the cellulose solution is homogenized with hph machine for as much as five cycles at 150 bars. then filtered using a vacuum filter to remove excess water [25]. d. synthesis of composite films bnc/gnp bnc with mass 10 grams were diluted in 100 ml of purified water. gnp with percentage 2.5% and ctab with percentage 0.3%, diluted in 100 ml of distilled water. a magnetic stirrer is used to stir both solutions for 45 minutes. after that, the solutions merge and sonicate for an hour using an ultrasonic homogenizer. the slurry is put on a glass mold with aluminium-paper lamination and dried in an oven at 80 degrees celcius for 14 hours [26]. e. morphological studies morphology of the composite film's observation was conducted using sem, with 20 kv operating voltage at advanced mineral and material laboratory, universitas negeri malang, indonesia. the composite films' dimensions were cut into 10 mm x 10 mm and then coated with 10 nm gold before observation. the composite films were observed at 10.000x magnification. f. ftir analysis ftir analysis was conducted to analyze the functional groups. the sample is scanned with a wavenumber range of 4000 to 400 cm-1 with 4 cm-1 resolution. composite films were cut into 10 mm x 10 mm. the machine used in this test is shimadzu ir prestige-21 that belong to advanced mineral and material laboratory, universitas negeri malang, indonesia. g. x-ray diffraction analysis xrd analysis was conducted (using pan analytical x-pert pro diffractometer) at advanced mineral and material laboratory, universita negeri malang, indonesia. the dimension of composite films was cut into 10 mm x 10 mm. scanning steps were done at 2θ degree from 10o to 90o. segal equation was used to calculate the crystallinity and crystallinity index [27]. h. tensile strength test the composite films' tensile strength was tested using the techno tensile test machine according to the astm d638-v standard, and the dimension of composite films was cut to 63.5 mm overall length and 9.53 mm overall width [28]. the test was carried out at the laboratory of nano materials and advanced materials, mechanical engineering, state university of malang. 148 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. (characterization of bacterial nanocellulose graphite nanoplatelets composite films) iii. results and discussions a. morphology morphology and microstructure were very important to produce nanocomposites with specific final properties and applications. fig. 1 (a) shows an sem micrograph of pure bnc films. previously studied the bnc fiber diameter about 46 nm [29]. bnc has a higher surface area than bc because the cellulose fiber had been split from its hydrogen bond into a nanofiber. the pores size on bnc matrix is different because of the random arrangement of ribbon-shaped nanofiber with different. this condition makes bnc would be easier to mix uniformly with gnp. the morphology of bnc/gnp composite films shows in fig. 1(c). gnp tends to clump due to the van der waals force between carbon atoms and form bundles [30]. there can be seen that gnp create many bundles and does not disperse uniformly into the bnc matrix. in this work, ctab was used as a surfactant to separate gnp bundles individually and become stable against van der waals attraction before mixing it with bnc. fig. 1 (b) shows the sem micrograph of bnc/gnp composite films with the addition ctab as surfactant. ctab will lower the surface tension of water solvent and lower hydrophobic properties from gnp. therefore gnp could disperse uniformly in a water solvent. fig. 1 (b) shows nanofiber in composite films becomes more porous after mixing gnp-ctab solution into bnc solution with less bundle of nanofiber or gnp. this could be the surfactant also. the gnps are shown as flat and smooth flakes with sharp corners. the sonication process also effectively incorporates the gnp into the bnc matrix. higher gnp content in the composite film will result in a larger surface area of bnc covered by gnp. gnp was used to improve the thermal and electrical conductivity, so higher gnp content will result in better thermal and electrical conductivity [21, 34].[31]. fig. 1. sem micrograph of composite films: a. bnc;b. bnc/gnp 2.5 wt% with ctab addition; c. bnc/gnp 2.5 wt%. a. b. c. issn: 2580-0817 journal of mechanical engineering science and technology 149 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. (characterization of bacterial nanocellulose graphite nanoplatelets composite films) b. ftir analysis the functional groups from bnc/gnp composite films analysis were conducted based on the ftir spectra shown in fig. 2. the peak that corresponds to o-h stretching found at wavenumber 3379 cm-1, and peak corresponds to c-h stretching peak was detected at 2893 cm-1 [32]. the presence of gnp in the composite films result in a lower number of o-h stretching. the peak corresponds to c≡c stretching of alkynes was identified at wavenumber 2135 cm-1. after bnc was added with gnp, this peak was not appearing anymore. peak at 1685 cm-1 corresponds to the o-h band from the absorbed water of the composite films. gnp's presence caused this peak to disappear because gnp made composite films temperature higher and removed the absorbed water. the peak that corresponds to ch3 stretching was identified at wavenumber 1340 cm-1, and this peak became lower after bnc was added with gnp. fig. 2. ftir spectra of bnc/gnp composite films. c. xrd analysis the structure of bnc/gnp composite films was analyzed using x-ray diffractogram presented in fig. 3. the xrd spectra of bnc composite films show three distinct peaks, which appear at 2θ 14.2o, 18.2o, and 22.8o, corresponding to crystallographic planes of (101), (101) and (002) [18]. for bnc/gnp composite films, the xrd spectrum show one more distinct peak at 2θ 26.4o that correspond to gnp crystal (002). crystalline index (c.i), and % of crystalline were calculated based on x-ray diffractogram, and the results were listed in table 1. the c.i value of bnc film increase after penetration and interaction by gnp. this gnp agglomerates and form a bundle on the surface of bnc and does not disperse uniformly into the bnc matrix. ci value decrease in bnc/gnp composite film with ctab 150 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. (characterization of bacterial nanocellulose graphite nanoplatelets composite films) addition. the interaction of ctab with gnp cause polar and hydrophobic properties of gnp to lower. this condition makes gnp disperse uniformly in water solvent and evenly distributed into the bnc matrix. they result in lower crystallinity for bnc/ctab/gnp composite films. table 1. crystallinity index and % crystalline of the composite films no sample c.i % crystalline 1 control 0.565631 69.71707 2 bnc/gnp 2.5% 0.98676 98.69334 3 bnc/ctab/gnp 2.5% 0.825846 85.16771 fig. 3. x-ray diffraction spectra of bnc/gnp composite films d. tensile strength analysis the mechanical strength of bnc/gnp composite films was analyzed from the tensile test result. fig. 4 shows the tensile stress-strain diagrams of bnc/gnp composite films. pure bnc films have the lowest tensile strength, about 10.4 ± 0.415. the addition of gnp as filler into bnc matrix has successfully significantly increased the mechanical strength of bnc/gnp composite film [33]. interactions between the bnc and gnp might become crucial contributors to increasing the mechanical properties of composite film because of the existence of hydroxyl groups of bnc and the functional groups of gnp during the sonication treatment [[21]. but after the addition of ctab into bnc/gnp composite film, the mechanical strength has become weaker. the presence of ctab results in a lower amount of o-h bond, which is affected the mechanical properties of the composite film. issn: 2580-0817 journal of mechanical engineering science and technology 151 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. (characterization of bacterial nanocellulose graphite nanoplatelets composite films) fig. 4. tensile stress-strain diagrams of bnc/gnp composite films. table 2 shows the mechanical properties of bnc/gnp composite films. the strongest tensile strength belongs to bnc/gnp composite films which the maximum stress strength reaches 103.17 ± 8.5 mpa with young’s modulus 77.01 ± 8.564. bnc/gnp composite films with ctab addition has lower mechanical properties, and bnc film has the lowest mechanical properties with a stress strength of 13.99 ± 2.769 mpa. table 2. mechanical properties of bnc./gnp composite films sampel thickness (mm) stress (mpa) strain (%) young's modulus bnc 0.04 ± 0.002 13.99 ± 2.769 1.63 ± 0.431 10.4 ± 0.415 bnc/gnp 2.5% 0.04 ± 0.001 103.17 ± 8.5 2.61 ± 0.349 77.01 ± 8.564 bnc/gnp 2.5%/ctab 0.06 ± 0.003 34.35 ± 3.505 2.11 ± 0.469 31.14 ± 1.97 iv. conclusions bnc/gnp composite films with addition ctab were successfully prepared through incorporating gnp-ctab solution into bnc solution with sonication process and dried by an oven. ctab addition to bnc/gnp composite changes its morphology. gnp seems evenly distributed into the bnc matrix. this also identified at c.i of bnc/ctab/gnp composite films that are lower than bnc/gnp composite films. o-h peak stretching was detected at wavenumber 3379 cm-1, and it tends to decrease while the amount of gnp increase in the composite films. bnc/gnp composite films have the best mechanical 152 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 145-154 susilo et al. 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[33] f. wang and l. t. drzal, “the use of cellulose nanofibrils to enhance the mechanical properties of graphene nanoplatelets papers with high electrical conductivity,” ind. crops prod., vol. 124, no. august, pp. 519–529, 2018, doi: 10.1016/j.indcrop.2018.08.019. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 62-72 62 doi: 10.17977/um016v5i12021p062 the effect of multi-extrusion process of polylactic acid on tensile strength and fracture morphology of filament product muhamad syaifuddin, heru suryanto*, suprayitno department of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang no. 5, malang, east java, indonesia *corresponding author: heru.suryanto.ft@um.ac.id abstract polylactic acid (pla) is one of the most used materials in fdm 3d printing. large-scale consumption of pla on an industrial scale could cause environmental and efficiency problems. thus, pla waste and industry waste need to be recycled to limit excessive waste. this study aimed to investigate the change in mechanical property, morphology, and structure of mechanically recycled pla. recycling was performed 12 times using the extrusion process with an extrusion temperature nozzle of 170°c. the sem, structural analysis, and amorphous-crystalline analysis used xrd. the results showed a gradual decrease of tensile strength from each recycle with a total of 20% (13.22 mpa). the decrease percentage equalled the number of recycling. after the 9th recycle, pla experienced a drastic tensile strength decrease, in which the 12th recycle tensile strength had a 14% (8.17 mpa) reduction. the morphology analysis of the tensile test sample presented significant morphology change, in which morphology defects such as void, flakes, and cracks appeared after the 6th recycle. although, until 12 times extrusion, it did not significantly affect the pla phase shape. mechanical recycle using a multi-extrusion process is not recommended exceeding six times. copyright © 2021. journal of mechanical engineering science and technology. keywords: extrusion, microstructure, pla, recycle, tensile strength. i. introduction 3d printing technology is an innovative and versatile additive manufacturing because it can print various materials such as thermoplastics, ceramics, and metals. this technology grows in various fields, including medical, pharmaceutical, automotive, and aerospace, with a growth rate of 18% in 2018 and predicted to increase to 32% in 2026 [1]. this situation improves manufacturing efficiency while also fulfilling custom products following customer order specifications [2]. the common polymer materials used in 3d printing manufacture are acrylonitrile butadiene styrene, polypropylene, polylactic acid (pla), and polyethylene [2]. the quality of the filament is crucial so that the manufacturing process is not hampered and to get good manufactured product quality. pla is a biopolymer obtained from the lactide ring-opening polymerisation of sugar raw materials fermentation [3] and has the most potential to replace conventional petroleumbased plastics [4]. this polymer has good mechanical and thermal properties and does not harm the environment [5]. pla can be easily processed using various conventional thermoplastic material processing, such as extrusion [6]. extrusion is the process of forming a polymer or workpiece by pushing the material in a closed cavity using a screw or cylinder through a die to produce a particular shape [7]. 63 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) although pla has many advantages over conventional plastics, large-scale consumption of pla on an industrial scale will cause environmental and efficiency problems. [8]. therefore, the finished biopolymer waste and industrial waste from the product manufacturers need to be recycled to limit excessive waste. recycling is considered better from an environmental perspective than waste burning to avoid related environmental impacts such as global warming [9]. biopolymer recycling is a challenge for researchers because the materials are heterogeneous [10]. methods to recycle biopolymer materials can be classified into mechanical recycling, chemical recycling, and thermal processing [11]. mechanical recycling is accomplished by melting and re-moulding the biopolymer using multiple extrusion and/or injection cycles. of the several recycling methods that can be done, mechanical recycling is considered one of the best material recovery methods because it is easy to do, low cost, and has easier parameter control [12]. in recent years, several studies have been conducted to determine the recycling effect of pla, focusing on changes in its mechanical properties. anderson [13] used pla, which was recycled five times and reused for 3d printing, showing a 10% reduction in tensile strain. chaitanya [14] performed a pla recycling test for up to eight extrusion cycles in a different study. the tensile strength of recycled pla decreased by 11.64% after the first recycling and a 20.9% decrease in the second recycling. additionally, repeated extrusion of pla causes changes in rheological, thermal, and mechanical properties [14], [15]. hence, it is essential to investigate the limitation of total pla recycling cycles so that its waste can still be used in good quality, especially as 3d printing filaments. pla was relatively easy to recycle into filaments than other bioplastics for 3d printing. recycle was intended to reduce the plastic waste volume that has the potential to cause environmental and efficiency problems. so, this study aimed to characterize the influence of multiple recycling of pla using extrusion process on microstructure, mechanical performance, and structure. ii. material and methods a. material the material in this research was pla filament produced by sunhokey technology, guangdong, china. blue pla filaments were selected in diameter due to their good thermal performance and environmentally friendly nature [16]. pla has 1.24 g/cm 3 density, 48.5 mpa tensile strength, 82.7 mpa bending strength, and 150–165°c melting point. b. polylactic acid recycling pla recycling was conducted by the mechanical process using a double screw polymer extruder, xh-dse-10 type (dongguan xihua, china), equipped with 40 l/d ratios and a 25 mm diameter screw. before the extrusion process, the pla filament was cut into 4 mm pellets using a pelletiser machine with a constant speed of 70 rpm. after the pelletising process, the pellets were extruded with a 60 rpm screw speed, a 55 rpm filament puller speed, and a temperature profile set to 175°c, 175°c, 175°c, 180°c, 170°c, 170°c (for the different zones from the hopper to the die-head, respectively) to obtain the samples from the extrusion. before recycling, the samples were re-pelletised and dried for 2 hours at 35°c, below the glass transition temperature (tg), to reduce the water content as much as possible and avoid hydrolytic degradation [16]. the pla material was then re-extruded under the issn: 2580-0817 journal of mechanical engineering science and technology 64 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) same conditions in the first processing step to obtain a recycled pla sample. the recycling/repeated extrusion process was performed in 5 groups: the first/virgin polylactic acid (vpla), third recycled polylactic acid (rpla-3), sixth recycled polylactic acid (rpla-6), ninth recycled polylactic acid (rpla-9) and twelve recycled polylactic acid (rpla-12). the filament product of each group was taken as the test specimens. c. mechanical properties tensile testing was done on reprocessed pla using a tensile testing machine of type ly-1066a (dongguan liyi environmental technology, china) to investigate changes in macroscopic mechanical properties according to the astm d638 standard [17]. the specimen was a single-filament material with 1.75 (±0.5) mm diameter and 200 mm overall length, as shown in figure 1. the tensile test in static stress was measured at 100 mm/min speed. the analysis was conducted using four samples in each test specimen with the average tensile strength, modulus of elasticity, and elongation as the representative values. d. morphological analysis morphological analysis of the pla biopolymer tensile test sample was performed using a scanning electron microscope, fei inspect-s50 type (fei, china). samples from each specimen were prepared by cutting a randomly selected portion of the filament from the tensile test specimen. all specimens were coated in gold-palladium (au-pd) on 10 nm thickness before sem observations to provide good conductivity. micrographs were taken at 500x magnification, and the accelerating voltage was set at 20 kv. a) b) fig. 1. tensile test of filament. a) speciment sample and b) testing on tensile testing machine 10 0 65 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) e. x-ray diffraction (xrd) x-ray diffraction (xrd) instrument x'pert pro pananalytical diffractometer (panalytical, almelo, the netherlands) with cukα radiation (λ = 1.54 ) was used to analyse the phase change of pla biopolymer by comparing the virgin sample with recycled samples. tests were performed on powders made from extruded samples. the diffraction intensity of cukα radiation was recorded between 10° to 90° (2θ angle range) at 40 kv and 35 ma. iii. results and discussions a. mechanical properties the tensile stress-strain curves of the tensile test specimens extruded using the virgin pla and 12th recycled pla (rpla-12) produced by the extrusion process are shown in figure 2 to show the changes in the recycling process. the curves for the remaining samples (not shown here) fall between the curves drawn in this figure. the curve represents the decrease in tensile strength of pla, which was recycled 12 times using the extrusion process. fig. 2. stress-strain curves of vpla and rpla-12 the pla tensile test results with different recycling amounts are shown in figure 3. the tensile strengths from vpla to rpla-12 are 65.35 mpa, 63.35 mpa, 62.15 mpa, 60.3 mpa, and 52.13 mpa. the tensile strength of pla gradually decreased as the amount of recycling was increased by the extrusion process. the decrease in tensile strength in the whole recycling process was 13.22 mpa or 20%. the percentage decrease in tensile strength increased with the increase in recycling, in which the 3rd recycling (rpla-3) decreased by 3% (2 mpa). after the twelfth recycling (rpla-12), the pla experienced a drastic reduction in tensile strength with a percentage of 14% (8.17 mpa). rpla-12 showed a significant decrease in tensile strength and elastic modulus. the decrease in pla filament tensile strength was caused by the recycling cycle and control parameters such as screw 0 1 2 3 4 5 6 7 0 10 20 30 40 50 60 70 s tr e s s ( m p a ) strain (%) vpla rpla-12 issn: 2580-0817 journal of mechanical engineering science and technology 66 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) speed, barrel temperatures, pelletising speed, and other parameters such as water cooler temperature, heating process duration, humidity, etc. several studies about mechanical recycling on other polymers investigate their mechanical properties, as shown in table 1. in general, the mechanical recycling of biobased polymers will cause biodegradation and a decrease in tensile strength. table 1. mechanical properties of recycled polymers polymer tensile strength (mpa) young's modulus (mpa) source virgin 3𝑟𝑑 recycle virgin 3𝑟𝑑 recycle pla (polylactic acid) 65.3 63.3 13.5 13.2 plla (poly l-lactic acid) 64.1 57.4 2600 2600 [18] p3hb (poly 3hydroxybutyrate) 32.1 13.4 [19] bio-pet (bio-polyethylene terephthalate) 23.7 29 1405 1783 [20] hdpe (high-density polyethylene) 23.4 25.8 240 290 [21] the main factor that causes a decrease in the tensile strength of pla filaments is the thermo-mechanical degradation during the extrusion process. there is a heating process using a heating barrel until the material reaches its melting point in the filament extrusion process. thermal degradation occurs during the extrusion process at high temperatures when the polymer changes from a solid to a liquid. the thermal degradation of biopolymers mechanism is chain scission and depolymerisation reactions (unzipping). it causes polymer chains to degrade to monomers, dimers, or oligomers [22]. random degradation reactions involve hydrolysis with the water amount, oxidative degradation, cis-elimination, and inter and intramolecular transesterification reactions [23]. at high temperatures (above the fig. 3. mechanical properties of virgin and recycled pla vpla rpla-3 rpla-6 rpla-9 rpla-12 52 54 56 58 60 62 64 66 tensile strength (mpa) young's modulus (mpa) elongation (%) 12.0 12.5 13.0 13.5 14.0 4.2 4.4 4.6 4.8 67 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) melting point), pla can be degraded through interand intramolecular ester exchange, ciselimination, and radical and concerted non-radical reactions, resulting in the formation of co, co2, acetaldehyde and methyl ketene [24]. besides material heating, the extrusion process also involves mechanical stress generated by the screw rotation to press the material through the die to produce the desired shape. mechanical stresses such as shear forces, stresses, and compressions during the extrusion process resulted in polymer degradation [25]. shear forces, stresses, and compressions can cause biopolymer mechanical degradation. molecular damage is the phenomenon that occurs when mechanical stress occurs in polymer processing. mechanical degradation reduces the molecular mass of the polymer. although mechanical factors are not dominant during biodegradation, they can trigger or accelerate it. temperature, oxygen, humidity, mechanical stress, and light lead to thermo-mechanical biopolymer degradation, either individually or together [26]. thermo-mechanical degradation involves oxidation, hydrolysis, and chain-cutting reactions that cause a decrease in molar mass and affect morphological properties in terms of amorphous-crystalline ratio, chirality, or steric rearrangement [27]. the temperature in pla processing should not be too high to avoid thermal degradation through non-radical reactions that could cause a significant decrease in molar mass which has an essential effect on pla performance. in figure 3, the value of the elastic modulus (young modulus) fluctuates following previous studies with similar pla values [28] [29]. meanwhile, elongation shows a decrease due to recycling. thus, the decrease in the pla bioplastics tensile strength was caused by the lack of the material's ability to accept progressive deformation. in the first extrusion process, the pla could maintain a maximum elongation before experienced 4.83% breaking. however, after twelve recycling processes, the material tolerated elongation of only 4.31%. the decrease in elasticity properties of the recycled pla material caused the material's ability to absorb energy (tensile energy absorption) to drop drastically [18]. b. morphology observation the pla biopolymer morphology results from the sem testing with 500x magnifications are shown in figure 4. the sem testing was done on the fracture surface of the tensile test sample. observations showed that the difference in the total pla biopolymer recycling cycles exhibited different morphology and characteristics in the tensile test sample fracture. the identification in the virgin pla sample (figure 4a) shows a fracture surface that is much flatter and smoother than the recycled pla. fault topography in pla that was not recycled does not show any morphological defects found in a previous study where pla showed a similar morphology [12]. after the 3rd recycling (rpla-3), the pla does not show any significant morphological changes other than that the specimen surface looked rougher and drier than virgin pla. the 6th recycled pla/rpla-6 micrograph (figure 4c) shows a damaged surface characterised by the appearance of voids and scales. in addition, the surface appears rough and is more susceptible to mechanical scratches. this condition is attributed to the crystalline increase in pla and the change in the glass transition temperature (𝑇𝑔) that causing air trap in the heating process. in figure 4, visual observation presents that the specimens' surfaces are gradually getting more brittle as a result of successive recycling processes. the morphological defects on the recycled pla surface increased significantly after the fourth recycling. rpla-9 micrograph shows a hardened surface with cracks, scaly, and heterogeneous in which the melting particles made it inefficient compared to vpla. recycling causes hydrolysis and increases the melt flow rate issn: 2580-0817 journal of mechanical engineering science and technology 68 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) (mfr) [30]. this factor may have contributed to the surface imperfections in the recycled samples. therefore, pla biopolymers should not be recycled after the sixth recycling. then, the rpla-12 micrograph (figure 4e) shows that the surface had the roughest pattern, indicating a brittle phenomenon with irregular morphology. it shows that pla recycling causes hardened surfaces, holes and cracks, discolouration, and heterogeneity in which molten particles appeared and made it inefficient compared to vpla [12]. figure 4 observation exhibits that the fracture morphology has significant differences. the fracture morphology is getting worse following the increasing number of pla polymer recycling processes characterised by morphological defects. this condition can be directly related to the degradation of the pla matrix [30]. morphological defects are possible because repeated recycling causes hydrolytic degradation, which reduces the molecular mass and causes the material's ability to absorb energy (tensile energy absorption) to drop dramatically, as evident by the decrease in the value of young modulus [28], [31]. in addition, morphological defects may arise due to the structural alignment and new conformation of pla. the chain cutting effect caused by thermo-mechanical degradation can be monitored by techniques such as differential scanning calorimetry (dsc) in terms of amorphous-to-crystalline ratio and thermal transition [32]. fig. 4. sem images of the tensile fracture of (a) vpla, (b) rpla-3, (c) rpla-6, (d) rpla-9, and (e) rpla-12 69 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) c. x-ray diffraction analysis x-ray diffraction analysis was used to identify the crystal structure, including the pla polymer phase state. polymers may contain crystalline regions that randomly mix with amorphous regions. pla has two possible phases: semi-crystalline and amorphous phases [33]. what distinguishes between polymers with semi-crystalline and amorphous phases is that semi-crystalline polymers exhibit relatively broad diffraction peaks and crystalline peaks. in contrast, amorphous polymers have broad x-ray diffractograms, which are difficult to determine by any crystalline model [34]. figure 5 shows the diffractogram of pla samples with recycling amount variations in the data range between 10.01°–89.99° with a scanning step of 0.02°. the results show several diffraction peaks with not many different intensities in the two ranges between 13.07° and 28.75°. pla has a shape and exhibits a 10/3 helical conformation packed into an orthorhombic (or pseudo-orthorhombic) unit cell. to date, pla is known to have four distinct crystalline forms: α, β, γ, and ε forms and two irregular modifications of the α forms, namely α′ and α″ forms [35]. the intensity relationship curve for 2θ obtained a broad diffraction peak and did not have a defined and sharp peak from the test results. it indicated that the resulting pla tended to be amorphous. another study that used dsc found that the pla remained dominant in having an amorphous phase regardless of the number of reprocessing cycles [36] [12]. iv. conclusions this experimental study observed the performance of pla, which was recycled 12 times using the extrusion process. the tensile test results showed a gradual decrease at each recycling, with a total of 20% (13.22 mpa). the percentage decrease in tensile strength increased with the increase in the number of recycling. after the ninth recycling, pla experienced a drastic decrease in tensile strength, decreasing 14% (8.17 mpa). the fracture 10 20 30 40 50 60 70 80 90 0 50 100 150 200 250 17 18 19 20 21 22 220 240 260 in te n s it y ( a .u .) 2 theta (degrees) vpla rpla 3 rpla 6 rpla 9 rpla 12 249 243 240 238 226 fig. 5. diffractogram of the virgin and recycled pla issn: 2580-0817 journal of mechanical engineering science and technology 70 vol. 5, no. 1, july 2021, pp. 62-72 syaifuddin et al. (the effect of multi-extrusion process of polylactic acid on tensile strength) morphology analysis that was observed using the sem showed significant morphological changes. the fracture morphology was getting worse following the increasing number of recycling which was indicated by morphological defects in voids, flakes, and crystallisation. thus, the amount of recycling did not have much effect on the pla phase shape. based on these findings, mechanical recycling using a multi-extrusion process exceeding six cycles is not recommended. acknowledgement lp2m universitas negeri malang supported this research work through hibah skripsi 2021. references [1] wickramasinghe, s., do, t., and tran, p., “fdm-based 3d printing of polymer and associated composite: a review on mechanical properties, defects and treatments,” polymers (basel)., vol. 12 (7), pp. 1–42, 2020, doi: 10.3390/polym12071529. 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[36] brüster, b., addiego, f., hassouna, f., ruch, d., raquez, j. m., and dubois, p., “thermo-mechanical degradation of plasticized poly(lactide) after multiple reprocessing to simulate recycling: multi-scale analysis and underlying mechanisms,” polym. degrad. stab., vol. 131, pp. 132–144, 2016. journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 39-46 39 doi: 10.17977/um016v7i12023p039 effect of current and pulse-on time on material removal rate and surface roughness of tungsten carbide in electric discharge machine die-sinking mochamad deny riyanto, andoko*, heru suryanto mechanical and industrial engineering department, universitas negeri malang, jl. semarang 5 malang, 65145, indonesia *corresponding author: andoko.ft@um.ac.id article history: received: 06 january 2022 / received in revised form: 11 may 2023 / accepted: 17 may 2023 available online 5 june 2023 abstract the focus of manufacturing for tungsten carbide applications often demands a smooth surface quality as the result of the electric discharge machine (edm) die-sinking process, especially in the manufacture of die and mold with tungsten carbide material processed using a die-sinking edm machine. the purpose of this study is to analyze the effect of electric current and pulse-on time on the material removal rate (mrr) and surface roughness of tungsten carbide. through the experimental method, the parameters varied, namely electric current 17 a, 20 a, 23 a, and pulse-on time 30 µs, 55 µs, and 80 µs. mrr was calculated through weight loss. surface roughness was obtained from a surface roughness tester and a scanning electron microscope for surface morphology. the results showed that the highest material removal rate was 1.509 mm3/min at 23 a and 30 µs, and the lowest material removal rate was 0.262 mm3/min at 17 a and 80 µs. the highest surface roughness value was 4.278 µm at 23 a and 80 µs. the lowest surface roughness value was 2.166 µm at 17 a and 30 µs. the tungsten carbide surface topography results are crater, globule, crack, and porous. the greater the current used, the higher the mrr value and surface roughness. meanwhile, the greater the pulse-on time used, the mrr value decreases, and the surface roughness increases. copyright © 2023. journal of mechanical engineering science and technology. keywords: current, edm, mrr, pulse-on time, roughness, sem, tungsten carbide i. introduction electric discharge machine (edm) die-sinking is a non-conventional machining process that is widely used in the manufacturing industry. the working principle of a edm die-sinking machine is a jump of electric sparks in material processing that occurs in the electrode gap with the workpiece [1]. edm die-sinking machines are commonly used to work very hard metals that cannot be worked using conventional machines [2]. one material that has a very high hardness level is tungsten carbide [3]. in recent years, tungsten carbide has been widely used in the manufacturing industry as cutting tools, dies, and molds because it has the advantage of resistance to wear and very high temperatures [4]. tungsten carbide has a very high hardness level with a vickers hardness value of up to 2600 and has a scale rating of about 9 on the mohs scale, so conventional machining processes cannot be performed properly [5]. some of these tungsten carbide applications often demand a smooth surface quality as the end result of the edm die-sinking process [6]. moreover, in the manufacture of dies and molds with tungsten carbide, which are processed using an edm die-sinking machine, the mailto:andoko.ft@um.ac.id 40 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 39-46 riyanto et al. (effect of current and time to mrr and roughness of titanium carbide edm die singking) final result of the surface of the mold cavity determines the product of the mold, therefore surface roughness is very important in the edm die-sinking process of tungsten carbide [7]. in the current research, surface roughness is related to the material removal rate (mrr) produced on edm die-sinking machines [8], [9]. bodukori conducted an mrr analysis and surface roughness on ti-6al-4v eli titanium alloy using the edm diesinking process. the results showed that increasing the current formed a large and deep crater, resulting in lower surface quality. mrr increased with increasing current strength, and pulse on time had a second effect. taguchi optimization analysis on mrr and surface roughness in the edm die-sinking material 17-ph steel. process parameters such as current strength and pulse on time significantly affect mrr and surface roughness [10]. in contrast, pulse-off time shows the least significant effect compared to other parameters [11]. the effect of current and pulse-on time on bulk metallic glass (bmg) to mrr showed that increasing the current will result in a higher mrr value and surface roughness, then increasing pulse-on time results in a lower mrr value and higher surface roughness value [12]. based on previous research, current and pulse-on time affected mrr and surface roughness during edm die-sinking machining. this study aims to analyze the current and pulse-on time on tungsten carbide during edm die-sinking machining to contribute more information, especially on the use of tungsten carbide. ii. material and methods workpiece used was a cylindrical tungsten carbide with a diameter of 10 mm and a length of 75 mm. the electrode used to scrape the workpiece is a copper (cu) cylinder with a diameter of 15 mm and a length of 100 mm. the surfaces of the workpieces and electrodes were polished using sandpaper to make it easier to determine the reference points between the workpieces and ensure the surface roughness level of each experiment. the c-tek znc 320 edm machine was used in this study by varying the current and pulse-on time. during the edm die-sinking machining process, the workpiece gap and electrodes were submerged by chevron honilo 409 dielectric fluid. edm die-sinking machining parameters are shown in table 1. table 1. parameter of edm die-sinking parameter value unit depth of cut 0.2 mm current 17, 20, 23 a pulse on time 30, 55, 80 µs pulse off time (µs) 4 µs gap voltage (v) 40 v jumping 8 mm mrr was obtained by collecting a mass of the workpiece before and after the edm die-sinking process was measured using the optima opd-e204 digital balance and the working time of the edm die sinking process. after the three data have been collected, the material removal rate data can be determined by equation (1). issn: 2580-0817 journal of mechanical engineering science and technology 41 vol. 7, no. 1, july 2023, pp. 39-46 riyanto et al. (effect of current and time to mrr and roughness of titanium carbide edm die singking) 𝑀𝑅𝑅 = 𝑊1−𝑊2 𝜌𝑡 …………………………………………………………………. (1) where mrr is a material removal rate (mm3/min), w1 and w2 are the mass of the workpiece before and after machining, respectively, and 𝜌 is the density of the workpiece (0.01563 g/mm3). a surface roughness tester (mitutoyo sj 301) was used to measure the surface roughness value of the workpiece after die-sinking edm machining. a scanning electron microscope (sem fei inspect-s50) was used to evaluate the surface morphology of tungsten carbide after machining. iii. results and discussions 1. effect of current on mrr and surface roughness the current in the edm die-sinking machine is used to generate electric sparks that are used to remove the workpiece. the experimental results are shown in figure 1 by a graph of increasing current to mrr. fig. 1. effect of current on mrr based on figure 1, at the current of 17 a with a pulse on time of 30 µs, the mrr is 0.460 mm3/min. the value of the mrr increases with increasing current with the same pulse-on time until it reaches the highest mrr (1.509 mm3/min) when using a current of 23 a and a pulse-on time of 30 µs. the greater the current used, the higher the material removal rate obtained. the increase in mrr value also occurs in other current parameters with the same pulse-on time. the highest mrr value was obtained at a current of 23 a, while the lowest mrr value was at 17 a. an increase in amperage is proportional to the increase in mrr. a larger current in the edm die-sinking process can produce more spark energy between the gap of the workpiece and the electrode resulting in a high-temperature rise [13]. the increase in temperature can melt and vaporize the material quickly to form a crater [14]. 42 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 39-46 riyanto et al. (effect of current and time to mrr and roughness of titanium carbide edm die singking) fig. 2. effect of current on surface roughness the experimental results for surface roughness are shown in figure 2. at a current of 17 a with a pulse-on time of 30 µs, the surface roughness value of 2.166 µm. the average surface roughness (ra) value increases with increasing current with the same pulse-on time until the highest surface roughness (ra) (4.278 µm) at 23 a and pulse-on time 80 µs. the higher the current used in the edm die-sinking machining process, the higher the surface's average roughness (ra) value so that the quality of the tungsten carbide material surface decreases. an increase in current strength will result in an increase in surface roughness value. after all, an increase in current causes larger craters to form, reducing the surface finish. good surface quality occurs when the current is low [15]. (a) (b) fig. 3. surface morphology of tungsten carbide at (a) lowest mrr (b) highest mrr the surface morphology of tungsten carbide that yields the lowest and highest mrr is shown in figure 3. figure 3 (a) and (b) show the sem results at 500x magnification showing issn: 2580-0817 journal of mechanical engineering science and technology 43 vol. 7, no. 1, july 2023, pp. 39-46 riyanto et al. (effect of current and time to mrr and roughness of titanium carbide edm die singking) the craters, cracks, and porous. craters are formed from the material removal process when the current generates heat energy and then melts and vaporizes the workpiece [8]. the use of high currents causes the formation of larger craters, can reduce surface quality results, and impact high roughness values. the size of the crater at the highest and lowest mrr is different due to the use of high current, which produces more spark energy [16]. globules are residual machining particles attached to the surface of the workpiece that is not washed away by the dielectric fluid. figure 3 (a) shows the surface topography of the lowest mrr, and the globules appear smaller. in figure 3 (b) the surface topography of the highest mrr, the globules formed appear larger and thicker. the use of high current followed by the use of low pulse-on time causes the melting of the workpiece material to occur faster, or the resulting material removal rate is higher so that the formation of multi-layered globules, in this case with the formation of larger and thicker globules which increases in surface roughness value. in morphology, cracks appeared on the surface [8]. during the machining process, the heat from the spark melts the material's surface, then the melted surface layer is quickly cooled by the dielectric liquid and solidifies again. because the solidification process is followed by volume shrinkage on the surface of the workpiece, then from this volume shrinkage causes tensile stress, and cracks on the surface of the workpiece are caused by tensile stress that exceeds the material's ultimate tensile strength [17]. figure 3 shows that the porous is formed because when the heat from the electric sparks generated during the machining process causes the workpiece to melt, at that time, the gas dissolves into the liquid metal. the dielectric liquid quickly cools the liquid metal. the gas that does not escape from the liquid metal is trapped in the material and hardens again [17]. 2. effect of pulse-on time on mrr and surface roughness during the edm die-sinking process, pulse-on time is an electric current discharge cycle between the workpiece gap and the electrode. a graph of the increase in pulse on time to mrr from the experimental results is shown in figure 4. fig. 4. effect of pulse-on time on mrr at a pulse-on time of 30 µs with a current of 17 a, the mrr value is 0.460 mm3/min. the highest mrr value is obtained using a low pulse-on time of 30 µs, while the lowest 44 journal of mechanical engineering science and technology issn 2580-0817 vol. 7, no. 1, july 2023, pp. 39-46 riyanto et al. (effect of current and time to mrr and roughness of titanium carbide edm die singking) mrr value is obtained using the highest pulse-on time of 80 µs. the mrr value decreases as the pulse-on time increases with the same current. this is because by increasing the pulse on time, the plasma channel formed at the gap between the workpiece and the electrode continues to expand so that when the electric sparks jump, it will inhibit the transfer of heat energy to the surface of the workpiece to erode the workpiece [9] through the dielectric liquid that is able to clean the debris on the surface of the workpiece. as a result, the particles formed from the melting on the surface of the workpiece are not washed away properly. therefore, the resulting mrr value decreases [18]. in addition, using a lower or shorter pulse-on time will cause more debris between the workpiece gap and the electrode to be removed by the dielectric liquid during the same pulse-off time, resulting in higher mrr values. fig. 5. effect pulse on time to surface roughness the graph shows the effect of pulse-on time on roughness in figure 5. the resulting average surface roughness (ra) value varies from a range of 2.166-4.278 µm. at a pulse-on time of 30 µs with a current of 17 a produces an average surface roughness value (ra) of 2.166 µm. this surface roughness value will continue increasing along with the pulse-on time. at a pulse-on time of 55 µs and a current of 17 a, the average surface roughness value (ra) increased to 2.279 µm, as well as a pulse-on time of 80 µs with a current of 17 a which increased the surface roughness value by 2.887 µm. the average surface roughness value (ra) increases at other larger pulse-on-time values with the same current value. the lowest average surface roughness (ra) value occurs when using a pulse on time of 80 µs and a current of 17 a of 2.166 µm, while the highest average surface roughness (ra) value is 4.278 µm, which is at a pulse on time of 80 µs and 23 a. the higher the pulse-on time used in the edm die-sinking machining process, the higher the average surface roughness value (ra) so that the quality of the tungsten carbide material surface decreases. the electric sparks during the edm die-sinking process last longer, so the greater the heat energy for melting and vaporizing the material, thus the larger and deeper the crater produced, resulting in high surface roughness. issn: 2580-0817 journal of mechanical engineering science and technology 45 vol. 7, no. 1, july 2023, pp. 39-46 riyanto et al. (effect of current and time to mrr and roughness of titanium carbide edm die singking) iv. conclusions experiments were conducted on the effect of current and pulse-on time on mrr and surface roughness of tungsten carbide during edm die-sinking machining. based on the results, an increase in electrical current caused an increase in mrr value and surface roughness. increased pulse-on time affects the low mrr value and high surface roughness. in tungsten carbide surface morphology, crater, globule, crack, and porous were found. acknowledgment this publication was funded by pnbp um. references [1] a. a. fikri, m. romlie, and a. aminnudin, “factors affecting the surface roughness in sinking edm process,” j. mech. eng. sci. technol. jmest, vol. 1, no. 1, art. no. 1, aug. 2017, doi: 10.17977/um016v1i12017p009. [2] k. s. banker, a. d. oza, and r. b. dave, “performance capabilities of edm machining using aluminum, brass and copper for aisi 304l material.,” vol. 2, no. 8, 2013. 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[12] y. r. a. pradana, a. ferara, a. aminnudin, w. wahono, and j. s.-c. jang, “the effect of discharge current and pulse-on time on biocompatible zr-based bmg sinkingedm,” open eng., vol. 10, no. 1, pp. 401–407, jan. 2020, doi: 10.1515/eng-20200049. [13] d. mishra and s. rizvi, “ influence of edm parameters on mrr, twr and surface integrity of aisi 4340 ,” int. j. tech. res. appl., pp. 163–169, mar. 2017. [14] b. jabbaripour, m. h. sadeghi, sh. faridvand, and m. r. shabgard, “investigating the effects of edm parameters on surface integrity, mrr and twr in machining of ti– 6al–4v,” mach. sci. technol., vol. 16, no. 3, pp. 419–444, jul. 2012, doi: 10.1080/10910344.2012.698971. [15] s. kumari, s. datta, m. masanta, g. nandi, and p. k. pal, “electro-discharge machining of inconel 825 super alloy: effects of tool material and dielectric flushing,” silicon, vol. 10, no. 5, pp. 2079–2099, sep. 2018, doi: 10.1007/s12633-0179728-5. [16] m. zhang, q. zhang, l. dou, q. liu, and c. dong, “comparisons of single pulse discharge crater geometries in edm and eam,” j. manuf. process., vol. 22, pp. 74– 81, apr. 2016, doi: 10.1016/j.jmapro.2016.01.013. [17] k. salonitis, a. stournaras, p. stavropoulos, and g. chryssolouris, “thermal modeling of the material removal rate and surface roughness for die-sinking edm,” int. j. adv. manuf. technol., vol. 40, no. 3–4, pp. 316–323, jan. 2009, doi: 10.1007/s00170-0071327-y. [18] s. ahmad, r. n. chendang, a. supawi, m. a. lajis, and m. h. k. zaman, “material removal rate and machining accuracy of electrical discharge machining (edm) of inconel 718 using copper electrode,” iop conf. ser. mater. sci. eng., vol. 607, no. 1, p. 012006, aug. 2019, doi: 10.1088/1757-899x/607/1/012006. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 34-39 34 doi: 10.17977/um016v6i12022p034 effect of homogenization pressure on bacterial cellulose membrane characteristic made from pineapple peel waste muhamad muhajir1, heru suryanto1,2, yanuar rohmat aji pradana1, uun yanuhar3 1department of mechanical engineering, faculty of engineering, universitas negeri malang, jl. semarang 5, malang, indonesia 2center of excellence for cellulose composite (ceccom), department of mechanical engineering, universitas negeri malang, jl. semarang 5, malang 65145, indonesia 3department of waters resources management, faculty of fisheries and marine sciences, brawijaya university, jl. veteran malang, east java, indonesia *corresponding author:heru.suryanto.ft@um.ac.id article history: received: 31 august 2021 / received in revised form: 8 march 2022 / accepted: 20 april 2022 abstract many studies were conducted to maintain the environment by reducing the waste, especially pineapple peel waste. this study aims to explore the effect of various pressure of the homogenization process on bacterial cellulose membrane surface morphology and structure produced using extract of pineapple peel waste. the methods include the preparation of pellicle samples from the product of the fermentation process of acetobacter xylinum using a medium from the extract of pineapple peel waste. bacterial cellulose pellicles were crushed using a blender. mashed bacterial cellulose pellicle was homogenized in high-pressure homogenizer with pressure variation of 150 bar, 300 bar, 450 bar, dan 600 bar and then cast into a mold. the bacterial cellulose solutions were dried in an oven at 60°c for 8 hours. the dried bacterial cellulose membrane was analyzed using xrd for the structure and sem analysis for the morphology. the results indicate that the crystalline properties of bcm were shifted after being treated by various pressure processing in a high-pressure homogenizer. it was found that the high-pressure homogenizer with higher pressure reduced the peak intensity, decreased crystalline index from 87% to 70%, and decreased the degree of crystalline from 88% to 77% without changing the cellulose structure. the higher pressure of the homogenization process causes the porosity of the membrane to be decreased. copyright © 2022. journal of mechanical engineering science and technology. keywords: bacterial cellulose, high-pressure homogenizer, morphology, pineapple waste, xrd i. introduction cellulose is an abundant biopolymer resulted in almost plants. it is composed of many compounds such as lignin, pectin, and hemicellulose, so its need many process and energy to purify plant cellulose. in this case, bacterial cellulose (bc) offers a higher purity source of cellulose than plant cellulose [1]. bc is produced from bacteria secretion in a fermentation medium that acts as a nutrient source, and the most famous bacteria used in the fermentation process for producing bc is acetobacter xylinum instead of gluconobacter xylinum [2]. nowadays, many studies have been conducted to maintain the environment by reducing waste. agricultural waste has been used as carbon source for many applications. indonesia is a big product of pineapple till to 200,000 tons per year [4]. pineapple peels are types of substrates that can be utilized as a carbon source. thus, it is big opportunities to develop pineapple peel waste as a nitrogen and carbon source [3] to produce bc. therefore, this issn: 2580-0817 journal of mechanical engineering science and technology 35 vol. 6, no. 1, july 2022, pp. 34-39 muhajir et al. (effect of of homogenization pressure on bacterial cellulose membrane characteristic) study was conducted to apply pineapple peel waste extract as a medium source in bc production and for the waste's utilization. bc, as natural fibers, has biodegradable properties. it makes bc as one of the favorite materials for various applications. in its natural state, bc has very good properties with a purity of almost 100%. it is getting advantages for getting pure cellulose compared to plant cellulose for future development. the bc structure is constructed of a network of fibrils with a high surface area, making it porous. its hydrophilic property causes bc has a high water holding capacity. the high purity of bc implied a high crystallinity property causing high mechanical properties [1]. but, bc still has some limitations in the utilization of this biopolymer. so, a composites system was introduced to overcome the limitations of bc. by composting the bc, it can get advantages functions such as; photocatalyst, optical, antibacterial, anti-fungal, bio-regeneration, and conductivity properties [5]. in this case, nanoparticles are a way to make nanocomposites by dispersion methods and bc regeneration. a regeneration method is needed to disintegrate bc fibers into nano-size. high pressure homogenizer (hph) is a method to fibrillate bc into nanosized. hph promotes traditional non-thermal processes for emulsion stabilization and improves color uniformity, viscosity, taste, and texture in the food industry [6]. hph has been applied for the treatment of micro-fibrillated cellulose suspensions in cellulose [7][8], pulp, and bagasse [9]. it was reported that the hph process was applied in the isolation of cellulose nanofibers to reduce the diameter of the nanofibers from 117 to 67 nm through crushing force, shear stress, and cavitation [10][11] furthermore, ease of upgrading and continuous operation are benefit of the hph process. the problem of homogenizer clogging, which occurs cause of the higher fiber diameter, can be suppressed either by increasing the number of cycles or the pressure in the hph process. mechanisms of cavitation, friction, shear, turbulence, rapid pressure drop, velocity, compression, and heat initiate the hph process [12]. its process is free from organic solvent and has highly efficiency. repeatedly application of hph with pressure treatment can produce high cellulose nanofibers and high fibrillation rates [13][14]. hph leads to increased entanglements because of nanoformation in the networks structures [15]. hph processes on bc reduce dimensions from microscales to nanoscales [16]. microstructural information is needed in engineering bc film to find out the film structure relationship to mechanical properties and parameters in expansion, water release, and water absorption. this study purposed for analyzing the influence of the pressure in hph process on the characteristics of the bc membrane (bcm). ii. material and methods materials the bcm synthesis applied bacteria species of acetobacter xylinum (microbiology laboratory, um, malang, indonesia). the main medium for the fermentation process used an extract of pineapple peels. chemical reagents such as glucose (c6h12o6), distilled water (h2o), sodium hydroxide (naoh), ammonium sulfate (nh4)2so4, and acetic acid (ch3cooh) were used in technical grade [6]. synthesis of bc bc production was conducted according to previously published methods [17]. 5 kg pineapple peel waste was blended and then filtered to get the extract. 10 l of water was 36 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 34-39 muhajir et al. (effect of of homogenization pressure on bacterial cellulose membrane characteristic) added into a container and boiled on hot plate equipment. ammonium sulfate 0.5% (w/v) and sugar 10% (w/v) were added into suspension and adjusted the ph using acetic acid until about ph 4.5. the boiled medium was then cooled until room temperature. a.xylinum 10% (v/v) was added to the culture medium, and after 10 days pellicle was then floated on the medium and then harvested. pellicle boiled in a sodium hydroxide (naoh)1% at 90c for an hour, then rinsed with water until neutral. synthesis of bcm the cleaned pellicle was crushed using a high-speed blender. water as much as 750 ml was added into suspension of 250 ml, then suspensions were inputted into hph, then the homogenization process was conducted at a pressure of 0 bar, 150 bar, 300 bar, 450 bar, and 600 bar at 5 cycles. the bc solution from hph was cast into a mold and dried in an oven at 60°c for 8 hr. bcm was saved in a dry box. morphological observation observation of the surface morphology of bcm was conducted under sem, fei, inspect-s50. before observation, specimens were coated using a gold coater (sc7-620 emitech). structure analysis the structure of bcm includes the degree of crystallinity, and crystalline index was conducted using xrd (pananalytical, x-pert pro). cu-kα radiation is used at λ=1.54 å, at 30 ma and 40 kv. scanning was conducted in the 2θ range from 10° to 40°. the degree of crystallinity (%cr) and crystallinity index (cri) were calculated using segal’s equation. iii. results and discussions morphology analysis the morphology of bcm before and after hph treatment with various pressures (0 bar, 150 bar, 300 bar, 450 bar, and 600 bar) are shown in figure 1. the membrane shows a change in pore size to nanometers, and the cellulose fibers are clearly split and peel off into nano-sized particles with increasing pressure in the hph process. figure 1a, bcm with hph pressure of 0 bar shows the highest amount of porosity and the fibers are still not completely split. figure 1b of bcm with hph pressure of 150 bar shows that the fibers begin to split and peel to form particles to fill the pores between the random fiber structures of bc. figure 1c bcm treated with hph pressure of 300 bar showed reduced porosity compared to figures 1a and b. however, the bc fibers were still not fragmented and completely exfoliated. figures 1d and 1e, bcm with hph pressures of 450 and 600 bar show the least amount of porosity. even with increasing pressure treatment in hph processes, the bc fibers completely disintegrate into uniform particles. bcm structure analysis the form of diffractogram of hph treatment with cycle and pressure variations (150 bar, 300 bar, 450 bar, and 600 bar) is presented in figure 2. diffractograms of bcm before and after hph treatment using various pressures results in crystallinity degree, crystallinity index, 2θ angle, peak height, and crystal size are presented in table 1. issn: 2580-0817 journal of mechanical engineering science and technology 37 vol. 6, no. 1, july 2022, pp. 34-39 muhajir et al. (effect of of homogenization pressure on bacterial cellulose membrane characteristic) fig. 1. surface morphology of bc membrane: (a) hph 0 bar, (b) hph 150 bar, (c) hph 300 bar, (d) hph 450 bar, dan (e) hph 600 bar fig. 2. diffractogram of bcm produced by various hph pressure table 1 shows the 2θ angle (a1) is between 14.27°–14.33°. 2θ angle (b2) is between 16.45°–16.83°, 2θ angle (c3) is between 22.45°–22.45°. the lowest peak intensity value (a1) is 116.62, and the highest value is 244.82. the lowest peak intensity value (b2) is 76.76, and the highest value is 115.42. the lowest peak intensity value (c3) is 196.81, and the highest value is 439.41. the lowest crystallinity index value is 62%, and the highest value is 87%. 38 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 34-39 muhajir et al. (effect of of homogenization pressure on bacterial cellulose membrane characteristic) the value of the lowest degree of crystallinity is 72% and the highest value is 88%. the lowest crystal size value is 4.76 nm, and the highest value is 5 nm. table 1. parameter of bcm resulted from xrd analysis parameter high pressure homogenizer (hph) pressure (bar) 0 150 300 450 600 2θ degree a1 14.27 14.23 14.09 14.33 14.27 b2 16.45 16.47 16.35 16.83 16.49 c3 22.45 22.43 22.45 22.45 22.45 peak intensity a1 244.82 213.97 116.62 118.87 120.72 b2 115.42 107.83 76.76 76.83 90.46 c3 439.41 391.47 196.81 201.71 213.16 crystalline index (ci%) 87 84 62 70 70 degree of crystalline (% cr) 88 86 72 77 77 iv. conclusions the present study reports the influences of hph pressure on bcm properties. after different pressure of the hph process, bcm was prepared. after hph treatment with various pressure, the hph with higher pressure cause a reduction in the peak intensity, then the crystalline index decreases from 87% to 70%, and also degree of crystalline decreases from 88% to 77% without raising a new peak in diffractogram. in the future, the engineered bcm could be developed into many applications in fields of engineering such as membrane filter, membrane separator in battery, sensor, active paper, etc. acknowledgment a great appreciation was delivered to the drpm dikti for the grant of penelitian kompetitif nasional, fundamental research with contract no. 8.3.13/un32.14.1/lt/2021. references [1] k. qiu and a. n. netravali, “a review of fabrication and applications of bacterial cellulose based nanocomposites,” polym. rev., vol. 54, no. 4, pp. 598–626, oct. 2014, doi: 10.1080/15583724.2014.896018. [2] p. r. chawla, i. b. bajaj, s. a. survase, and r. s. singhal, “microbial cellulose: fermentative production and applications,” p. 18, 2009. [3] a. retegi, n. gabilondo, c. peña, r. zuluaga, c. castro, p. gañan, k. de la caba, and i. mondragon, “bacterial cellulose films with controlled microstructuremechanical property relationships,” cellulose, vol. 17, no. 3, pp. 661–669, 2010, doi: 10.1007/s10570-009-9389-7. [4] katadata, “nanas jadi komoditas buah unggulan dengan volume ekspor tertinggi | databoks,” 2020. https://databoks.katadata.co.id/datapublish/2021/03/12/nanasjadi-komoditas-buah-unggulan-dengan-volume-ekspor-tertinggi (accessed nov. 12, 2021). [5] n. shah, m. ul-islam, w. ahmad, and j. kon, “overview of bacterial cellulose issn: 2580-0817 journal of mechanical engineering science and technology 39 vol. 6, no. 1, july 2022, pp. 34-39 muhajir et al. (effect of of homogenization pressure on bacterial cellulose membrane characteristic) composites : a multipurpose advanced material,” carbohydr. polym., vol. 98, no. 2, pp. 1585–1598, 2013, doi: 10.1016/j.carbpol.2013.08.018. [6] m. le troedec, d. sedan, c. peyratout, j. p. bonnet, a. smith, r. guinebretiere, v. gloaguen, p. krausz, “influence of various chemical treatments on the composition and structure of hemp fibres,” compos. part a appl. sci. manuf., vol. 39, no. 3, pp. 514–522, mar. 2008, doi: 10.1016/j.compositesa.2007.12.001. [7] l. y. mwaikambo, “tensile properties of alkalised jute fibres,” bioresources, vol. 4, no. 2, pp. 566–588, 2009, doi: 10.15376/biores.4.2.566-588. [8] n. reddy and y. yang, “preparation and characterization of long natural cellulose fibers from wheat straw,” j. agric. food chem., vol. 55, no. 21, pp. 8570–8575, oct. 2007, doi: 10.1021/jf071470g. 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[15] s. ang, v. haritos, and w. batchelor, “effect of refining and homogenization on nanocellulose fiber development, sheet strength and energy consumption,” cellulose, vol. 26, no. 8, pp. 4767–4786, 2019, doi: 10.1007/s10570-019-02400-5. [16] n. kawee, n. t. lam, and p. sukyai, “homogenous isolation of individualized bacterial nanofibrillated cellulose by high-pressure homogenization,” carbohydr. polym., vol. 179, pp. 394–401, jan. 2018, doi: 10.1016/j.carbpol.2017.09.101. [17] h. suryanto, t. a. sutrisno, m. muhajir, n. zakia, and u. yanuhar, “effect of peroxide treatment on the structure and transparency of bacterial cellulose film,” in matec web of conferences, 2018, vol. 204, doi: 10.1051/matecconf/201820405015. journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 110-122 110 doi: 10.17977/um016v5i22021p110 wear property of machined ultra high molecular weight polyethylene (uhmwpe) acetabular liner product with cnc milling w d lestari1*, a t danaryanto2, a nugroho3, r ismail2, j jamari2, a p bayuseno2 1department of mechanical engineering, faculty of engineering, university of pembangunan nasional “veteran” jawa timur, jl. raya rungkut madya, gunung anyar, surabaya, 60294, indonesia 2department of mechanical engineering, faculty of engineering, diponegoro university, jl. prof. soedarto, tembalang, semarang, 50275, indonesia 3putp (pusat unggulan teknologi plastik) politeknik atmi, jl. mojo no.1, karangasem, laweyan, surakarta, 57102, indonesia *corresponding author:wahyu.dwi.tm@upnjatim.ac.id abstract uhmwpe has been used as a cushion in artificial hip joint for the last decades. the reliability of the components of a hip joint implant can be achieved by understanding their wear behavior. this study observed the tribological performance of the uhmwpe acetabular liner manufactured with a cnc milling machine on the femoral head made of ss 316l. materials commonly used for tribo pairs in hip joint replacement. the wear tests were performed on a hip joint simulator in dry condition. the wear test is carried out by applying a constant load of 800n. before and after the wear test, measurements of surface roughness and dimensional accuracy were carried out on the uhmwpe acetabular liner specimen. the correlation between the surface roughness of the machining process and the wear rate is seen from the value of the wear depth and the wear coefficient obtained. the results showed that the machining process affects the surface roughness of the acetabular liner, where the roughness also affects the wear rate of acetabular liner product. copyright © 2021. journal of mechanical engineering science and technology keywords: acetabular liner, milling, surface roughness, uhmwpe, wear i. introduction one of the vital parts of the human body is the hips [1]. the hip joint has an important role in the human body such as performing daily activities (walking, going downstairs, running, exercising, salat for muslim, etc.) because of its ability to transmit static and dynamic loads. some of the problems that are often experienced by the hip joint include osteoarthritis, joint fractures, damage to the components of the femoral head and acetabular cup, and reduced synovial fluid in the joints. this makes the delivery painful, and an artificial hip implant is needed. the process of removing the diseased hip joint with an artificial hip joint that is similar in shape and function to the natural hip joint which is made of biocompatible materials, is known as total hip replacement (thr). many pairs of materials have been used for artificial hip joints. one of the most successful and widely used material pairs is uhmwpe against metal [2]. uhmwpe is the superior material used for today’s artificial hip joint components [3]. as for metal components commonly used for biomedical applications is stainless steel 316 l due to its strength, thermal stability, high specific moduli and most importantly good wear resistance [4]. 111 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) despite its excellent properties, uhmwpe as a cushioning material in artificial joints has significant tribological problems. these problems include the appearance of wear debris of small size, which causes an adverse reaction in the surrounding tissue, resulting in aseptic loosening of the prosthesis components [5]. because of this, uhmwpe materials have a limited lifespan of 15-20 years [6]. the wear behavior of hip implant materials depends on the condition of the surface, which can be obtained through the manufacturing process. several scientific papers report on the effect of the manufacturing process on the characteristics of the resulting surface, which will certainly have an impact on the performance of the implant. the application of multiple passes and cryogenic cooling to achieve high surface quality can improve wear performance [7], and also, there are correlation between surface integrity, surface topography, and material response [8]. furthermore, the effect of surface roughness on the wear rate was also studied on the cocrmo femoral head [9], mom pairs material [10], and due to manufacturing process [11]. the wear of implant products is appreciated by the fact that the appearance of a large amount of wear has an adverse effect that can impact the life of the implant [12]. this wear rate can be reduced, and its life can be significantly extended by improving the quality of the bearing material [13-14]. based on these reasons, research analysis and testing is an important part in the design and development of the hip joint to improve function and quality before the implantation process. wear tests on hip prosthetics are usually performed on a steady motion walking cycle obtained from the biomechanical literature [15-16]. the hip simulator is an experimentally proven tool for basic investigations and preclinical testing to minimize patient harm when receiving a new type of implant. hip joint simulator conducted to observe the changes in surface topography at the research stage of ball and socket friction pair [17], the wear performance of a non-cross linked uhmwpe pair versus two metal counterfaces, namely stainless steel (ss) and cobaltchromium (cocr) alloys, ceramic on ceramic [18], and cross linked ultra-high molecular weight polyethylene liners [19] on a variety of daily activities [16]. however, from some of the available literature, no one has paid attention to the influence of the uhmwpe acetabular liner machining process using a milling machine on the wear rate. therefore, the purpose of this study was to observe the effect of the acetabular liner machining process for uhmwpe hip joints on wear behavior. the machining process is carried out using a cnc milling machine in dry conditions. a hip joint simulator was used to evaluate the wear rate of the uhmwpe acetabular liner from the machining process. wear resistance tested for 30.000 cycles under walking cycle conditions. wear quantity is calculated based on weight loss. ii. material and methods a. specimens preparation the hip joint was consists of a ball and socket located between the acetabulum and the femur in the pelvis [20]. in this study, the acetabular liner component is derived from uhmwpe rod-shaped material which is manufactured using a cnc milling machine in dry conditions (figure 1). the cnc milling machine used is ycm 1020 ev 20 with 3 axes. in this research, 9 samples of acetabular liner were produced with cnc milling machine cutting parameters such as feed rate, toolpath strategy, step over, and spindle speed [21]. the size of the uhmwpe acetabular liner formed is with an inner diameter of 28.2 mm. the result of this acetabular liner milling process must have a surface roughness below 2 μm and issn: 2580-0817 journal of mechanical engineering science and technology 112 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) dimensional tolerance in the range of +0.3 and -0.0 according to astm f2033-12. furthermore, optimization was carried out on 9 samples of acetabular liner from the results of the manufacturing process to get 3 samples with the best roughness value. the 3 samples (figure 2) of the acetabular liner from the optimization results were then tested for wear. based on the measurement results, the size range of the acetabular liner specimen is obtained, namely the outer radius of 18.5 mm and the inner radius of 14.1 mm, where the three samples are still within the dimensional tolerance. the femoral head component is made of ss 316 l material with a diameter of 28 mm. fig. 1. experimental set up for the milling of uhmwpe acetabular liner fig. 2. acetabular liner uhmwpe acetabular liner products resulting from the machining process are measured for surface roughness before wear testing is carried out. the process of measuring surface roughness was carried out using the mark surf ps1 surface roughness tester. the surface roughness measurement is carried out again after going through the wear test process, where the results can be seen in table 1. table 1. the value of roughness of the inner acetabular liner before and after the test acetabular liner surface roughness before after specimen 1 0.926 0.7756 specimen 2 1.161 0.7182 specimen 3 0.848 0.6786 113 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) the surface roughness values obtained from this study are in accordance with previous studies [22], which stated that the initial surface roughness of the polymer ranged from 0.4 μm 2.2 µm, but generally has a surface roughness level of about 1 µm 2 µm. in another study showed that the maximum initial surface roughness level of uhmwpe was 2µm before the wear test was carried out [23-24]. b. wear test using hip joint simulator the prototype joint generated from the manufacturing process is then carried out preclinical testing using a simulator that is able to imitate motion behavior, biomechanics, and environmental conditions in the human body [24]. tribological measurements in this study were carried out using a specially modified tribometer in the chamber to test the wear of the acetabular liner. the working principle of this tribometer machine is similar to the human hip joint, where there is a femoral head which is a parable of a human femur and a cup as a human pelvis. the maximum load that this testing machine can accept is 3000n. according to hua et al. [25], the resultant force of the hip joint is 2500n, which is equivalent to 3-4 times the human body weight of 70 kg. the test design applied in this study is to provide as much insight as possible about the physical loading and motion that occurs between the femoral head and the acetabular liner upon contact. fig. 3. flowchart of the testing procedure of the uhmwpe acetabular liner using a tribometer issn: 2580-0817 journal of mechanical engineering science and technology 114 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) the testing parameters in this study are based on the iso 14242 standard and previous research [26]. this study focuses on the effect of the uhmwpe acetabular liner machining process with cnc milling machine on the wear rate. the amount of force on the acetabular liner is determined by the weight of the human body. in this study, the amount of force applied is 800n which is based on the assumption of the patient's average weight [26]. the number of cycles applied in this test is 30000 cycles. the uhmwpe acetabular liner is attached to the ss 316l femoral head and encapsulated in the specimen chambers. the pair of specimens were sterilized first using 70% alcohol before being installed on the test machine. the wear testing process is carried out in dry conditions and at a temperature of 200c. gravimetric wear was obtained from the test results based on mass transformation. the entire experimental process in this study is shown in the flow chart in figure 3. c. dimensional accuracy measurement in addition to surface roughness, this study also measures the dimensional accuracy of the acetabular liner product. this measurement is carried out to ensure whether the resulting product conforms to the specified dimensional tolerance or not. dimensional accuracy measurement using a coordinate measuring machine (cmm). measurements are also carried out before and after the wear test process. iii. results and discussion the results of this study will be used as a reference to improve the hip implant prototype. the resulting data in the form of the number of cycles and the depth of wear will be made into a graph of the relationship between the cycles and the depth of wear of the three test specimens. changes in the volume of the acetabular liner were obtained by weighing. changes in the initial and final weight data of the acetabular liner are shown in table 2. changes in the weight of the three samples prove that there is wear caused by the testing process in the walking cycle. based on the weight change data contained in table 2, it can be seen that test sample 2 has the largest weight change among the three samples. furthermore, the data changes in the three samples are compared into a single graph to determine the difference in the depth level of each specimen (figure 4). the wear rate is determined by linear regression of the wear (mm) with the number of cycles. the wear depth (mm) of the uhmwpe acetabular liner is recorded as a function of the cycle length with a force of 800n. table 2. the initial and final weight of the acetabular liner specimens initial weight (g) final weight (g) weight change (g) specimen 1 6.8274 6.8260 0.0014 specimen 2 6.3646 6.3350 0.0296 specimen 3 6.1734 6.1720 0.0014 115 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) fig. 4. comparison of test results of 1,2,3 specimen with 800 n force based on figure 5, it can be seen that the test results of the three specimens showed almost the same trend. the lowest wear depth is owned by specimen 3, where the largest wear depth is owned by specimen 1. there is a difference in the wear depth on the test results of specimen 1 from cycle 0 to cycle 3000 compared to specimen 2 and specimen 3. furthermore, the trend of the three objects shows the same trend after cycle 3000 to cycle 30000. the test results in this study indicate that there are different wear values of each acetabular liner specimen, where this is influenced by the presence of different roughness as well. based on the graph, the value of the depth of wear for each specimen is obtained through 30000 cycles of wear testing. each specimen has a wear depth of 0.52 mm, 0.471 mm, and 0.454 mm from specimen 1, specimen 2, and specimen 3, respectively. an understanding of wear behavior is an urgent part of obtaining preclinical data on the prosthesis prior to implantation. in this regard, in this study, we conducted a wear test on a laboratory scale to determine the wear behavior of the acetabular liner from the machining process as a bearing on an artificial hip joint. wear measurement is especially needed to measure new designs and materials because of the continuous need to manufacture new joints. one solution to get the right component prosthesis design is to take geometry measurements before, during, and after wear testing. for this purpose, this study uses a coordinate measuring machine (cmm) to measure the dimensional accuracy of the acetabular liner specimen before and after the wear test. the results of dimensional accuracy measurements on the three acetabular liner specimens are presented in table 3. table 3. the value of dimension accuracy of the inner acetabular liner before and after testing acetabular liner accuracy dimensions before after specimen 1 14.439 mm 14.331 mm specimen 2 14.470 mm 14.134 mm specimen 3 14.354 mm 14.228 mm issn: 2580-0817 journal of mechanical engineering science and technology 116 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) uddin et al.[27], in their research, measured the wear of polyethylene acetabular liner with cmm where the average linear and volumetric wear rates were 0.12 mm/year and 37.18 mm3/year, respectively. previous studies [28] also reported acetabular linear and volumetric wear rates with xlpe materials of 0.024 mm/year and 4.5 mm3/year, respectively. in this study, specimen 2 had the biggest difference between before and after the test, which was 0.336 mm during the testing of 30000 cycles. furthermore, specimens 1 and specimens 3 had differences in accuracy dimensions of 0.108 mm and 0.126 mm, respectively. this result is bigger when compared to previous studies. validation is needed before carrying out the wear testing process using a tribometer machine to find out whether the tool used is valid enough to take data. the validation method is to calculate the wear coefficient value generated from the test using the archad equation with the femoral head radius of 14 mm and the acetabular liner radius of 14.1 mm. the load used is equal to 800 n with 30000 cycles. the value of the wear coefficient produced in this test is equal to 1.945 x 10-4 mm3 n-1 m-1. this value is then compared with the results of research conducted by dowson [29] by entering the research parameters in the formula. dowson et al. [29] conducted a wear test and obtained two wear coefficient values, namely 1.35x10-7 mm3 / nm and 4.49x10-7 mm3 n-1 m-1. the results of the validation can be seen in figure 5 as for the wear depth formula [29], namely: 𝑝 = 0.001186 𝜋 ( 𝑘𝐵𝑁 𝑅1 ) [1 + √1 + 1686𝜋 𝑅1(𝑅2−𝑅1) 𝑘𝐵𝑁 ] (1) where p is penetration or wear depth (mm), k is wear coefficient (mm3 n-1 m-1), b is body weight (n), n is number of cycles (cycles), r1 is femoral head radius (mm), and r2 is acetabular liner radius (mm). the results show that there are differences in the test results where the wear value obtained is higher than that produced by dowson when the cycle runs more than 4,500 cycles, but the trend is almost the same. thus, it can be concluded that the tools used are valid enough to be used in conducting research. fig. 5. validation of test with dowson model 117 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) the level of wear on biomedical components such as acetabular liners with variations in specifications and materials can be predicted through in vitro tests. the hip simulator test is the most commonly used tool by researchers to test the wear level of the acetabular liner with various parameter tests. in this study, the tribological behavior of the uhmwpe acetabular liner from the results of the cnc milling process with the femoral head pair was observed using a hip simulator based on the walking cycle. the difference in the wear rate of each specimen is caused by the difference in the surface roughness values obtained from the machining process [30]. this study took three samples of uhmwpe acetabular liner with the best roughness value based on the optimization results of nine samples made. the calculation results of the wear coefficient with the difference in the surface roughness values are shown in figure 6, where the values of the wear volume and the level of penetration are presented in table 4. table 4. summary of uhmwpe wear behaviour in the simulator test condition. sample wear volume (mm3) penetration rate (mm/year) wear coefficient (mm3n-1m-1) specimen 1 102.98 0.33 2.78 x 10-4 specimen 2 79.54 0.289 2.2 x 10-4 specimen 3 75.46 0.279 1.95 x 10-4 fig. 6. graph of wear coefficient calculations based on the graph in figure 6, it can be seen that the highest wear coefficient value is found in specimen 1 of 2.78 x 10-4 mm3 n-1 m-1. they were then followed by specimens 2 and 3 with values of 2.2 x 10-4 mm3 n-1 m-1 and 1.95 x 10-4 mm3 n-1 m-1, respectively. if observed, these results are related to the value of surface roughness. in accordance with previous studies [31], where the wear coefficient value produced is different in the contact test between uhmwpe which has an initial roughness value range of 1-2 µm with highdensity alumina ceramic in dry conditions and lubricated with distilled water. after the wear test process, the surface roughness of the uhmwpe acetabular liner became smoother and issn: 2580-0817 journal of mechanical engineering science and technology 118 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. (wear property of machined uhmwpe acetabular liner product with cnc milling) the value decreased from the initial surface roughness value (table 2). this is as a result of the contact surface. this is also supported by previous research where the surface roughness value of uhmwpe was reduced from the initial value after going through a wear test process with a hip joint simulator for 5 million cycles [23-24]. furthermore, the average surface roughness of uhmwpe acetabular liner decreased, ranging from 0.053 µm and 0.25 µm from the initial average surface roughness of 0.95 µm [32-33]. the observations results on the surface of the acetabular liner sample after testing 30,000 cycles indicate the presence of wear areas such as polish due to continuous loading. the surface of the acetabular liner may be scratched due to the appearance of a third body particle trapped between the polymer and metal surfaces.the scratch occurs because the counterface metallic is forced to move against the surface of the acetabular liner polymer and also a third body abrasion characterized by random directional scratches on the acetabular liner [23-24]. in this study, the wear mechanism that occurs is the third body abrasion with the test results in the form of wear depth and wear coefficient. the amount of wear in vivo generally ranges from 50-100 mg per year [33]. in various simulators, it is found that the wear value of polyethylene is in the range of 20-35 mg per 1 million cycles [34]. the total wear of the uhmwpe acetabular liner was 6378 mg for the acetabular liner with gamma irradiation and 7672 mg for the acetabular liner with eto sterilization after going through five million cycles of testing [35-36].with a linear wear rate of 0.16 mm/year, uhmwpe wear around 48 mg/106 cycles [23-24]. furthermore, uhmwpe wear about 31.73 mg/million cycles and 15.20 mg/million cycles at 784 n and 392 n loadings, respectively [36]. an annual wear rate similar to the annual wear rate obtained from the observed popular mop hip reconstruction, which was 25 mg per million cycles [37-38]. in this study, the lowest weight obtained after going through the wear testing process was 0.0014 g (1.4 mg/30000 cycles). the data obtained from this study cannot be compared directly with the results of wear experiments from the literature using a hip endoprosthesis simulator because the mechanism used is still simple on a laboratory scale [36]. the focus of this research is to examine the effect of the uhmwpe acetabular liner manufacturing process with cnc milling on surface roughness, where this roughness will affect the wear level of product for artificial hip joints. however, if plotted on a graph and calculated based on a linear equation of 1 million cycles, the wear rate of uhmwpe manufactured using a cnc milling machine is still in accordance with the in vivo wear rate provisions in the literature [38]. the wear tests performed in this study are in accordance with the literature, which describes the material wear of a commonly applied hip implant component under appropriate loading. based on the test data and observations on the sample, it can be obtained that the surface roughness of the acetabular liner resulting from the milling process affects the depth and coefficient of wear. iv. conclusions this study explores the influence of the uhmwpe acetabular liner manufacturing process with a cnc milling machine on the level of wear. based on the results of the study, the conclusions obtained that the results of the wear coefficient calculation of the uhmwpe acetabular liner specimen indicate that the greater the surface roughness value of the acetabular liner, the greater the wear coefficient value, where the highest wear coefficient value is owned by specimen 1 of 2.57 x 10-4 mm3/nm. the rate of wear depth and the wear coefficient of the uhmwpe acetabular liner produced in this study is influenced by the surface roughness value of the machining process with cnc milling. 119 journal of mechanical engineering science and technology issn 2580-0817 vol. 5, no. 2, november 2021, pp. 110-122 lestari et al. 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[38] j. m. kabo, j. s. gebhard, g. loren, h.c. amstutz, “in vivo wear of polyethylene acetabular components,” the journal of bone and joint surgery, vol. 75-b (2), pp. 254–258, 1993. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 95-106 95 doi: 10.17977/um016v6i22022p095 true stress-strain behavior of al-based cast automotive alloy under different ageing conditions and the effect of trace zr mashiur rahman shoummo1, akib abdullah khan1, mohammad salim kaiser2* 1department of mechanical engineering, bangladesh university of engineering and technology, dhaka-1000, bangladesh 2directorate of advisory, extension and research services, bangladesh university of engineering and technology, dhaka-1000, bangladesh *corresponding author:mskaiser@iat.buet.ac.bd article history: received: 27 july 2022 / received in revised form: 13 september 2022 / accepted: 14 october 2022 abstract a thorough investigation has been carried out on the al-12si-1mg-1cu-1ni automotive alloy considering different properties, specially mechanical properties associated with true stress and true strain with zr addition of trace amount. a commercially available piston is melted to produce the alloy, and trace amount of zr is added to make another. the base alloy along with the zr added alloy had been applied to homogenization, solution treatment, quenching, and ageing in order to get the age-hardening response. the alloys have been heat-treated at 25 ºc, 200 ºc, and 300 ºc, respectively, for four hours for attaining the under, peak and over-aged states, respectively. during ageing, al2cu and mg2si phases are formed in the aluminium matrix leading to peak-aged strength, which is reduced at over-aged state because of coarsening of precipitation and recrystallizing, shown by the tensile and hardness properties. when zr is added to the alloy, al3zr phases appear while casting and heat-treatment, resisting the drop of strength at over-aged state. it is visible in the stress-strain diagram that at over-aged conditions, the alloy with trace zr shows improved strength and ductility. in the micrographs of zr added alloy, finer distributed grains are visible through the grain refinement of zr, which also prevents recrystallization at over-aged conditions. the homogeneity of the grains as a result of the zr addition's microstructural change was further confirmed by fractography. it is clear that adding zr to such alloys does not greatly increase their strength, but it does restrict the declining of strength by preventing the production of thermally stable al3zr precipitates, which coarsens the resisting behavior of various intermetallics in the thermally damaged alloy. copyright © 2022. journal of mechanical engineering science and technology. keywords: cast al-alloy, fractured surface, grain refinement, heat-treatment, zirconium. i. introduction castability, weldability, machinability, wear resistance, and corrosion resistance are among the mechanical qualities of the 4xxx series aluminum alloys, which have been widely employed in vehicle parts [1]-[3]. the amount of alloying element si is used depending on the needs of the structure as it will be light or heavy duty. the range of si level is generally considered to be 5 to 23 wt%. the cast alloys of lower si content consist of primary α-al and al–si eutectic mixture. however, increasing si percentages exhibit a coarse microstructure that leads to poor mechanical properties. beyond the eutectic composition 12.6% wt. primary si particles begin to develop the massive phase of star-shape block morphology which direct to further degradation in mechanical properties [4], [5]. in most cases, 12-13 wt.% si is well thought out to get better performance considering all the features. heat treatment is not possible with these alloys. magnesium and copper are used 96 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) to give the product age-hardening properties [6], [7]. these alloys are used to make automotive components because of their excellent mechanical properties. aluminium's best qualities are obtained through alloying additives and subsequent heat treatment operations [8], [9]. major and minor elements, microstructure modifiers, and impurities are the four categories of alloying elements. in some alloys, the impurity elements may be majors, while in others, they may be minors [10]-[12]. major elements like as si, cu, and mg are commonly used. minor elements ni and sn are also considered. ti, zr, sc, b, sr, be, mn, cr are considered microstructure modifiers, while fe and zn are considered impurity elements. they alter the microstructures and mechanical characteristics of aluminum alloys. when zr is added to aluminum alloys, it creates the al3zr phase, which is much finer and more coherent with the matrix. it's a great way to make the dispersoid stronger. this type of dispersoid can reduce recrystallization, refine the microstructure, and raise the recrystallization temperature and strength of matrix alloys [13], [14]. there are just a few researches on the impact of zirconium on cast al-si alloys. it is well known that the mechanical properties of such age hardenable alloys provide the most benefit while they are at their peak age and that the strength of the qualities decreases as the hardening temperature rises. the goal of this research is to look at the impact of trace zr on the mechanical properties of an al-si automotive alloy, as well as the influence of ageing. ii. material and methods a. preparation of the alloys the master alloy was made by melting aluminum pistons in a clay-graphite crucible. in a resistance-heating furnace with a proper flux cover, the melting process took place. the al-12si-1mg-1cu-1ni base alloy and the al-12si-1mg-1cu-1ni alloy with trace zirconium were then developed from two samples. within an aluminium foil cover, 99.98% pure zr powder was taken and then immersed into the master alloy during melting. table 1 shows the chemical composition, which were determined using spectrochemical techniques. table 1. chemical composition of both the alloys by wt.% si mg cu ni fe zr al alloy 1 12.280 0.919 1.120 1.306 0.521 0.001 bal. alloy 2 12.410 0.938 1.130 1.328 0.554 0.024 bal. b. preparation of the test specimen the temperature of the base alloy melt was always been kept at 750°c, with a 2% temperature variation tolerance. the cast iron metal mould, which measures 16 x 150 x 300 millimetres, was preheated to 200°c. following the casting process, the cast alloy was homogenized in a muffle furnace at 400°c for 18 hours. following that, it was air cooled to ease internal stresses. the homogenized alloys were then solutionized for 120 minutes at 530°c to generate a supersaturated single phase zone, which was then quenched with saltice-water. the solutionized alloys were aged for 240 minutes at temperatures of 25°c, 200°c, and 300°c. normally, ageing was perfected at 200°c, but samples were aged at the other two temperatures to account for the under-aged and over-aged scenarios [15]. issn: 2580-0817 journal of mechanical engineering science and technology 97 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) c. working instruments and test data collection methods tensile test tensile testing was conducted out at room temperature. the test was carried out on an instron testing machine, with a fixed cross head designed to maintain a constant strain rate of 10-3s-1. the samples have been set up to perform the tests in accordance with astm specifications. the gauge length of the samples was 25 mm. five tests were undertaken at each condition and the closest value of the average of the results is used to build the true stress-strain curve. hardness test the automatic turret micro vickers hardness tester, model hv-1000dt, was used to measure the micro hardness of the aged samples. for the knoop hardness test, a 1 kg load was given to the indenter for 10 seconds. the sample size of 5x 16x 16 mm was considered for this microhardness measurement. on each polished surface created by the fine grade emery paper of the aged hardened samples, a minimum of 10 indentations are made at varied locations. impact test the heat-treatedspecimens utilized were standard 10 x 10 x 55 mm specimens with a 2 mm deep v-shaped notch at a 45° angle. the impact testing was carried out in accordance with astm guidelines. the impact resistance of five test pieces was evaluated for each test. microstructural study heat-treated alloy specimens were subjected to optical metallographic inspections following the tensile test. the specimens were etched with keller's reagent after being polished with alumina. a versamet-ii microscope is then used to analyze the samples. a jeol jsm-5200 scanning electron microscope was used to investigate the microstructure and fractography of fractured surfaces induced by tensile testing. iii. results and discussions a. interpretation of tensile tests the true stress and true strain findings obtained from the tensile test at under-aged, peak-aged, and over-aged conditions are depicted in figures 1, 2, and 3. the slopes of the graph of alloy 1 decrease from the under-aged to the peak aged condition, as can be shown. the dislocation theory can explain this rise in strength. a precipitated particle acts as a barrier to dislocation motion. as a result of the obstruction, dislocation motion is slowed, and the slope lowers, with a corresponding increase in tensile strength. it is well recognized that at the peak aged condition this type of alloys attain the maximum amount of fine dispersoids precipitates as it strengthens the alloys. significant differences in the slope of alloy 2 cannot be seen in the under-aged condition, however due to grain refinement, morphological changes have occurred, resulting in a decrease in brittleness in the peak aged condition [16], [17]. stress reliving of the cast alloys due to ageing also responsible for higher elongation. at the under-aged condition that is solutionizing state the maximum concentration of the elements remains in solid solution, so in this condition the alloys do not offer the additional strength. 98 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) the slope of the stress-strain curve of the alloys rises as it reached at over-aged circumstances. it is due to precipitation coarsening phenomenon into the alloys. the coarsening precipitate loses its inhibitory property to hinder dislocation migration as it becomes coarsen. the trace zr alloy 2, on the other hand, forms al3zr trialuminide particles that are extremely resistant to coarsening and re-dissolution, cause a more uniform distribution of dislocations and pin grain boundaries even after peak aging, and undergo morphological changes that result in silicon precipitate modification. when compared to the base alloy, alloy 1, the strength improves [18]. fig. 1. true stress-true strain curves of the experimental alloys at under-aged condition. fig. 2. true stress-true strain curves of the experimental alloys at peak-aged condition. issn: 2580-0817 journal of mechanical engineering science and technology 99 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) fig. 3. true stress-true strain curves of the experimental alloys at over-aged condition for better understanding the yield strength of both the alloys at under aged, peak aged and overaged condition is exposed the following bar chart in figure 4. at under aged condition the yield strength is lower becase of alloying elements remain in solid solution. in this stage there is no additional benefit of zr more over the yield strengthcompactdue to morphological change of brittle si particles. at the peak aged condition, the yield strength improved due formation of different intermetallics as stated earlier but zr added alloy shows healthier strength only for grain refining effects. the major benefit in terms of lower damagesof strength is displayed at over aged condition where zr inhibit the precipitation coarsening and dislocation movement of the alloy [19]. fig. 4. yield strength deviation of the experimental alloys at under aged, peak aged and over aged condition 100 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) b. interpretation of micro-hardness test similar patterns can be seen in the histogram provided in figure 5 based on the findings of the micro-hardness test of the samples. the hardness of both alloys increases as the peak aged condition, however the rate of decline of hardness from peak aged to over-aged condition for alloy 1 is greater than that of alloy 2. the precipitation of both al2cu and /or al2cumg and mg2si phases can explain this result. the presence of these intermetallic phases adds to a significant increase in matrix strength. the hardness drop in alloy 1 is due to precipitation coarsening, as stated earlier in the over-aged condition. the al3zr intermetallic, on the other hand, minimizes the softening effect of alloy 2 under over-aged conditions [15], [19]. at the under aged condition the precipitates are not created into the alloys so lower the hardness values and the minimum difference of harness between the alloys. fig. 5. micro hardness variation of the experimental alloys at under aged, peak aged and over aged condition c. interpretation of impact test figure 6 depicts the impact toughness parameters of the experimental alloys at three different aged condition namely under-aged, peak-aged, and over-aged. it has been noticed that as precipitates get older, their impact energy declines. at the peak aged condition those are indication. the precipitation of both al2cu and mg2si phases resulted in a significant increase in matrix strength at the expense of ductility, resulting in this detection. due to the reduced volume proportion of precipitates, the variation in impact strength of under-aged alloys is quite minor. the impact energy increases considerably from the peak-aged to overaged condition due to precipitation and microstructural coarsening of the alloys. the figure also shows how trace added alloy as a microstructural alteration by zr addition has a favorable impact on impact energy [19], [20]. it can be said in other words that the addition of zr obviously reduced the si particle size and changed its morphology resulting in reduced brittleness. issn: 2580-0817 journal of mechanical engineering science and technology 101 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) fig. 6. fracture toughness variation of the experimental alloys at under aged, peak aged and over aged condition d. interpretation of the microstructural study figure 7 shows the optical microstructure of base alloy 1 and trace zr added alloy 2 at under aged, peak aged and over-aged conditions. aluminumα-phase, eutectic silicon, and intermetallic compound particles make up the microstructures of these alloys. the microstructure of trace zr added alloy 2 reveals a finer grain than that of base alloy 1 at solution treated state that is considered as under aged conditionsof the alloys (figure 7a and 7b). zr refines the grain structure of all the al-alloys through the formation of al3zr particles, at the same time acts as nuclei during solidification as previously indicated [13]. there is also evidence of different intermetallics uniformly distributed within the microstructure. when the alloys are aged at 200°c for 240 minutes to achieve the peak aged condition, there are different types of fine precipitates are form within the matrix. the common precipitates are produced during ageing of this type of al-12si-1mg-1cu-1ni alloy such as al2cu, mg2si, al5fesi, al8mg3fes, al3cuni, al3ni etc. but all the precipitates do not take part for strengthening of the alloys. however, this type of optical microstructure cannot reveal the precipitates, whereas trace-added alloy reveals a grain structure that is quite thin (figure7c and 7d). both the alloys show relatively clear space of α-matrix becase most of the elements take part to form the precipitates. when the alloys are aged at 300°c for 240 minutes, that is the over aged condition the microstructure of the base alloy 1 entirely recrystallized, revealing the equiaxed grains, but the microstructure of the trace added alloy 2 partially recrystallized, revealing the grain (figure7e and 7f). it is already stated earlier that during solification and ageing zr form the numerous nanosized al3zr precipitates which is fully coherent with the matrix. the precipitates create an effective barrier of dislocation motion and hinder the precipitation coarsening of the alloys. as a result, it can able to prevent the alloy from the process of recrystallization [21]-[23]. 102 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) fig. 7. optical microstructure of solution treated al–12si–1mg-1cu automotive aged at 25°c for 240 minutes (under aged) (a) alloy 1, (b) alloy 2, aged at 200°c for 240 minutes (peak aged) (c) alloy 1, (d) alloy 2, aged at 300°c for 240 minutes (over aged) (e) alloy 1 and (f) alloy 2 a sem images is used to confirm the findings as displayed in figure 8. both the alloys aged at 200°c for 240 minutes in peak aged condition, the effect of recrystallization is not very noticeable. due to solution treatment and ageing the elements along with the intermetallic into the microstructure is well distributed. it is also visible that the silicon particles included plate like and niddle like morphology of different dimension relatively largein the base alloy 1. in disparity, the particles turn into smallerwhen trace zr is 25m (a) (c) (b) (d) (e) (f) si intermetallics intermetallics si intermetallics si intermetallics si intermetallics grain intermetallics equiaxed grain issn: 2580-0817 journal of mechanical engineering science and technology 103 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) supplementary to the alloy 2. the low solubility along with the diffusivity properties of zr creates the coherent particles which are more stable as a result refinementof siparticlein the al matrix [23], [24]. fig. 8. sem microstructure of al–si automotive alloy aged at 200°c for 240 minutes (a) alloy 1 and (b) trace zr added alloy furthermore, once the alloys were fractured at the peak aged condition, sem was performed as shown in figure 9. mode of brittle fracture clearly appears on the fracture surfaces of the base alloy 1. the surface also consists of few dimples along with a feature of quasi-cleavage. with the addition of trace zr the fracture surface of alloy 2 displays the higher amount of the dimples. it also indicates the mixed mode of both ductility and brittle fractures. it is noticeable that the improvement of mechanical properties occurred through the grain refinement and eutectic si modification. as a result, when zr is added to an alloy, it improves its ductility [25]-[26]. fig. 9. sem fractograph of al–si automotive alloy (a) alloy 1 and (b) alloy 2 aged at 200°c for 240 minutes and tensile tested at strain rate of 10-3s-1 20m 20m 100m 100m (a) (b) (b) (a) mixed fracture brittle fracture si si 104 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, november 2022, pp. 95-106 shoummo et al. (true stress-strain behavior of al-based cast automotive alloy) iv. conclusion after all the experimental interpretation it can be concluded that addition of zr does not significantly improve the tensile strength of al-si automotive alloy, but it slows down the rate of reduction in strength. the strength of the alloy decreases significantly in over aged condition due to coarsening of different intermetallic in order to reach in an equilibrium state. in contrast, the inclusion of trace zirconium holds the tensile strength at higher ageing temperatures due to the development of al3zr precipitates, which build up the coarsening resistance and thermal stability of the alloy. along with tensile strength the hardness also increases in the over aged condition due to the addition of zr but this increase in strength and hardness is compensated at the expense of ductility which is evident from the impact test. it can be understand from the fractography that relatively higher strength and hardness can be gained at peak aged condition at the expense of ductility, addition of trace zr can relatively improve ductility which is evident from the fracture surface at peak aged condition. this happens due to morphological change of zr added alloy. acknowledgement this work is supported by daers office of bangladesh university of engineering and technology, dhaka. thanks to department of glass and ceramics engineering for providing the laboratory facilities. references [1] h. ye, “an overview of the development of al-si-alloy based material for engine applications,” journal of materials engineering and performance,” vol. 12, no. 3, pp. 288–297, 2003, https://doi.org/10.1361/105994903770343132. 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[26] a. a. razin, d. s. ahammed, m. a. nur and m. s. kaiser, “role of si on machined surfaces of al-based automotive alloys under varying machining parameters,” journal of mechanical and energy engineering, vol. 6(46), no. 1, pp. 43-52, 2022, https://doi.org/10.30464/jmee.2021.6.1.43 https://doi.org/10.1007/s40033-017-0140-5 http://dx.doi.org/10.2320/matertrans.45.399 https://www.hindawi.com/journals/amse/ https://doi.org/10.1155/2021/9933168 https://www.cjmr.org/ https://www.cjmr.org/ http://dx.doi.org/10.30464/jmee.2021.6.1.43 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 78 doi: 10.17977/um016v1i22017p078 modeling of antenna for deep target hydrocarbon exploration nadeem nasir1, *, noorhana yahya2, hasnah mohd zaid2, afza shafie2, and norhisham hamid1 1electrical and electronic engineering department, universiti teknologi petronas, 31750 bandar seri iskandar, tronoh, perak, malaysia 2fundamental and applied science department, universiti teknologi petronas, 31750 bandar seri iskandar, tronoh, perak, malaysia * nadeemntu@hotmail.com abstract nowadays control source electromagnetic method is used for offshore hydrocarbon exploration. hydrocarbon detection in sea bed logging (sbl) is a very challenging task for deep target hydrocarbon reservoir. response of electromagnetic (em) field from marine environment is very low and it is very difficult to predict deep target reservoir below 2km from the sea floor. this work premise deals with modeling of new antenna for deep water deep target hydrocarbon exploration. conventional and new em antennas at 0.125hz frequency are used in modeling for the detection of deep target hydrocarbon reservoir. the proposed area of the seabed model (40km ́ 40km) was simulated by using cst (computer simulation technology) em studio based on finite integration method (fim). electromagnetic field components were compared at 500m target depth and it was concluded that ex and hz components shows better resistivity contrast. comparison of conventional and new antenna for different target depths was done in our proposed model. from the results, it was observed that conventional antenna at 0.125hz shows 70% ,86% resistivity contrast at target depth of 1000m where as new antenna showed 329%, 355% resistivity contrast at the same target depth for ex and hz field respectively. it was also investigated that at frequency of0.125hz, new antenna gave 46% better delineation of hydrocarbon at 4000m target depth. this is due to focusing of electromagnetic waves by using new antenna. new antenna design gave 125% more extra depth than straight antenna for deep target hydrocarbon detection. numerical modeling for straight and new antenna was also done to know general equation for electromagnetic field behavior with target depth. from this numerical model it was speculated that this new antenna can detect up to 4.5 km target depth. this new em antenna may open new frontiers for oil and gas industry for the detection of deep target hydrocarbon reservoir (hc). copyright © 2017journal of mechanical engineering science and technology all rights reserved keywords: bentonite, portland cement, strength of moulding sand i. introduction sea bed logging is an application of control source electromagnetic method which is used to locate an oil reservoir beneath the sea floor by measuring electromagnetic fields [1-4]. in typical control source method a horizontal electric dipole antenna is towed by a surface vessel at a short distance 30m above from the sea floor [5-7]. dipole antenna transmits very low frequency electromagnetic waves with frequency ranges from 0.25hz-10hz due to low frequency transmitted energy propagates down through the subsurface [8-10]. low frequency electromagnetic waves attenuate more in the conductive layer and less in the resistance layer due to the skin depth. in a large resistive layer such as hydrocarbon electromagnetic energy flows along the reservoir (described as guided wave) is detected by the stationary sea floor electric or magnetic field detectors which are deployed on the sea floor. control source electromagnetic method depends on the resistivity of the hydrocarbon and surrounding sediments. hydrocarbon in the sea bed has resistivity of few tens to hundred ohm meter (30ωm-500ωm), sea water (0.5ωm-2ωm) while all other layers including sediments in the sea have resistivity (1 ωm -2 ωm) [11-17]. in deep water the air wave effect is negligible so the wave guided back from the hydrocarbon can predict the presence of hydrocarbon [18]. target depth is also very important in sea bed logging. frequency and offset plays an important role to determine target depth. shallow targets shows measurable response at near offset with high frequency where as deep targets at large offset with low frequency. g. michael hoversten reports that simulated oil-water contact at 2 km depth below the sea floor shows a response below the expected noise levels. the resistivity model in which maximum target depth response measured was 3km for 8km offset [19]. multiple frequency range of electromagnetic waves is used to improve control source electromagnetic data for deep target hydrocarbon reservoir. mailto:nadeemntu@hotmail.com issn: 2580-0817 journal of mechanical engineering science and technology 79 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) deep target having variable size and depth can cause the risk factor so high and low frequency reduces this risk factor. deep water field survey in nigeria two fundamental frequencies (0.05hz and 0.25hz) with higher frequency are used which shows very promising survey results. for shallow target depth 0.25hz frequency and the first two harmonics is useful to detect the thin resistive hydrocarbon reservoir. low frequency (0.05hz) data provide useful information about 2km resistivity background model. this wide range of multiple frequencies is used to reduce the drilling risk factor [20]. direct detection of hydrocarbon which is deeply buried can be done by subsea em sounding technique. survey was done across twgp, norway offshore and they found the target at the depth of 1100m below the sea floor was reported [21]. transmitter height changing above the sea floor was investigated in a noise model and also included the data which create uncertainty by changing the transmitter height. inversion of the data with multilayers and four layers models was done. it was observed that this model can detect the resistive layer at a depth of 15001600m below the sea floor for control source csem electromagnetic method where as 2km depth for seismic method [22]. propagation of electromagnetic (em) waves travelling in seawater can be predicted by using maxwell’s equations. if the propagating of electromagnetic wave in the y direction then it can be described in terms of the electric field strength ex and the magnetic field strength hz [23]. (1) (2) (3) where (γ) is the propagation constant, (ε) permittivity, (μ) permeability, (σ) conductivity, α attenuation factor, β phase factor and ω = 2πf the angular frequency as given in equation (3). electromagnetic wave propagation can be described by a wave number k as given in equation 4. (4) where k is the wave number and i=ö-1 is the complex number, cp phase velocity and is the skin depth. first term in equation (4) inside the square root represent the displacement current and second term represent conduction current in maxwell's equation. numerical model is a very important to know the location hydrocarbon in sea bed logging. it can provide the information about the target depth at which target depth the electromagnetic wave signal provide information about hydrocarbon reservoir [24]. table 1. simulated model parameters with different resistive layers (air, sea water, overburden and under burden) target depth air thickness under burden hydrocarbon sea water depth frequency (m) (m) (m) (hz) 5 500 4500 100 2000 0.125 7 500 4250 100 2000 0.125 1 500 4000 100 2000 0.125 1 500 3750 100 2000 0.125 1 500 3500 100 2000 0.125 2 500 3250 100 2000 0.125 up to 500 500 100 2000 0.125 4500 80 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) table 2. relative permittivity, conductivity values of air, sea water overburden/under burden and hydrocarbon material parameters air sea water under burden/ over burden hydrocarbon conductivity 1.006 80 30 4 relative pemittivity 1.0e-11 4 1.5 0.001 thermal conductivity 0.024 0.593 2 0.492 density 1.293 1025 2600 900 this work premise deals with the study of electromagnetic field components, conventional and new antenna electromagnetic field comparison for deep target hydrocarbon reservoir detection. new antenna electric field data of different curvatures is used for numerical model to know the exact target depth with this new antenna design. ii. methods. we use cst (computer simulation technology) software for finite integration method (fim). computer simulation technology (cst) is used to discritize each maxwell's equations at low frequency to investigate the resistivity contrast.forfinite integration technique,computer simulation technology software is used as a tool for low frequency to solve any problem. fim was used to detect deep target hydrocarbon below 3000m from seafloor by using cst software. cst software was used to detect deep target hydrocarbon between 1000m to 400m underneath seabed. model area was assigned as 40´40 km to replicate the real seabed environment with various target positions. environment with and without hydrocarbon were also prepared for comparison purpose later. there were few steps involved in generating the cst simulated model. first step was to set parameters for aluminium antenna. in this case we used length of 270m, frequency of 0.125hz and current of 1250a. second step was to set parameters for the model. airthickness was set as 500m, sea water depth of 2000m, overburden thickness of 1000m, hydrocarbon thickness of 100m and under burden with their different conductivities and permeability values (table 2). thickness of the overburden was increased as the target depth varied gradually (every 250m) from 500m to 5000m.third step was to apply electric boundary conditions (table 1). fourth step was to run low frequency full wave solver to simulate sea bed model. the final step was post processing to generate the simulated data for results analysis at different target depths. maxwell's equations for magnetic and electric fields are used as a code in the software to get electric and magnetic field response with and without hc. schematic diagram of proposed seabed model with cst simulated model is shown in figure 1. fig. 1. (a) schematic diagram of proposed model and (b) cst simulated model issn: 2580-0817 journal of mechanical engineering science and technology 81 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) fig. 2. comparison of e-filed components (ex, ey, ez) response at 500m target depth fig. 3. comparison of b-filed components (bx, by, bz) response at 500m target depth iii. results and discussion. electromagnetic field components response from hydrocarbon reservoir in sea bed logging is very important to show better resistivity contrast. in sea bed logging both electric and magnetic field sensors are placed on the sea floor to record the electromagnetic field data. electromagnetic field data consists of three components i.e. (x, y, and z). choice of the electromagnetic field components depends on the electromagnetic waves propagation. all three components of electric field response were measured with conventional hed antenna within the proposed area (40 km x 40km). components study was done in deep water (2000m) where no air waves effect take place. comparison of e-field components is given in figure 2. ex component shows better e field response at 500m target depth as compared to ey and ez. magnetic field components comparison was also done to know which component gave high magnetic field response with the presence of hydrocarbon reservoir. magnetic field strength is although lower than the electric field strength but it is also very important for hydrocarbon prediction but only for shallow target where as for deep target the signal strength is very low which cannot be able to predict the presence of hydrocarbon reservoir. magnetic field comparison is given in figure 3. bz component gave higher magnetic field response with the presence of hydrocarbon reservoir at 500m depth. hfield response was also analyzed at 500m target depth is given in figure 4. h-field response of all three components was recorded and plotted to know which component gave higher response. hz component shows better response with the presence of hydrocarbon reservoir than hx and hy. selection of e, b and h field components was done and it was conclude that ex, bz and hz gave better delineation of hydrocarbon reservoir at 500m target depth. 82 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) finally ex, bz and hz electromagnetic field components were plotted as given figure 5. from these results, it was observed that the ex and hz components gave better delineation of hydrocarbon reservoirs according to maxwell’s equations; if the electromagnetic wave is propagating in y direction then ex and hz components gave better delineation of hydrocarbon reservoirs [25]. these two components were chosen for deep target hydrocarbon detection with straight and new antenna. a. straight antenna mvo results straight antenna magnitude verses offset data was plotted to compare with new antenna in full scale sea bed logging environment. conventional antenna and new antenna length, frequency and model were kept same to check the performance of new antenna for deep water-deep target. fig. 4. comparison of h-field components (hx, hy, hz) response at500m target depth fig. 5. comparison of hz, ex and bz field response at 500m target depth (a) issn: 2580-0817 journal of mechanical engineering science and technology 83 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) (b) (c) (d) fig. 6. straight antenna ex-field mvo with different target positions (a) 500m (b) 750m (c) 1000m (d) 1250m (e) 1500m (f) 1750m (g) 2000m straight antenna magnitude verses offset data was plotted by changing the target depth from 500m until 2000m. ex field response with and without hydrocarbon was measured to know the exact target depth which can be detected by the straight hed antenna in deep water. at 500m target depth straight antenna shows 70% resistivity contrast is given figure 6 (a). target depth was varied from 500m to 750m but the simulated model total layers depth keep constant by reducing the under burden depth. ex field response decreases by increasing the target depth due to the skin depth. at 750m target depth resistivity contrast drops to 57% is shown figure 6b).ex field response was measured until no hydrocarbon detected. it was analyzed that 42%, 26% and12% difference with and without hydrocarbon at 1000m, 1250m and 1500m respectively. further target depth was decreased from 1500m to 2000m the difference between with and without hydrocarbon reservoir is 5% and 2% which is less than 10%. straight antenna can detect up to 1500m target depth below the sea floor because drilling risk factor is involved below 10%. 84 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) (a) (b) (c) (d) issn: 2580-0817 journal of mechanical engineering science and technology 85 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) (e) (f) (g) (h) 86 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) (i) (j) fig. 7. new antenna ex-field mvo with different target positions (a) 500 m (b) 1000 m (c) 1500 m (d) 2000 m (e) 2500 m (f) 3000 m (g) 3500 m (h) 4000 m (i) 4500 m (j) 5000 m hz field response was also measured with straight antenna to get better delineation of hydrocarbon reservoir. analysis between ex and hz at 500m target depth shows 16% better delineation of hydrocarbon reservoir than ex field response. at 1500m target depth hz field response was 12% higher than ex field response. it was also conclude that hz field shows 10% difference at 1750m target depth. magnetic field hz component able to detect the hydrocarbon reservoir at 1750m target depth where as ex field response for 1500m target depth respectively. due to high h-field strength it can detect 250m extra depth than ex field response is given figure 7. below 2000m strong electromagnetic signal strength is required for deep target hydrocarbon detection. b. new antenna mvo results deep target detection is a challenging task in sea bed logging. response from deep target hydrocarbon reservoir is very weak from straight antenna. the guided wave from the high resistive deep target has very low signal strength which is very difficult to predict the presence of hydrocarbon reservoir. a strong em field is required and some modification of the hed antenna is highly needed by the oil and gas industry to ensure deep target. to enhance the signal strength and focus more electromagnetic (em) waves for deep target new antenna was simulated with and without the presence of hydrocarbon reservoir to check the performance of new antenna. the proposed area of the seabed model which was simulated by using cst (computer simulation technology) em studio based on finite integration method (fim). new antenna has the ability to focus electromagnetic waves. new antenna was used to get the magnitude verses offset (mvo) response for 4000m target depth as given figure 7. solid lines indicate the response with presence of hydrocarbon where as dotted line represents without hydrocarbon response. it was analyzed that this new antenna shows 510% difference between the hydrocarbon or without hydrocarbon at 500m target depth than issn: 2580-0817 journal of mechanical engineering science and technology 87 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) straight antenna. this difference motivates to go for further target depth to predict the presence of high resistive layers hydrocarbon (hc). new antenna ex field response shows 46% difference between with and without hydrocarbon resrvior at 4000m target depth is given figure 8. this new antenna shows 12% difference at 4250m target depth in deep water and can be used to reduce the drilling risk factor for oil and gas industry until 4250m target depth. comparison of straight and new antenna is shown in table 3 and table 4 respectively. the presence of high resistive layers hydrocarbon (hc). new antenna ex field response shows 46% difference between with and without hydrocarbon resrvior at 4000m target depth is given figure 8. this new antenna shows 12% difference at 4250m target depth in deep water and can be used to reduce the drilling risk factor for oil and gas industry until 4250m target depth. comparison of straight and new antenna is shown in table 3 and table 4 respectively. (a) (b) (c) 88 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) (d) (e) (f) (g) issn: 2580-0817 journal of mechanical engineering science and technology 89 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) (h) (i) (j) fig. 8. new antenna hz-field mvo with different target positions (a) 500m (b) 1000m (c) 1500m (d) 2000m (e) 2500m (f) 3000m (g) 3500m (h) 4000m (i) 4500m (j) 5000m. new antenna hz magnitude verses offset comparison with different target depth is given figure 8. solid lines in mvo plot represent hydrocarbon response where as dotted lines without hydrocarbon reservoir. for near offset less than 3km direct wave dominate and hydrocarbon reservoir presence cannot be predicted. greater than 3km offset in deepwater guided response dominate the direct wave’s response. due to this reason greater than 3km offset can predict about the presence of hydrocarbon reservoir. magnetic field response curve width is more as compared to electric field because magnetic field decreases 1/r2 where as electric field 1/r3 (r is the radial distance from the center of dipole to the measurement point) [26]. at 500m target depth new antenna shows 540% hz field strength than without hydrocarbon reservoir. as the target depth 90 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) increases the hz field strength decreases due to the skin depth effect. at 4250m target depth ex response was 12% where as hz 16% with new antenna design and hz component able to delineate deep target better than ex component. analysis of new antenna results reveals that it can be used to detect deep target up to 4500m target depth below the sea floor in deep water. table 3. straight antenna exand hz field response % difference comparison at different target depth with and without hc target depth (m) straight antenna % difference in ex field with and without hc at different target depth straight antenna % difference in hz field with and without hc at different target depth 500 70 84 750 57 76 1000 42 58 1250 26 40 1500 12 22 1750 5 10 2000 2 5 table 4. at different target depth with and without hc target depth (m) new antenna % difference in ex field with and without hc at different target depth new antenna % difference in hz field with and without hc at different target depth 1000 329 335 1500 298 305 2000 221 229 2500 160 168 3000 107 114 3500 64 68 4000 46 51 4250 12 16 4500 2 5 fig. 9. numerical model with straight antenna used for sea bed logging different curvatures were compared at 500m target depth in deep water environment to know which curvature gave higher signal strength with the presence of hydrocarbon reservoir. from results it was anal yzed that curvature h= r/3 gave higher magnitude verses offset response as given in figure 9. issn: 2580-0817 journal of mechanical engineering science and technology 91 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) fig. 10. numerical model with straight antenna used for sea bed logging c. numerical model for straight and new antenna for deep target in deep water environment numerical model is a very important to know the location hydrocarbon in sea bed logging. it can provide the information about the target depth at which target depth the electromagnetic wave signal provide information about hydrocarbon reservoir. regression analysis was done for numerical model of electric field data at different target depths. nonlinear regression technique is used to get the best fit mathematical function for input data. simulated data for different target depth is used for numerical model for straight and new antenna data. guided wave response data at different target depth is used for numerical model. data fitting tool is used to fit the sea bed logging data for various target depths. target depth 500m to 2000m target depth fitting of our proposed sea bed model data fitting. guided wave response is used for fitting the data. more than 800 data points are used for data fitting for survey area of 40kmx40km. these equations were used for numerical model. the numerical model for the straight antenna is given figure 10. the electromagnetic field response decreases with the inverse square of the distance between the source/receiver offset. from these equations, the electric field response was calculated at far offset. at each target depth, the electric field response was used to plot the numerical model for the straight antenna. circles represent the numerical model of the straight antenna with different target depths where as triangles without a hydrocarbon reservoir. to know the numerical model behavior again, data fitting was used which is represented by the solid line in the model. from this fitting, the general equation for the straight antenna numerical model was obtained as given (5). e  exp(cons   x   x2 ) (5) where e is the electric field response (ex), x is the target depth where as constants α, β represent the decay rate of guided wave from hydrocarbon reservoir and direct wave response. decay rate of guided wave response (1.57×10-7) is slower than the direct wave response (-1.41×10-4) [27]. from this numerical model, the electric field response at different target depths can be calculated and the presence of the hydrocarbon reservoir can be predicted. at different target depths, the electric field response is given in table 6. with the numerical model of the straight antenna, by changing the target depth it ensures that this antenna can be used to detect the 1750m target depth. estimated electric field response with this numerical model equation also proves the accuracy of this model because at all target depths response is within the range of the with and without hydrocarbon reservoir model. the numerical model for the curved antenna with the curvature h=r/3 was plotted with the help of data fit equations for different target depths andis given (figure11). e  exp(cons   x   x2 ) (6) 92 journal of mechanical engineering science and technology issn: 2580-0817 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) fig. 11. numerical model with antenna curvature h= r/3 with different target depth table 5. straight antenna e field response calculation at different target depth with the help of numerical model target depth new antenna e field response with target depth (v/m) 510 2.24 × 10-9 610 1.96 × 10-9 710 1.76 × 10-9 810 1.56 × 10-9 910 1.41 ×10-9 1110 1.25 × 10-9 1210 1.11 × 10-9 1310 1.01 × 10-9 1410 8.34 × 10-10 1510 7.53 × 10-10 without hydrocarbon 4.55 × 10-10 table 6. new antenna e field response calculation at different target depth with the help of numerical model target depth new antenna e field response with target depth (v/m) 510 6.5 × 10-8 975 5.2 × 10-8 1450 4.1 × 10-8 1925 3.4 × 10-8 2400 2.8 ×10-8 2875 2.4 × 10-8 3350 2.1 × 10-8 3825 1.9 × 10-8 4300 1.7 × 10-8 4775 1.6 × 10-8 without hydrocarbon 1.5 × 10-8 analytical results show that scattered field from hydrocarbon reservoir takes the form of exponential decay function [27]. scattered field from hydrocarbon reservoir decay slower than the direct wave response. the equation shows the electromagnetic field behavior with target depths where x is the target depth and e the electric field response with the corresponding target depth. in equation, 5.5 constants α, β represents the decay rate of guided and direct wave from hydrocarbon reservoir. decay rate of guided wave response with curve antenna curvature h=r/3 (0.54×10-7) is slower than straight antenna (-1.41×10-4). the decay rate is 66% slower than straight antenna, which indicates this antenna can detect further deeper target. different target depth issn: 2580-0817 journal of mechanical engineering science and technology 93 vol. 1, no. 2, november 2017, pp. 78-94 nadeem nasir et.al (modeling of antenna for deep target hydrocarbon exploration) equations were plotted to get the numerical model, and it was observed that, the curved antenna with the curvature h=r/3 can detect up to a 4.5km target depth. numerical model (equations 5, 6) was used to validate the electric field response for straight antenna and new antenna design for deep hydrocarbon target. at different target depths the electric field response from numerical model equation was within the range of electric field response as got from the simulated results. straight and new antenna electric field response is given (table 5, 6) respectively. iv. conclusion. electromagnetic field components response with hydrocarbon reservoir at 500m target depth was done which shows that ex and hz components shows better delineation than other components. ex field response for new antenna shows 329% resistivity contrast at target depth of 1000m where as straight antenna showed 70% resistivity contrast at same target depth. hz field shows 355% resistivity contrast where as straight antenna shows 86%. from these results it was analyzed that hz field shows better delineation for hydrocarbon detection. it was also observed that at frequency of 0.125 hz, new antenna gave 46% better delineation of hydrocarbon at 4000m target depth. numerical modeling was done to know the exact target depth at which this new antenna can detect in deep water environment. it was observed that new antenna can detect 4.5 km target depth. references [1] l . m acgregor, & m.sinha, "use of marine controlled-source electromagnetic sounding for sub-basalt exploration "geophysical prospecting vol. 48,1091-1106. 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[18] t.eidesmo, s.ellingsrud, l.m.mac gregor, s.c.constable, m.c.sinha, s.johansen, f.n.kong, h.westerdahl,"seabed logging (sbl), a new method for remote and direct identification of filled layers in deepwater areas using controlled source electromagnetic sounding," first break, vol.20, pp.144152,(2002). journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 9 doi: 10.17977/um016v6i12022p009 surface quality of fe, ni, and cr added hyper-eutectic al-si automotive alloys under up-milling and down-milling operation akib abdullah khan1, mashiur rahman shoummo1, mohammad salim kaiser2* 1department of mechanical engineering, bangladesh university of engineering and technology, dhaka-1000, bangladesh 2directorate of advisory, extension and research services, bangladesh university of engineering and technology, dhaka-1000, bangladesh *corresponding author: mskaiser@iat.buet.ac.bd article history: received: 26 march 2022 / received in revised form: 25 april 2022 / accepted: 25 may 2022 abstract effect of the elements fe, ni, and cr on the surface quality under machining of hyper-eutectic aluminiumbased al-si automotive alloys has been carried out as the elements improve the properties of this alloy. machining is done on a horizontal type milling machine using a high-speed steel slab milling cutter in dry condition. only the cutting speed varies throughout the experiment, while the machining feed and depth of cut remain fixed. the experimental results show that the addition of these alloying elements increases the roughness and hardness specially due to formation of fe-rich intermetallic 𝛽−𝐴𝑙5𝐹𝑒𝑆𝑖. however, the needle-like 𝛽−𝐴𝑙5𝐹𝑒𝑆𝑖 has been refined with the addition of cr, as seen by the microstructure. the sem fractography shows a huge cleavage of the brittle 𝛽−𝐴𝑙5𝐹𝑒𝑆𝑖 phase, which initiates the crack propagation for fe added alloys. the downward force causes compressive stress exerted in down-milling operation, so the results depict higher hardness and better surface finish. besides, shorter chips are formed in downmilling than up-milling process, which rather causes the brittleness of the alloys. when the cutting speed is raised, the surface quality deteriorates due to high temperature, while the hardness improves initially due to formation of precipitates then decreases due to coarsening of precipitates. copyright © 2022. journal of mechanical engineering science and technology. keywords: chips, hardness, microstructure, roughness, surface i. introduction al-si alloys are used to manufacture connecting rods, pistons, cylinder liners, engine blocks, etc., components of engine construction in automotive applications, as they are light in weight and have high strength [1]-[5]. to develop the diverse properties of this alloy, several other components are added. when minor elements cu and mg are alloyed, it improves the involuntary properties. moreover, the alloy offers the quick response to heat treatment [4], [5]. iron is found in aluminum as the most common impurity. small amount of iron into pure alloys provides slightly higher strength [6], [7]. the addition of ni effectively increases the properties associated with the elevated temperature of the al-si alloy. a number of complex thermally stable intermetallic are formed, which enhance the mechanical properties of the alloys, especially at higher temperatures ahead of 250 °c [8], [9]. the acceptance of higher amount of fe in al-si alloy can be effectively enhanced by adding ni [10]. chromium is alloyed to aluminium alloys for controlling the grain structure, preventing the grain growth and to slow down the recrystallization during heat treatment. chromium reduces aluminum susceptibility and stress corrosion improving the toughness mailto:mskaiser@iat.buet.ac.bd 10 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) property [11]. iron forms intermetallic phases, which are brittle and hard, so the amount of iron in al-si alloys should not be high. addition of adapt elements such as manganese, nickel, zinc, lead, vanadium, chromium, magnesium, copper etc. modifies the morphology of the harmful platelet iron intermetallic compounds to harmless shapes [10]-[12]. the inclusion of cr accelerates the transformation of fe-containing phases from β-alfesi to αal(fe,cr)si. β-alfesi has a needle-like shape, while α-al(fe,cr)si has a fishbone-like morphology [13]. a brief literature review also has been made on the morphological change of different aluminum alloys under machining [14]. however, for manufacturing or repairing the final product, the alloy is machined using several methods and machine tools to produce the desired shape. it can also be observed that the internal structure of the alloys is dramatically affected by the machinability [15]. this structure can be modified through adding alloying elements, process selection, or heat treating subsequently [15]. one of the methods of machining is milling, which is done on milling machines. milling is a machining operation that removes material from a workpiece by combining the rotation of a multiple-point cutting tool with the advancement (or feeding) of the workpiece at an angle to the tool's axis [16]. milling can be divided into two types: traditional (or up) milling and climb (or down) milling. the relationship between the cutter's rotation and the feed direction is the distinction between these two approaches. "up-milling" is when the cutter rotates in the opposite direction of the workpiece, while "down-milling" is when the cutter rotates in the same direction as the workpiece. this machining method affects various properties of the surface being machined. experimental studies reveal that the quality of the machined surface not only depends on the cutting parameters applied but also the composition and conditions of the alloy samples [17]-[19]. as there is little information in the literature, this study is to find out the effect of the alloying elements like fe, ni, and cr on the machinability using milling machine in terms of roughness, hardness, chips formation, surface quality and microstructural observation of the automotive al-si alloys. a comparison also has been made between both the processes of up-milling and down-milling. ii. material and methods a 390 grade aluminium engine block was melted as master alloy. no alloying element was added to the first alloy. then some fe was added while casting the second alloy. ni and cr were further added to cast the third and fourth alloys, respectively. the prepared alloys are analysed by spectrochemical methods, as shown in table 1. table 1. values of wt.% composition for the experimental alloys alloy si fe ni cr cu mg zn mn ti al 1 19.209 0.795 0.089 0.040 2.826 0.245 1.117 0.214 0.099 bal 2 17.947 5.910 0.091 0.086 2.881 0.186 1.139 0.183 0.071 bal 3 18.913 6.256 0.567 0.057 2.889 0.193 1.124 0.178 0.090 bal 4 19.363 5.501 0.621 1.267 3.112 0.232 1.085 0.217 0.076 bal the melting was carried out in a ceramic fiber type laboratory-scale resistance heating furnace where degasser and borax were used as suitable flux cover. the chamber of the furnace was sized at 450 × 450 × 450 millimeters with a maximum working temperature of issn: 2580-0817 journal of mechanical engineering science and technology 11 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) 930 °c. four heats were taken to develop an al-si-based alloy for engine construction. the master alloy was remelted to prepare alloy 1. then, to prepare alloy 2, which mainly contained fe, mild steel chips were added to the master alloy. next, chips created from mild steel and some ni were added to prepare alloy 3, which mainly contained fe and ni. finally, alloy 4 was developed through the some stainless-steel chips addition in to the master alloy to full fill the requirement of the level of fe and ni along with cr. for casting, the furnace temperature was always maintained at 750±15 °c with the help of electronic controller. iron metal moulds were preheated to 200 °c, and casting was done into them. mould sizes were 20 × 150 × 300 millimeters. the cast alloy was kept in a muffle furnace at 400 °c for 18 hours of homogenization and was air-cooled. afterward, the homogenized samples were solutionized at 530 °c for 2 hours, and then the samples were salt ice water quenched to get a supersaturated single-phase region. next, the alloys were isothermally aged at 175 °c for 240 minutes, as the peak hardness of the alloys is achieved at that condition [19], [20]. the samples were wet sanded mechanically with sic papers of 120, 320, and 1200 grit. the machining operation was done with an hss (high-speed steel) slab milling cutter mounted on a horizontal milling machine on 300 × 50 × 20 millimeters bars of the four alloys. the experimental setup is shown in figure 1. the feed was 9.5 mm and kept constant throughout the experiment. machining parameters, including cutting speed, feed rate, and depth of cut are crucial in terms of the workpiece's process-structure-performance relationship, so they must be chosen carefully [21]. so, the experiment was carried out by varying the cutting speed without the influence of any cutting fluids. the cutter was frequently being cleaned with a brush during the milling operation so that chips were removed from the cutter, which was spoiling the machined surface. a tylor hubson surface roughness tester was used to measure surface roughness. an average of five measurements was taken to calculate roughness. a zwick rockwell hardness tester with 1/8 inch ball was used to get hardness values in the b scale. a usb microscope was used for observing the machined surfaces, and a dslr camera was used to capture digital photographs of the generated chips. table 2 shows the tool geometry and cutting conditions used in the experiment. the specimens were polished with alumina and etched with keller’s reagent for scanning electron microscopy as well as fractographic observations of the surfaces of the alloys using the jeol scanning electron microscope jsm-5200. fig. 1. experimental setup. hss slab milling cutter specimen chips collection 12 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) table 2. tool geometry and cutting condition. cutter diameter 76.2 mm cutter height 101.6 mm cutter helix angle 20 cutter rake angle 8 cutter teeth 16 no. feed 9.5 mm/min depth of cut 1.0 mm cutting speed 7.9, 12.9, 14.8, 18.9, 23.9 m/min cutting condition dry iii. results and discussions a. surface roughness surface roughness variation with the cutting speed of the cast and aged hypereutectic different experimental al-si automotive alloys is shown in figures 2 and 3 under up-milling and down-milling machining processes, respectively. from both figures, it can be noted that base alloy 1 be evidence for lower roughness, whereas fe added alloy 2 has rougher surface, and the roughness increases accordingly as ni and cr are added too. common needle-like 𝛽−𝐴𝑙5𝐹𝑒𝑆𝑖 intermetallic phases are formed due to the presence of fe in the hypereutectic based alloys, which strongly degrades the mechanical and physical properties of alloy 2 and 3. because intermetallic compounds are brittle and rigid, they can operate as stress raisers and sources of weakness, reducing the alloy's strength and ductility. in the alloy matrix, the compounds behave as distinct particles having a highly faceted character. as a result, it has a poor bonding within the matrix, resulting in the lowest impact strength [22]. when the cutter in a milling machine is worked upon, these needle-like brittle intermetallic compounds break down into smaller particles, resulting in an uneven surface finish. it can be seen that when ni is added, alsifeni and chinese script intermetallics develop. according to the ni content, these intermetallic structures are more common in al dendrites [23]. these intermetallics are long needle-like, making the alloy more prone to blow-holes and porosity. as a result, the bond strength with the matrix is lower, resulting in a rougher surface. when cr is added, the morphology of the platelet iron intermetallic complex changes to innocuous forms, improving the mechanical capabilities but lowering the surface quality [11], [23]. an earlier investigator has discovered a similar result in cr added al-si alloy with 0.52 wt% fe [24]. the intermetallic compound is broken down into tiny bits and disseminated throughout the matrix [23]. an interesting fact can be observed from the figures that the surface quality of downmilled surfaces is superior than that of up-milled surfaces. the cause for this could be al has a tendency to form the built-up edge through the attachment with cutting tool during machining. it has an unfavorable outcome on the surface finish, making it undesirable [24], [25]. during up-milling, the cutter applies outward force to the material, shearing it and increasing bue. down-milling, on the other hand, exerts an inward force on the alloy, compressing it and smoothing the surface. from figures 2 and 3, it is also evident that the surface quality reduces while the cutting speed is gradually increased. increase in cutting speed increases the surface temperature, and at high temperature grains are coarsed, the issn: 2580-0817 journal of mechanical engineering science and technology 13 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) intermetallics are broken into pieces and brittle state of the intermetallics appears at the surface, creating rougher surface. the heat is generated by the friction between the cutting tool and workpiece interface during chip removal since it raises the temperature in the cutting zone which reduces the cutting tool material's hardness [26]. many studies have found that as the cutting tool hardness decreases, the wear of cutting tool goes faster, changing the cutting edge and shape of the broken chip. as a result, this wear has an undesirable effect on surface roughness and dimensional accuracy [26], [27]. 6 8 10 12 14 16 18 20 22 24 26 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 r o u g h n e s s ,  m cutting speed, m/min alloy 1 alloy 2 alloy 3 alloy 4 fig. 2. surface roughness variation with cutting speed of the experimental alloys under up-milling process. 6 8 10 12 14 16 18 20 22 24 26 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 r o u g h n e s s ,  m cutting speed, m/min alloy 1 alloy 2 alloy 3 alloy 4 fig. 3. surface roughness variation with cutting speed of the experimental alloys under down-milling process. 14 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) b. hardness figures 4 and 5 show the hardness of the machined surfaces of the experimental alloys for up-milling and down-milling operations at various cutting speeds. it is clear that alloys 2, 3, and 4 have higher hardness ratings than alloy 1. the higher amount of fe produced iron rich intermetallic during solidification and ageing, which increases the hardness of the alloys [27]. there are the five main fe-rich phases: 𝐴𝑙3𝐹𝑒, 𝛼 − 𝐴𝑙8𝐹𝑒2𝑆𝑖, 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖, 𝛿 − 𝐴𝑙4𝐹𝑒𝑆𝑖2 𝑎𝑛𝑑 𝛾 − 𝐴𝑙3𝐹𝑒𝑆𝑖. among them, 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖 phase is usually accountable for the higher hardness. it can be seen that the same intermetallics which are responsible for degrading surface quality are also responsible for improving hardness rating. alloy 3 shows a further improvement of the hardness. adding ni after age hardening increases the hardness, which could be related to the development of harder precipitated phases such as 𝑁𝑖3𝐴𝑙 𝑎𝑛𝑑 𝑁𝑖3𝑆𝑖 during the aging process [28], [29]. conversely, cr alters the morphology and type of fe-rich intermetallic phases in cast aluminum alloys, resulting in a loss of hardness in alloy 4 [11]. however, another intriguing finding is that down-milling produces superior quality in terms of hardness than up-milling. the reason for this could be that when down-milling, the cutter provides compressive force, which is similar to cold rolling, and cold rolling improves hardness by reducing defects such as pinholes and porosity, and increasing dislocation density [30]. 0 2 4 6 8 10 12 14 16 18 20 22 24 26 70 75 80 85 90 95 100 105 h a rd n e s s , h r b cutting speed, m/min alloy 1 alloy 2 alloy 3 alloy 4 fig. 4. rockwell hardness variation with cutting speed of the experimental alloys under up-milling process. figures 4 and 5 depict again that the rockwell hardness number increases as cutting speed is raised up to a certain speed, then the hardness starts to fall again. the surface temperature rises as the speed of the cutter increases, and after a certain point, the precipitates grow coarser, and coarse precipitates are less effective at resisting dislocation movement than finely dispersed precipitates. it is possible that the softening of the alloys at higher temperatures is related to particle coarsening. it can be seen from figures 2 to 5 that the surface roughness and hardness variation with cutting speed are opposite to each other. issn: 2580-0817 journal of mechanical engineering science and technology 15 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) as the speed is increased, the surface roughness rises, whereas the hardness is improved. previous research suggests that the harder the ductile material, the higher the surface roughness values. however, in the case of brittle material, it was discovered that the variation was very closer between them. it was also stated that the porous-like defects into the alloy play a significant task on machinability of brittle materials, with the higher level of porous material recording higher roughness values owing to such microstructure of the alloy [31]. 0 2 4 6 8 10 12 14 16 18 20 22 24 26 70 75 80 85 90 95 100 105 h a rd n e s s , h r b cutting speed, m/min alloy 1 alloy 2 alloy 3 alloy 4 fig. 5. rockwell hardness variation with cutting speed of the experimental alloys under down-milling process. c. chips photo micrographs figure 6 shows photomicrographs of chips produced as a result of machining. in the case of up-milling, the chips are longer. down-milling, on the other hand, results in shorter chips. when down-milling, a compressive force is applied to the surface, and due to high amount of force, the bonds between molecules are frequently broken. as a result, the chips are shattered during down-milling and got shorter in length. the chip size decreases from figures 6(a) to 6(c) for up-milling and from 6(e) to 6(g) for down-milling. as previously discussed, the intermetallics which are formed due to alloy addition are responsible for this result. as intermetallic compounds with fe and ni are formed, the alloys become more brittle. the intermetallics are broken into pieces as machining force is applied and are dispersed throughout the material and the surface. thus, the mechanical property decreases [21], [22]. hence, the chips are broken in short segments. on the other hand, from figure 6(d) for up-milling and figure 6(h) for down-milling, it is noticeable that the chips are rather longer relatively. when cr is added, however, the morphology of the intermetallic compound changes to a more favorable state, improving mechanical properties [11], [23]. 16 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) fig. 6. optical images of the machined chips at cutting speed 23.9 m/min and depth of cut 1 mm, under up-milling (a) alloy 1 (b) alloy 2 (c) alloy 3 (d) alloy 4 and under downmilling (e) alloy 1 (f) alloy 2 (g) alloy 3 (h) alloy 4. ( e ) ( a ) ( b ) ( f ) ( g ) ( c ) ( d ) ( h ) (f) (a) (e) (b) (h) (d) (g) (c) issn: 2580-0817 journal of mechanical engineering science and technology 17 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) d. microstructural observations before machining, polished surfaces are smooth, and no plastic deformation is observed on the surface, which can be seen from the optical images in figure 7. much information cannot be extracted from this type of optical micrographs. however, for polished surfaces of alloy 1 to 4, as alloying elements (fe, ni, cr) are added, the tone becomes slightly different. the variation in the amount of elements present into the alloys is responsible for some variation in terms of different levels of tones in different alloys. the similar variation of tone was observed in previous studies of al-si alloy, too [32]. unmachined up-milling down-milling alloy 1 alloy 2 alloy 3 alloy 4 fig. 7. optical images of the machined surface at cutting speed 23.9 m/min and depth of cut 1 mm of the experimental alloys under up-milling and down-milling conditions. 150m smooth surface crack compressed surface crack crack crack compressed surface compressed surface compressed surface smooth surface smooth surface smooth surface 18 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) after machining under up-milling condition, the micrographs consist of different cracks and more uneven surfaces than those created by down-milling. it is due to the tensile shear occurring during up-milling operation. micrograph of alloy 1 displays relatively the minimum cracks on the surface. but fe added alloy 2 shows more cracks due to presence of higher level of fe-rich intermetallic followed by fe and ni added alloy 3 which is due to both fe and ni rich needle-like intermetallics. however, cr added alloy 4 can reduce this phenomenon by changing the morphology of fe-rich intermetallic phases [11], [23]. in case of down-milling operation, lower cracks and pinholes are observed due to compressive stress, which occurs like cold rolling. on the other hand, the uneven surfaces are produced similarly as up-milling operation, but in different intensity, due to presence of different hard intermetallics. e. scanning electron microscopy the sem in figure 8 shows the microstructure of experimental automotive alloys at peak aged condition. the microstructures as usual consist of primary al dendrites with eutectic si phases and a number of intermetallic phases in the matrix. mixtures of intermetallic compounds are formed in the matrix due to the presence of fe, ni, cr, cu, and mg in the alloys. platelets and acicular morphologies can be seen in eutectic si particles. voids and hollow space can be noticed in the microstructure as a casting defect of cast alloys [28]. fig. 8. sem images of the peak aged (a) alloy 1, (b) alloy 2, (c) alloy 3, and (d) alloy 4. the microstructure in figure 8(a) shows of the base alloy as it contains 0.85 wt% fe. as the percentage of iron is low, it has a small amount of 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖 phase, which can be ( a ) (c) (b) (a) (d) distributed intermetallics modified intermetallics niddle-like intermetallics large intermetallics issn: 2580-0817 journal of mechanical engineering science and technology 19 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) witnessed in figure 8(a). figure 8(b) shows that the microstructure of fe accompanying alloy 2 has a higher amount of 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖 phase than alloy 1 in figure 8(a) due to the excess fe in the alloy. because alloy 3 contains a considerable quantity of ni, there are two types of 𝐴𝑙3𝑁𝑖 phases: plate-like and needle-like. the long needle-like structures can be seen in figure 8(c), which covers most of the area. as previously discussed, these structures are responsible for blow-holes, pinholes, and porosity, which again is responsible for the degraded quality of surface. figure 8(d) shows sem micrographs of cr-added alloy 4, which has a changed structure with plate-like and needle-like morphologies missing. figure 9 shows the sem fractographs of the tensile tested peak aged alloys. the sem fractograph of alloy 1 is shown in figure 9(a), which indicates a cleavage fracture. it occurs due to the high deformation rates during loading. every grain has different orientation of the fracture plane. as secondary cracks, intergranular cleavage is visible too. crack initiation occurs by significant cleavage of the brittle 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖 phase, according to the sem fractograph of alloy 2 (figure 9(b)). at such fe levels, a proliferation of β-platelets is expected in the alloy microstructure. the crack propagates from one β-platelet to the next, which can be seen in the figure 9(b). in comparison to si particles, the plate-like 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖 phase has substantially greater dimensions, making it more vulnerable to crack initiation. increased number of secondary cracks is visible in figure 9(c), because during age-hardening, the alloy becomes more brittle due to more precipitation hardening of the ni-rich phases. as cr changes, the 𝛽 − 𝐴𝑙5𝐹𝑒𝑆𝑖 phases in the alloy, no cracks propagating between the matrix and β-particles are detected in the sem picture of alloy 4 (figure 9(d)) [33]. fig. 9. sem fractograph of peak aged (a) alloy 1, (b) alloy 2, (c) alloy 3 and (d) alloy 4. (b) (d) (a) (c) brittle cleavage fracture massive brittle cleavage fracture massive brittle cleavage fracture modified brittle cleavage fracture 20 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 9-22 khan et al. (surface quality of fe, ni, and cr added hyper-eutectic al-si alloys under milling operation) iv. conclusion from this study following results may be concluded regading the alloying elements’ effect on the surface quality of discussed al-si hyper-eutectic automotive alloy under upmilling and down-milling conditions. surface quality degrades as fe, ni, and cr are added in subsequent alloys, because of intermetallic formation as well as creation of porosity and blow holes. the better surface quality and hardness can be achieved through down-milling operation due to compressive force and minimized bue than for up-milling, acting as tensile-like force. the surface roughness and hardness both are found to be proportional to cutting speed for producing higher temperature at higher speed. the fractured surfaces of fe and ni added alloys show more cracks than the base alloy for the formation of different brittle intermetallics, whereas cr added alloy shows lesser cracks for better morphology of the intermetallic precipitates. the chips produced are shorter in case of down-milling as compressive force acts on the brittle materials unlike of up-milling. the shorter chips are found for fe and ni added alloys as increased brittleness, but relatively longer chips are created in case of cr added alloy due to intermetallic modification. acknowledgement the authors thank to the gce department as well as daers office of bangladesh university of engineering and technology, dhaka for providing the equipment for this study. references [1] d. k. dwivedi, “sliding temperature and wear behaviour of cast al-si base alloy,” mater. sci. technol., vol. 19, no. 8, pp. 1091–1096, 2003, doi: 10.1179/026708303225004657. 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[33] m. mahta, m. emamy, a. daman, a. keyvani, and j. campbell, “precipitation of fe rich intermetallics in crand co-modified a413 alloy,” int. j. cast met. res., vol. 18, no. 2, pp. 73–79, 2005, doi: 10.1179/136404605225022928. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 107-118 107 doi: 10.17977/um016v6i22022p107 effect of graphene addition on bacterial cellulose-based nanocomposite jibril maulana1,2, heru suryanto2,3, aminnudin aminnudin2 1master program of mechanical engineering, universitas negeri malang, jl. semarang 5, malang, 65145, indonesia 2center of excellence for cellulose composite (ceccom), department of mechanical engineering, universitas negeri malang, jl. semarang 5, malang, 65145, indonesia 3centre of advanced material for renewable energy (camry), universitas negeri malang, jl. semarang 5, malang 65145, indonesia *corresponding author: jibrilm49@gmail.com article history: received: 3 october 2022 / received in revised form: 3 september 2022 / accepted: 9 november 2022 abstract bacterial cellulose (bc) is a widespread, low-cost biopolymer that has generally been produced from plants and biomass waste. a method for improving the range of applications for bacterial cellulose is adding graphene material. it has an outstanding feature that can increase the performance of nanocomposite materials. the research aims to observe the effect of graphene on the surface morphology, crystallinity, chemical bonding, and tensile strength of bc/cuo nanocomposite. for this study's synthesis, bc was synthesized by fermenting pineapple peel extract for 10 to 14 days. the produced bc was crushed, homogenized with a nano homogenizer machine, and filtered. filtered bc, cuo, and graphene were added to obtain a solution, and the mixture was first stirred magnetically, followed by an ultrasonic homogenizer, and finally dried using a freeze-dry method to make a porous nanocomposite. according to sem analysis, the addition of cuo and graphene can fill porosity nanocomposite. by xrd analysis, the addition of graphene reduces the crystallinity of bc/cuo. the ftir data showed that adding graphene reduces hydrogen bonding and makes some cu-o-c bonding. the tensile test has demonstrated that the tensile strength of bc-based nanocomposite with graphene reinforcement tends to decrease. copyright © 2022. journal of mechanical engineering science and technology. keywords: bacterial cellulose, cuo, ftir, graphene, sem, tensile strength, xrd i. introduction bacterial cellulose (bc) is a bacterial fermentation product that generates a matrix by hydrogen bonding [1]. because they include active o-h sites on their chemical chains, cellulose molecules form a network of microfibrils that communicate with each other through hydrogen bonding [2]. bc has the benefits of a high degree of purity, strong mechanical qualities, crystallinity, and distinctive physical characteristics [1], [3]–[6]. bacterial cellulose is useful for making many materials like paper with high-quality sensors, synthesized artificial skin, packaging with biodegradable capability, and air filters due to its variety of qualities [1], [6]–[10]. because of this bacterium's poor production under agitated conditions, implementing it in a large-scale fermentation system can be challenging. the creation of techniques to produce bc as cheaply as possible is crucial. indonesia is one of the largest pineapple producers in the world, producing around 1,396,153 million tons per year [11]. pineapples are exclusively used on the fruit's flesh, and 23% of it becomes pineapple peel waste [12]. mailto:jibrilm49@gmail.com 108 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) pineapple peel was easy to obtain, affordable, and environmentally friendly for carbon sources. there have been many attempts to manufacture bacterial cellulose-based nanocomposites. many material has been added to support bc such as tio2[13], zno[14], fe3o4[15], graphite [16], ag[17], al2o3[18] and cuo[19]. this nanomaterial's application is intended following its function, such as enhancing antibacterial, thermal, electrical, and mechanical properties. the metal substance with antibacterial capabilities is copper oxide (cuo), which enters the microbe network and damages the microbe cell membrane [20]. according to previous studies, the inclusion of cuo may also have an impact on the composite made of chitosan and cellulose's mechanical strength [21]. furthermore, cu has the ability to increase mechanical strength to 59.77 mpa [22] because cu can produce a molecular bonding with a composite matrix. graphene is an allotrope of carbon consisting of atoms arranged with a single layer and a two-dimensional honeycomb lattice nanostructure. graphene is a good candidate for binding metals and other inorganic precursors [23]. according to a different study, bonded silver's antibacterial capabilities could be improved by adding graphene [24], [25]. another research has also demonstrated that adding graphene can improve cuo antibacterial capabilities [26]. therefore, there is already a very wide range of possibilities for using graphene in hybrid nanomaterials. the current study was conducted to know the effects of adding graphene on the properties of bc/cuo nanocomposite synthesized from pineapple peel waste. ii. material and methods a. materials the honey pineapple peel that is used was purchased in the indonesian city of malang, in the province of east java. acetobacter xylinum was the bacteria used to produce bacterial cellulose. the reagents for bacterial fermentation, sugar (c12h22o11) as carbon source and urea (ch4n2o) as nitrogen culturing, were both applied, and cetyl trimethylammonium bromide (ctab) with the merck brand served as the surfactant. cuo was purchased from guangzhou hongwu material technology co., ltd., and graphene, which had a thickness of 1–5 nm, was supplied by skyspring nanomaterials, inc. b. bc pellicle synthesis this synthesis referred to the approach utilized in a prior study by suryanto et al. [27]. pineapple peel (300 g) was blended at high speed with 2l of water to extract the juice. the pineapple peel extract was boiled, then 150g of sugar and 5g of urea was added to the solution. after the mixture has reached a temperature of 30°c, add 20% of the solution that contains a. xylinum. the culture then underwent 10-14 day fermentation. the produced bc pellicle will float on top of the culture medium. c. homogenization process the synthesized bc pellicle was sliced and washed with a 1% naoh solution for 2 hours at 90oc to remove contaminants. the pellicle was rinsed till its ph returned to normal. 5g of pellicle are added to 1l of water and blended for 5 min. at 26,000 rpm in a blender. the material was then homogenized for 5 cycles with 150 bar using a high-pressure homogenizer (hph), and the solution was filtered via whatman paper 42. issn: 2580-0817 journal of mechanical engineering science and technology 109 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) d. nanocomposite synthesis 3g of crushed bc, 1% cuo, 1% ctab, and various graphenes (0.1%, 0.3%, and 0.5%) were needed to synthesize a nanocomposite. such substances were then added to 200ml of water and stirred for 1h 45 min. and homogenize with ultrasonic waves for 30 min. the solution was vacuum filtered with whatman paper no. 42. the nanocomposite formed on the paper was dried with the freeze-dried method at -62oc for 2 days. e. surface morphology surface morphology studies were observed under scanning electron microscope with a magnification of 25,000x. before observation, the surface of nanocomposite was coated by a sputter coater to boost its conductivity. f. crystallinity analysis the diffraction angle of bc/cuo nanocomposite was determined using x-ray diffraction (xrd) (panalitycal expert-pro). the segal equations were then applied to calculate a crystallinity degree (cr) and crystallinity index (ci) of the membrane, as illustrated in equations 1 and 2. the scanning was performed at a diffraction angle of 10o80o. 𝐶𝑟 = 𝐼(002) 𝐼(002)+𝐼(𝑎𝑚) 𝑥100% (1) 𝐶𝐼 = 𝐼(002)−𝐼(𝑎𝑚) 𝐼(002) 𝑥100% (2) where i(am) represents the diffraction amorf intensity at about 18° and i(002) refers to the highest diffraction intensity at 22°-23°. g. functional group analysis the fourier transform infra-red (ftir) test was conducted to identify the changes in intermolecular interactions and chemical bonding in bc/cuo/graphene nanocomposite membranes. spectra were collected at a range of 400-4000 cm-1 and then matched with ir correlation table to see bond issues of bc/cuo/graphene nanocomposite. h. mechanical strength the mechanical strength of the nanocomposite was performed using an astm d638v tensile test. tensile testing was performed with tensile test equipment (techno lab, indonesia) at a maximum load of 50 n. the samples were sliced with a scissor according to astm d638-v and put between tensile testing holders. for each sample, the rate used was 3 mm/min. iii. results and discussions a. morphology analysis figure 1 represents the surface morphology of bc control (a), with the addition of cuo on bc nanocomposites (b) and the addition of graphene to bc/cuo nanocomposites. 110 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) surface porosity was created during the synthesis of the bc/cuo/graphene nanocomposite by freeze-dry method. in the vacuum freeze-drying operations, the water content of the bc/cuo/graphene nanocomposite is frozen to restrict the material's mobility and then sublimated, limiting form modifications, resulting in porosity in the nanocomposite surface. fig. 1. surface morphology of bc nanocomposite with 0% cuo (a), 1% cuo (b), cuo and 0.1% graphene (c), cuo and 0.3% graphene (d), and cuo and 0.5% graphene (e) figure 1(b) reveals an interaction between cuo and bc. the spherical, dark, aggregated cuo is clearly visible, and 1% cuo is evenly distributed uniformly on the surface. this is owing to the surfactant ctab's assistance in the binding between bc and cuo, as described in earlier investigations [16]. the graphene was filled porosity by adding graphene to bc/cuo nanocomposite tissue. the porosity of bc was also confirmed in another study, in which the addition of go/cuo was also able to fill the porosity of bacterial cellulose issn: 2580-0817 journal of mechanical engineering science and technology 111 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) membranes [23]. graphene is represented by a dark, flat plate. as figure 1 (d), the addition of graphene also makes some bonds with cuo, which is indicated by the sticking of cuo spheres on the graphene sheet [26]. this is indicated by bonding from cuo and graphene and assisted by ctab as a surfactant [28]. b. crystallinity analysis figure 2 shows the diffraction angle obtained from the xrd characterization. in all samples, 4 main peaks can be observed in figure 2: 14.4o, 16.7o, 22.6o, and 26.3o, which are indicated the cellulose i by these peaks [29]. bc has a form of cellulose i with crystal planes [110], [110], and [200]. by addition cuo-nps, new peaks appear at 35.4o and 38.6o [13, 21]. these peaks reflect the monoclinic crystal plane bonding type, which is the index miller is [111] and [111] [19]. table 1 presents further information regarding comparing cellulose crystallinity on bc/cuo/graphene nanocomposite. fig. 2. x-ray diffraction angle of bc/cuo/graphene nanocomposite table 1 is a presentation that is used to facilitate a comparison of the effect of the addition cuo-nps, and graphene in a bacterial cellulose network. the crystallinity of nanocomposite can be described by the crystallinity index (ci) and degree crystallinity (cr). when the segal equation is used to compute the degree of crystallinity and crystal index in each sample, the crystallinity of cellulose may be seen at 22.6o [32]. as described in table 1, the bacterial cellulose peak angle at 22.6o gets the effect of adding graphene where the crystallinity is reduced so that it will result in changes to other properties [27]. the peak angle at 22.6o represents [200] plane, which is the crystallinity of 10 15 20 25 30 35 40 45 50 55 60 in te n s it y ( a .u ) 2theta (degree) cuo 1% + graphene 0.5% cuo 1% + graphene 0.3% cuo 1% + graphene 0.1% cuo 1% control 1 1 1 1 1 1 1 1 0 1 1 0 2 0 0 112 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) cellulose. this peak continues to decrease along increase in the graphene content [28]. this result contrasted with the previous study, which found that adding graphene oxide can increase bacterial cellulose's crystallinity and tensile strength. this is due to the fact that cellulosic polymeric chains are prone to crystalline conformation due to intermolecular interaction between crystal cellulose chains [35]. the conjunction of this fluctuation with increasing nanofibril crystallization might lead to a crystallinity reduction. although more study is needed to pinpoint the specific mechanisms by which graphene affects crystallinity, the xrd data showed that graphene had an impact on bc's crystal structure. table 1. crystallinity and peak bc/cuo/graphene nanocomposite samples diffraction angle (degree) crystallinity (%) ci cr bc control 14.3 16.4 22.5 26.4 87.4 88.8 bc + 1% cuo 14.3 16.7 22.5 26.4 35.6 38.7 81.1 84.1 bc + 1% cuo + 0.1% graphene 14.4 16.8 22.6 26.4 35.6 38.7 78.0 81.9 bc + 1% cuo + 0.3% graphene 14.4 16.5 22.6 26.4 35.6 38.7 77.1 81.4 bc + 1% cuo + 0.5% graphene 14.3 16.6 22.6 26.4 35.6 38.7 74.6 79.7 c. ftir analysis figure 3 represents the intermolecular bonding of bc/cuo/graphene nanocomposites. at 3400-3500 cm-1 range represent intramolecular bonding 3o· · ·h–o5 of bc [34]. both the lowered depths indicate that the o-h bond is affected by the contribution of graphene to the bc network. peaks in absorption at wavelengths about 2900 cm-1 on bc/cuo nanocomposites and graphene in alkyl form reveal the nature of c-h bonds [30]. the spectra of 1595 cm-1 until 1597cm-1 demonstrate that aromatic carbon (c=o) has a double bond [31]. the findings of the ftir characterization generally did not show any notable changes. no new peaks or bonds can be identified in the transmittance readings, which just vary little. the graphene was indicated by c=o stretching bonding, which is indicated by the presence of a valley in the wavelength of 1591 cm-1 by bc/cuo/graphene nanocomposites spectrum. this transmittance demonstrates that graphene is present in the nanocomposite [32]. the molecular bonding between bc, cuo, and graphene is illustrated in figure 4. nonetheless, the bonding of cu-o-h formation, which come about as a result of the interface among both carboxyl or hydroxyl groups and copper, has a significant impact on the adsorption of graphene on the copper oxide nanoparticles [28]. the formation of bonds between graphene and cu can be seen with changes in the depth of the cu-o-h transmittance valley, which decreases, and the hydrogen content is replaced by graphene and forms cuo-c bonds [38]. because there is no free molecular bonding of oh on graphene oxide, the reduced tensile strength of this research assumed that the graphene we used was a substance that potentially ruined and disrupted the bacteria's cellulose chain network [29]. this issn: 2580-0817 journal of mechanical engineering science and technology 113 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) interaction damaged the main network of cellulose crystals, causing the tensile strength of the bc/cuo/graphene nanocomposite to continue to decrease. figure 3. ftir spectra of bc/cuo/graphene nanocomposite fig. 4. illustration of molecular bonding of bc/cuo/graphene nanocomposite d. mechanical strength the comparison of tensile strength of bc/cuo/ nanocomposite with variations adding of graphene was illustrated in figure 5. according to the bar graph, a bc with 1% cuo nanocomposite with a tensile strength of 69.643 mpa has the maximum tensile strength. the bc/cuo/ graphene 0.1% of 54.078 mpa, bc/cuo/graphene 0.3% was 44.031 mpa after that control material has a tensile strength in 40.652 mpa, and for the last, bc/cuo/graphene 0.5% was 29.324 mpa. 4000 3500 3000 2500 2000 1500 1000 500 0 50 100 150 200 250 300 350 400 450 500 550 600 t ra n s m it ta n c e ( % ) wavenumber (cm-1) cuo 1% graphene 0,5% cuo 1% graphene 0,3% cuo 1% graphene 0,1% cuo 1% control cu-o-c c=oc-ho-h 114 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) fig. 5. comparison bar of tensile strength of bc/cuo/graphene nanocomposite molecular interactions in bc/cuo/graphene nanocomposites have a significant impact on the variations in mechanical strength. this finding implies that the connection between bc and cuo was strong but that the interaction between bc/cuo and graphene did not contribute much to mechanical improvement. bonding bc/cuo/graphene makes agglomeration and bc fiber randomly dispersion and makes stress distribution not uniform. the non-uniform distribution of cuo/graphene bonding causes agglomeration of nanoaprticles in the bc network, which makes bc fiber disperse erratically and results in an uneven distribution of stress in bc/cuo/graphene. asymmetrical network and distribution stress cause the dispersed load increases only shortly so that accelerating the cracking process and weakening the network on the composite [33]. iv. conclusions the study of bc/cuo nanocomposites with variations of graphene has been completed properly. a vacuum filtration process and freeze-drying are used to retain porosity. adding graphene forms some connections with cuo, which is clearly apparent from the cuo spheres' adhesion to the graphene sheet. also, graphene can reduce crystallinity at a diffraction angle of 22.6(, indicating that the addition of graphene interferes with the cellulose crystals by splitting the molecular bonding bacterial cellulose. besides, graphene affects o-h, c-h, c≡c, and c=o bonds. the adsorption of graphene on the copper oxide nanoparticles is significantly influenced by the bonding of cu-o-c formation, which results from the interface between both carboxyl or hydroxyl groups and copper. but, the mechanical properties of bc/cuo/graphene nanocomposite were reduced from 69.643 mpa issn: 2580-0817 journal of mechanical engineering science and technology 115 vol. 6, no. 2, november 2022, pp. 107-118 maulana et al. (effect of graphene addition on bacterial cellulose-based nanocomposite) to 29.324 mpa. in the future, the nanocomposite bc/cuo/graphene potentially be used in a variety of applications, including packaging, the food sector, and medicine. acknowledgment we would like to express our gratitude to drtpm kemendikbud-ristek, particularly for providing funding for penelitian kompetitif nasional, penelitian dasar, with a contract number of a research project is 034/e5/pg.02.00.pt/2022. references [1] h. j. song, h. li, j. h. seo, m. j. kim, and s. j. kim, "pilot-scale production of bacterial cellulose by a spherical type bubble column bioreactor using saccharified food wastes," korean j. chem. eng., vol. 26, no. 1, pp. 141–146, 2009, doi: 10.1007/s11814-009-0022-0. [2] m. pahlevan, m. toivakka, and p. alam, "mechanical properties of tempo-oxidised bacterial cellulose-amino acid biomaterials," eur. polym. j., vol. 101, pp. 29–36, 2018, doi: 10.1016/j.eurpolymj.2018.02.013. 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(effect of graphene addition on bacterial cellulose-based nanocomposite) [36] ž. mitić, g. s. nikolić, m. cakić, p. premović, and l. ilić, "ftir spectroscopic characterization of cu(ii) coordination compounds with exopolysaccharide pullulan and its derivatives," j. mol. struct., vol. 924–926, no. c, pp. 264–273, 2009, doi: 10.1016/j.molstruc.2009.01.019. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 85-94 85 doi: 10.17977/um016v6i22022p085 study on predictive maintenance of v-belt in milling machines using machine learning reza aulia rahman1*, mohammad faishol erikyatna1, achmad fauzan hery soegiharto1 1mechanical engineering department, university of muhammadiyah malang, jalan raya tlogomas no. 246, malang, 65144, indonesia *corresponding author:rezarahman@umm.ac.id article history: received: 8 december 2021 / received in revised form: 4 september 2022 / accepted: 29 september 2022 abstract towards industry 4.0, monitoring the degradation of machine tools’ components becomes a key feature so that smooth productivity is achieved. to preserve the functionality and performance of the machine tools, proper maintenance activities must be planned and carried out. v-belt is important component in machine tools that transmits power from the electric motor spindle in order to machine to work and cut desired material properly. the purpose of this research is to develop a predictive maintenance system for v-belt milling machine krisbow 31n2f using machine learning. the machine learning algorithm models using multiple and simple linear regression algorithm was developed in an open-source program. the test results show that the machine learning model has a high accuracy value in both the training data and the testing data. the multiple linear regression model has mse value of 5.8830x10-6 and mae value of 0.002. the simple linear regression model has an mse value of 0.0004x10-6 and mae value of 0.162. the results shows that the use of the linear regression algorithm as a support for determining the prediction of rul vbelt milling machine model 31n2f (bs) is successfully carried out. copyright © 2022. journal of mechanical engineering science and technology. keywords: linear regression, machine learning, milling machine, predictive maintenance, v-belt i. introduction the manufacturing sector is witnessing a rapid digital transition to smart manufacturing with more emphasis on efficiency and effectiveness [1], [2]. the development of smart manufacturing intended to result in intelligent and autonomous products and production processes such as cyber-physical systems (cpss), cloud computing, the internet of things (iot), the internet of services (ios), big data, robotics, and augmented reality under a single system [2–4]. towards the so-called industry 4.0, monitoring the degradation of machine tools’ components becomes a key feature so that smooth productivity is achieved [4]. however, many manufacturing companies are still reluctant to adapt to this new situation [5]. machine tools are designed and constructed according to the standards and specifications in order to make a good quality product. machine tools comprise hundreds of components that interact and function together during the machining process. therefore, the cause and effect of machine tool degradation at the component and its subsystem becomes complex [6]. this complexity can lead to a lack of understanding of machine tool degradation. thus, the effects of the failure of a single mechanical component and its propagation cannot be properly identified and assessed [7]. to preserve the functionality 86 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) and performance of the machine tools, proper maintenance activities must be planned and carried out. predictive maintenance is a strategy for maintenance that takes the current state of the equipment into consideration when performing maintenance. predictive maintenance allows corrective maintenance to be scheduled in time prior to a failure situation. in predictive maintenance, repetitive analysis and evaluation of gathered data drive failure mode forecasting models. these models are trained to forecast a component's health, failure probability, or remaining useful lifetime (rul) [6], [7]. by predicting rul, machine tools’ condition could be monitored and might prevent failure prior to the event. current technological advancements provide a tremendous opportunity for predictive maintenance to use intelligent data condition monitoring. machine learning (ml) has the potential to be applied [8]. ml can improve system availability, lowered maintenance costs, and boost workload. in addition, ml is capable of making recommendations about the optimal timing and actions to perform maintenance interventions [9]. luo et al. and kim et al. resume their review that almost all machining processes ranging from conventional to non-conventional, have been made through using ml [10], [11]. milling machines are one of the machine tools that have been studied using ml. tool wear monitoring and prediction using ml in milling machines have been studied by cho et al. [12], wu et al. [13], and d’addona et al. [14]. besides, chatter and vibration during the machining process in milling machines using ml have been studied by peng et al. [15], yuan et al. [16], and zapciu et al. [17]. however, the v-belt in milling machine has not yet studied, although v-belt is important to transmit power from motor to spindle machine in order for machine to work and cut desired material properly. in this research, the milling machine krisbow type 31n2f in mechanical engineering laboratory at the university of muhammadiyah malang with the photo showed in figure 1a is the subject of the research. in this milling machine, the electric motor generates power and transmits it to pulley 1 that attached in the output shaft of the motor to pulley 2 by vbelt 1. then, the power is transmitted to pulley 3 that attached to the spindle system by vbelt 2 as it is shown using the flowchart in figure 1b. this research only focuses on v-belt 1, since the development of the predictive maintenance program for v-belt 2 is coherence and identical to v-belt 1. ii. material and methods ml has enabled machines to learn, improve, and perform a certain activity using data without being explicitly programmed. the problem-solving process using ml is shown in figure 2. at first, the problem must be defined, and a suitable ml analysis method must be chosen. there are several ml algorithms provided, such as supervised learning, unsupervised learning, and reinforced learning [11]. therefore, the data must be collected and preprocessed into a form that can be directly used for the analysis. a model for the data is then developed and evaluated. finally, the results are analyzed to obtain the solution to the problem. several iterations are typically required in order to obtain the desired results. traini et al. have made an initial machine-learning framework for the wear level of the tools at milling machines with a variety of cutting parameters [18]. issn: 2580-0817 journal of mechanical engineering science and technology 87 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) fig. 1. (a) krisbow milling machine type 31n2f and (b) its power transmission flowchart. fig. 2. problem-solving process using machine learning [11]. in this research, the rotational motor speed and the usage duration of the milling machine are the most critical parameters. rotational motor speed is the main input value from an electric motor that could be further calculated for the force analysis in the v-belt during the machining process. this force is further analyzed in the v-belt life calculation. usage duration determines how long v-belt life remained until the program that we used gives a warning to the operator. a. v-belt life calculation the calculation was carried out using several parameters shown in table 1. belt circumferential speed (v) was calculated using equation 1, where d is motor pulley diameter and n is rotational motor speed. thus, by measurements and using known data obtained from the machine catalogue and measurement, we got 43 mm for d and 1420 rpm for n. we then obtained v was 3.195 m/s. the value of n is not changed, although the variation of cutting speed used to cut workpiece material varied, since the variation of cutting speed is subject to change with v-belt configuration. then, motor torque (t) was calculated using equation 2, where p is the motor power. using data from the machine catalogue and checking it by observation, we got p is 1.5 kw, and we then got t equal to 1,028.873 kgf.mm. 𝑉 =  𝐷 𝑁 60,000 ............................................................................................................ (1) 𝑇 = 9.74 × 105 × 𝑃 𝑛 ............................................................................................ (2) 88 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) table 1. parameters and calculation results to calculate the rul of the v-belt. parameter symbol calculation result belt circumferential speed v 3.195 m/s motor torque t 1,028.873 kgf.mm belt effective force 𝑭𝒆 47,854 kgf number of belt revolutions per second u 3.496 rev/s maximum belt tension 𝛔𝒎𝒂𝒙 102.293 kg/cm² fatigue limit or endurance limit 𝛔𝒇𝒂𝒕 90 kg/cm² the basis of fatigue test 𝑵𝒃𝒂𝒔𝒆 10⁷ number of pulleys x 2 for materials made of rubber and cotton m 8 next, the value of motor torque (t) obtained was used to calculate belt circumference force (𝐹𝑒 ) with r is pulley radius 21.5 mm as shown in equation 3. we then obtain 𝐹𝑒 47,854 kgf. the value of belt circumferential speed (v) was used to calculate number of belt revolutions per second (u) in equation 4 where l is the length of v-belt. the length of vbelt was 0.914 m obtained from measurement. we then obtained u 3.496 turns/s. 𝐹𝑒 = 𝑇 𝑟 ................................................................................................................. (3) 𝑈 = 𝑉 𝐿 ................................................................................................................... (4) next, the value of 𝐹𝑒 was used to calculate the maximum tension on belt (𝜎𝑚𝑎𝑥) with the formula shown in equation 5 where 𝜎𝑜 is stress within v-belt 12 kg/cm 2 obtained from machine catalog, a is the surface area of v-belt 1.38 cm2 obtained by measurement, eb is modulus elasticity of the belt 300 kg/cm2 obtained from machine catalog, h is belt width 10.5 mm, dmin is motor pulley diameter 43 mm,  is the density of solid woven cotton belt which is 7.5 × 10−4 kg/cm3 obtained from machine catalogue, and g is gravitational value 9.81 m/s2. therefore, we obtained 𝜎𝑚𝑎𝑥 is 102.293 kg/cm 2. σ𝑚𝑎𝑥 = 𝜎0 + 𝐹𝑒 2𝐴 + 𝐸𝑏 ℎ 𝐷𝑚𝑖𝑛 + γ 𝑣2 10.𝑔 ................................................................... (5) at last, the life of the v-belt (h) was calculated using equation 6 where the basis of fatigue test (nbase) is 10 7, number of pulleys (x) is 2, 𝜎𝑓𝑎𝑡 is fatigue limit of the given v-belt material 90 kg/cm2, and m is a constant value of the given v-belt material made of rubber and cotton 8. hence, according to the calculation, the age of the belt reaches 142,486 hours which means v-belt could be used properly without any wear and fatigue issues until 142,486 hours of use. based on our observation, rotational motor speed (n) does not change whether the milling machine is idle or in a cutting state. this number was used as the basis for determining the rul, as shown in equation 7. 40 hours is selected as a threshold time by our observation in a factory where the milling machine is fully operational for five days with eight hours for each workday. threshold time is used to give the operator a warning that the issn: 2580-0817 journal of mechanical engineering science and technology 89 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) v-belt is going to not work properly in the upcoming 40 hours. so, the rul used in this study is 102,486 hours. as a result, if the rul is reached at a certain time in the future, the maintenance operator could order a new v-belt and schedule the maintenance to change the v-belt. however, observation of the exact time of milling machine usage is quite tough. therefore, we build and try the implementation of a machine learning algorithm to help the operator monitor the condition of the milling machine. 𝐻 = 𝑁𝑏𝑎𝑠𝑒 3600 𝑈 𝑋 ( σ 𝑓𝑎𝑡 σ 𝑚𝑎𝑥 ) 𝑚 ..................................................................................... (6) 𝑯 = 𝟏𝟎⁷ 𝟑𝟔𝟎𝟎. 𝟑. 𝟓. 𝟐 ( 𝟗𝟎 𝒌𝒈/𝒄𝒎² 𝟏𝟎𝟐. 𝟐𝟗𝟑 𝒌𝒈/𝒄𝒎² ) 𝟖 = 𝟏𝟒𝟐, 𝟒𝟖𝟔 𝒉𝒐𝒖𝒓𝒔 remaining useful life (rul) = belt life (h) – threshold time ....................... (7) rul = 142,486 hours – 40 hours = 102,486 hours b. data collection machine learning was implemented using a synthetic dataset of 50 data points starting from 5 minutes to 250 minutes with increments of 5 minutes for each data as shown in table 2. we use a synthetic dataset to develop the predictive maintenance program since no prior sensor has been applied to the machine yet so that history data could not be obtained. several studies have used synthetic datasets for driver telematics, telemedicine, and healthcare [19]– [21]. these studies depend on the synthetic dataset as an input because real data were lacking. those studies show great promise to develop the machine learning prediction with up to 96% data compared to real data were included. therefore, the use of synthetic data is appropriate for this research. table 2. synthetic dataset for krisbow 31n2f usage history data. time 𝑡1 𝑡2 𝑡3 … 𝑡49 𝑡50 usage duration [min.] 5 10 15 … 245 250 c. modelling the step to implement machine learning for predictive maintenance is shown in figure 3. preparing the dataset is the first step in implementing machine learning. the data for this research were derived from a historical synthetic dataset about milling machine usage. the data was manually entered into microsoft excel. this data collection eventually result in training data, test data, and data containing predicted rul targets. the datasets were inputted and managed in python language using pandas dataframe library in anaconda navigator with a jupyter notebook and laragon integration software, which are all opensource programs. laragon software is used as a data processor for the latest research results. the laragon software can input the value of the result of python programming so that the value obtained was used in the decision-making program. 90 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) fig. 3. flowchart of implementing machine learning [22]. next, the data is processed to determine the independent and dependent variables from the uploaded data, which are usage time and rul, subsequently. then, we separated the datasets for model selection. the data were divided into training data, which accounts for 80% of the total sample synthetic data, and testing data for the rest. the algorithm is determined at this stage. a linear regression algorithm will be used in this study as supervised learning is one of the most high-applicable method in ml [23]. training data and testing data will be used to measure the accuracy value of the machine learning model created to be evaluated. further, the linear regression model is trained using training data. python is the programming language used to train this model. then, the model was evaluated. if the result is satisfactory, the step is continued to predict the rul. on other hand, if the result is still considered unsatisfactory, hyperparameter tuning needs to be done to improve the result from the model. the term "tuning hyperparameters" refers to selecting parameter groups for machine learning. hyperparameter tuning is used to obtain performance results that are significantly better than those obtained previously. in short, when creating a complex model, the variables affecting the output must be remapped. typically, hyperparameter tuning is performed to optimize the performance of the created model. after training, evaluating, and testing the model with additional hyperparameters, the goal is to obtain the best performance, or the model with the lowest error value, and then predict the rul using the test data. the predicted values are then compared to the test data's rul target values. this is done to ascertain the model's performance on actual data. following the result, the obtained predicted value will serve as supporting data for the decision-making program. the decision-making program is updated in real-time using the most recent data from the database. the most recent data retrieval from the database is used to determine the age of the v-belt. thus, the program will display the decisions that must be made based on the most recent data received by the program during this process. the results of the operation calculations will be entered into the database, serving as the most up-to-date information on the v-belt's rul. issn: 2580-0817 journal of mechanical engineering science and technology 91 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) iii. results and discussions it can be said that “machine learning algorithms use computational methods to learn information directly from data without using predefined equations as a model” [24]. using our training and testing data, we evaluated using a scikit-learn library that our ml model has a 99.00% accuracy rate on all pieces of data, both training and testing, as shown in figure 4a and figure 4b, respectively. this accuracy value indicates that the machine learning model's primary performance has only a few errors. this demonstrates that the machine learning model performs optimally when the desired output is specified. the accuracy of the developed model is high due to only milling machine usage time is needed for predicting vbelt’s rul calculation as in a real condition. therefore, we use synthetic dataset with milling machine usage time only. the value of belt life (h) and threshold are the one to look for in further research because of variety of belt used in another machine tools and ordering time of the machine tools’ components according to its companies’ policy. apart from determining the accuracy value, it can also determine the magnitude of an error in a machine-learning model using a scikit-learn library. the mean square error (mse) and the mean absolute error (mae) can determine the magnitude of the model error. the smaller mse and mae values, the better the regression model performs. as shown in table 3, the mse and mae values are both less than one. this test demonstrates that the mse and mae values for each model are acceptable. this shows the effectiveness of the linear regression method in determining the prediction of the rul v-belt milling machine model 31n2f compared to the support vector regression (svr) model by 98.95% for tool wear and rul prediction by benkedjouh et al. [25] and decision tree model by 94.30% for tool condition monitoring by krishnakumar et al. [26]. table 3. model accuracy test results. model value accuracy evaluation size training testing mse mae 1 99% 99% 5.8830x10-6 0.002 2 99% 99% 0.0004x10-6 0.162 fig. 4. data visualization and their linear regression on (a) data training and (b) data testing. 92 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 2, november 2022, pp. 85-94 reza et al. (study on predictive maintenance of v-belt in milling machines using machine learning) iv. conclusions this study obtained that the rul of the v-belt in a milling machine could be predicted using the linear regression method using machine learning to use an open-source program such as phyton programming, anaconda, laragon, and jupyter notebook. the use of simple and multiple linear regression algorithms has an accuracy of about 99% on all data, both training data and testing data. in addition, these two algorithm models have low error rates. the multiple linear regression model has an mse value of 5.3880x10-6 and an mae value of 0.002. the simple linear regression model has an mse value of 0.0004x10-6 and an mae value of 0.162. further research needs to be carried out using real historical data to test the developed model, and further measurement system needs to be implemented in the machine to monitor the usage duration of the machine. all in all, the prediction of the rul of v-belt krisbow milling machine model 31n2f has been successfully carried out. acknowledgment this work was supported by blockgrant puskarekatek 2022 faculty of engineering university of muhammadiyah malang. references [1] e. brynjolfsson and a. mcafee, the second machine age: work, progress, and prosperity in a time of brilliant technologies. w.w. norton & company inc., new york, united states, 2014. 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[26] p. krishnakumar, k. rameshkumar, and k. i. ramachandran, “tool wear condition prediction using vibration signals in high speed machining (hsm) of titanium (ti6al-4v) alloy,” in procedia computer science, 2015, vol. 50, doi: 10.1016/j.procs.2015.04.049. journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 23-33 23 doi: 10.17977/um016v6i12022p023 effect of variation of sic and mg mass fraction on mechanical properties of al-sic composite using stir casting method sumarji1, naufal fardio albajili1, mahros darsin1*, rahma rei sakura1, andi sanata1 1department of mechanical engineering, faculty of engineering, university of jember, jl. kalimantan 37, jember, indonesia 68121 *corresponding author: mahros.teknik@unej.ac.id article history: received: 26 january 2022 / received in revised form: 9 june 2022 / accepted: 12 june 2022 abstract al-sic is a composite composed of aa6061 as a matrix and sic as a reinforcement particle. the variation of mass added will affect the mechanical properties of the composite because al-sic is hardenable, which means that its mechanical properties can be improved by adding the reinforcement component. however, an excessive portion of sic leads to a decrease in mechanical properties. the purpose of this study was to find the optimal composition of the addition of sic into the aluminium matrix to gain maximum tensile strength and hardness. the mass fraction variation that would be used in this composite was the addition of 6%, 8%, and 10% sic with the addition of 1% mg as a wetting agent. the mixing process used the stir casting method. the process of adding sic and mg was carried out by melting the aluminium while stirring it for a certain time before it went to the furnace. the astm e8/e8m standard was used for observing the tensile strength of the specimens. machining was carried out before testing. the specimens were also tested for hardness using the rockwell hardness method. the result shows that the addition of sic at the amount of 6%, 8%, and 10% sic increased the ultimate tensile strength by154.10 mpa, 175.01 mpa, and 198.14 mpa, respectively. similarly, the hardness also increased up to 30.1 hrf, 48.1 hrf, and 66 hrf, respectively. microstructure observation also confirmed that a 10% sic fraction results in less defect and good wettability. the addition of 10% sic and 1% mg resulted in maximum tensile strength and hardness and the best microstructure. copyright © 2022. journal of mechanical engineering science and technology. keywords: al-sic, composite, mass fraction, stir casting i. introduction in this modern era, many industries are trying to improve material properties. they compete to find materials and also higher technology, one of which is to make technology or materials that are lighter and more practical but have better mechanical properties. composite is an alternative material that complies with these requirements [1]. in addition, some composites are corrosion resistance, design flexibility, durable [2], and fire resistance [3]. many kind of composites: metal matrix [4]–[9], polymers-ceramic [3],[10],[11], metalceramic [12]. normally, composite consists of a matrix filled with reinforcement material. there are three forms of reinforcement phase: fibre, flake, or particulate [13]. al-sic is a kind of composite that is made of aluminum as a matrix, and sic particles are added as reinforcement. the properties of al-sic are well known for their lightweight, high strength, high specific modulus, high fatigue strength, high hardness, low density, and good thermal conductivity [1]. it is reported that al-sic composite has a high mechanical property yet is lightweight [14]. 24 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) the al-sic is commonly produced by stir casting [15]–[19]. this popularity of this method because stir casting is less expensive and has the ability for mass production [18]. some attempts have been carried out to improve the mechanical properties of al-sic composite. there are three concerns: (i) design of the stirrer, (ii) addition of another element as a strengthening agent, and (iii) varying the sic composition. of the first group, it is reported that adding the stirring speed was able to increase the hardness but decrease the tensile strength [19]. sahu & sahu [14] introduced a variety of stirrer designs (number of stirrers, impeller blades, position of stirrer to the base of the crucible, and stirrer speed). optimization of the combination of those stirrer designs might be able to achieve higher strength, lighter weight, yet lower cost [14]. another researcher introduced a vortex-free stir casting to avoid air trapping in the composite, which results in increasing tensile strength, hardness, and decreasing wear rate and porosity [20]. the second group of researchers is concerned with adding another element to the composite as a reinforcement. krisna & xavior [9] reported that adding graphite to the alsic composite would increase the strength but decrease the density [20]. while the addition of fly ash on al-sic followed by heat treatment could increase the hardness and impact strength of al-sic/fly ash composite [5]. another effort to improve the mechanical properties of al-sic composite was by increasing the sic mass fraction in the composite. the strength and hardness of the al-sic composite can be increased by adding the sic mass fraction as reinforcement. maurya et al. [16] investigated the effect of adding sic to al6061/sic metal matrix composite. they added a variety of mass fractions of sic up to 5%. the result showed that the maximum tensile strength and hardness were achieved by 5%wt sic [16]. rahman & rashed [21] added up to 20% of sic with a tier of 5%. they found that the addition of 20% wt of sic results in the maximum tensile strength and hardness [21]. the increase of tensile strength was linear with the increase of the sic percentage except for 15% wt. the addition of evenly distributed sic particles on the aluminium matrix makes the mechanical properties of alsic better [22]. moses et al. [23] studied the strengthening mechanism of the aa6061 matrix by adding sic for wt% of 0, 5, 10, and 15. they found that the tensile strength increased by 119 mpa, 158 mpa, 192 mpa, and 188 mpa, respectively [23]. increasing up to 10% of sic effects increase the strength, while 15% results in reducing it. hashim et al. [4] stated that hardness, tensile strength, and wear resistance increase with the addition of 10-15% sic. if the addition of sic is more than 15%, the hardness value will increase but will decrease other mechanisms [4]. therefore, it is necessary to find out an ideal proportion of sic which will produce optimal mechanical properties. the purpose of this research was to obtain the maximum tensile strength and hardness in al-sic composites by varying the composition of the addition of sic. ii. material and methods the aluminium was used as matrix material, and sic particles were added as reinforcements to prepare composites in this study. we did not test the composition of the aluminium. however, according to the literature, the chemical composition of aluminium was presented in table 1. the sic as the reinforcement was in a powder form with a maximum grain size of 50 µm. the composite manufacturing used stir casting. this method was chosen because it is easy, simple, and low cost. figure 1 shows a schematic of a stir casting process. issn: 2580-0817 journal of mechanical engineering science and technology 25 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) table 1. the aluminium composition used as matrix material (wt%) in this experiments [21] elements fe si mn cu mg al % 0.16 0.19 0.01 0.01 0.01 balance fig. 1. stir casting scheme [6] the addition of sic as reinforcement varied in amounts of 6%, 8%, and 10%. magnesium (mg) 1% was added as a wetting agent. the mould was made of steel and produced a solid cylindrical shape and produced 3 specimens at a time. figure 2 shows an example of casting results. the amount of material to be smelted according to the weight ratio, based on the total weight of 650g. the detailed composition of the matrix (al), reinforcement (sic), and wetting agent (mg) is presented in table 2. table 2. details of composite composition sic (wt%) sic (g) mg 1% (g) al (g) total (g) 6% 39 6.5 604.5 650 8% 52 6.5 591.5 650 10% 65 6.5 578.5 650 the amount of each element was weighted carefully using a scale. the crucible was coated with a mortar, and then started to heat up to 750 oc. then aluminium was put in the furnace, while, preheating of sic and mg powder was in a different furnace. when aluminium was melted, pour the sic and mg powder into a smelting furnace, and stir it at a speed of 450 rpm for five minutes. argos gas was blown into the furnace during the stirring and lifting process. before pouring the melted into the mould, ensure to remove the slag on the melt. the mould was opened when it was already cold. an example of the casting result is presented in fig. 2. tensile testing was carried out according to astm e8/e8m – 13a standards. the specimens were machined lathe to obtain standard dimensions. each composition was 26 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) replicated thrice. figure 3(a) shows a test specimen ready for tensile testing. the dimensions of the tensile test specimen can be seen in figure 3(b). fig. 2. casting result fig. 3. casting result after machining (left), and astm e8/e8m – 13a standards (right) hardness testing was carried out using the rockwell method. this test was carried out on an f scale using a 1/16 inch indenter ball and using a load of 60 kgf. before the hardness test, the specimens were polished using 200 to 600 grit sandpaper, then polished using an autosol and velvet cloth. the next step is the etching process using an etchant, which is composed of 2 ml hf, 3 ml hcl, 5 ml hno3, and 190 ml h2o. the data collection process was carried out with 10 experiments for each specimen. figure 4 shows the hardness testing specimens. fig. 4. hardness testing specimens issn: 2580-0817 journal of mechanical engineering science and technology 27 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) microstructure testing was carried out using a scanning electron microscope (sem) and an optical microscope. the optical microscope bx451m was used, which has a fine focus movement of 100 μm and minimum graduation of 1 μm. sem hitachi tm3030plus was employed for insight microstructure observations. it has a magnification capacity of 120,000× and a filament image resolution of 640×480 pixels and 1,280×960 pixels. iii. results and discussions tensile test in this study, tensile testing was carried out with astm e8/e8m. figure 5 shows the value of the tensile strength of the al-sic composite chart. it is obvious that the more the wt% sic, the stronger the composite is. fig 5. the value of the tensile strength of the al-sic composite chart it can be seen that the highest tensile strength value is the al-sic composite of 10% sic. increasing the percentage of sic in aluminium makes the composite stronger. it proved that sic as the reinforcement agent in the aluminium matrix worked properly. it is also supported by stirring which results in a well-mixed and well-distributed composite. equally distribution of sic particles can improve the mechanical properties of the composite [4]. according to zamheri (2011) [24], the addition of % volume fraction into molten metal affects changes in viscosity. the larger the volume fraction percentage will give a homogeneous mixture spread, and the particle deposition in the matrix becomes larger [24]. sic reinforcing particles greatly affect the mechanical properties (hardness) and the microstructure of the tested material. mohamed and abdallah (2018) explained that sic could increase the overall strength of composites as well as corrosion resistance and wear resistance [21]. according to sadi, et al. [25], porosity is a defect in the form of fine cavities formed by gases trapped during the mixing process with stirring and shrinkage during solidifying [25]. porosity is also formed by interfacial reactions because oxygen causes water vapour to appear on the surface of the sic reinforcing particles. porosity is very difficult to get rid of completely but there are ways to reduce it. one way is to add argon gas during casting because argon can inhibit the entry of air into the aluminium so that the gas content (air) in 154.17 172.01 196.36 0.00 50.00 100.00 150.00 200.00 250.00 6 8 10 t e n si le s tr e n g th ( m p a ) sic (%) 28 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) the aluminium does not change. the decrease in tensile strength of the composite can also be caused by poor wetting of the composite and its reinforcement. poor wetting can cause porosity in the interface layer which causes the stresses between the matrices to not flow properly [26]. moses, et al. [23] also studied the aa6061 matrix with sic strengthening for wt% of 0, 5, 10, and 15, and got the results that mechanical properties such as hardness and tensile strength increased by 33%, 133%, and 65.2%, respectively [23]. from this study, the most optimum result was the addition of 10% sic, and the addition of 15% sic decreased the other mechanical properties. hardness test hardness testing was carried out to determine the hardness value of the al-sic composite. the average hardness value is taken from 10 different points to get more optimal results. figure 6 shows a graph of the al-sic hardness value with mass fraction variations of 6%, 8%, and 10%. it can be seen that the more mass fraction of sic used, the hardness value increase. figure 6 shows the lowest hardness value using 6% sic with a hardness value of 30.15 hrf, while the highest hardness value uses 10% sic with a value of 66 hrf. this indicates that adding sic to aluminium will increase the hardness. following the result of krishna & xavior [9], the more sic mass fraction in the aluminium matrix, the hardest the composite be. in different matrix materials, such as ammc, the addition of sic also increased the hardness. however, an excessive of sic added to the matrix would the hardness. rahman et al. [21] found that the maximum hardness is obtained at a percentage of 10% sic. this is following the most optimum hardness value of this research with 10% sic. bandil et al. [8] also conducted experiments to determine the density, hardness (hrb), wear, and corrosion resistance of al-sic composites. they found that the density of al-sic will decrease with increasing sic booster if it is added to more than 12%, and corrosion hardness increases to 12% and then decreases when more than this amount. wear resistance also increases with the addition of sic up to 12% in al-sic composites [8]. inegbenebor et al, [27] investigated the al-sic composite particles through the stir casting process and explained that the addition of mg and sic can increase the wettability of aluminium, increase the hardness value, and reduce grain boundaries. sic is very hard compared to aluminium. if sic is added to aluminium, it will increase the hardness [28]. research conducted by rahman [21] also states that adding mg as a wetting agent can increase wettability and hardness. several things cause lower hardness values, including porosity due to gas trapped during the melting to pouring process, shrinkage during solidification, and poor interface between the matrix and the reinforcement. porosity can occur as a result of the composite manufacturing process where air from outside the melt, especially at the surface, is trapped when mixing during melting. the pressure difference between the top and bottom of the melt causes the composite particles to be sucked into the melt together with air and other impurities. porosity can also occur due to air bubbles trapped in the molten al-sic mmc during the casting process [28]. porosity can also occur due to the agglomeration of sic particles. agglomeration is a size enlargement process in which the size of the initial material in the form of fine particles will be combined or bonded to each other, resulting in a porous structure that is much larger than the starting material [29]. issn: 2580-0817 journal of mechanical engineering science and technology 29 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) fig 6. al-sic hardness values with mass fraction variations 6%, 8%, 10%. the presence of dimensional defects will reduce the mechanical properties of the composite, such as decreasing the value of strength and hardness. one of the most important things in a composite regarding the improvement of its mechanical properties is the matrix with the reinforcing interface. if the interface between sic particles and aluminium is not good enough, then the load cannot be completely distributed by aluminium to sic. the poor condition of the reinforcement interface with the matrix is caused by the difference in the thermal coefficient between aluminium and sic. this can also cause a decrease in the mechanical properties of the composite [28]. microstructure observation observation of the microstructure using an optical microscope can show conditions that show the mechanical properties and characteristics of the al-sic composite by observing the visible elements so that the image or data seen on the optical microscope can be used as the main support for the evidence that the al-sic composite improved mechanical properties. observation of the microstructure on an optical microscope can also show deficiencies or defects in the results of adding sic to aluminum and mg as a wetting agent. figure 7 is the result of observing al-sic using an optical microscope with 100× magnification. fig 7. composite with 10% sic viewed through an optical microscope with 100× magnification 30 journal of mechanical engineering science and technology issn 2580-0817 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) figure 7 shows that many sic particles are scattered on the aluminium matrix, but it can also be seen that the al-sic composite has porosity. this porosity can be caused by trapped gases during the mixing process of aluminium with sic and can also occur due to shrinkage of grain boundaries. to minimize the porosity, the addition of argon gas can be used during the process of mixing aluminium with sic. the addition of argon gas during the stirring process can prevent the bond between molten aluminium and atmospheric air to reduce the risk of porosity in the composite [7]. figure 8 presents a comparison of al-sic composites with mass fraction variations of 6%, 8%, and 10%. it can be seen from the micro observations with 10% sic variation seen that more sic particles are scattered on the aluminium matrix. this causes the tensile strength value and composite hardness value to increase. fig 8. comparison of al-sic with mass fraction variations of 6%, 8%, and 10% with 500x magnification. sem observation sem observation aims to see the characteristics of the bond between the matrix and reinforcing particles. it can be seen in figure 9 that the sic particles get a good wetting. fig. 9. sem photo of al-sic with 1000x magnification in figure 9, it can be seen that the sic particles are well wetted. this shows a good interface between the matrix and sic as a reinforced. the interface that occurs in the composite is caused by a chemical reaction on the sic surface with the aluminium matrix. issn: 2580-0817 journal of mechanical engineering science and technology 31 vol. 6, no. 1, july 2022, pp. 23-33 sumarji et al. (effect of variation of sic and mg on mechanical properties of al-sic composite) with the chemical reaction, wetting will occur better to minimize defects that may occur [30]. the addition of mg as a wetting agent also has an effect because mg can bind oxygen so that no oxygen inhibits the binding of sic with the matrix. the addition of mg affects the formation of an interface layer that can improve the mechanical properties between the matrix and the reinforcement. there is also no visible porosity around sic. the addition of mg as a wetting agent and the addition of argon gas during the mixing process can reduce the probability of voids around the sic particles, which causes porosity. if the wetting composite is not good, then what will happen is increased mechanical properties are not optimal, and also many voids are formed and making the porosity level high. iv. conclusions three conclusions can be drawn from this research. firstly, the addition of sic affects increasing the mechanical properties of the al-sic composite, especially on the tensile strength. the highest tensile strength value is 196.36 mpa with a 10% sic mass fraction. secondly, the addition of sic affects increasing the mechanical properties of the al-sic composite, especially the hardness. al-sic composites have the highest hardness value of 66 hrf with a 10% sic mass fraction. last but the least that from the observation of the microstructure, the most optimum addition of sic to aluminium aa6061 is the addition of 10% sic, because more sic is dispersed in aluminium so that the tensile strength and hardness values are more optimal. acknowledgement the authors would like to appreciate the universitas jember which provides the facilities to conduct the research. we also thank mas deny junas priawan, the technician of the materials laboratory. references [1] k. karvanis, d. fasnakis, a. maropoulos, and s. papanikolaou, “production and mechanical properties of al-sic metal matrix composites,” iop conf. ser. mater. sci. eng., vol. 161, no. 1, 2016, doi: 10.1088/1757-899x/161/1/012070. 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