Microsoft Word - numero 15 articolo 5 Fr w Iva NA No Ge Ky AT Da NA AB Co un me ov KE Wi IN spa spa fro jet des Th env E racture wing-lead atury S. Ra ASA Enginee orman F. K eneral Dynami yongchan S TK Space Div awn R. Ph ASA Marsha BSTRACT. Th oating spalla derstand thi echanics ana erview of th EYWORDS. F ing leading e NTRODUCTIO ach Spa (RCC). takes p allation of RC allation anom om various dis testing, coup scribes an ove he paper is o vironments to E mechan ding-ed aju ering and Safe Knight, Jr. ics Information Song vision, Hampt illips all Space Fligh he Space Sh tion was ob is phenomen alyses of the he fracture m Fracture me edge panels. ON ace Shuttle O These pane place during e CC coating w maly, a root-ca sciplines such pon testing, v erview of the organized as o which the S nics ana dge pan ety Center, NA n Technology, ton, VA ht Center, Hu huttle wing-le bserved near non, a root- e slip-side jo mechanics an echanics; Str Orbiter wing is ls are part of entry into Ea was observed i ause investiga h as structure vibro-acoustic structural an follows. Fir Shuttle is subj I. S. Raju et alyses o els ASA Langley Chantilly, VA untsville, AL eading edge r the slip-sid cause invest oggle region nalyses. rain energy r s comprised o f the thermal p arth’s atmosp in the slip-sid ation was con s, materials, n c testing, aero nd fracture me rst, the Shut jected are des alii, Frattura ed of the sli y Research Cen A consists of de region of tigation was ns of the ho release rates of 22 leading protection sy phere [1]. On de regions of nducted. The non-destructiv oloading testi echanics anal ttle wing-lead scribed. Nex d Integrità Struttu ip-side nter, Hampton panels that f the panels conducted. t panels wer s; Re-entry h edge panels t ystem that pro n some of th the panels. T e root-cause i ve evaluation ing, photo-m lyses that wer ding-edge con xt, the buildin urale, 15 (2011) joggle r n, VA are made of that experi As part of re conducte heating; On that are made otects the win he panels that To understan investigation n (NDE), aero micrographic i re conducted. nfiguration is ng-block appr ) 35-49; DOI: 10 regions f reinforced ience extrem f that investi ed. This pap n orbit cold; e of reinforce ngs from extr t experience nd the reason team consiste othermal, flig investigation, s presented, roach and ana .3221/IGF-ESIS.1 of carbon-carb me heating. igation, fract per presents ; Space Shu ed carbon-car reme heating extreme heat s for this coa ed of researc ght hardware, etc. This pa and the load alysis models 15.05 35 bon. To ture s an uttle; rbon that ting, ating hers arc- aper ding that http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 36 we me WI pan on jog loc are aro def cra con Th Aft are reg 1 ST 2 O T S. Raju et alii, Fr re used for ethods used to ING-LEADIN he Spac panels, T 1(c) sho nels that have Panel 9; that ggle on Panel ck side and sli e the configur ound the WL fined in Fig. acks, as show nversion proc he conversion (c) Cross-sec ter two differ eas of the RC gion, as shown TS – Space Tran OV – Orbiting V T Frattura ed Integri the stress an o characterize NG-EDGE C e Shuttle win T-seals are in ow a close-up e S-shaped cu t side of the 10; that side ip side of eac ration bound LE and is def 1(c). The RC wn in Fig. 1(d cess of fabric -coating regio (a) Wing- ctional view of rent Space Sh CC coating w n in Fig. 2. T nsportation Syste Vehicle. rità Strutturale, 1 nd fracture m e defects in th CONFIGURA ng-leading edg nstalled to clo p and cross-se urvature are c panel is calle e of the panel ch panel is ca daries on the fined in Fig. CC material c d). Note th cation. Then ons are comm -leading edge. Panels 9 and 1 Figure 1: Spac huttle landing were observed The two spall em. 15 (2011) 35-49 mechanics an he panels are ATION ge (WLE) con ose or cover t ectional view, called “joggles ed the “lock s l is called the alled the acre outer and in 1(b), while t contains a su hat these craz a sealant is a monly referred 10 and T-seal 1 ce Shuttle wing gs (Missions S d to be missi lation events 9; DOI: 10.3221/I nalyses are de presented. F nfiguration an the gap. Fig , respectively, s” (see Fig. 1 side” and is s e “slip side” a age region. T nner surfaces the span dire ubstrate region ze cracks for applied to bo d to as coatin 10. g-leading-edge STS1-102 and ing from the occurred (a) IGF-ESIS.15.05 escribed. Th Finally, analys nd geometry . 1(a) shows , of Panels 9 (c)). When T shown in Fig and is also sh The outer mo s of the WLE ection runs a n and two co rm in the co oth the OML ng layers. (b) (d) C configuration d STS-103) at WLE apex n after STS-10 hen, the frac sis results and are presented the Space Sh and 10 and T T-seal 10 is in . 1(c). In add hown in Fig. 1 old line (OM E, respectivel cross the WL onversion coa ating during and IML sur Panels 9 and 1 Cross-section o and geometry t the NASA near the top 3 on OV2-10 cture mechan d findings are d in Fig. 1. B huttle WLE, a T-seal 10. Th nstalled, it is lo dition, T-seal 1(c). The reg ML) and inner ly. The chor LE panels an ating regions the cool-dow rfaces, filling 10 and T-seal 1 of slip-side jogg y. Kennedy Spa of the joggle 03 Panel 8L an nics analyses discussed. Between adja and Fig. 1(b) he regions of ocked to a jo l 10 floats ov gion between mold line (IM rd direction r nd T-seals an containing c wn phase of the craze cra 10. ggle. ace Center, sm e in the slip- nd (b) after S and cent and f the oggle ver a n the ML) runs nd is craze f the acks. mall -side STS- http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true 102 the In cau eve LO aer Lo me loa sec He con Du rep jog 165 tem D 2 on OV-10 ermography in addition, the use investigat ents (e.g., see (c) Post OADING ENV uring ascent tempe rodynamic loa ads analyses echanics analy ading conditio conds after lif ence, both th ntributors to uring entry, t presentative e ggle regions f 50°C (3000°F mperature ran D 03 Panel 10L ndication (fro e spallation ev tion was subs Ref. 1-6). (a) Post-STS-1 t-STS-114 ther VIRONMENT a mission, th t, aerodynam eratures; duri ads act on the showed that yses were pe on. The bou ft-off. The de he lift-off an the spallation the Shuttle W entry trajector for each of t F) and occu nge is -130°C L. After the om NDE) wa vent on the n sequently con 103: OV-103 8 rmography: OV TS he Space Shu mic loads act ing entry, the e Shuttle. t the lift-off a rformed usin unding pressu efect driving nd ascent co n root cause [ WLE panels ry from the In the 22 WLE rs in the ho ≤ T ≤ 90°C I. S. Raju et e Shuttle land as observed o nose cap on nducted to d 8L. V-103 8R. Figure 2: uttle is subjec on the Shut e Shuttle exp and ascent lo ng a boundin ure load occu forces were c ondition and [6]. experience e nternational S panels is ind ot panels 8, (±200°F), wi alii, Frattura ed ded followin on OV-103 P OV-105 was determine wh : RCC spallatio cted to four d ttle; while th periences pea oading bound ng pressure lo urs at the ma calculated for descent and entry heating Space Station dicated in Fig 9, and 10. ith -130°C (-2 d Integrità Struttu ng the return anel 8R (Fig. observed du hat factors an (b) (d) Observed d on history. distinct loadi he Shuttle is ak heating; a ds the loading oad over an a aximum dynam r the boundin d landing co that depend n, the peak-he g. 3. Peak h For the on- 200°F) being urale, 15 (2011) n-to-flight mi 2(c)), indicat uring refurbis nd scenarios c Post-STS-103 during refurbis ing environm in orbit, it i and during d g on descent assumed defe mic pressure ng pressure lo ondition were ds in part on eating entry te heating reach -orbit heating the cold con ) 35-49; DOI: 10 ission (STS-1 ting a loss of shment (Fig. contribute to 3: OV-103 10L shment: OV-1 ments [1]. Du is subjected escent and l t and landing ect for the lif condition (m ad, and they e dismissed n the entry tr emperature al hes temperatu g/cooling th ndition. In th .3221/IGF-ESIS.1 114), an infra coating stren 2(d)). The r o these spalla L. 05 nose cap. uring lift-off to extreme c anding, diffe g. Thus, frac ft-off and as max-Q) abou were nearly z as being ben rajectory. Fo long the slip- ures up to ab hermal cycle, his paper, frac 15.05 37 ared ngth. oot- ation and cold erent cture cent ut 80 zero. nign or a -side bout the cture http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 38 me we BU pro loa mo bou sol unt are ass tha res sub Th An A S. Raju et alii, Fr echanics analy re performed UILDING-BL buildin progres overall oblem, object ads, materials odels such as undary condi lved and veri til the results e assembled, i sembled mod at is repeated ults are prese bjected to rigo his building-bl nalysis assum A Frattura ed Integri yses for thes d in support o Figure 3: T LOCK APPRO ng-block anal ssive manner response de tives, produc , boundary/in s finite-eleme itions, and o fied for accu can be verifie incorporating dels are solved until confide ented to exte orous peer re lock analysis mptions can b rità Strutturale, 1 e two bound of the root-ca (b) RCC WLE Typical peak en OACH AND A lysis approac [2]. Such an etermined. T cts, resources nterface cond ent models o ther approxim uracy. The p ed by compar g component d, and the re ence in the re ernal reviewer eview. If nece approach pr be challenged 15 (2011) 35-49 ding thermal ause investigat (a) D E slip-side inbo ntry temperatur ANALYSIS M ch begins wi n approach pe The hierarchy , schedule, an ditions, and t of the individ mations are a rocess at the rison to refer interface con sults are asse esults can be d rs and the st essary, the pr rovides differ d and revised 9; DOI: 10.3221/I loading cond tion are prese Definition of z oard joggle non re distribution MODELS ith basic elem ermits each st y of the build nd stakehold tools to be u dual compon assigned to t e individual c rence solution nditions, diffe essed. The p demonstrated takeholders, e ocess may be rent entry po d, analysis fi IGF-ESIS.15.05 ditions (i.e., o ented. zones. n-catalytic peak for the Space ments and b tep in the pro ding-block ap ders are defin used to solve nents are cre the individual omponent le ns or test data erent design c rocess at the d and advoca engineering re e repeated fro oints for anal indings can b on-orbit cold k temperatures Shuttle wing-le builds in com ocess to be ve pproach is pr ned. Second, to problem eated. The m l component evel is an iter a. Then, the configurations assembly lev ted by the an eports are wr om any of the lysts, stakeho be compared and entry pe s. eading edge. mplexity in a erified and its resented in F , the structur are identified material mod t models, and rative process individual co s, and various vel is also an nalysis team it ritten, and th e building-blo olders, and ex d to observe eak heating) a systematic influence on Fig. 4. First, ral configurat d. Next, ana deling proced d the models s that is repe mponent mo s load cases. iterative pro tself. Finally, he entire effo ock steps. xternal review ed behavior, that and n the the tion, alysis dure, s are ated odels The ocess , the ort is wers. and http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true bou def as p usi An Th (se pea Pan con Ne ent elem res clea the dir per Fin ana nea pla bee A f spr spa sin loc me 3 A unding respo fined. This ty part of the R ng the ABAQ nalysis Models he finite eleme e Fig. 5(a)) in ak-heating tem nel 10 and T nditions. ext, the Panel try temperatu ments in the ulting throug arly, the coat e slip-side jog ection (i.e., t rpendicular to nally, the plan alysis, the fin ar the panel ane-strain mo en removed) i failure criterio read spallatio allation did n gle event at cations where echanics analy ABAQUS is a re onses can be ype of buildin RCC spallation QUS3 comme s ent models u ncluding Pane mperature dis T-seal 10. T l 10 model sh ure of the inte acreage regio gh-the-thickne ting elements ggle in the loc the gradient o the chord d ne-strain mod nite element m apex are nea odel. The res is presented i on (or criteria n would occ not occur. N a single loca e potential sub yses. egistered tradema determined; ng-block app n root-cause ercial softwar used for the a els 9 and 10 (i stribution wa These results hown in Fig. egrated mode ons. The pea ess (TTT) str are removed cal region nea of stress in direction could del of the Pan model did no arly constant sulting throu in Fig. 8. a) that is (or ur on many ote that the o ation on a si bsurface defe ark of Dassault S I. S. Raju et and the anal proach was ap investigation re [7]. Figure 4: B analysis effort i.e., two of th as applied to t demonstrate 5(b) was co el. The mode ak entry temp ress distributi d in Fig. 7). A ar the panel a the chord di d be taken an nel 10 slip-sid ot include cra (see Fig. 6(c) ugh-the-thickn are) based on WLE panels observed spa ingle panel o ects may cont Systèmes. alii, Frattura ed lysis end-prod pplied to the n. All finite e Building-block t are presente he hot panels) this integrate e that a singl nsidered bec el had 3D elem perature distri ion in the sub As shown in apex (i.e., the irection is ne nd used in a p de joggle regi aze cracks or )), the maxim ness stress di n linear-elasti on every mi allation event on each occu tribute to a sp d Integrità Struttu ducts have te global structu element analy k approach. ed in Fig. 5. ), their adjoin d model. Ne le panel can ause its slip-s ments all alon ibution show bstrate is pres Fig. 7(c), an e hot region) early zero). plane-strain an ion (shown in defects. Bec mum peak en istribution in ic stress analy ission, while s shown in F urrence. Ho pallation ano urale, 15 (2011) echnical rigor ural and fract yses reported First, an inte ning T-seal, an egligible inter be analyzed side joggle re ng the chord wn in Fig. 6 w sented in Fig elevated stre and is nearly These result nalysis of the n Fig. 5(c)) w cause the tem ntry temperat n the substrat ysis results al the flight hi Fig. 2 from fl owever, the s omaly and pro ) 35-49; DOI: 10 r and their ap ture mechani in this paper egrated mode nd attachmen raction was o alone for th egion experie in the joggle was applied to . 7 (to show ess value is ob y constant all ts demonstra slip-side jogg was considered mperatures in ture was appl te (the coatin lone would su story shows light history w stress analysis ompted the fo .3221/IGF-ESIS.1 pplicability lim ics analysis ef r were perform el was conside nt hardware. observed betw he entry ther enced the hig regions and s the model. the TTT stre bserved all al l along the ch ate that any gle [5]. d. For the st n the local reg lied to the en ng elements h uggest that w that wide-spr were limited s results indi following frac 15.05 39 mits ffort med ered The ween rmal ghest shell The esses long hord slice tress gion ntire have wide- read to a icate cture http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 40 S. Raju et alii, FrFrattura ed Integrirità Strutturale, 1 Figure 6 15 (2011) 35-49 (a) (b (c) P Figur 6: Peak entry t 9; DOI: 10.3221/I Integrated mo b) Panel 10 mod Plain strain m re 5: Analysis m temperature dis IGF-ESIS.15.05 odel. del. model. models. stribution for P Panel 10. http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true FR ana ma inte bot and T RACTURE M he objec the strai The fra alyses, subsur aximum tensil erface), subst th regions). d substrate de T Figu Figure MECHANICS A ctive of the fr in energy rele acture mecha rface defects le TTT stress trate defects Typical inter efects are disc ure 7: TTT stre e 8: TTT stress ANALYSES fracture mech ease rates, and anics analyses s were introd s. Three type (those comp face and sub cussed. Fig I. S. Raju et ess distribution s distribution f hanics analyse d determine if s were perfo duced at the es of defects w pletely within strate defects gure 9: Typical (a (b alii, Frattura ed n for peak-heat for peak-heatin es is to evalua f defects can ormed using e maximum s were conside the substrat s are presente l interface and a) Interface def b) Substrate de d Integrità Struttu ting condition ng condition fo ate the defect become unst the plane-str stress locatio red: interface te), and comb ed schematica substrate defe fect. efect. urale, 15 (2011) for Panel 10 m or plane-strain driving force table for each rain model. on (see Fig. e defects (tho bined interfac ally in Fig. 9. ects. ) 35-49; DOI: 10 model. model. es, which are h of the loadin For the fra 8) and perp se along the ce-substrate d In this pap .3221/IGF-ESIS.1 characterized ng conditions acture mecha pendicular to coating-subst defects (thos er, only inter 15.05 41 d by s. anics the trate se in rface http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 42 Th the rem ins D a the orig cra nor cra Fig con righ Int Fig hea For con Wh oth Th usi com mix In elem the len tip at n uj S. Raju et alii, Fr he finite eleme e left of the m mainder of th erted by intro and E-H, nod e connectivity ginal nodes; aze cracks are rmal to the jo ack as specifie g. 5(c)). Th nsecutive tow ht tips of the terface and su g. 9(a), the cra ating occurs, r this reason ntrast, as sho hen heating o her, as shown he capability o ng fracture m mputed, it ca xity for plane this paper, th ment analysis e defect tip [8 ngth (a) of th in a 2D analy node i. The j,k = uj – uk, ar Frattura ed Integri ent model an model. (Note he paper.) Th oducing coinc des 2-4 are du y of elements i.e., both set e modeled ex oggle surface ed by the De he craze crac wards the pan defect are to ubstrate defec aze crack sur the two craz n, friction is own in Fig. 9 occurs, the tw n in Fig. 12(b) of a structure mechanics ana an be compar e strain). he G calculat s, the VCCT 8-10]. In the he elements a ysis. The def e internal fo re used to eva rità Strutturale, 1 nd terminolog e that the orie he substrate a cident nodes, uplicated to c E-H is modi s of nodes h xplicitly by us e, as shown in efect Location cks are num nel acreage, an owards the acr Figure 10 Figure cts interact wi rfaces above e crack edges included in 9(b), the craz wo craze crac . with an emb alyses; i.e., the red to materia tion for the d uses the nod analyses in t ahead and be fect tip is rep orces at node aluate the ind 15 (2011) 35-49 gy are present entation of Fi and coating m , as demonstr create new no ified to use th have identical sing coinciden n Fig. 10. Th n Index. Lo bered consec nd positive-nu reage and tow 0: Plane-strain e 11: Defect m ith the craze an interface d s may come i the finite ele ze crack surf ck edges may bedded defec e problem is n al toughness defects is perf dal forces at th this paper, th ehind the defe resented by n e i and the r dividual G com 9; DOI: 10.3221/I ted in Fig. 10 ig. 10 is oppo materials are s rated in Fig. odes 2'-4'. Th he new nodes coordinates. nt nodes in th he defects ar ocation 0 corr cutively from umbered craz wards the jogg model for frac modeling in the cracks differe defect are co into contact a ement model faces above a y come into c t can be desc no longer a st values for th formed via th he node at th e finite eleme ect tip was of node i. Elem relative displ mponent valu IGF-ESIS.15.05 0 (mesh is exc osite to Fig. 8 shown in yello 11. To insert he connectivi 2'-4'. These Nodes 1 an he finite elem e placed sym responds to t m Location 0 ze cracks are gle, respective cture mechanic e finite element ently for elev mpletely disc and try to slid to account a substrate de contact, but cribed using t tress analysis e different m he Virtual Cr he defect tip a ent models w f equal size. ments I and J c lacements be ues as cluded for cla 8. The orient ow and blue, t a subsurfac ity of elemen new nodes a nd 5 define t ment mesh. T mmetrically an the craze crac 0. Negative consecutive d ely. cs analyses. t mesh. vated tempera connected fro de past each for the craz efect are con they are restr the total defe problem. O modes of fract rack Closure T and the displa were develope Fig. 13 show contribute to etween node arity). The pa tation of Fig. respectively. e defect betw nts A-D is left are initially co the defect tip The craze cra nd directly un ck at the jogg e-numbered c down the jogg ature conditio om the substr other, as sho e crack edge nnected to su rained from ect driving for nce the defec ture (Mode I Technique (V acements at t ed such that t ws local mode the internal f es j and k, w anel acreage i 10 is used in The defects ween element t unaltered, w oincident with ps. Similarly, acks are orien nderneath a c gle shoulder craze cracks gle. The left ons. As show rate material. own in Fig. 12 e interaction. ubstrate mate sliding past e rce GT calcul ct driving forc , II, and/or t VCCT). In fi the nodes beh the element e eling at the de forces, Zi and wj,k = wj – wk is to n the s are s A- while h the , the nted craze (see are and wn in As 2(a). In erial. each ated ce is their finite hind edge efect d Xi, and http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true In rate In Mo Z G I Eq. 1, GI and e GT can be e TG  this paper, a ode I fracture a wZ kji   2 , , G d GII are the M evaluated usin III GG  a somewhat c e toughness G a uX G ji    2II Mode I and M ng (a) In Figure Figure conservative c GIc, which is I. S. Raju et a kj, Mode II strai nterface defect (b) e 12: Deflectio 13: VCCT sch comparison i the smallest o alii, Frattura ed in energy rele t with craze cra ) Substrate def n of interface eme for 4-nod is made by co of the fractur d Integrità Struttu ease rates, the ack edge intera fect. and substrate d de (linear) 2D e omparing the re toughness urale, 15 (2011) e G values. T action. defects. elements. e total strain values for th ) 35-49; DOI: 10 The total stra energy releas he different m .3221/IGF-ESIS.1 (1) ain energy rel (2) se rate GT to modes. Unst 15.05 43 lease o the table http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 44 def i.e. Alt the crit wh driv the wh mo 14. rati For in F test crit to mo Sin GII bas RE I S. Raju et alii, Fr fect growth (i , GT/GIc ≥ 1. ternately, a m e two-dimens terion. This B T  R G here GT repre ving force. T e resistance R GR  here GIc and G ode-mixity rat . When the r io equals or e r a mixed-mo Fig. 14. This ting. For a v terion. Mixed fit mixed-mo ode-mixity rat ngle cantilever Ic. In the abs sis fracture to ESULTS AND n this secti the on-orb analyses anI Frattura ed Integri (i.e., defect is mixed-mode fr sional plane-s B-K criterion 1 esents the tot The resistanc R is given by  III cc GG  GIIc represent tio, and m rep ratio of GT to exceeds unity, ode response, s exponent is value of m=1, d-mode fract ode fracture d tios less than r beam and e ence of furth oughness valu D DISCUSSIO ion, only repr bit cold cond nd results can G rità Strutturale, 1 likely to grow fracture criteri strain criterio n is expressed tal defect dri e R is also re  T II I m c G G G       the Mode I presents the e o R is less tha , the defect is Figure , the B-K resi s typically det a linear respo ture tests of p data accurately , the respon end-notch fle her test data, ues are used in ON resentative re dition are pre n be found in 0 Gc GIc GIIc ~ Line 15 (2011) 35-49 w in a catast rion is used to on given by B d as iving force, g eferred to as Ic m GG  and Mode II exponent of  an unity, the s said to be un 14: Typical cu istance R give termined usin onse like the polymeric mat y. A typical m nse is domina exure test con a value of tw n evaluating E esults in term esented. Bo Ref. 1-6. GI 0.2 Mode ear m=1 curve fit 9; DOI: 10.3221/I rophic mann o determine w Benzeggagh given in Eq. Gc, the critica  III cc GG  I material tou  used to fit th defect is said nstable, and c urve fit of mixe en in Eq. 4 is ng a curve fit green dashed trix composit mixed-mode ated by Mode nfigurations w wo was select Eq. 4 as they ms of defect d oth interface II/GT e I dominated IGF-ESIS.15.05 ner) may occu whether the d and Kenane 2, and R rep al fracture tou m ughness value he mixed-mo d to be stable catastrophic d ed-mode fractu dependent o t for mixed-m d line in Fig. 1 tes show that fracture crite e I behavior. were used in ed as the valu provide a sm riving forces, and substrat 1 Mixed mode dominated Deter to mix ur when GT is defect is stab [11] is used presents the ughness base es, respectivel ode test data a e, and defect g defect growth ure data. on the value o mode fracture 14 is obtained t the B-K crit erion curve is RCC fracture ue of the exp maller value fo , the GT value te defects are 1 rmined as a curve f xed-mode data, m> s greater than ble or unstabl as the mixe resistance to ed on test dat ly,  = GII/G as shown syst growth is unl h is likely. of the expone e data obtain d, which is a n terion using m shown as red e testing to d ponent m. In or R, which is es, for entry p e considered fit >1 n or equal to le. In this pa ed-mode frac (3) o the total de ta. The value (4) GT represents tematically in likely. When ent m as indic ed from mat non-conserva m=2 or 3 app d in Fig. 14. determine GIc n addition, th conservative peak heating . More deta GIc; aper, cture efect e for s the Fig. n the ated terial ative pears For and e B- e. and ailed http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true Int Int hea rati Val cat com En in F nor For val tha occ nor for Th val On 16( nor are dec wh geo terface Defects terface defect ating and the io GT/GIc. V lues greater tastrophically, mponent G v ntry Peak Heati Fig. 15(a), an rmalized GT r each locatio lues are plotte an the right ti curs at the sh rmalized GT rce. he individual m lues. This res n-Orbit Cold. F (a), and the c rmalized GT v ea (for the lef crease and rea here the left t ometry; at Lo – Effect of D ts were studie e on-orbit col Values of GT than unity r , or they co values need to ting. For entry nd friction alo values for tw on, the interf ed as a functi ip values for houlder of the for  = 0.4 i mode G valu sult suggests t (a) Interface (b) Normaliz Figure 15 For the on-o craze crack e values as a fu ft tip at Loca ach a plateau tip (towards ocation 0, half Defect Location ed by assumi ld condition w T/GIc less tha require furthe ould mean th o be calculated y peak heatin ong the craze wo values of t face defect is ion of the de all defect loc e joggle, Loc indicating tha ues were also that the defec defect at craze at varyin zed GT for = 5: Normalized rbit cold con dges do not unction of th ations -1 and . Both the le the acreage) f of the defec I. S. Raju et ing a constan were conside an unity indic er study. Su he mode of d and assesse ng, the craze c crack edges i the coefficien s centered be efect location cations consi cation 0. How at the craze c o examined. ct opening for e crack Locatio ng craze crack l 0. GT as a functi ndition, the cr interact and he interface d d 0). As the eft and right t has the high t is in the acr alii, Frattura ed nt-length defe ered. The res cate that the uch values co fracture is n ed. crack surfaces influences the nt of friction eneath the cr . For  = 0 idered. For b wever, the no crack edge in For both  r entry peak h on +1 and defo locations (defo ion of interface raze crack su do not influ efect location defect is mo tips have near her value. Th reage, and hal d Integrità Struttu ect at differen sults for the n defect is sta ould mean t not Mode-I s come into c e defect defo  for variou raze crack. B (Fig. 15(b)), both  = 0 a ormalized GT teraction is a = 0 and = heating is dom formed configu ormation scaled (c e defect locatio rfaces displac uence the defe n. The maxim oved into the rly the same n his difference lf is down the urale, 15 (2011) nt craze crac normalized G able and unlik the defect is dominated. contact and sl rmations. Fi us locations o Both the left the left tip v and  = 0.4, T for  = 0 is an important = 0.4, the GI minated by M urations for int d by 20x). c) Normalized on – Entry pea ce away from fect deformat mum normal e joggle regio normalized G e in behavior e joggle curve ) 35-49; DOI: 10 k locations. GT values are kely to grow unstable and Hence, the lide past each ig. 15(b) and of the defect t and right tip alues are con the maximum s considerably variable to th values are lar Mode I. terface defects GT for =0.4. ak heating. m each other, tions. Fig. 16 lized GT occu on, the norm GT values exce r at Location e. .3221/IGF-ESIS.1 Both entry p presented as w catastrophic d likely to g e total indivi h other, as sho 15(c) present along the jog p normalized nsiderably sm m normalized y higher than he defect driv rger than the . as shown in 6(b) presents urs in the acre malized GT va ept at Locatio n 0 is due to 15.05 45 peak s the cally. grow dual own t the ggle. d GT aller d GT n the ving e GII Fig. the eage alues on 0, the http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 46 Th ope ove Sub Th loc use tips En and 17( nor Eq cas righ cas EF A S. Raju et alii, Fr he individual m ening for on- erly conserva bstrate Defects he fracture me cations and th ed in this pap s are located ntry Peak Heati d the location (b) for the le rmalized by G q. 4 and norm ses -2→+1 an ht tip becom se -2→+4), th FFECT OF VA s menti applica qualitatA Frattura ed Integri mode G value -orbit cold is tive. (a) Interface Figure s – Effect of D echanics resp hen extending er to indicate at Locations ing. To study n of the right ft tip and in GIc, and the g malized by GI nd -2→+2), t mes larger than he left tip nor ARIOUS VAR ioned previou tion. Some o tively. rità Strutturale, 1 es were also e dominated b defect at craze at varyin e 16: Normaliz Defect Length ponse for sub g the defect a e that a subsu A and B, resp “very long” s defect tip is v Fig. 17(c) fo green dashed Ic. For the in the left tip is s n the normal rmalized GT e RIABLES ON usly, there are of these variab 15 (2011) 35-49 examined. Th by Mode II an e crack Locatio ng craze crack l (b ed GT as a fun bstrate defects along the jogg urface defect e pectively, as i substrate defe varied along or the right ti curves repres nitial case (i.e stable, but th lized GT sugg exceeds the n N THE DEFE e many variab bles are ident 9; DOI: 10.3221/I he GII values nd indicating on +1 and defo locations (defo b) Normalized nction of interf s is examined gle (i.e., chan exists between illustrated in F ects for entry the joggle up ip. The blue sent the resis e., case -2→0 he right tip is u gesting a retu ormalized R a ECT DRIVIN bles that cont tified in Fig. 1 IGF-ESIS.15.05 are larger tha g that the com formed configu ormation scaled GT. face defect loca d by fixing th ging the defe n Location A Fig. 17(a). peak heating, p to Location curves repre stance to the 0), both defec unstable. Fo urn to a stabl and hence th NG FORCE tribute to the 18, and the ef an the GI valu mparison of G urations for int d by 20x). ation – On-orb he left tip of t ect size or len A and Locatio , the left defe +4. The frac esent the tota defect drivin ct tips are sta r the case -2→ e region. Fo e left tip beco defect drivin ffect of each ues, suggestin GT to GIc in F terface defects bit cold. the defect at ngth). The no n B. The left ect tip is place cture respons al defect driv ng force, or R able. For lon →+3, the nor or the “very l omes unstable ng force, the G of these varia ng that the de Fig. 16(b) may different acre otation ‘A→B ft and right de ed at Location se is given in ving force, or R, evaluated u nger defects rmalized R at long” defect e. GT value, for ables is discu efect y be eage B’ is efect n -2, Fig. GT, using (i.e., t the (i.e., this ssed http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true Th like Th ana coa con low GT he effect of th e the one sho he effect of th alyses like tho ating/substra nducted using wer GT values T values than Figure 17: he variable in own in the cen he variables ose presented ate interface a g different si s. For defect those compu (a) Va (b) Left : Fracture mec Figure 18 the green clo nter of this fig in the orang d in this pape and yielded hi ize zones wh t size, larger d uted using pla I. S. Raju et arious defects w tip. hanics respons 8: Effect of var oud (i.e., defe gure. ge clouds was r. For the co igher GT valu ere the mater defects yield ane-strain ana alii, Frattura ed with the left tip se for the left s rious variables ect initiation s s determined oating/substr ues. Because rial propertie higher GT va alysis (i.e., sim d Integrità Struttu p fixed at Loca substrate defec s on defect driv site) was dete d [1, 6] throu rate transition a sharp interf es were transi alues. For 3D mulating a th urale, 15 (2011) ation -2. (c) Right tip ct tip fixed at L ving force. ermined by st ugh finite elem n zone, the in face does not itioned from D effects, par hrough defect ) 35-49; DOI: 10 p. Location -2. tudying the ph ment and fra nitial analyses t exist in reali substrate to rt-through de t). These res .3221/IGF-ESIS.1 hotomicrogra acture mecha assumed a sh ity, analyses w coating, yield efects yield lo sults demonst 15.05 47 aphs anics harp were ding ower trate http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true I. S 48 tha For usi fric a sm jog Th qua tem CO roo bet tem loa inc tak sub con rate Va hav frac elem def mo coa and hel RE [1] [2] [3] [4] [5] [6] [7] [8] [9] T S. Raju et alii, Fr at plane strain r the extent ng a stress-fr ction in the a mooth edge u ggle yield the l he effect of th antified becau mperatures is ONCLUDING he Spac panels t panels. ot cause inve tween adjacen mperature dist ading conditio creased values ken, and the bstrate defect nducted for e es were used rious parame ve been ident cture mechan ment models fect driving f ode fracture ating/substra d edge intera lped in under EFERENCES N. F. Knigh USA, (2010 N. F. Knigh USA, (2010 D. R. Philli USA, (2010 N. F. Knigh USA, (2010 N. F. Knigh No. AIAA- I. S. Raju, D USA, (2010 Anon, ABA RI (2007). E. F. Rybick I. S. Raju, E T Frattura ed Integri n is the boun of ply convo ree temperatu nalysis affect using zero fri lowest GT val he variables in use enough R much more c G REMARKS ce Shuttle wi that experienc Global struc estigation of t nt panels and tribution was on, the thro s in the vicini cross section ts were intro entry peak hea to characteriz eters that affe tified. In thi nics analyses, s of the slip-s forces were c criterion w ate transition ction. The f rstanding poss S ht, Jr., I. S. R 0) No. ICCES ht, Jr., I. S. R 0) No. ICCES ips, I. S. Raju 0) No. ICCES ht, Jr., K. Son 0) No. ICCES ht, Jr., K. Son 2010-2688. D. R. Phillips, 0) No. AIAA- AQUS Analys ki, M. F. Kan Engineering F rità Strutturale, 1 nding case. F olutions, inclu ure that incre ts the results; iction yields h lues. n the gray clo RCC material complex than ing-leading ed ce extreme h ctural and loc this coating d T-seals that s applied to a ugh-the-thick ity of the slip n was analyz oduced. Var ating and on- ze the defects ect the drivin is paper, the , interface, su side joggle re computed usi was considere region, fiber fracture mech sible factors a Raju, K. Song S10200912241 Raju, K. Song S10200912241 u, N. F. Knig S10200912241 ng, I. S. Raju S10200912241 ng, I. S. Raju, , N. F. Knigh -2010-2689. sis User’s Man nninen, Engin Fracture Mech 15 (2011) 35-49 For the exten uding knuckle ases the T y high values f higher GT valu ouds (i.e., defe was not avail n at room tem dge consists heating, spalla cal fracture m spallation an t bridge the g representativ kness normal p-side joggle s ed using pla rious size de -orbit cold co s. This paper ng force of de effects of de ubstrate, and gion. 3D an ing the Virtu ed. Paramete bridging, ply hanics analysi and scenarios g, D. R. Philli 163. g, D. R. Philli 164. ght, Jr., K. So 165. u, D. R. Philli 166. , In: Proceedi ht, Jr., K. Song nual: Volume neering Fractu hanics, 28 (19 9; DOI: 10.3221/I nt of fiber bri es, voids, etc yields higher for the coeffi ues. For craz ect growth m lable to perfo mperature. of panels th ation of coati mechanics ana omaly. The gaps between ve panel, and l stresses sho shoulder. As ne-strain ana efects were c onditions. De r presents som efects present efect initiatio combined d nalyses showe ual Crack Clo ers that affe y convolution is results wer s that contribu ips, In: Proce ips, In: Proce ong, In: Proce ips, In: Proce ings of the 51 g, In: Proceed es I – VI, Ver ure Mechanic 987) 251. IGF-ESIS.15.05 idging, includ . yields highe GT values. F icient of fricti ze crack orien model and non orm compreh hat are made ing was obse alyses were p global struct n the panels f the resulting owed negligi such, a repre alysis. In the considered. efect driving me of the frac t in the Spac n site and de defects were i ed that the pl osure Techni ect the defec ns, stress-free re ultimately u ute to the RC eedings of th eedings of th eedings of th eedings of th 1st AIAA SDM dings of the 5 rsion 6.7, Das cs, 9(4) (1977) ding fiber bri er GT values. For craze cra ion yield low ntation, craze nlinear stress- hensive testing of reinforce erved in the s performed on tural analyses for entry ther stress distrib ible variation esentative spa e plane-strain Plane-strain forces in term cture mechan e Shuttle win efect size wer introduced in lane-strain ca ique, and the ct driving f e temperature used to defin CC spallation he ICCES ’10 he ICCES ’10 he ICCES ’10 he ICCES ’10 M Conferenc 51st AIAA SD ssault Systèm ) 931. idging yields For stress-f ack edge inter er GT values, cracks orient -strain respon g, and also, te ed carbon-car slip-side jogg n these panels s showed min rmal conditio bution was exa n in the chor an-wise slice n models, bo finite elemen ms of the stra nics analyses a ng-leading-edg re briefly pre nto the 2D p se is the bou e Benzeggagh force include e, and craze c ne tests and t anomaly. Conference, Conference, 0 Conference, 0 Conference, ce, Orlando, F DM Conferen mes Simulia Co lower GT val free temperat raction, includ while simula ted normal to nse) could no esting at elev rbon. On so gle regions of s as a part of nimal interac ons. A bound amined. For rd direction on the panel oth interface nt analyses w ain energy rel and results. ge joggle regi esented. For plane-strain fi unding case. h-Kenane mix e effects of crack orienta test methods , Las Vegas, N , Las Vegas, N , Las Vegas, N , Las Vegas, N FL, USA, (20 nce, Orlando, orp., Provide lues. ture, ding ating o the ot be vated ome f the f the ction ding this and was and were ease gions r the finite The xed- the ation and NV, NV, NV, NV, 010) FL, ence, http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true [10 [11 0] R. Krueger, 1] M. L. Benze , Applied Mec eggagh, M. K chanics Revie Kenane, Comp I. S. Raju et ews, 57(2) (20 posites Scienc alii, Frattura ed 004) 109. ce and Techn d Integrità Struttu nology, 56(4) urale, 15 (2011) (1996) 439. ) 35-49; DOI: 10.3221/IGF-ESIS.115.05 49 http://www.gruppofrattura.it http://dx.medra.org/10.3221/IGF-ESIS.15.05&auth=true << /ASCII85EncodePages false /AllowTransparency false /AutoPositionEPSFiles true /AutoRotatePages /None /Binding /Left /CalGrayProfile (Dot Gain 20%) /CalRGBProfile (sRGB IEC61966-2.1) /CalCMYKProfile (U.S. Web Coated \050SWOP\051 v2) /sRGBProfile (sRGB IEC61966-2.1) /CannotEmbedFontPolicy /Error /CompatibilityLevel 1.4 /CompressObjects /Tags /CompressPages true /ConvertImagesToIndexed true /PassThroughJPEGImages true /CreateJobTicket false /DefaultRenderingIntent /Default /DetectBlends true /DetectCurves 0.0000 /ColorConversionStrategy /CMYK /DoThumbnails false /EmbedAllFonts true /EmbedOpenType false /ParseICCProfilesInComments true /EmbedJobOptions true /DSCReportingLevel 0 /EmitDSCWarnings false /EndPage -1 /ImageMemory 1048576 /LockDistillerParams false /MaxSubsetPct 100 /Optimize true /OPM 1 /ParseDSCComments true /ParseDSCCommentsForDocInfo true /PreserveCopyPage true /PreserveDICMYKValues true /PreserveEPSInfo true /PreserveFlatness true /PreserveHalftoneInfo false /PreserveOPIComments true /PreserveOverprintSettings true /StartPage 1 /SubsetFonts true /TransferFunctionInfo /Apply /UCRandBGInfo /Preserve /UsePrologue false /ColorSettingsFile () /AlwaysEmbed [ true ] /NeverEmbed [ true ] /AntiAliasColorImages false /CropColorImages true /ColorImageMinResolution 300 /ColorImageMinResolutionPolicy /OK /DownsampleColorImages true /ColorImageDownsampleType /Bicubic /ColorImageResolution 300 /ColorImageDepth -1 /ColorImageMinDownsampleDepth 1 /ColorImageDownsampleThreshold 1.50000 /EncodeColorImages true /ColorImageFilter /DCTEncode /AutoFilterColorImages true /ColorImageAutoFilterStrategy /JPEG /ColorACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /ColorImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000ColorACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000ColorImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasGrayImages false /CropGrayImages true /GrayImageMinResolution 300 /GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true /GrayImageDownsampleType /Bicubic /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageMinDownsampleDepth 2 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /GrayImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000GrayACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000GrayImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasMonoImages false /CropMonoImages true /MonoImageMinResolution 1200 /MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true /MonoImageDownsampleType /Bicubic /MonoImageResolution 1200 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode /MonoImageDict << /K -1 >> /AllowPSXObjects false /CheckCompliance [ /None ] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier () /PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped /False /CreateJDFFile false /Description << /ARA /BGR /CHS /CHT /CZE /DAN /DEU /ESP /ETI /FRA /GRE /HEB /HRV (Za stvaranje Adobe PDF dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. 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