PEER-REVIEW ARTICLE PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7723 Research on Willow Furniture Design Based on Kano- AHP and TRIZ Yanming Chen, Mingbin Liu,* Jinyang Xu, Shun Yu, and Longping Chen Willow wood furniture has become one of the most popular types of wood furniture in the Chinese furniture market. Research was undertaken to solve the pain points of product design and meet the requirements of green development. Firstly, the Kano model was used to classify user requirements. Secondly, the Analytic Hierarchy Process was used to calculate each design factors’ comprehensive weights, ensuring consistency between the design objectives and user requirements. Thirdly, the TRIZ contradiction matrix was used to identify and solve engineering difficulties in the design process. During the design process, the Kano-AHP-TRIZ was combined to realize a scientific design strategy that combines qualitative and quantitative approaches. The results showed that the design scheme of willow furniture based on user requirements had consistency, matching, and effectiveness with the furniture market development trend, which makes the furniture design process more scientific and rigorous. It also provided a new research perspective and design strategy for the innovative development of the furniture industry. DOI: 10.15376/biores.19.4.7723-7736 Keywords: Willow furniture; Furniture design; User requirements; Design factor Contact information: Department of Design, Anhui Polytechnic University, Wuhu, Anhui, China; * Corresponding author: Liumbdesign@163.com INTRODUCTION In the early stage of development, the Chinese furniture industry followed the international style represented by Italy for a long time, and most enterprises were keen on imitation and paid less attention to innovation (Xu 2024). In the international furniture industry, the core element of competition focuses on innovative design, which is essentially a deep competition for furniture innovative capabilities. The traditional approach taken in the Chinese furniture industry has been to gradually shape and developing unique design styles. “New Chinese style” is a designer’s exploration of the modernization of traditional Chinese furniture, which is of positive significance to the promotion of national culture and the development of original Chinese furniture (Zhang et al. 2022). In recent years, willow weaving has received more attention as an important branch of traditional folk art (Zhou et al. 2018). Integrating willow weaving into furniture design can improve the social and cultural value of furniture. Willow weaving is an important form of willow furniture, and its main material is the branches of trees such as Salix babylonica, Salix chaenomeloides, Salix integra (Latin nomenclature), and so on. Willow has the characteristics of being natural, free of pollution, renewable, and widely used in green household products (Cui 2020). The combination of willow and traditional Chinese handicrafts also gives the furniture a unique artistic value. PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7724 Wu and Wang (2020) combined willow weaving technology and sofas to integrate modern product design concepts into the design, and they proposed a green innovative design method that conforms to modern aesthetics. Wang (2023) took the willow round-backed armchair as the research object and analyzed the design advantages and disadvantages of willow circle chair products, which provided a theoretical basis for the inheritance and development of traditional handicrafts. The combination of modern aesthetics and traditional craftsmanship provides a new research perspective for furniture innovation. Yu et al. (2023) researched a number of willow furniture enterprises and applied the combination of willow craftsmanship and modern technology to furniture design, which broadened the ideas for the innovative design of willow furniture. The innovative application of willow weaving in furniture is the inheritance of traditional culture and the deep integration of modern lifestyle. Currently, in the environment of diversification and personalization of user requirements, emotional requirements become more and more important in the customer’s decision to buy products (Li et al. 2021). The Kano model is an analysis method used for product design and user requirement capture. Taifa and Desai (2016) and Kapuria et al. (2020) used the Kano model to analyze students’ demand, satisfaction, and demand classification for existing classroom furniture. Their scientifically effective redesign of classroom furniture has gained recognition from people. Lyu et al. (2022) used the Kano model to analyze the problems that users encountered in the office and combined it with QFD to translate the users’ needs into rules in the development of office furniture, which facilitates the development and design of furniture in an open-plan office scenario. This integrated modeling approach also provides a new research strategy for other furniture designs. The Kano model can effectively solve the problem of categorizing and ranking the importance of user requirements, but differences in user perception can lead to decision-making hesitation between demand attributes. This type of user perception difference requires a scientific evaluation method for quantitative analysis. Analytic Hierarchy Process (AHP), as a combination of qualitative and quantitative analysis methods, can solve the problem of user perception difference requirements. Liu et al. (2023) used AHP and F-AHP to establish an evaluation system for dining chair design, which provided designers with design priorities and quantitative indicators. Zhao and Xu (2023) used the Kano model to screen the functional indicators and proposed an evaluation method for modular children’s wooden locker furniture design by combining AHP and GRA, providing a new innovative idea for children's furniture manufacturers. Wang and Fan (2024) used the Kano model to determine the user requirements of shoe-changing seats for the elderly, and combined AHP and QFD to comprehensively rank the relative importance of the design elements, which provided a new research idea for the development of suitable aging furniture. The combination of AHP and Kano can effectively solve the problem of comprehensive ranking of demand indicators, user requirement weighting analysis, and obtaining real user requirements for subsequent design. User requirements are emotional and changeable, so inaccurate acquisition will affect the subsequent design program. Teoriya Resheniya Izobreatelskikh Zadatch (TRIZ) is a methodology for solving practical problems using scientific and rigorous methods. It provides a systematic approach to finding solutions to technical problems and innovating technical systems (Ilevbare et al. 2013), which can accurately complete design decisions based on user requirements. Yao et al. (2022) investigated the rapid assembly and deployment features of a folding chair, using TRIZ theory to explore the innovative design of a folding chair. Tandiono and Rau (2022) combined the Kano model with QFDE, PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7725 analyzed the contradiction problems in lamp design using TRIZ theory, and proposed solutions in the process of enterprise product development. Yi (2023) used QFD and TRIZ to analyze the contradiction points of human-pet shared furniture in terms of shape, material, color, and function, and proposed a new design scheme, which compensated for the limitations of the traditional design methods to a certain extent. The virtuous cycle of ecosystem of human-pet shared living space is realized. Existing research has shown that Kano, AHP, and TRIZ have been widely used to acquire user requirements and refine design decisions, and their scientific, novelty, systematicity, and effectiveness have been proved through long-term practical validation. The combination of Kano, AHP, and TRIZ can effectively shorten the product development cycle and save the product development cost. This research aims to explore innovative willow wood furniture using Kano-AHP-TRIZ. This furniture can satisfy users’ requirements, improve users’ aesthetic level and user experience, and provide a new realization path for the optimization and improvement of the willow furniture process, as well as provide a new evaluation system, design strategy, and design method for the design innovation of willow furniture and other related products, to promote the differentiation and competitiveness of furniture products. EXPERIMENTAL Experimental Processes The changes in living environment and lifestyle make people’s consumption ideas and consumption behavior tend toward the rational (Xiong et al. 2017). Designers relying solely on product attribute satisfaction to obtain real user requirements have limitations, and they also are required to make the design process more scientific and rigorous. Therefore, this study takes the willow sofa as an example to organize a willow furniture design process that combines the Kano-AHP-TRIZ theory. Fig. 1. Flowchart of experimental process PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7726 Through the methods of user interviews and market research, the Kano model was used to get the user’s functional requirements for the sofa, and then combined with the AHP to determine the priority level of the functional design of the furniture and come up with the problems that requirement to be solved for the willow sofa. Finally, the invention principle of TRIZ theory is used to solve the contradictions generated in the design process, to obtain a complete willow sofa design scheme. The specific experimental process is illustrated in Fig. 1. Design evaluation for furniture is mainly inextricably linked to consumers’ purchase decisions, so integrating consumers into design decisions is a wise decision (Zhao and Xu 2023). For this reason, users were invited to score for evaluation at the end of the experiment to finalize the feasibility of the design solution. Construct the Kano Model The Kano model offers a better understanding of how customers evaluate a product. Thus, this can be used to assist enterprises in focusing on the improvement of the most important attributes (Ilevbare et al. 2013). The Kano model can be categorized according to the requirements: must-be requirements, one-dimensional requirements, attractive requirements, indifference requirements, and reverse requirements. Anhui Funan is one of the three major production and export bases for willow products in China. In this work, interviews were conducted with local willow weaving manufacturing enterprises to understand the current development status of willow furniture products and discuss how to innovate the design of willow furniture. The research revealed that users use sofas most frequently in their homes, and for this reason, the focus of this work became the design of willow sofas. Under the guidance of professionals, the Willow Sofa is targeted at the 30 to 50 age group. These users have high demands for quality of life and have a certain purchasing power. After the target user and the product have been identified, user requirements are categorized according to the basic functions of the sofa: functionality, appearance, and emotion. Detailed requirements are shown in Table 1. Table 1. User Requirements Segmentation Table Number User Requirement Attribute Number User Requirement Attribute A1 Storage Function A11 Lumbar Support Function A2 Back Regulation Function B1 Warmth Emotion A3 Modularization Function B2 Security Emotion A4 Easier Installation Function B3 Interesting Emotion A5 Easy Washing Function C1 Organic Forms Appearance A6 Desk Board Function C2 Modern Style Appearance A7 Health Massage Function C3 Human-machine Engineering Appearance A8 Entertainment Function Function C4 Crude Wood Appearance A9 Easy Moving Function C5 Harmonious Proportion Appearance A10 Head Support Function C6 Composite Material Appearance Design and Analysis Questionnaire The design team conducted a Kano questionnaire survey at recent furniture exhibitions and online, distributing a total of 110 questionnaires (97 valid and 13 invalid), PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7727 with a final effective recovery rate of 88.1%. Among them, 50 questionnaires were distributed to visitors and resident designers at the furniture exhibition, and 47 were effectively collected. We continued to distribute 60 questionnaires online to have a more comprehensive coverage of our target users, with 50 effective responses. Analysis Satisfaction According to the Kano model, the user quality requirements in the early stages of design can be clearly classified into different attribute types through a two-factor questionnaire survey comparison table. (M) must-be requirement, (O) one-dimensional requirement, (A) attractive requirement, (I) indifference requirement, and (R) reverse requirement. The Better-Worse coefficient was then used to analyze each functional requirement indicator, calculating its satisfaction coefficient and dissatisfaction coefficient. The specific value was calculated by (Zhao and Chen 2021) using Eqs. 1 and 2. )( )( )( IMOA OA SIBETTER +++ + = (1) )( )()1( )( IMOA MO DSIWORSE +++ +− = (2) The results obtained by combining the Kano models were tabulated. The user requirement attribute categorization and satisfaction coefficients are shown in Table 2. Table 2. User Requirement Attributes and Satisfaction Coefficients Number M A O I R Attribute SI DSI A1 10 23 42 23 0 A 0.67 -0.34 A2 10 25 26 35 1 I 0.531 -0.365 A3 15 25 36 19 2 A 0.642 -0.421 A4 39 21 20 17 0 M 0.423 -0.619 A5 24 43 20 10 0 O 0.649 -0.69 A6 8 25 37 25 1 A 0.656 -0.343 A7 12 24 25 35 1 I 0.51 -0.375 A8 3 17 21 23 33 R 0.594 -0.313 A9 19 16 23 39 0 I 0.402 -0.361 A10 16 29 33 19 0 A 0.639 -0.464 A11 13 26 35 23 0 A 0.63 -0.402 B1 17 46 24 9 1 O 0.729 -0.656 B2 43 20 25 9 0 M 0.464 -0.649 B3 13 21 26 36 1 I 0.49 -0.354 C1 21 21 16 37 2 I 0.389 -0.442 C2 19 36 28 12 2 O 0.674 -0.579 C3 47 26 24 0 0 M 0.515 -0.753 C4 18 42 27 10 0 O 0.711 -0.619 C5 26 39 29 3 0 O 0.701 -0.67 C6 13 21 38 24 1 A 0.615 -0.354 Note: M. A, O, I, and R represent Must-be Requirement, Attractive Requirement, One- dimensional Requirement, Indifferent Requirement, and Reverse Requirement, respectively. PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7728 A scatter plot of user demand elements was drawn based on the average of the 20 demand elements satisfaction SI and |DSI| in Table 2 (0.5, 0.6) as the origin of the horizontal and vertical coordinates, as shown in Fig. 2. Table 2 shows the situation for 20 functional attributes. When SI>0.6, |DSI|>0.5, belongs to the one-dimensional requirement, including easy washing, warmth, modern style, crude wood, and harmonious proportion of five items; when SI>0.6, |DSI|<0.5, belongs to the attractive requirement, including storage, modularization, desk board, head support, lumbar support, and composite material of six items; when SI <0.6, |DSI|<0.5, belongs to the indifference requirement, including back regulation, health massage, easy moving, entertainment function and organic forms of five items; when SI <0.6, |DSI|> 0.5, belongs to the necessary type of demand, including easy installation, security, and human- machine engineering of three items. The next step was to draw a scatter plot based on the SI and DSI of user requirements, and determine the priority of user requirements for the willow sofa based on the distance between each demand point and the coordinate origin (0.2, 0.2). The further away the demand point is from the origin, the higher the priority of development. As can be seen from Fig. 2, the priority order of development and design is B1>C5>A5>C4>C3>C2>B2>A10>A3>A1>A6>A4>A11>C6, but due to the fact that A2, A7, B3, C1, and A9 belong to the indifference requirements, they can be disregarded for the time being in the development of the design of the willow sofa. Whereas C3, B2, and A4 are must-be requirements that must be met during design and development. Therefore, the willow sofa should mainly focus on B1, C5, A5, C4, C2, A10, A3, A1, A6, A11, and C6 in the design and development, and the improvement of the design to meet these requirements can make the product better accepted by the user and improve the user's satisfaction. The scatter plot of user requirements elements is shown in Fig. 2. Fig. 2. The scatter plot of user requirement elements PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7729 Construct the Hierarchy Model In order to further clarify the design focus of the willow sofa, the Analytic Hierarchy Process (AHP) was introduced to refine the results of the Kano model. It outperforms other options by being easy to use, structuring problems systematically, and calculating both criteria weights and alternative priorities (Liu et al. 2020). With the advantages of objectivity and convenience, AHP has been widely used in product design and development in recent years. The design focus was determined based on the prioritization of user needs for willow sofas identified by the Kano model and the market analysis report provided by Funan willow furniture companies. The current furniture market is dominated by modern style wooden furniture, which combines the characteristics of warmth, harmonious proportion, and easy washing to form the overall trend of furniture. Therefore, during the design process, we directly satisfy the five one-dimensional requirements of ease washing, warmth, modern style, crude wood, and harmonious proportion in accordance with market standardization. And the 3 must-be requirements of easy installation, security, and human- machine engineering are directly met. Storage, modularization, desk board, head support, lumbar support, and composite materials totaling 6 attractive types of needs should be used as a design focus to increase the satisfaction of user needs and provide innovative ideas for willow furniture. These requirements were categorized into 18 design elements to serve as evaluation criteria for the willow sofa. Using the AHP, a hierarchical structure model was constructed based on these criteria. See Fig. 3. for the user requirement hierarchical structure model. Fig. 3. The hierarchical structure model of user requirements The team organized a panel of six experts (including three furniture designers, two professors of industrial design, and one consumer). Through Saaty’s 9-point scale (Yang et al. 2019), the requirement categories were compared in pairs to construct the judgment matrix. The weight values were calculated using the arithmetic mean method. See Table 3 for the judgment of requirement indicator weights. PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7730 Table 3. The Judgment of Requirement Indicator Weights X A1 A6 A3 A10 A11 C6 A1 1.000 1.957 2.667 4.329 1.364 3.077 A6 0.511 1.000 0.238 0.391 0.300 0.370 A3 0.375 4.200 1.000 2.770 0.907 0.529 A10 0.231 2.556 0.361 1.000 0.461 0.349 C11 0.733 3.333 1.103 2.167 1.000 0.394 C6 0.325 2.700 1.889 2.867 2.538 1.000 The results were subjected to a consistency test, see the Eq. 3. RIn n CR − − = )1( max (3) where λmax is the maximum characteristic of the judgment matrix, n is the matrix order, and RI is the average random consistency index. Consistency of <0.1 is required during data entry. If it is not satisfied, the data will be readjusted (Yue et al. 2022). According to the formula, the consistency ratio (CR) is calculated to be 0.008, passing the consistency test. Experts were again organized to score the judgment matrix constructed at the target hierarchy. The weight values were calculated according to the arithmetic mean method, and the consistency test was calculated. CR was calculated as follows: 0.02, 0.016, 0.035, 0.016, 0.031, and 0.061, all passing the consistency test. Subsequently, the comprehensive weight values for the 18 secondary criteria layers were calculated, resulting in the final ranking of the willow sofa requirements' comprehensive weight. Table 4 shows the comprehensive weight ranking of willow sofas. Table 4. Combined Weighted Order of Willow Weaving Sofa Criterion Hierarchy Weights Object Hierarchy Weights Comprehensive Weights Rank A1 0.312 E1 0.621 0.1938 1 E2 0.261 0.0814 5 E3 0.118 0.0368 11 A6 0.066 E4 0.091 0.0060 20 E5 0.616 0.0407 9 E6 0.293 0.0193 14 A3 0.159 E7 0.105 0.0167 16 E8 0.086 0.0137 18 E9 0.566 0.0900 4 E10 0.243 0.0386 10 A10 0.082 E11 0.091 0.0075 19 E12 0.616 0.0505 6 E13 0.293 0.0240 13 A11 0.163 E14 0.6 0.0978 3 E15 0.282 0.0460 8 E16 0.118 0.0192 15 C6 0.218 E17 0.544 0.1186 2 E18 0.222 0.0484 7 E19 0.072 0.0157 17 E20 0.162 0.0353 12 PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7731 The importance of the criterion hierarchy is ranked as A1 > C6 > A11 > A3 > A10 > A6. The composite ranking of the object hierarchy is E1 > E17 > E14 > E9 > E2 > E12 > E18 > E15 > E5 > E10 > E3 > E20 > E13 > E6 > E16 > E7 > E19 > E8 > E11 > E4. This indicates that users urgently require the storage function of furniture, which provides a systematic solution for efficient utilization of space. The diversity of modern home decoration also makes users highly value the beauty and comfort brought by composite materials. With the improvement of life, users have begun to pay attention to healthy sitting posture, head support, and lumbar support design to meet the user’s health requirements. Through the above comprehensive weighting ranking, the top 10 target hierarchy requirements will be selected as the key design guidelines to focus on problem solving. However, there are certain contradictions and conflicts in the design process of different design indexes, so it is necessary to use TRIZ theory to solve the existing technical and physical contradictions. Use the TRIZ Theory During the design and development process, the team uncovered the contradictory conflicts that attractive requirements (A), must-be requirements (M), one-dimensional requirements (O), and requirement weighting of the objective hierarchy would create in practical application. Firstly, reference was made to the Chinese government’s “Custom furniture—Specification for installation acceptance” standard to ensure compliance with policy requirements for market development. Secondly, for the physical contradiction, drawer storage space and open storage space are categorized as space separation according to the separation principle in TRIZ theory, whose corresponding solution principles are 1, 2, 3, 4, 7, 13, 17, 24, 26, and 30. Fixed lumbar support and pillowcase are categorized as conditional separation, which corresponds to solution principles 1, 5, 6, 7, 8, 13, 14, 22, 23, 25, 27, 33, and 35. For the technical contradiction, the Improved Parameters and Deteriorating Parameters are determined according to TRIZ theory, the sofa needs to be easy to install, but the drawer storage will cause the structure to become complicated. This is a contradiction between the engineering parameter 33 (operability) and the engineering parameter 36 (complexity of device), in order to reduce the complex structure of the sofa, in accordance with Archimedes contradiction matrix, found in invention numbers 32, 26, 12 and 17. Four solutions were obtained against 40 inventive principles No.32 (Change the color), No.26 (Copying), No.12 (Equipotentiality), and No.17 (Shift to a new dimension). The ease of washing the sofa and the use of composite materials also create a contradiction between the maneuverability and complexity of the device. To reduce the complexity of the sofa’s structure, four solutions have been found by the same methodology as in invention numbers No. 32, No. 26, No. 12, and No. 17. A design strategy for the willow sofa was obtained. Refer to Table 5 for physical contradiction analysis and resolution principles and Table 6 for technical contradiction analysis and resolution principles. Table 5. Principles of Physical Contradiction Analysis and Resolution Conflict Number Conflict Type of Contradiction Separation Mode Inventive Principle 01 Drawer storage space- Open storage space Physical Contradiction Space 1, 2, 3, 4, 7, 13, 17, 24, 26, 30 02 Fixed lumbar support- Pillowcase Conditional 1, 5, 6, 7, 8, 13, 14, 22, 23, 25, 27, 33, 35 PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7732 Currently, to improve the user’s home comfort and maximize the use of space resources, the storage function is the user’s primary demand for furniture. Items No. 1 (Segmentation) and No. 3 (Local conditions) were used to resolve the physical contradiction between drawer storage space and open storage space. Specifically, two types of storage are divided into two or more different areas to meet the basic function of the sofa while addressing the storage requirements of the user. Users require furniture to provide a better living experience for the improvement of their living standards. Lumbar support allows users to have a healthy and comfortable sitting posture when using the sofa. Items No. 5 (Consolidation), No. 6 (Universality), and No. 33 (Homogeneity) were used to resolve the physical contradiction between fixed lumbar support and pillowcases. The characteristics of the pillow and lumbar support are combined, and thereby the lumbar support has the comfort of a pillow and is fixed on the sofa to serve as a lumbar support. Table 6. Principles of Technical Contradiction Analysis and Resolution Conflict Number Conflict Type of Contradiction Improved Parameters Deteriorating Parameter Inventive Principle 01 Easy installation- Drawer storage space Technical Contradiction No.33 Homogeneity No.36 Phase transition 32，26， 12，17 02 Easy washing - Composite Material No.33 Homogeneity No.36 Phase transition To resolve the technical contradiction between easy installation and drawer storage space, No. 26 (Copying) was used. By abandoning the complex mechanical slide structure and adopting wooden nested slides to achieve the pull-out function, the environmentally friendly drawer structure is also easier to install. To address the conflicts between easy cleaning and composite materials, No. 26 (Copying) and No. 17 (Shift to a new dimension) were used to resolve them. Specifically, use fabric materials that are easy to clean and discard complex decorative components. Willow weaving is designed in a vertical orientation as a decorative piece, with inlays to reduce dust buildup and cleaning difficulty. RESULTS AND DISCUSSION The final product design scheme is shown in Fig. 4. Component “a” is the head support, which is made of a memory sponge as padding and cloth fiber material on the outside. This material is comfortable, waterproof, stain-resistant, and aging-resistant. Component “b” is the backrest of the sofa. Its interior is a willow wood frame with a mixture of density and high elasticity sponge padding for optimal support and comfort. Component “c” is open storage space for increased use of storage organizers. Component “d” is a folding tabletop, designed to take into account the additional functions of the sofa, providing users with a wider range of use scenarios and realizing the diversity of functions. Component “e” is an open storage space with a composite material combining willow and cloth fibers, a design that enhances the supportive strength of the seat surface while guaranteeing structural stability. Component “f” is a willow weaving decoration that enhances the overall aesthetics of the sofa. Component “g” is the sofa base, made of white PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7733 wax wood. Its characteristics are good processing performance, toughness, and elasticity, making the sofa base sturdy and durable. Component “h” is a drawer storage space with willow weaving as a decorative element, providing users with the convenience of storing small items and books. Component “i” is the lumbar support, made of materials consistent with the head support and ergonomic, which ensures optimal lumbar cushioning and comfort for the user. Component “j” is a willow drawer, which has good breathability and aesthetics while increasing storage space. Component “k” is the stackable modular sofa armrest, designed with harmonious proportions and curves to provide arm support for users and create a serene psychological atmosphere. Fig. 4. Willow weaving sofa scheme drawing DISCUSSION To determine whether the final solution meets the consumer requirements of the Chinese market, the design team organized a 10-member evaluation team (2 furniture designers, 3 product design professors, and 5 consumers) with an age range of 30 to 50 years old. The evaluation team selected two sets of willow wood sofa products with high sales in the Chinese market (Scheme A and Scheme B) and compared them with the current design scheme (Scheme C) in the form of pictures. The team quantitatively evaluated the M, O, and A of three sets of willow sofas on a scale of 1 to 10, and the final results show that B (106.7) < A (126.7) < C (185.3). Therefore, this design scheme was found to meet the requirements of Chinese users. Figure 5 shows the user scoring statistics. Fig. 5. User scoring statistics PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. (2024). “Design of willow furniture,” BioResources 19(4), 7723-7736. 7734 CONCLUSIONS 1. This research focused on the specific requirements of consumers for willow sofas and explored the innovative design direction of willow sofas with user satisfaction as the core. The Kano model was used to obtain the classification of user requirements, AHP was used to quantify the weight ranking of each requirement, and TRIZ theory was used to solve the engineering problems in the design process to ensure the scientific and effectiveness of the design process. Through the comprehensive application of the Kano-AHP-TRIZ combination, the willow sofa was designed to meet the current market trends, which not only satisfies the diversified requirements of consumers, as well as provides new research perspectives and design strategies for the innovative development of the furniture industry. 2. The Kano model analysis indicated that Warmth, Harmonious proportion, Easy washing, Crude wood, Human-machine engineering, Modern style, Security, Head support, Modularization, Storage, Desk board, Easy installation, Lumbar support, and Composite material were the primary requirements of the user for willow furniture, clarifying the focus of the subsequent design. The AHP method was used to rank user requirement weights to improve the accuracy of user requirement assessment during the design process. In the criterion hierarchy: Storage> Composite Material> Lumbar Support > Modularization > Head Support > Desk Board. The object hierarchy was ranked as follows: Drawer Storage Space > Willow and Fabric > Fixed Lumbar support> Combination > Open Storage Space > Fixed Head Support > Willow and Other Wood > Pillowcase > Folding Desk Board > Stack > Cabinet Storage Space> Willow and Leather>Pillowcase > Rotating Desk Board > Adjustable Lumbar Support > Shared Component > Willow and Metal > Interchangeable Component > Elevating Head Support > Fixed Desk Board. 3. The TRIZ theory was introduced to resolve the contradictions in user requirements. The physical contradiction between drawer storage space and open storage space was resolved using No. 1 (Segmentation) and No. 3 (Local conditions). The physical contradiction of the fixed lumbar support pillowcase was addressed through combination No. 5 (Consolidation), No. 6 (Universality), and No. 33 (Homogeneity). The technical contradiction between easy installation and drawer storage space was solved by applying No. 26 (Copying). The technical contradiction of easy-washing composite material was addressed through No. 26 (Copying) and No. 17 (Shift to a new dimension). The final design development was thus completed. 4. In order to verify the scientific validity of the evaluation system, the design scheme was compared and evaluated with the two most popular willow sofas in the Chinese market. The design schemes were ranked as follows: scheme C (185.5) > scheme A (126.7) > scheme B (106.7). These findings demonstrate the superiority of this design over other similar products. However, due to the limited number of samples in this research, the results will still be affected by subjective factors. In the future, the authors plan to expand the scope of sample collection and obtain more data to make the research results more comprehensive, so as to further improve the design research of willow furniture. PEER-REVIEWED ARTICLE bioresources.cnr.ncsu.edu Chen et al. 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