An upgradable product is a product in which the valuable life is extended by exchanging or adding components. An upgradable product is both environmentally and economically advantageous compared with products requiring replacement because its functions can be improved by adding only a few components. Therefore, the design and sale of upgradable products represent effective methods for attaining a sustainable society. Previous studies of upgradable product design methods have assumed that products have a modular architecture, in which all components are functionally independent. However, actual products have both integral architectures and modular architectures. Achieving high-performance products through component optimization is easier with an integral architecture than with a modular architecture. However, the integral architecture makes it difficult to disassemble and replace individual components. It is difficult to achieve high levels of performance in products with modular architecture, but it is easy to disassemble and replace components. Therefore, upgradable product design must determine the most appropriate product architecture. Hence, this paper focuses on the product architecture of upgradable products and proposes a decision support method that yields the appropriate combination of product architecture and upgrade cycle. In addition, the authors propose evaluation models for the environmental load, cost, and customer dissatisfaction, as well as a comprehensive evaluation index based on these models. The overall model, which gives the evaluation index, considers the differences in the evaluated values resulting from differences in the product architecture and the number of upgrades. The proposed method was applied to a motherboard module design problem for a laptop computer. The results of this case study confirm that the proposed method successfully supports the designer during upgradable product design by deriving the most suitable combination from a set of product architectures and upgrade cycle candidates.

1. [1] https://ec.europa.eu/environment/circular-economy/index_en.htm [Accessed February 28, 2020]
2. [2] O. Pialot, D. Millet, and J. Bisiaux, “Upgradable PSS: Clarifying a new concept of sustainable consumption/production based on upgradability,” J. Clean. Prod., Vol.141, pp. 538-550, doi: 10.1016/j.jclepro.2016.08.161, 2017.
3. [3] M. Inoue, R. Mogi, Y. E. Nahm, and H. Ishikawa, “Design support for ‘Suriawase’: Japanese way for negotiation among several teams,” Improving Complex Systems Today, London: Springer, pp. 385-392, doi: 10.1007/978-0-85729-799-0_45, 2011.
4. [4] K. Fujita and H. Sakaguchi, “Optimization methodologies for product variety design (2nd report, optimization method for module commonalization),” Trans. Jpn. Soc. Mech. Eng., Series C, Vol.68, No.666, pp. 683-691, doi: 10.1299/kikaic.68.1329, 2002 (in Japanese).
5. [5] K. Oizumi, K. Aruga, and K. Aoyama, “Module commonization in product family incorporating fine-tune improvement,” Trans. Jpn. Soc. Mech. Eng., Vol.82, No.843, 16-00071, doi: 10.1299/transjsme.16-00071, 2016 (in Japanese).
6. [6] S. D. Eppinger and T. R. Browning, “Design Structure Matrix Methods and Applications,” MIT Press, 2012.
7. [7] S. Sarkar, A. Dong, J. A. Henderson, and P. A. Robinson, “Spectral characterization of hierarchical modularity in product architectures,” J. Mech. Des., Vol.136, No.1, pp. 0110061-01100612, doi: 10.1115/1.4025490, 2013.
8. [8] H. Zheng, Y. Feng, J. Tan, and Z. Zhang, “An integrated modular design methodology based on maintenance performance consideration,” Proc. Inst. Mech. Eng. B. J. Eng. Manuf., Vol.231, No.2, pp. 313-328, doi: 10.1177/0954405415573060, 2017.
9. [9] S. Shoval, L. Qiao, M. Efatmaneshnik, and M. Ryan, “Dynamic modular architecture for product lifecycle,” Procedia CIRP, Vol.48, pp. 271-276, doi: 10.1016/j.procir.2016.03.037, 2016.
10. [10] H. E. Tseng, C. C. Chang, and J. D. Li, “Modular design to support green life-cycle engineering,” Expert Syst. Appl., Vol.34, No.4, pp. 2524-2537, doi: 10.1016/j.eswa.2007.04.018, 2008.
11. [11] S. Kim and S. K. Moon, “Eco-modular product architecture identification and assessment for product recovery,” J. Intell. Manuf., Vol.30, pp. 383-403, doi: 10.1007/s10845-016-1253-7, 2019.
12. [12] M. Inoue, S. Yamada, S. Miyajima, K. Ishii, R. Hasebe, K. Aoyama, T. Yamada, and S. Bracke, “A modular design strategy considering sustainability and supplier selection,” J. Adv. Mech. Des. Syst. Manuf., Vol.14, No.2, pp. 1-10, doi: 10.1299/jamdsm.2020jamdsm0023, 2020.
13. [13] Y. Yoshizaki, T. Yamada, N. Itsubo, and M. Inoue, “Material based low-carbon and economic supplier selection with estimation of GHG emissions and affordable cost increment for parts production among multiple Asian countries,” J. Jpn. Ind. Manage. Assoc., Vol.66, No.4E, pp. 435-442, doi: 10.11221/jima.66.435, 2016.
14. [14] S. Yamada, T. Yamada, S. Bracke, and M. Inoue, “Upgradable design for sustainable manufacturer performance and profitability and reduction of environmental load,” Int. J. Automation Technol., Vol.10, No.5, pp. 690-698, doi: 10.20965/ijat.2016.p0690, 2016.
15. [15] K. Watanabe, Y. Shimomura, A. Matsuda, S. Kondoh, and Y. Umeda, “Upgrade planning for upgradeable product design,” Quantified Eco-Efficiency, Vol.22, pp. 261-281, doi: 10.1007/1-4020-5399-1_11, 2007.
16. [16] C. Michaud, I. Joly, D. Llerena, and V. Lobasenko, “Consumers’ willingness to pay for sustainable and innovative products: a choice experiment with upgradeable products,” Int. J. Sustain. Dev., Vol.20, Nos.1/2, pp. 8-32, doi: 10.1504/IJSD.2017.083493, 2017.
17. [17] V. Lobasenko and D. Llerena, “Elicitation of willingness to pay for upgradeable products with calibrated auction-conjoint method,” J. Environ. Plan. Manag., Vol.60, No.11, pp. 2036-2055, doi: 10.1080/09640568.2016.1271776, 2017.
18. [18] Y. Umeda, T. Daimon, and S. Kondoh, “Proposal of decision support method for life cycle strategy by estimating value and physical lifetimes – Case study,” Proc. of the 4th Int. Symp. on Environmentally Conscious Design and Inverse Manufacturing (EcoDesign 2005), pp. 606-613, doi: 10.1109/ECODIM.2005.1619308, 2005.
19. [19] H. Kobayashi, “Strategic evolution of eco-products: a product life cycle planning methodology,” Res. Eng. Des., Vol.16, pp. 1-16, doi: 10.1007/s00163-005-0001-3, 2005.
20. [20] S. Yamada, T. Sugiura, T. Yamada, S. Bracke, and M. Inoue, “A strategy of providing upgradable product service system for economic and environmental balance,” M. Peruzzini, M. Pellicciari, C. Bil, J. Stjepandić, and N. Wognum (Eds.), “Transdisciplinary Engineering Methods for Social Innovation of Industry 4.0,” IOS Press, pp. 1155-1164, doi: 10.3233/978-1-61499-898-3-1155, 2018.
21. [21] Y. Shimomura, T. Hara, and T. Arai, “A unified representation scheme for effective PSS development,” CIRP Ann. Manuf. Technol., Vol.58, pp. 379-382, doi: 10.1016/j.cirp.2009.03.025, 2009.
22. [22] Y. Umeda, K. Hijihara, M. Oono, Y. Ogawa, H. Kobayashi, M. Hattori, K. Masui, and A. Fukano, “Proposal of life cycle design support method using disposal cause analysis matrix,” Proc. of the Int. Conf. on Engineering Design, Stockholm, pp. 19-21, 2003.