Green modular design for material efficiency: a leader–follower joint optimization model

Green modular design can facilitate life-cycle material efficiency through component material reuse and minimizing resource commitment throughout the product realization process. Traditional modular design has been motivated toward delivering variety at low cost, but with little incentive for material efficiency per se. The key technical challenge for incorporating material efficiency considerations into the prevailing modularization theories and methods lies in that such material reuse modularity must be consistent with and conform to the legacy structure of a technical system. This paper is geared toward a total system approach and emphasizes leader–follower joint optimization in order to leverage technical system modularity (TSM) and material reuse modularity (MRM) within a coherent framework. To measure component interactions and cluster components into modules, taxonomy of modularity metrics is developed encompassing the entire life cycle of material fulfillment. The quantification and aggregation of modularity measures are formulated by multi-attribute utilities of different dimensions of component similarity. Furthermore, a bilevel optimization model based on a constrained genetic algorithm is put forward for joint decisions of TSM and MRM. A case study of refrigerator green modular design is reported. Results and analyses reveal that the leader–follower bilevel optimization model is robust and excels in supporting green modular design with material reuse.