Product-service system (PSS) complexity is rapidly increasing in order to meet complex user requirements. Increased complexity leads to PSSs failing to meet sustainability requirements in their initial design. To enhance PSS sustainability and support social benefits, this paper proposes a sustainable PSS development framework based on design-centric complexity (DCC) theory. In the early design stage of a PSS, DCC theory is used to analyze the complexity of the system. Determination of the types of complexity in the system and the corresponding problems is then performed. By combining the sub-field model of TRIZ, the problems can be converted and solved, and the functional periodicity may be established to reduce system complexity. By using this development framework, the conflicts and potential problems of design attributes can be reduced and the possibility of achieving PSSs functional requirements (FRs) can be enhanced. This will maintain the long-term operation stability for the system and enhance the sustainability of the PSS. Finally, the feasibility of the development framework is verified here through the case analysis of a bicycle sharing service and management system.

The application of design knowledge determines the innovativeness of a technical scheme obtained by trimming (a tool for problem analysis and solving in TRIZ). However, limitations in the knowledge, experience and expertise of designers constrain the range of design knowledge that they can apply, thus reducing the effectiveness of trimming. In this paper, biological strategies are introduced to the trimming process to compensate for limitations imposed by the insufficient professional knowledge of designers, thereby improving design innovation. Therefore, this paper proposes a new design method that combines the trimming method and bio-inspired design (BID). First, a trimming analysis of the target system is carried out. Taking the missing functions of the trimmed system as a potential breakthrough point, a keyword search mode based on “V(verb)O(object)P(property) + the effect/features of the associated function” is used to search for biological prototypes in the biological knowledge base. Second, a fuzzy comprehensive evaluation method is used to analyze the biological prototypes from three dimensions, namely, compatibility, completeness and feasibility, and the best-matching biological prototype is selected. Finally, the biological solution is transformed into an engineering design scheme through a resource derivation process based on structure–function–attribute analogies. The proposed method can expand the range of design solutions by adding biological strategies as a new resource to solve trimming problems. The feasibility and effectiveness of the method are verified by redesigning a steel tape armoring machine.

Analogy-based design is an effective approach for innovative design. However, existing research on analogy design mainly focuses on methods to form innovative schemes, without considering feasibility or practicality in applications. This research proposes a multi-analogy innovation design (M-AID) model based on analogy in both design-centric complexity (DCC) and solution of inventive problems (TRIZ). To improve practicality, digital twin (DT) is introduced to apply real design information, manufacturing production data, and maintenance information in the design process. The method includes six steps: (1) analyze a target product based on users and market requirements to synthesize general function requirements; (2) acquire analogy function source using knowledge base and patent base; (3) call digital twin resources to obtain real product data for the design; (4) reduce the complexity of the design system after fusion using DCC theory; (5) use TRIZ to solve problems of design conflicts; and (6) evaluate design solutions according to product requirements. The current proposed method enhances the design scheme feasibility and reduces the number of iterations from the conceptual scheme to the final scheme in the design process, thus improving the efficiency of the innovative design process. The applicability of the currently proposed method is demonstrated through exemplification of innovative design of a dust removal system for a solar panel.

No abstract