Contrasting function with affordance in design for additive manufacturing

Additive Manufacturing (AM)'s advance from rapid prototyping to the end-of-use products inevitably challenges conventional design theories and methodologies. Especially while adopting systematic engineering design methodologies to design for AM (DfAM), it is essential to develop new design methods that explore the new design space enabled by AM's design freedom from the early design stage. To address the challenge, this study provides a new design framework and a design method for modeling AM-enabled product behaviors in the conceptual design phase of DfAM. Firstly, this study contrasts function-based methods with affordance-based methods. The device-centric, form independent and input/output-based transformative properties of the functionbased methods such as function decompositions have strengths in modeling product's internal behaviors. However, the function-based methods show limitations in the new area of AM-enabled mass personalization which requires design approaches for representing user-centric structural design requirements acquired only by AM's design freedom. On the other hand, the affordance-based methods can address the function-based methods in DfAM due to their user-centric (artifact-user interactive), form dependent and nontransformative properties. After the contradiction, we propose an affordance-based DfAM framework and an affordance structure as a formal modeling technique for AM-enabled personalized product behaviors. A case study of a trans-Tibial prosthesis socket provides an illustration in this study. The contribution of the study is in developing a design method for the conceptual design phase of DfAM that fulfills the objectives of achieving AM-enabled mass personalization with systematic engineering design approaches.