A User Study to Evaluate the Function Model and Function Interaction Model for Concept Generation

Function modeling is often performed during the conceptual design phase to identify what the product must do in a solution independent form. However, function-based design approaches do not adequately enable designers to capture and analyze the non-functional requirements, interactions between the product of interest and other products and interactions between the product of interest and human users. This paper presents the results of a user study to evaluate how two models: (1) traditional function models (FM) and (2) the function interaction model (FIM), relate to functional and non-functional engineering requirements, and how they affect the creation of design solutions. Forty students were divided into two groups and asked to generate solutions for a design problem using either the function model (FM) or the function interaction model (FIM). The concepts were then evaluated in terms of quantity and quality by an external panel. Results from this study indicate that the quantity of solutions generated by the function model (FM) group is greater than the function interaction model (FIM) group. However, the quality of design concepts from the function interaction model (FIM) group is greater than the function model (FM) group. Further, nonfunctional requirements that are important to the design solutions cannot be captured in function model and thus are not reflected in the associated solution concepts.Copyright © 2011 by ASME