Managing Function Concepts in the Design Process

Abstract

In this paper, we discuss how and why function conceptsare managed in the early stage of the design process. Conventional design methodologies have pointed out that functional decompositionis a key to the synthetic natureof the design process [Pahl & Beitz, 1988]. Especially in the case of original design, function decomposition is said to be indispensable. However, the reasons and mechanisms for decomposing the required functions have not been clarified. The importance of these processes has been understood only experientially. In this paper, we discuss the function decomposing process from a theoretical point of view. First, we outline a study on design methodology by Pahl and Beitz. Next, we present a mathematical framework for design knowledge which we developed in our previous paper. In this framework, functionis recognized as an abstract conceptand represented as a class in set theory. As one approach to formulating a mechanism for managing function concepts, we present a convergent policy for design solutions. Our model is useful for theoretical discussions on the function decomposingprocess. We show that managing function conceptscan be viewed as one approach to an NP complete problem.