Functional Evaluation Based on Function Content

Function is a key concept to integrate design object mod eling and design process modeling in design We here propose the FEP Functional Evolution Process model in order to inte grate design object modeling and design process modeling In the FEP model the model of a design object is evolved through three steps i e function description function actualization and function evaluation Function description is the step in which a designer modi es required functions of a design object Function actualization depicts a process to obtain physical descriptions from functional description Function evaluation is a process to measure realizability of functions of the design object However among other steps how to treat the function evaluation is one of the most important theme because evaluation executed by designers is based on subjective ambiguous and tacit standards We discuss a methodology for evaluating function and pro pose the function content that quanti es functions and enables evaluation of functions The function content is a similar con cept of Shannon s information content and we show an example of functional optimization based on this scheme INTRODUCTION Treating functions is cruicial not only for representing design object but also for describing design process which is important to aid design by computers On the other hand although designers somehow evaluate functions of design objects criteria of the evaluation di er according to each designer and it is di cult to make them explicit In order to support design and maintenance of machines by a computer methodology for evaluating functions should be developed Problems for this computerization include the facts that function is subjective and relations between function and physical parameter are not clear In this paper we discuss relation among design and function about this function evaluation and design process representation We rst introduce the FEP model that is a framework of design object and process modeling and discuss features of the function evaluation which is one of the basic steps of the FEP model Second we propose function content as a meter for evaluating functions Finally we represent some