%0 Journal Article
%T A Functional Representation Model Facilitating Design Space Expansion
%A Wei Xu
%A Ke Zhao
%A Yatao Li
%A Peitao Cheng
%J ISRN Mechanical Engineering
%D 2013
%R 10.1155/2013/686402
%X This paper addresses the functional representation based on the event model. In the event model, the ontology is defined based on the theory of propositional logic to describe the connotation of the event, and the variant is defined based on the theories of domain relational calculus and set theory to express the variation range of the event, which is alterable part of the event under the constraints of the ontology. Function is an important concept in conceptual design and has its connotation and extension. The functional representation is proposed based on the event model. The ontology of event is used to describe the connotation of function and to reflect the stability of function. The variant of the event is used to represent the extension and to incarnate the variety of function. The extension of function is the change range of function under the constraints of the connotation. The proposed functional representation divides the function into the immutable part and the alterable part, facilitating the expansion of design space. A functional reasoning model is also put forward based on the event model to support the function reasoning on the computers. Finally, a simple case validates the feasibility of the model. 1. Introduction Product is the realization of functions. It is the core issue of product design to study and realize functions of products. The functional representation [1] is an important method to express a product and is vital in the whole design process. It is an important research content of the design theory and methodology. The functional representation functionally abstracts and describes the market demands and user requirements by computer analysis, highlights the design task, and facilitates finding out the novel design solutions. The basic concern of functional representation is how to represent the knowledge of functions [2]. The functional representation should meet the following three conditions.(1)The functional representation should be able to completely express the requirements of product design and should not lose information in the entire design process.(2)The functional representation should be convenient to realize the mapping and transformation functions to behaviours and structures.(3)The functional representation should contain constraint information. Constraints play a very important role in any design. The functional representation relies on constraints to limit the search space of design. In addition, the function serves as an important concept in the conceptual design and must have its connotation and extension.
%U http://www.hindawi.com/journals/isrn.mechanical.engineering/2013/686402/