FBS-Based Conceptual Design Methodology For Mechanical Products And Its Application

Product design can be described as a process which converts a set of functional requirements into one or more concrete structures. Conceptual design is the most important, critical and creative stage of the whole design process. It is the first consider and solve the problem in the product design process that how its function and structure conversion, also it directly affects the product development process. It can support the detailed design effectively to apply product model established that getting and understanding the information of product features. At present, the mapping of the function and structure has no improved uniform conclusion although there are many scholars have in-depth study about the product conceptual design. Based on the existing design model of FBS (function-behavior-structure), this thesis first investigates the behavior characteristics of mechanical products. By systematically analyzing the behavioral characteristics of mechanical products, it proposes to evaluate the design by Rough sets theory. Other methods proposed can be summarized as follows: First, a new method to represent the behavior of mechanical products is presented, where graphical Petri nets are employed to describe the behavior characteristic of mechanical products. Through graphics, behavior relation between the parts is clear, which can be used to disclose problems in the operation process of mechanical products and then supplies the method for design modification or optimization. Second, by analyzing multi-attributes of mechanical product behaviors, the thesis proposes a conceptual design framework based on FBS design model. The concepts of behavioral effect, elemental behavior and behavioral chain are proposed and five kinds of links within behavioral chains are summarized, including sequence, parallel, selection, repeat and feedback. With these, the behavioral model scheme is proposed for conceptual design of mechanical product. It then investigates the design process of interface between behavioral blocks, where a case study was conducted to demonstrate the feasibility of the proposed methodologies. Third, it applies Rough Sets to evaluate product designs. The method expedites the evaluation process by refining the evaluation criteria from those initially specified. It calculates the weighting factors of the evaluation criteria by taking into account their discriminating capability. At last, a system is built, in which 12 kinds of behavioral characteristics are incorporated, together with the structures they are mapped to, which can be a reference for...