Research On The Conceptual Design Of Mechanical Products Based On Functional Feature-Drived

Product design method and creative design play an essential role in product development, and effective product design can determine the product performance, directly affect the consumer and increase market share. The central objective of conceptual design is to generate physical descriptions of designs, sufficient for their implementation, which would provide the intended function to users' satisfaction. Therefore, the investigation into how the knowledge of functionality can be used to improve quality, reduce cost, and reduce time to market, is very important for present conceptual design research of mechanical products.Using the relevant theoretical research achievements for reference, the functional feature and conceptual design theory of mechanical product are deeply researched in this dissertation, in which new methods of computational intelligence and creative design theory are introduced. The relation between functional features and conceptual design is discussed, and a new approach to the theoretical research on conceptual design and creative design of mechanical product is presented.Firstly, designing should be guided by functions. In other words, the knowledge of functionality can be used to guide, constrain and shape the design activity, which is an important strand of present design research. Then an iteration-based function-behavior-mechanisms-structure (FBMS) model is proposed. the generation of problem solutions satisfying function requirement is supported by the model, in which the strategy of hierarchy in relative to the function and the mechanisms of building and transferring component base are produced, as well as the methods of recursive problem and solution redefinition are adopted.Secondly, an automated method for conceptual design of mechanisms using enumeration and functional reasoning is presented. Based on principle of combination and categories of functions, design requirements and building blocks are expressed by function codes, an enumeration process is proposed to enumerate all possible and feasible functional connections of each building block in the knowledge base. Then a new combinatorial algorithm is computerized to automatically yield many candidate solutions to the desired function requirements using bidirectional search, and functional reasoning is introduced to filter out infeasible solutions.Thirdly, product design is considered as functional satisfaction problem, and an innovative approach of mechanical product design using function parameter mutation operation is presented. In view of the complexity of the function of mechanical products, the functional characteristic model and the knowledge library of function parameters were established. Through the function parameter mutation operation, then function and structure of products were modified and generated. The design processes can be used to obtain a variety of innovative products.Finally, configuration design is also studied in this dissertation. Directed by the idea of the function of product determining the structure, and also based on the description of mapping from functional domain to configuration domain, a new method for creative configuration design of product using functional feature is established. Then functional requirements and design parameters are classified and formalized in terms of characteristics set, and after constructing the mathematical model of searching for the possible combinatorial solution, a general co-evolutionary algorithm is introduced to automately generate a lot of creative configuration of product, which is according to the accordant relation between structure and function.Using the above methods, a prototype system for computer-aided conceptual design of mechanical products is developed, and by means of which the design of honeycomb briquette machine is successfully accomplished. The case study indicates that the proposed methods are feasible and effective.