Study On Some Key Problems In Parametric Design Of Complex Products

Parametric design is always a very important topic in the research field of CAD. Especially, parametric design of complex products is becoming one of the studying hotspots in recent years. Complex products are referred to the products with complex requirement, composing, inside technology and process of development, which involve much domain knowledge in the design process. Then, to represent and utilize this complicated knowledge effectively and efficiently in parametric design is a big challenge, which will undoubtedly help to avoid lots of repetitive work, shorten the cycle of development and lower the cost of products. Furthermore, the domain knowledge should be saved and updated with the improvement of technologies and products.Many approaches to the parametric design of complex products and domain knowledge representing have been brought forward; however, most of them are related to a certain process and cannot describe the whole process of design, modeling and assembly. In this thesis, we discuss the classification of design knowledge to represent and maintain it effectively, propose design features integrating domain knowledge and assembly semantics to utilize it in parametric modeling and assembly, put forward the knowledge description of products, components, templates, instances to implement the management and reusing of parametric models. Meanwhile, this work is part of the research and development of the projects "Some Key Technologies and Representative Application Research on Virtual Prototype" sponsored by National 863 Hi-Tech Program and "Virtual Manufacturing Technology in Semantic Web" sponsored by Science & Technology Comm. ofShandong Province, which has important academic and practical meanings. Some of the results have been used practically in JIER MACHINE-TOOL GROUP CO. LTD., which is the largest press maker in China.The contributions of this thesis are:1. After analyzing the current status of computer-aided design systems, we provide a framework of knowledge-based parametric design of complex products. Through design features integrating domain knowledge and assembly semantics, we integrate more engineering information and design intention into parametric modeling and assembly. A design instance of the multi-linkage drive system of mechanical presses is provided to illustrate the realization.2. We classify domain knowledge in design process into table knowledge, process knowledge and interactive knowledge. Then, we propose the uniform description of them and use the Table Solver to represent and solve table knowledge. Furthermore, through converting these kinds of knowledge to "resource", useful knowledge may to be solidified, which does help to the effective utilization and dynamic expending of the various and abundant design knowledge.3. We discuss the knowledge description of products, components, templates, instances, based on which we has developed a parametric part-component management system. With this system, designers may manage the models in product logic, which are built in different systems. Besides, the system supports the designers to use or upload design tools, which may make the modeling process more convenient.