Research On Mechanical CAD System Using Symmetry Knowledge

Symmetry is widely used in mechanical systems.Deeply and systematically researching on mechanical symmetry knowledge and the developing of corresponding CAD system are helpful to improve the efficiency and quality of the knowledge reuse of mechanical symmetry,and can make better use of symmetry knowledge to design mechanical products.This thesis mainly studies the theoretical knowledge required for the development of mechanical CAD system based on symmetry knowledge.The main research contents and results can be classified into the following four aspects:Firstly,based on the analysis of more than 1,000 symmetric instances,the functional library and design requirement system of mechanical products are established,which are refined and developed from three aspects:technical,economic and social.Secondly,an extensible mechanical structure symmetry storage system is established.Combined with the symmetry system,the mechanical symmetry instance knowledge storage model is put forward.Thirdly,according to the design demand system,a systematic knowledge base for the application of mechanical symmetry is established and expanded from the technical,economic and social aspects of mechanical products.Fourthly,on the basis of the above theory,a mechanical CAD system based on symmetry knowledge is developed.And the software framework consists of five basic modules:basic knowledge management,symmetric instances and application knowledge management,knowledge mining and application and so on.This CAD system can be used to mine mechanical symmetry association knowledge and guide the design of mechanical products.Finally,an improved design of the scissor jacks was put forward which increased stability,and proved the useful of the CAD system.And the new design is applying for a patent.