Mechanical Structure Multi-Symmetry Theory And Its Application In Design

Symmetry phenomenon widely exists in mechanical structure, especially the multi-symmetry. Numerous design cases demonstrated that multi-symmetry played a vital role in implementing functions, improving performance and satisfying constraints and more than 600 classical mechanical design cases were collected and deeply analyzed to support those roles. Despite its significance, there were few studies on mechanical multi-symmetry by now. This thesis reviewed the literature of multi-symmetry in inter-disciplines and got a systematic summary and discussion of the deficiencies in current studies on mechanical multi-symmetry. The major contents and main achievements can be classified into following four aspects:Firstly, based on the analysis of multi-symmetry design instances, the definition of mechanical structure multi-symmetry was proposed, and the classification system which includes combination symmetry and composition symmetry was built to show their existence and application in different hierarchies in mechanical system. Furthermore, through the analysis of symmetrical body, symmetrical benchmark and symmetrical element, the multi-kinds, the multi-dimension, the multi-variant, and the multiplicity of multi-symmetry property was proposed and systematically analyzed.Secondly, aiming to meet the demands of the mechanical parts and system, analyzed the effects and principles of combination symmetry in implementing functions, improving performance and satisfying constraints. Besides, the mapping from function and principle symmetry to combination symmetry was briefly described.Thirdly, aiming to meet the demands of the mechanical parts, analyzed the effects and principles of composition symmetry in implementing functions, improving performance and satisfying constraints. Furthermore, extract the symmetry principles in the research area of DFA (design for assembly), then give a summary of the application of composition symmetry in DFA.Fourthly, considering the double-effecting factors in and outside the system, the external induction mechanical multi-symmetry and internal self-induction mechanical multi-symmetry was proposed to constitute the multi-symmetry theory. Then the classification and definition was based on multi-symmetry counteracting principle and multi-symmetry matching principle.