Research On Mechanical Function Symmetry And Prinple Symmetry Concept,and It’s Application Knowledge System

Symmetry widespreads in all aspects of mechanical systems:space-time symmetry exists at all levels of mechanical parts, components, the whole machines and product families; effect symmetry exists in various products those could realize the same targeted function with different means. Deep and systemic research on mechanical space-time symmetry and effect symmetry, can guide the process of conceptual design to better realize the function of mechanical systems, improve their performances, meet their design restrictions, shorten their design cycle, and finally improve their competitiveness on the market. After systematic analysis on the research situation of symmetry in different domains, aiming at the drawbacks of current research in mechanical symmetry, the concept arctechture and application knowledge of mechanical function symmetry and principle symmetry were rigorously studied. The main research and primary contributions are reflected in the following four aspects:Firstly, the concept architecture of mechanical function symmetry and principle symmetry was established. After the research on the existence of symmetry in mechanics and other domains, the concept and hierarchical structure framework of mechanical function symmetry and principle symmetry was proposed. According to the symmetry creterion mechanical symmetry is classified into space-time symmetry and effect symmetry. Effect symmetry means to discuss the equivalence of several solutions those could satisfy the same requirements. And effect symmetry is classified into decomposition symmetry, combination symmetry and permutation symmetry according to the transformation operations. Based on above classification function effect symmetry and principle effect symmetry were discussed and classified further, and then the hierarchical tree of the function effect symmetry and principle effect symmetry was established. Mechanical space-time symmetry is classified into function space-time symmetry and principle space-time symmetry, and their symmetry elements were analysed carefully, which are composed by symmetry body, symmetry unit and symmetry criterion. Thereby, the hierarchical tree of the function space-time symmetry and principle space-time symmetry was established. Based on above concept system, an instance model of mechanical space-time symmetry was constructed, by which the symmetry instances were standardized and entered into the database to form the mechanical space-time symmetry instance base. Much relational knowledge was mined from the instance base, by way of rigorous ananlysing and refining some application knowledge of space-time symmetry was summeried.Secondly, the application knowledge system of mechanical function effect symmetry was established. Based on the function effect symmetry concept system, the instance model of function effect symmetry was constructed, and an instance base including400instances was established. Much relational knowledge was excavated from the instance base, such as "targeted function=>function structures","performances=>transformation operations of function effect symmetry" et al. Then26design guidelines and3design principles of function effect symmetry used for "simplify system","improve efficiency","improve man-machine-friendly" and "improve response speed" et al were summarized. And a relational model for "performances-defaults of function structures-design guidelines/principles for function design" was constructed. Based on above instance knowledge, relational knowledge and design guidelines/principles, a process for function innovative design with the application knowledge of function effect symmetry was put forward.Thirdly, the application knowledge system of mechanical principle effect symmetry was established. Based on the principle effect symmetry concept system, the instance model of principle effect symmetry was constructed, and an instance base including200instances was established. Much relational knowledge was excavated from the instance base,36design guidelines and2design principles of principle effect symmetry used for "expand working scope","improve man-machine-friendly","improve efficiency","improve measurement accuracy" and "abating harmful side effects" et al were summarized. And a relational model for "performances-defaults of working principle-design guidelines/principles for principle design" was constructed. Based on above instance knowledge, relational knowledge and design guidelines/principles, a process for principle innovative design with the application knowledge of principle effect symmetry was put forward.Fourthly, Computer Aided Innovative Design Platform for Mechanical Function Principle Symmetry (CAIDPMFPS) was established. On the basis of above concept system and application knowledge of mechanical function symmetry and principle symmetry, the CAIDPMFPS was established, which is composed by instance management module, knowledge management module, knowledge mining module and knowledge application module. At last,"a kettle used on electromagnetic oven which could activate the electromagnetic oven to switch off the power automatically" and "a compact electric hammer drill which could counteract the additional magnetic torque" were invented by the use of above application knowledge, which were used as two instances to describe the process of performing function innovative design and principle innovative design with help of CAIDPMFPS.