Fuzzy Optimal Method And Engineering Application Of Complex Mechanical Structure

There is a large number of fuzzy information in the initial stage of structuraldesign. There exits different fuzzy factors in the range of design variables,evaluation of design objects, allowable range of constraints and loads in practice.Multi-object fuzzy optimization of mechanical structures is described by fuzzytheory in this thesis. The main research focuses on method of structural fuzzymulti-object and its application in engineering.Firstly, basic principles and conceptions of fuzzy optimization areintroduced. Then, single-objective fuzzy model, method of fuzzy optimizationand mathematic model, basic principles, and solutions of multi-objective fuzzyoptimization are given. The multi-objective fuzzy optimization theory is appliedto analyze helical gear model and the optimal solutions of different fuzzy optimalmodels are obtained based on Matlab optimization toolbox.The optimization design of mechanical engineering structure is usually inmulti-objective form. Multi-objective optimization is a difficult problem and aresearch focus in the fields of science and engineering. Classical multi-objectiveoptimization methods have several shortcomings in solving high dimension andmulti-modal problems. In order to solve these problems, the basic theory of AFast and Elitist Multi-objective Genetic Algorithm (NSGA-â…¡) is studied in thisthesis. The Algorithm using m-file in Matlab to test typical applied functions,computational efficiency can be improved, more reasonable distributed solutioncan be obtained, and diversified distribution of the solutions can be maintained.The thesis applies the algorithm to the structural fuzzy multi-objectiveoptimization project of three-bar truss. It also provides beneficial references forother structural fuzzy multi-objective optimization projects.However due to the complication of mechanical structure, lots of fuzzy information is difficult to be described by math functions. According to theprinciple of fuzzy mathematics and finite element, the thesis focuses on analysisand fuzzy optimal design of complex mechanical structure by an example of thevalve body of full-bore type safety valve manufactured by Harbin HBC ValveCompany Limited. The fuzzy finite element main model of valve body isdeveloped under virtual environment by using VC. NET platform and APDLprovided by ANSYS. The complicated and indigestible ANSYS command streamis encapsulated in background process. So the system can reduce largely valvebody study and design workload.The reliability design of effective load parts of spacecraft instruments is keystep in ensuring the reliability of parts products. So it has particularly significantmeanings in the process of the products manufacture. Finally principles of fuzzymathematic are applied. Multi-objective fuzzy reliability optimization is appliedto worm driving mechanism based on NSGA-â…¡. A better objective solutionbalance is obtained between variety and astringency. It is applied to the reliabilityof thermal control shutter worm gear mechanism to ensure the success of thermalcontrol task of lunar exploration satellite (ChangE I Satellite). ANSYS/PDS toolis applied to verify reliability design. All provides references for part reliabilityanalysis.