Study On Key Technologies Of Multidisciplinary Design Optimization And Its Application In Mechanisms Design

With the development of Science and Technology,mechanical systems are becoming more and more complex,the interaction between parts of them becomes increasingly obvious.The design of mechanical systems usually involves multidisciplinary,multi-objective,multi-constraint and multivariable.In order to improve design quality and develop design potential,the theory of multidisciplinary design optimization(MDO) is developed.It can be described as a methodology for the design of systems where the interaction between several disciplines must be considered,and where the designer is free to significantly affect the system performance in more than one discipline.At present,MDO has received much widely attention recently in academic circles,both at home and abroad.The success in the field of aerospace has been paid attention to by the researchers in non-aerospace fields.The yield of MDO application has been expanded to the field of weapon,automobile,computer,the mechanical design and other fields.The MDO idea is applied to the design of mechanism system.Three modes of mechanism design,such as serial design,integrated design and MDO mode are investigated systematically,including the definitions,the ideas and the optimization models.The merits and demerits of design mode are studied.Coupling complexity of MDO is studied.With the analyzing method of sensitivity information,coupling factors are researched.The factors of effecting coupling degree are analyzed.The conception of coupling strength is presented, the function of membership degree is defined with the method of fuzzy methematics,and the judgement criteria of coupling factors is proposed.Based on the conception and the judgement criteria,decoupling method of MDO is proprosed.The merit and demerit of collaborative optimization(CO) are analyzed.The local and global approximate technologies are introduced.The methods of experimental design are synthesized.According to the calculation problem of system level of CO,the uniform design is adopted to select sample points,the Kriging approximate technology is used to structure the system level constraints. The improved CO is proposed.In order to perfect the theory of MDO,the evaluation problem of feasible solution is researched.The characteristics of MDO systems are analyzed and summarized.The weights of disciplines are calculated. The definition of satisfactory solution is introduced.The satisfactory functions are enumerated.The satisfaction evaluation model of MDO feasible solution is established.The evaluation method of MDO feasible solution is proposed with offering guidance for further design.The dissertation introduces the idea of MDO to the field of mechanical design.The key technologies of MDO,such as design mode of the mechanism,MDO coupling complexity,MDO algorithms and evaluation method of MDO feasible solution,are studied,and all the research results has been successfully used in mechanism system and classical engineering example of MDO.