Reliability And Dynamics Comprehensive Optimization Of Composite Laminate Structures

Composites, especially composite laminate structures, have been applied more and more widely in aerospace industry. In order to increase the ratio of thrust to weight and improve the comprehensive performance of aircraft, optimization design must be carried out. Genetic algorithm (GA) is employed, which combines finite element method (FEM) and response surface method, to establish the reliability-based and dynamics comprehensive optimization design method of composite laminate structures in this thesis and the corresponding software code is written. The main research includes the followings:(1) Based on parametric and composite laminated structure FEM technique, the mechanical performance and modal of composite laminated structures are analyzed, the parametric program is designed.The failure function is defined and response surface--FEM is used to analyze the stability of composite laminate structures.(2) The dynamic multi-objective optimization model is obtained, and the weight, the maximum value of Tsai-Wu, the maximum displacement, the frequency of a structure are objective functions. Meanwhile, the last three variables are constraints in the optimization process. Based on the model the structure provides best performance with lighter weight. Considering the reliability, the integrated optimization model is built by regarding the reliability as constraint.(3) The dynamic optimization example is evaluated and validated by static tensile test and modal test. The results show that: the structure optimized provides better overall performance.(4) The results obtained by reliability and dynamic optimization example show that the structure comprehensively optimized provide better safety. Then the reliability and dynamics comprehensive optimization design is carried out for an aeroengine case.(5) Based on the characteristic of composite laminate structures, the encoding mode of GA is studied and a set of GA program is developed by VC++6.0. The operating system commands are called to achieve the overall optimization program design of genetic algorithm and parametric finite element.