Optimization Of Composite Laminate Structures Under The Constraint Of Strength And Fatigue Life

Composite materials have been widely used in the field of Aeronautics and Astronautics because of their excellent performance.Advanced carbon fiber reinforced polymer composites have been applied to fairing or outer casing of aircraft engines.Laminated structures are usually used as main structures in composite applications.Laminated composite structure,as an important structural component of aero engine,requires better static strength and fatigue life in its work process,so as to meet the needs of engineering.At the same time to improve the comprehensive performance of the aircraft,the aircraft engine thrust weight ratio and the increasing requirements,through the composite laminated structure to optimize the design,reduce the quality,so as to improve the thrust weight ratio of purpose.Therefore,in order to better use of the laminated composite structure of their own potential and methods developed to its static strength and fatigue life prediction value accurately,and the strength and the fatigue life as the influencing factors of laminated structure optimization,has certain practical significance in engineering.First of all,in view of the carbon fiber resin matrix composite laminated structure,this paper studies the static load and fatigue load under the action of three dimensional gradually cumulative damage analysis method and strength and fatigue life prediction model is established.Strength and fatigue life prediction model based on the established respectively for the one-way slab,the anisotropic laminated board,laminated plates containing hole three different strength of the specimens and to predict the fatigue life prediction and the result was compared with the test results.The results show that the intensity of three different specimens of prediction error absolute values are within 8%,the fatigue life prediction for three different specimens are within the error with three times,the rationality of the forecasting model is verified.Secondly,the optimization of laminated structure of composite materials is carried out.According to the laminated structure of composite materials,a composite algorithm based on genetic algorithm was compiled based on C ++ language.Because the structural optimization of laminated composites belongs to the problem of discrete design variables,this program designs and implements joint integer coding considering the number of ply and the ply.In order to converge to the global optimal value quickly and accurately,this program is designed and implemented Adaptive Genetic Algorithm Based on Improved Elite Algorithm.Finally,composite laminates and aero-engine composite casing were optimized.Taking the strength and the fatigue life value obtained from the predictive model as the constraints,the ply parameters were selected as the design variables by the analysis of the structural characteristics,and the structural quality was taken as the optimization objective.The improved genetic algorithm was used to optimize the laminated structure.The results show that the structure quality is obviously reduced after optimization,and the comparison of the optimal lay-up mechanical properties under single constraint and double constraint strength and fatigue life shows that the strength and the fatigue life value of the optimal lay-up are better than the single constraint obtain the corresponding strength and fatigue life value of the optimal ply.