Reliability Optimization Design Of Middle Cross Beam-roof Made Of Hybrid Braided Composites

Compared with the traditional composites,braided composites have the following advantages: more complete structural properties,more uniform and reasonable mechanical properties and better designability.In aerospace,sporting goods,automotive and shipbuilding industries,the depth and breadth of the application of braided composite materials are gradually increasing.Due to the high cost of carbon fiber and the relatively low price of glass fiber,this article will design a hybrid braided composite material and lay it on the middle cross beam-roof of an important part of the automobile,and carry out the optimization design and reliability optimization design of the middle cross beam-roof of the hybrid braided composite material.In this paper,the micro-structure of single cell of CFRP/GFRP was analyzed,and the bending characteristics of fiber bundles in CFRP were considered fully,and a finite element model was established to predict the macro-elastic properties of CFRP/GFRP.By comparing the calculated results with the experimental results,the rationality of the finite element model in this paper is proved.Based on the finite element model of hybrid braided composites,the properties of the fibers in the braided composites and the influence of the microstructure parameters on the macroscopic elastic properties of the braided composites were analyzed by using SOBOL global sensitivity analysis.The parameters which have great influence on the elastic properties of braided composites were selected as uncertain variables,which laid a foundation for reliability optimization design.Then multi-objective optimization genetic algorithm is applied to the optimization design and reliability optimization design of the middle cross beam-roof of the hybrid braided composite roof.The weight and cost of the middle cross beam-roof are reduced while the impact resistance and compression resistance of the middle cross beam-roof are guaranteed.The Monte Carlo method is used to calculate the reliability in the reliability optimization design of the middle cross beam-roof.In order to improve the computational efficiency,the Kriging proxy model was used in the process of optimization design and reliability optimization design.