Structure/material/function Integrated Design Of Free-form Surface CFRP Parts

The macro and micro integrated design of carbon fiber composite(CFRP)is an optimization design method which comprehensively consider the structure optimization and material layer optimization to improve the performance of CFRP structural parts.In order to solve the slow convergence of CFRP integrated design.The paper proposes a method of material function integration design for CFRP parts based on variable layering.In this method,the integrated design is divided into system level and sub level.The sub level includes structure level and material level.The cross-section control nodes and their weight factors of structural parts are used as local variables at the structural level for NURBS structural optimization design.The CFRP ply angle is used as the local variable at the material level for meso ply optimization design.The total thickness of structural parts is extracted as the system level common variables,through the interaction of design variables at sub level and system level,the functional integration design of CFRP parts is realized.The main research contents are as follows:(1)Taking the minimum weight of CFRP structure as the design objective,the control node x_i and its weight factor?_i of the structural part are taken as the design variables at the structural level.The structural parametric modeling and analysis are carried out by using APDL language.The optimization main program is compiled by MATLAB and the txt result file of APDL parametric modeling to realize the structural optimization design of automobile roof and fan shroud.(2)Aiming at the functional optimization of CFRP structural parts,the ply angle and ply thickness of CFRP are taken as the design variables of material layer.AGA is used to optimize the meso ply design of CFRP roof and fan shroud.(3)The results show that the quality of the CFRP roof decreased 74.5%and the natural frequency improved 125.5%compared with the whole optimization method,the iteration times of the method are 42 times less than the whole optimization method.The results of the optimization of the top cover of the automobile CFRP are verified by DOE center composite test method.The data of the test points and the corresponding response surface results,the candidate points of the experimental design,the local sensitivity and Pareto optimal solutions are obtained.(4)The overall optimization method and the layered collaborative optimization method are used to solve the optimization example of the fan CFRP shroud.The results show that:under the condition of meeting the stiffness performance,the maximum stress drop is 24%and the confluence air volume is increased by 9.1%.Compared with the overall optimization method,the iteration times of the hierarchical optimization method are reduced by 20 times,and the lightweight effect is significantly improved.The optimization results show that,on the premise of ensuring the accuracy of the optimization results,the optimization efficiency of the hierarchical collaborative optimization method is significantly better than that of the overall optimization method.Aiming at the structural/material/functional integrated design of free-form CFRP parts,this paper proposes a hierarchical collaborative optimization method for integrated design.The research results can provide theoretical guidance for integrated design of free-form CFRP structures,and have practical application significance.