| Carbon Fiber Reinforced Plastic（CFRP）/Metal is a hybrid material that combines a lightweight,high-strength carbon fiber composite material with a ductile metal material.Compared with CFRP,the cost of parts made with the hybrid material is low,and during the collision process,the interaction between different materials changes the brittle fracture mode of CFRP and improves the stability of energy absorption.Therefore,the use of CFRP/metal hybrid materials instead of some metal automotive parts is an effective method to achieve vehicle lightweight and improve collision safety.However,there are few studies on the crashworthiness of CFRP/metal hybrid materials,and the application of hybrid materials in automotive parts needs further investigation.This article focuses on the optimization design of automotive crash box.CFRP/AL（aluminum）hybrid materials are used instead of the original metal materials.The crashworthiness of CFRP/AL crash box is analyzed and its structure is optimized.The main work of this paper is as follows:（1）First,a finite element model（FEM） is established based on the quasi-static axial compression tset.The accuracy of the loading method and boundary condition are determined by comparing the results of experiment and simulation.Subsequently,the optimal cross section shape of the crash box is determined using the FEM accrding to the geometric dimensions given in the reference under the quasi-static axial compression and quasi-static 30° oblique compression.Then take the specific energy absorption（SEA）and average crushing load(Fmean)under quasi-static axial compression as the optimaztion goals,and limit the variation range of the total energy absorption of crash box under quasi-static 30°oblique compression.The overall shape and cross section size of the crash box are optimized and the initial model of the hybrid material crash box is determined.（2）The quasi-static axial compression tests of AL,CFRP,and CFRP/AL thin-walled circular tubes are performed,and the differences in failure modes and energy absorption performance of single-component materials and hybrid material thin-walled tubes are compared.Based on the quasi-static axial compression test of of CFRP/AL hybrid material thin-walled circular tubes,the CFRP material model and the mode of the bonding relationship between CFRP and AL are established,and the FEM of CFRP/AL hybrid tube is established.（3）Based on the validated CFRP/AL hybrid material model and the initial crash box model,the effects of three design variables:fiber filament winding angle（θ）,fiber thickness（n）and aluminum tube thickness（t）on the crashworthiness of CFRP/AL hybrid crash box are analyzed under axial and 30° impact respectively.According to the analysis results,the value range of the three design variables is determined.Taking the specific energy absorption（SEA） as the optimization objective under two kinds of impact,the NSGA-II optimization algorithm and TOPSIS method are used to determine theθ,n and t.Finally,compared with the original metal material crash box,the hybrid material crash box designed in this paper not only achieves the purpose of light weight,but also has a significant improvement in crashworthiness. |
