Lightweight Design And Safety Research Of Rear Bumper Of Electric Vehicle

With the rapid increase of car ownership and the deepening of people's concerns about environmental pollution and energy shortage,electric vehicles will be more and more popular.However,limited by its inability to achieve the coexistence of large capacity and lightweight battery technology,EV has been unable to fundamentally solve the problem that its endurance is inferior to the traditional vehicle with the same model and configuration,so it is particularly important to realize vehicle lightweight to increase the endurance of EV.As one of the important lightweight materials,carbon fiber reinforced composite(CFRP)is widely used in automobile body manufacturing because of its superior mechanical properties and obvious lightweight effect.Based on the low-speed collision regulation gb17354-1998,this paper takes the rear anti-collision beam of an electric vehicle as the research object,and applies CFRP to the rear anti-collision beam to carry out the following research:(1)The parameters of low-speed impact simulation of CFRP anti-collision beam are determined by experiments.According to the relevant mechanical property test standards of non-metallic composite materials,the tensile,compressive and shear tests of CFRP laminates were carried out.The parameters of tensile strength,shear strength,tensile modulus,shear modulus,tensile strength,compressive strength and shear strength of the material are obtained.Based on these parameters,the failure strain parameters are obtained by reverse calculation and debugging.(2)Orthogonal optimization of CFRP anti-collision beam lay way.Taking the main beam of the rear impact beam of an electric vehicle as the prototype,the same thickness CFRP is used to replace the original aluminum alloy material,and the frontal low-speed collision simulation based on gb17354-1998 standard is carried out.Using the orthogonal test method,the layer design of the anti-collision beam made of CFRP material is carried out.The design variables are layer thickness,layer number,the proportion of layer angle(±45°),layer laying mode,the optimization target is to minimize the peak impact force,and the constraint is the amount of intrusion.By solving nine groups of pavement combinations.At last,the optimized layer is[45/-45/0/90/45/-45/45/-45/45/-45/45/90/90/-45/45/-45/45/-45/45/-45/90/0/45/-45],and the thickness of each layer is 1.5mm.Through the comparative analysis,the results show that the peak force of the layer combination is significantly reduced.(3)The feasibility of CFRP anti-collision beam with orthogonal optimization is verified by low-speed collision simulation test.First,the free and constrained modes of the CFRP anti-collision beam and the aluminum alloy anti-collision beam obtained by the orthogonal optimization are analyzed and compared,and the conclusion is that the free modes and constrained modes of the CFRP anti-collision beam obtained by the orthogonal optimization are higher than those of the aluminum alloy anti-collision beam.Then,based on gb17354-1998 standard,two kinds of finite element models of aluminum alloy and CFRP are established for the anti-collision beam,the two models of aluminum alloy and CFRP are compared and analyzed from the aspects of material failure,specific energy absorption,the amount of intrusion,peak force and so on.The results show that the energy absorption ratio and peak force of the optimized CFRP are significantly lower than that of the aluminum alloy anti-collision beam,and the amount of intrusion is greater than that of the aluminum alloy anti-collision beam,but far less than the allowable intrusion.At the same time,the anti-collision beam made of CFRP is 43%less than that made of aluminum alloy,which is about 1.51kg.