Collision Performance Simulation And Optimization Of CFRP Energy Absorbing Structure For Automobile Front End

With the increasing demand for environmental protection and the increasingly serious energy crisis,new energy vehicles have attracted more and more attention.However,the durability of new energy vehicles has limited its development,and the lightweight body has a good effect on solving this problem.When the body structure tends to be perfect,the selection of lightweight materials becomes an important method to realize the lightweight of the body.Carbon fiber reinforced polymer(CFRP)has high specific stiffness,specific strength and excellent specific energy absorption,it has gradually become an important lightweight material for vehicles,so it is very important to study the performance of CFRP.From the point of view of body lightweight and safety,CFRP is applied to automobile bumper,and the following research is carried out:(1)According to the anisotropic characteristics of CFRP,the tensile,compressive and shear tests of CFRP in different directions were carried out,and the mechanical properties of CFRP in different directions were obtained.The material card of MAT054 type was established in LS-DYNA.The correctness of the material card is verified by comparing the simulation and test results,and the material parameters are provided for the establishment of the CFRP square tube simulation model.(2)The drop-tower test of the axial impact of the CFRP square tube was carried out to study the influence of the layup angle on the failure mode of the CFRP square tube.The finite element model of the CFRP square tube was established.The finite element analysis of the axial impact was carried out under the condition of the drop-tower test.The deformation and stress-strain curve of the square tube were obtained,which was consistent with the drop-tower test results.The correctness of the finite element modeling method.(3)For the study of CFRP bending resistance,the finite element model of CFRP hat-shaped structure was firstly established,and the bending resistance analysis was carried out to study the influence of the layer angle and structural fillet size on the bending resistance of CFRP materials Then the CFRP square tube was tested and simulated under three-point bending condition,and the failure mode of CFRP square tube under three-point bending condition and the influence of laying angle on the energy absorption effect of CFRP square tube under three-point bending condition were studied..(4)The material of the original bumper was replaced by CFRP material,and three kinds of bumpers of CFRP material with different ply angles were designed.Under the full-width frontal impact condition of 50 km/h,the best energy absorption angle was selected as the ply angle of the redesigned CFRP bumper assembly structure.The crash analysis of the designed CFRP bumper is carried out under the full front width condition of50km/h.The results show that the acceleration of the whole vehicle can trigger the restraint system within 15ms～20ms of the crash.According to the low-speed collision regulations,the low-speed longitudinal and “vehicle angle” collision simulations are carried out to analyze the deformation and energy absorption of the beam.The results show that the bumper meets the triggering conditions of the restraint system and meets the requirements of the low-speed collision regulations.Compared with the bumper of the steel material in the original car,the bumper is 58% lighter and realizes lightweight.