Design And Optimization Of Bumper Beam For Automotive Carbon Fiber Corrugated Sandwich Structure

With the increase in car ownership,cars consume more and more energy,resulting in a series of environmental problems.In order to achieve energy-saving and emission-reduction of automobiles,lightweight design has become a research hotspot for most carmakers and universities.Among the three major lightweight approaches,the use of lightweight materials is the most promising lightweight option.Carbon Fiber Reinforced Plastic(CFRP)have more advantages such as high specific strength,high specific modulus,high temperature resistance and excellent energy absorption among the composite materials.As the process progresses,the manufacturing cost is reduced year by year.Therefore CFRP is widely used in automobiles.Based on the advantages of CFRP,this study aims to design a carbon fiber corrugated sandwich structure crash beam to replace the existing aluminum alloy bumper beam.According to the requirements of China's laws and regulations,the crashworthiness in low-speed of two kinds of automobile bumper beams is compared and analyzed by the finite element method.Firstly,carbon fiber mechanical properties test specimens and carbon fiber corrugated core sandwich panels were prepared by preheating the prepreg.Quasi-static tests were performed according to ASTM standards to obtain the mechanical properties of carbon fibers.Three-point bending tests were performed on two kinds of carbon fiber corrugated core sandwich panels with different panel thicknesses.Three-point bending test was simulated by the finite element method and the results were compared with the tests to verify the reliability of the simulation.Secondly,according to the requirements of China's laws and regulations GB17354-1998,the finite element models were established for both the aluminum alloy bumper beams and carbon fiber corrugated sandwich beams.The solution calculations were performed under low speed frontal collision and low speed angle collision conditions,respectively.The comparative analysis of two kinds of bumper beams was carried out from the peak impact force,the intrusion of the punch and the specific energy absorption.Finally,according to results of finite element analysis in fourth chapter,an optimization design about the carbon fiber corrugated core bumper beam was implemented under low-speed front-end collision conditions.Three elements of optimal design and mathematical expressions were determined according to the relevant literatures and evaluation indicators in Chapter 4.The Kriging model was established and verified its accuracy in order to save the optimization solution time.The NSGA-II algorithm was chosen to solve the optimization problem according to the characteristics of optimization model.When the Perato front solution set was obtained,an optimal solution was selected as the final optimization result based on the preference.The effectiveness of the optimized design was verified in low-speed frontal and angular collisions,respectively.This study shows that,the carbon fiber corrugated sandwich structure bumper beam can improve the crashworthiness and reduce the weight by 42.9%.At the same time,it has certain reference significance for the application of carbon fiber materials in automobile bodies.