| In the urban city road traffic accidents,the most common car crash is frontal collision,mainly absorb the collision kinetic energy through the bumper plastic box deformation,reducing the damage to the crew and car parts.At present,there are researches on the foam aluminum filled crash-box at home and abroad to improve the anti-collision performance,but the systematic optimization of crash-box structural parameters is rarely reported at present.Therefore,this paper is mainly researching on systematic optimization of the structural parameters aimed for foam aluminum filled crash-box to improve the safety of vehicle driving.Based on traditional steel plate crash-box,the aluminum alloy crash-box filled with foamed aluminum is designed,simulating the vehicle anti-collision performance under collision condition through LS-DYNA dynamics analysis method.Analyzing the cross-sectional shape and inclination angle of the crash-box,the conclusion shows that square cross-section crash-box with 8° inclination angle has better energy absorption characteristics.The initial peak force is reduced by fixing the induction groove in the side wall of crash-box and gain better deformation mode,and crash-box structural parameters(groove type,groove number,groove position and size of the induction groove)are compared.It is concluded that in the upper half of the crash-box structure with a radius of 2.5mm semicircular induction groove get a lower collision peak force while ensuring the energy absorption.Besides,the crushing force and the deformation mode are more stable than the former model.On the basis of the finite element analysis results,the entity test models of crash-box are made,and the impact tests of entity crash-box are carried out on the hydraulic impact test bed.The evaluation indexes of the impact test,such as impact force and the total energy are compared and analyzed.Combining the physical experiment and finite element numerical simulation results,the new crash-box structure with better energy absorption characteristics is designed.Taking the total energy absorption,energy absorption rate,peak of collision force and the efficiency of the crushing force in the low-speed collision as target,the inclination of crash-box and the radius of the induction groove are sampled by the Latin hypercube sampling method to carry on the entity crash test.Based on the response surface method,the multi-objective optimization of crash-box is carried out,and the optimal crash-box model is designed by the design expert.The optimization crash-box model is verified to be with the better energy absorption and anti-collision performance by finite element simulation method.Finally,the optimized crash-box with batter energy absorption and anti-collision characteristics is achieved.Finally,installing the crash-box before and after optimization on the car bumper beam,the simplified car bumper three-dimensional models were established.Based on similarity theory,the finite element numerical simulation of the similarity bumper model before and after the optimization are carried out,and the anti-collision characteristics of the crash-box in low-speed collision process are analyzed.Energy absorption of the bumper entities before and after optimization was calculated by means of dimension analysis.The evaluation indexes of the energy absorption characteristics and the deformation mode of the bumper installed with the optimized crash-box are analyzed.A newly-design crash-box structure with better collision resistance and energy absorption characteristics is obtained,which provides the idea for the material and structure parameters optimization of car crash-box,and improves the anti-collision performance of the bumper in the low-speed collision process. |
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