| With the increase in vehicle ownership year by year and the frequent occurrence of low-speed collision safety accidents such as road congestion and rear-end collisions,it is imperative to improve the passive safety performance of automobiles and reduce the maintenance cost of low-speed collision vehicles.At present,the traditional crash box still has the problem of poor energy absorption effect and large peak collision force.The contradiction between the large peak collision force and the large intrusion amount of traditional crash boxes is the main reason for limiting the performance improvement of crash boxes.In order to solve these problems,this thesis uses the simulation numerical analysis method to optimize the square-section crash box structure,and designs a new crash box structure to alleviate the contradiction between the collision force peak and the intrusion amount.The research content of this thesis is as follows:Using 100% frontal low-speed collision conditions,SOLIDWORKS software was used to establish a three-dimensional model of the square-section crash box,and ANSYS Workbench LS-DYNA software was used to simulate the collision.In order to ensure simulation accuracy,the meshing,element type,and control settings of hourglass energy are studied.Finally,the square-section crash box is experimentally verified,and the empirical formula applied to the circular-section crash box is verified theoretically to verify the accuracy of the simulation method.In order to further improve the collision performance of the crash box,the square crash box is equipped with stiffeners,and the“yue-shaped”crash box is selected as the optimization target according to the simulation results.In order to achieve the maximum energy absorption efficiency of the crash box within the peak allowable collision force range,the response surface of the “yue-shaped”crash box is optimized.The energy absorption response surface,collision force response surface and intrusion response surface were fitted,and the best optimization scheme was selected by MOGA algorithm.After the error analysis of the optimization calculation,the reliability of the optimization calculation is verified.The optimization results show that within the the peak allowable collision force range,average collision force of the optimized square crash box increases by 28.96%,and finally,the guide groove is set for the optimized crash box model,which further reduces the peak collision force of the crash box.In order to explore the influence of the design parameters of the guide groove on the crash performance of the crash box,the influence of the depth of the guide groove,the width of the groove,the inclination angle and the concave and convex arrangement on the crash performance were explored by simulation method.In order to reduce the negative correlation between the peak of collision force and the decrease of intrusion,a lantern-type crash box structure is proposed.Feasibility analysis of lantern-type crash box.After that,the simulation experiment was carried out by changing the thickness of the lantern-shaped crash box and configuring the stiffeners,and the simulation results of the traditional “yue-shaped”crash box were compared.The comparison results show that under the condition that the average collision force is similar,the peak collision force of the lantern-type crash box is reduced by 26.8% compared with the “yue-shaped”crash box,so the lantern-shaped crash box is a better energy-absorbing structure.This thesis analyzes the influence of parameter changes on the performance changes of crash box from many aspects,which has reference significance for the design of crash box.A new structure of crash box is designed,which improves the contradiction between the reduction of the peak collision force and the decrease of the intrusion amount of the crash box,and provides a new inspiration for the structure design of the crash box. |
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