基于偏置碰撞工况汽车前纵梁结构优化设计

Optimization Design of Vehicle Front Longitudinal Beam Structure Based on Frontal Offset Impact

偏置碰撞工况发生时,前纵梁将出现折弯变形,严重影响其承载吸能作用的发挥。根据偏置碰撞的特点,搭建车辆正面40%可变形壁障碰撞仿真分析模型,选取三种不同的初速度50km/h、56km/h和60km/h进行分析,获取车身和前舱总成的变形过程;基于分析结果,对前纵梁弯曲变形的吸能过程和失效特点进行分析;采用引导槽和约束板相结合的结构形式对前纵梁进行优化设计,并对尺寸参数进行设计;基于碰撞模型,对优化前后的车辆安全性进行对比分析。结果可知:前纵梁弯曲失效中,向外胀形和向内径缩交替出现的变形形式可以提升承载能力;引导槽式结构和约束板结合的设计形式,可以提升前纵梁发生弯曲变形时的承载能力;引导板的布置间距应为外胀变形与径缩变形模式的波长之和;优化后,碰撞加速度、变形模式和各测点的侵入量均有明显的提升变化,各测点侵入量均较小,离合踏板侵入量在前纵梁改进后侵入量得到明显减小约为10%左右;纵梁前段优化结构的吸能特性己经充分发挥;分析结论为同类设计提供重要参考。

When the offset impact condition occurs,the front longitudinal beam will be bent and deformed,which seriously af⁃fects the performance of energy absorption.According to the characteristics of the offset impact,the impact simulation analysis model of the 40%deformablecrashworthiness during front impactwas built.Three different initial velocities of 50km/h,56km/h and 60km/h were selected for analysis to obtain the deformation process of the body and front compartment assembly.Based on the analysis results,the energy absorption process and failure characteristics of the front longitudinal beam in the process of bending deformation were analyzed.The front longitudinal beam was optimized by the combination of guiding groove and restraining plate,and the dimension parameters were designed.Based on the impact model,vehicle safety was compared and analyzed before and after optimization.The results show that the load bearing capacity can be improved bythe alternate deformation forms of bulg⁃ing and shrinking alternately during the process of bending failure of the front longitudinal beam.The design form of the combina⁃tion of the guiding trough structure and the restraining plate can improve the bearing capacity of the front longitudinal beam when it is bent and deformed.The arrangement spacing of the guide plates should be the sum of the wavelengths of the external ex⁃pansion deformation and the diameter reduction deformation mode.The impact acceleration,deformation mode and the intrusion amount of each measuring point have obvious improvement after optimization.The intrusion amount of the clutch pedal is signifi⁃cantly reduced by about 10%after the front longitudinal beam is improved.The energy absorption characteristics of the optimized structure in the front section of the stringer have been fully utilized.Analysis conclusions provide an important reference for similar designs.