汽车前副车架开裂失效分析

Fracture Failure Analysis for Suspension Bolt

某车型在整车耐久试验接近完成时,前副车架发生开裂,针对此项失效问题开展分析,对失效件痕迹、断口、材质进行分析,结合副车架设计、装配/结构、焊接状态排查结果,初步确定产品焊道未按照设计要求留出余量,加剧开裂对应位置应力集中,导致疲劳寿命降低,是副车架在试验过程中开裂的主要因素。通过CAE分析,得知在加速与制动工况下,开裂位置受力最大。分别选取2台设计状态与失效状态的副车架,模拟加速与制动工况进行台架试验验证。试验验证结果显示,设计状态下的副车架循环次数最低提升41%,能够满足整车耐久试验要求。

The front subframe of a vehicle model cracked when the durability test of the whole vehicle was nearly completed.In view of this failure problem,the traces,fracture surfaces and materials of the failure parts were analyzed.Combined with the inspection results of the design,assembly / structure and welding status of the sub frame,it was preliminarily determined that the product weld bead did not leave allowance according to the design requirements,which intensified the stress concentration at the corresponding position of the cracking,resulting in fatigue life Reduction is the main factor of the cracking of the subframe during the experiment.The results of CAE analysis show that the stress on the cracking position is the largest under the acceleration and braking conditions.Two subframes with design state and failure state were selected to simulate acceleration and braking conditions for bench test verification.The test results show that the cycle times of the subframe in the design state can be increased by 41 % at least,which can meet the requirements of vehicle durability test.