汽车后悬架拖曳臂台架疲劳试验失效分析及其改进

Analysis and Improvement of Durability Failure Trailing Arm of Automobile Rear Suspension Based on Bench Test

为解决某SUV后悬架拖曳臂台架试验耐久失效故障,首先建立后悬架系统有限元分析模型,根据悬挂系统耐久试验装置及其失效工况,在轮心处沿着纵向施加6 000 N,对其进行强度分析,以此确定应变片测试位置。然后基于胡克定律对测试数据进行处理计算,得到测试点的应力值,与有限元模型进行对标分析,分析结果表明两个应变片测试点的台架试验结果与有限元分析的误差率分别为4.5%和5.1%,因此该有限元模型具有很高的准确性。再基于对标成功的有限元分析模型,约束车身所有自由度,在轮心位置施加以纵向力12 000 N,分析结果表明拖曳臂的最大应力为397.3 MPa,并且其应力集中位置与裂纹源一致。通过在开裂的螺栓孔处焊接大垫片,改进之后拖曳臂的最大应力为313.74 MPa,其较改进之前降低了21.1%。最后基于Miner线性损伤理论和Ncode软件对拖曳臂原始方案和改进方案进行分析,其最大损伤值分别为2.3和0.9,相应的拖曳臂疲劳寿命提高了60.9%,改善效果非常明显,其最大损伤值位置也与失效件裂纹源位置相吻合,并且其改进方案最终顺利通过了悬挂系统的台架耐久试验验证。

Aming at solving the durability failure trailing arm of a SUV rear suspension base on bench test,the finite element analysis model of the rear suspension system was build,the wheel center of trailing arm was load 6000 N along longitudinal and strength analysised based on suspension system durability test device and its failure condition,so the test position of strain gauge were established. The stress value of test point were obtained based on Hooke＇s law,and they were comparative with finite element analysis model,the analysis result showed that the error rates of the bench test results and finite element analysis of two strain gauges were 4.5% and 5.1%,so the finite element model had high accuracy. The trailing arm was strength analysised by adopting constraining all degrees of freedom of the body and loading 12 000 N at wheel center based on the finite element analysis model,the analysis result showed that maximum stress was 397.3 MPa and the stress concentration position was consistent with the crack source. The improved scheme of maximum stress was 313.74 MPa by adopting welding gasket at the failure bolt hole,and it was reduced by 21.1%.The original scheme and improved scheme of the trailing arm were analyzed based on Miner linear damage theory and Ncode software,the analysis result showed that the maximum damage values were 2. 3 and 0. 9. The fatigue life of trailing arm was respectively increased by 60. 9%. So the improvement effect was very obvious,and the maximum damage position was consistent with the crack source,the improved scheme successfully passed the durability test of suspension system.