考虑低载荷强化效应的汽车转向节疲劳分析  

Fatigue Analysis of Automobile Steering Knuckle Considering the Effect of Low Load Strengthening

作　　者：董国疆[1] 杜飞 王威[1] 郎玉玲 Dong Guojiang;Du Fei;Wang Wei;Lang Yuling(Yanshan University,Hebei Key Laboratory of Special Delivery Equipment,Qinhuangdao 066004;Engineering Simulation Center of CITIC Dicastal Co.,Ltd.,Qinhuangdao 066004)

机构地区：[1]燕山大学,河北省特种运载装备重点实验室,秦皇岛066004 [2]中信戴卡股份有限公司工程仿真中心,秦皇岛066004

出　　处：《汽车工程》2020年第3期406-415,共10页Automotive Engineering

基　　金：国家自然科学基金(51775481);河北省自然科学基金(E2019203418);河北省教育厅高等学校科技计划重点项目(ZD2017078)资助。

摘　　要：本文中基于试验场强化道路实车测试,结合零部件有限元动力学仿真和疲劳耐久性能仿真,探求考虑小载荷强化效应与Miner准则两种疲劳分析方法对汽车零部件疲劳寿命预测的差异性。通过室内实车振动测试与有限元仿真联合分析,确定前转向节疲劳损伤危险点(即路试应变监测点);提取试验场强化道路实测应变监测点应变时间历程,经过预处理、时域加速、雨流矩阵外推和载荷谱分级得到10级等效应力谱。结合低载荷强化理论和线性累积损伤理论对10级等效应力谱的疲劳效应和损伤效应进行分析,相对于传统Miner准则而言,考虑了小载荷强化效应使构件在加载过程中疲劳极限呈现上升规律,进而需要修正构件S-N曲线(简化),较初始S-N曲线向上偏移,基于修正后构件S-N曲线并应用线性疲劳损伤累积理论预估的转向节疲劳寿命较Miner准则提高了40.6%。此种方法考虑了材料强化行为的影响,一定程度上弥补了Miner理论未考虑各级载荷间相互影响和材料硬化瞬态行为影响的缺陷,对实际零部件疲劳寿命估计与轻量化设计提供新的参考。Based on real vehicle test on the proving ground,combining with the finite element dynamic simulation and fatigue durability simulation of components,the difference of fatigue life prediction of automobile components with the consideration of small load strengthening effect and Miner criterion is explored in the paper.Fatigue damage risk point of the front knuckle(the road test strain monitoring point)is determined by joint analysis of indoor vehicle vibration test and finite element simulation;the strain time history of strain monitoring points of strengthened road on the proving ground is acquired,after pretreatment,time domain acceleration,extrapolation of rain flow matrix and load spectrum classification,ten-grade equivalent stress spectrum is obtained.Combining with the low load strengthening theory and the linear cumulative damage theory,the fatigue effect and damage effect of the ten-grade equivalent stress spectrum are analyzed,in contrast to the traditional Miner criteria,considering the strengthening effect of small load on the increase of the fatigue limit of the component in the process of loading,the component S-N(simplified)curve needs to be modified,offset upward from the initial S-N curve.The predicted fatigue life of the knuckle based on the modified S-N curve and linear fatigue damage accumulation theory is 40.6%higher than that of the Miner criterion.Taking into account of the effect of material strengthening behavior,this method makes up for the defect of the Miner theory which does not take into account of the interaction between different loads and the effect of material hardening transient behavior to a certain extent,and provides a new reference for fatigue life estimation and lightweight design of real components.

关 键 词：疲劳损伤 低载荷强化 Miner准则 转向节 载荷谱 

分 类 号：U463.46[机械工程—车辆工程]