基于等效结构应力的电阻点焊疲劳寿命预测
Fatigue life simulation of spot weld based on equivalent structure stresses
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摘要: 采用基于等效结构应力的点焊疲劳寿命预测方法对搭接和剥离两种受力状态下的电阻点焊疲劳寿命进行有限元模拟,运用简化粱单元、壳单元和刚性粱单元建立点焊有限元模型,利用商业有限元软件进行线弹性分析获得点焊周边单元节点的节点力,由节点力计算焊点周边单元的等效结构应力,根据单一主S-N曲线确定点焊疲劳寿命.为了验证有限元建模及疲劳预测方法的可靠性,进行搭接和剥离两种受力状态的点焊疲劳试验,结果表明,基于等效结构应力的电阻点焊疲劳预测方法具有较高精度,可以用于车身零部件点焊疲劳寿命的预测.Abstract: The fatigue life of spot-welds are predicted based on the stress-based method for tension shear and coach peel samples,the simplified beam、shell and rigid beam ware used to built the FE model of spot-weld,the grid force of elements around spot-weld nut ware gotten from elastic FE analysis using commercial software,the equivalent structure stresses were calculated using line force and moments,the fatigue life of spot-weld of tension shear and coach peel were predicted based on master S-N curve.The physical fatigue tests have been done to valid the simulation results.The results indicted that the prediction of spot-weld fatigue life based equivalent structure stresses had satisfactory approximation and could be used to predict the spot-weld fatigue life of body in white in automotive industry.