基于动态响应有限元模拟的点焊接头疲劳寿命预测

利用三维有限元模拟和动态响应试验对点焊接头疲劳裂纹萌生和扩展特性进行了研究。利用所模拟的裂纹长度和固有频率的关系,定义了点焊疲劳裂纹扩展的三个阶段。根据所定义的裂纹萌生阶段的定义,利用局部应力应变法预测了点焊接头的疲劳裂纹萌生寿命。结果表明,所预测的疲劳萌生寿命与试验结果相吻合。

FATIGUE LIFE PREDICTION BASED ON DYNAMIC RESPONSE FINITE ELEMENT SIMULATION FOR SPOT-WELDED JOINT

Fatigue crack characteristics are investigated based on the dynamic response simulation by finite element and the dynamic response experiments for tensile-shear spot-welded specimens. In the different fatigue damage cumulative quantity, the dynamic response frequency is measured during the fatigue damage process. The results show that the natural frequency varies non-linearly with the fatigue damage fraction. On the basis of the relationship between the crack length and the natural frequency, the definition of fatigue crack initiation stage is proposed. Fatigue crack initiation life is predicted by the local stress and strain approach with the proposed fatigue crack initiation stage for tensile-shear spot-welded specimens. The results show that good agreement is achieved with experimental data.