关键词: 3D有限元, 点焊接头, 固有频率, 疲劳裂纹萌生与扩展, 寿命预测

Abstract: 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 experi- mental data.

Key words: 3D Finite element, Fatigue crack initiation and propagation, Life prediction, Natural frequency, Spot-welded joint