Local Stress Intensity Factors for Kinked Cracks in Spot Weld Cup Specimens

In this paper, the local stress intensity factors for kinked cracks in spot weld cup specimens are investigated by finite element analyses. Based on the experimental observations of kinked crack growth mechanisms in square-cup specimens under cyclic loading conditions, axisymmetric finite element models are established to investigate the local stress intensity factor solutions for kinked cracks emanating from the main crack. Both circular and rectangular shaped notch tip and a sharp crack tip are considered for the main crack. Various kink lengths are considered. The local stress intensity factor solutions for kinked cracks are obtained. The results show that the local stress intensity factors for kinked cracks with finite kink lengths are much higher than those based on the closed-form solutions for kinked cracks with vanishing kink length. Finally, the implications of the local stress intensity factor solutions for kinked cracks on fatigue life prediction are discussed.