Fatigue life prediction for spot welds in coach-peel and lap-shear specimens based on fracture mechanics

A fracture mechanics approach is adopted here to examine the fatigue lives of spot welds in coach-peel and lap-shear specimens. The paths of fatigue cracks near the spot welds in these two types of specimens are first discussed. A fatigue crack growth model is then developed for spot welds in these two types of specimens based on the Paris law for crack propagation and the global and local stress intensity factor solutions for kinked cracks. Various global stress intensity factor solutions for spot welds in these specimens are used to obtain the local stress intensity factor solutions with the experimentally determined kink angles. The results indicate that the fatigue life predictions based on accurate global stress intensity factor solutions are compared well with the experimental results.