A fatigue crack growth model for spot welds under cyclic loading conditions

Based on the experimental results for spot welds in square-cup, lap-shear and coach-peel specimens of dual phase, low carbon and high strength steels, kinked fatigue crack paths near spot welds are first examined. A fatigue crack growth model is then developed for spot welds based on the local stress intensity factor solutions for kinked cracks. Various global stress intensity factor solutions for spot welds in the three types of specimens are used to obtain the local stress intensity factor solutions with the experimentally determined kink angles. The predicted fatigue lives based on the fatigue crack growth model are then compared with the experimental data. The results indicate that the fatigue crack growth model can predict reasonably well the fatigue lives of spot welds based on the global stress intensity factor solutions and the assumed material constants in the Paris law for fatigue crack growth.