Prediction of residual stress relaxations in shot-peened specimens for fatigue crack growth

The effect of residual stress, created by shot peening, on the fatigue crack growth for pre-cracked specimen, as well as the relaxation of residual stress during fatigue crack propagation are studied. The fatigue crack growth, incorporating with effects of shot peening, is investigated by two-dimensional FEM simulations. The cohesive zone model, with the feature accounting for the damage evolution under cyclic loading, is adopted into FEM calculations to simulate the potential fracture surfaces. The results show that the residual stress retards the fatigue crack propagation. The retardation effect depends on shot peening intensity. The residual stress nonlinearly relaxes with increasing loading cycles.