Evaluating the influence of residual stresses and surface damage on fatigue life of nickel superalloys

Abstract The effect of surface damage, such as dents caused due to the low velocity impact of hard blunt objects, on the fatigue life of mechanical components are investigated in this paper. A two-dimensional dislocation density approach is used to obtain the stress intensity factors of a crack propagating under dents. Both the contributions of the geometrical stress concentrator (notch), due to the presence of the dent, and the residual stress field, generated during the impact, on the stress intensity factor of the crack are obtained. A short crack growth model is then used to predict the fatigue life of nickel superalloys in the presence of two dent depths. The effect of the residual stress field has been shown to be the main contributor to the difference observed in predicted fatigue life between the two dent depths analysed.