Prediction of Bending Fatigue Life for Shot-Peened Face Gears Integrating Residual Stress Relaxation and Surface Topography Evolution

The fatigue performance of face gears can be effectively improved through shot peening strengthening. To reveal the influence mechanism of shot peening parameters on the strengthening effect, a random shot peening model was first established, through which the effects of shot peening parameters on the residual stress distribution and tooth surface morphology of face gears were analyzed. Furthermore, a bending fatigue life prediction model considering both residual stress and surface morphology was developed, and the influence mechanisms of process parameters, including shot diameter, shot velocity, and surface coverage, on the bending fatigue life were investigated. The results showed that the compressive residual stresses induced by shot peening could effectively offset the working tensile stresses and reduce the stress peak generated at the tooth root region under external loading conditions. Moreover, compared with surface coverage and shot diameter, shot velocity was found to have a more significant influence on fatigue life, and an appropriate increase in shot velocity could effectively enhance the strengthening effect.