Modelling Residual Stresses in Shot-Peened Magnesium Alloys: A Hybrid Method

Shot peening process can induce beneficial compressive residual stresses and thereby enhance fatigue properties of magnesium alloy sheets. Fully analytical and numerical (finite element) models have been commonly employed to provide a low-cost estimation of residual stresses induced by the shot peening. In the fully analytical method, stringent assumptions made to allow for closed-form analytical solutions, lead to ignoring friction and strain rate effects. Employing the fully numerical method for magnesium alloys, on the other hand, is not a straightforward task, due to magnesium complex unloading response. Moreover, finite element modelling of a full-coverage shot peening condition is both time-consuming and computationally expensive. A single-shot finite element model is herein combined with a full-coverage analytical approach using actual asymmetric loading-unloading material behaviour to propose a hybrid numerical-analytical model for prediction of the residual stress distribution in a shot-peened AZ31B-H24 rolled sheet. The proposed hybrid model can take into account the actual material behaviour, actual elastic-plastic contact analysis, friction, and strain rate effects. Predicted through-depth residual stress distributions are found to be in good agreement with experimental stress measurements, via x-ray diffraction and hole drilling methods, under various peening conditions.