A sequential DEM-FEM coupling method for shot peening simulation

Shot peening is a cold-working process widely used to form and enhance the fatigue life of metallic components. The process consists of projecting high-velocity particles onto a metallic surface. This study introduces a new, and experimentally validated, sequentially coupled Discrete Element Model (DEM) - Finite Element Model (FEM) to predict the process' effects in terms of residual stresses and roughness. A shot stream was first simulated in DEM to obtain the velocity distribution of impacting shots. The target's progressive hardening was accounted for by adjusting the Coefficients of Restitution (CoRs) for shot-target interactions as the number of impacts evolved through a meshless method. The extracted impacting shots were then impinged onto a representative cell in a dynamic FEM model to evaluate the shot peening effects. The simulations were compared against experimentally measured roughness and residual stresses at full coverage. The study shows that using a constant average CoR yields results that are quite similar to those with an evolving CoRs, for a fraction of the computational cost. Moreover, cases where shot-shot interactions were accounted for yielded lower residual stresses and roughness than cases where such interactions were not accounted for. Nevertheless, all simulated cases delivered simulations that were in good agreement with the experiments, which validates the proposed approach.