Three-dimensional elastoplastic finite element model for residual stresses in the shot peening process

Abstract

The fatigue life of mechanical components subjected to variable loading conditions is a crucial parameter in the design of automotive and aerospace mechanical components. The fatigue strength of the component can be improved by inducing compressive residual stress in the surface and subsurface layers by the shot peening process. This increases the failure strain magnitude for crack nucleation and propagation. Extensive experimental results have been published on the effect of shot peening process parameters on residual stress distributions and subsequently on fatigue performance. Numerical simulation of residual stres induced by the shot peening process is important for understanding and optimization of the process in terms of the residual stress profile and maximum shot coverage in the shortest time. In this paper, an elastoplastic finite element (FE) model will be presented to simulate the shot peening process in three-dimensional configuration. The FE model takes into account numerical and material damping, thermal elastic—plastic material behaviour, a rigid or deformable body for the shot and the effects of multiple shot impacts. The workpiece material modelled was AISI 4340 steel at HRC 52 ± 2. The effects of strain hardening, strain rate and temperature were considered in the non-linear material model. Results show that the predicted residual stress profile agreed well with that acquired from published experimental results provided the shot was modelled as a deformable body and material damping was considered.