Finite element modelling of coverage effects during shot peening of IN718

Current 3D shot peening simulation models proposed in literature do not take into account coverage as a process parameter influencing the residual state after shot peening. In this study a classic approach, using an ordered dimple pattern, and a new approach, using a stochastic dimple pattern were tested to describe the correlation between coverage, the surface topography and the residual stress state. Model verification was conducted based on X-ray and confocal white light microscopy measurements on shot peened test specimens. The test material was age hardened IN718. Simulations showed that the dimple pattern and the impact order of the shots can have a strong influence on the calculated macroscopic residual stress state. The stochastic approach enabled a realistic prediction of the surface topography and the residual stress state for arbitrary values of coverage while the classic approach strongly underestimated the number of shot impacts needed to achieve a certain value of coverage.