Jem1672 689..698

Impact modelling for shot peening or peen forming has progressed from simulating a single impact (or local multiple impacts) to simulating a large number of multiple impacts. It is the aim of this paper to provide quantitative results with a detailed finite element study, and to compare the effects of a single impact and global multiple impacts. Using a two-dimensional (2D) axisymmetric single impact model with a very fine mesh as reference, an appropriate three-dimensional (3D) mesh density for the target material is chosen by evaluating the 3D results against the axisymmetric results. A 3D explicit dynamic finite element analysis combined with a static springback analysis is then used to simulate a large number of steel shot impacts on an aluminium 2024-T351 target. The multiple impact modelling results indicate a clear difference of residual stress profiles between those obtained from single and multiple impact modelling. This difference is due to the global uniformity effects of shot peening, which involves numerous impacts. In addition, equivalent plastic strain obtained from the analysis is compared with microhardness test data on an experimental sample. Finally, the shot peen forming effect of multiple impacts is also evaluated by showing the macroscopic surface deformation. The comparison between single and multiple impact modelling results indicates that it is appropriate and important to model an appropriate coverage of multiple impacts for shot peening and peen forming at its various coverage.