3D FE analysis of peening of strain-rate sensitive materials using multiple impingement model

In spite of its importance to the aerospace and automobile industries, little or no attention has been devoted to the accurate modelling of the shot-peening process. It is therefore the purpose of this study to conduct dynamic elasto-plastic finite element analysis of the process using a realistic multiple impingement model using a rate sensitive material. In this analysis, we implement a novel “symmetry cell” approach to examine the impact effect of a large number of rigid and deformable shots on a high-strength steel target made from AISI 4340. A number of convergence tests, which account for element size and stiffness of contact elements, were carried out. In addition, efforts were devoted to determine the appropriate material damping parameters needed to dampen unwanted numerical oscillations associated with the explicit solver of LS-DYNA for this class of problems. The model was used to predict the effect of peening intensity and coverage upon the mechanically induced residual stress field and the plastic zone development for different classes of materials.