Explicit dynamics simulation of shot peening process induced by various types of shots impacts

摘要

Shot peening is a cold-working process that induces a small indentation on a metallic surface by impacting shots onto it causing residual compressive stresses which delays the initiation of fatigue cracking. The experimental assessment of shot-peening process parameters is not only very complex but costly as well. The most promising technique is the explicit dynamics finite-element (FE) analysis capable of determining the shot-peening process parameters subject to the selection of a suitable material's constitutive model and numerical technique. In this work, Ansys/LS-Dyna code was employed to simulate the impact of shots of various sizes made of steel and glass on an aluminium alloy plate defined with strain-rate-sensitive elasto-plastic material model. The impacts were carried out at various incident velocities. The effects of velocity, size, and material of the shots on the compressive residual stress, indentation, and force-time response were investigated. The results showed that impact with the steel shots caused more indentation and larger area of plastic deformation in target material than the glass shots due to higher kinetic energy. Furthermore, increasing the shot velocity and size resulted in an increase in indentation. However, a negligible effect of the shot velocity, size, and material was observed on target's surface and subsurface residual stress. The obtained results demonstrated that the proposed FE models simulated the shot-peening process in a realistic way. The study can be used to determine and optimise the shot-peening parameters such as shot size, material and velocity, and amount indentation and residual stresses in the aluminium alloy plate.