MOLECULAR DYNAMICS SIMULATION OF SHOT PEENING PROCESS AND RESIDUAL STRESS GENERATION: EFFECTS OF PARTICLE IMPACT SPEED AND IMPINGING ANGLE

摘要

Shot peening is a well-known surface finishing process that is often applied to enhance the residual stress distribution in the component surfaces. In this study, we carry out a molecular dynamics (MD) simulation study to investigate the single particle shot peening process on the (100) silicon surface at nano scale. The MD simulation enables in-situ observation and analysis of complex material deformation mechanisms in the presences of ultra-high strain rate, such as stress distribution, dislocation propagation, and particle/workpiece interface interaction. Three levels of shot speed (i.e., 200, 500, and 800 m/s) and three levels of impinging angle (i.e., 30°, 60°, and 90°) are configured in the simulation. It is found that higher shot speeds result in deeper depths of residual indentation, deeper penetration depths of residual stress below surface, and higher magnitude of maximum compressive stress. The residual stress distributions underneath the shot-peened surfaces exhibit strong anisotropic manner. Residual stress only concentrates in the area along the impact direction; and the decrease of impact angle results in shallower penetration of residual stress.