The Finite Element Analysis on the Effects of Overlapping Rate in Low-Energy Laser Shock Peening

Laser shock peening has been widely studied and pioneeringly applied in aerospace industry as a life-extension technology for structured mechanical components. However, in other promising fields such as nuclear power industry, little has been studied concerning such critical issues as long-distance transmission of the laser beam by optical fiber and optimized parameters of typically low pulse energy with micrometer-sized beam spots. In such scenario, the overlapping rate between adjacent small spots plays a critical role in obtaining homogenous residual stress and surface morphology. In this study, a three-dimensional finite element model in AISI 420 martensitic stainless steel has been developed to correlate the residual stress as well as surface morphology with varying overlapping rates. Multiple laser spots are loaded with VDLOAD user subroutine in Abaqus. The residual stress distribution is analyzed with respects of laser shocking and in-depth planes. And the surface morphology is evaluated in terms of depression depth as well as surface roughness. Combined results suggest that the overlapping rate of 61% as an optimized value, which can be used as a basis for future experimental studies and industrial applications.