Three-dimensional dynamic finite element analysis of multiple laser shock peening processes

Laser shock peening (LSP) is an innovative surface treatment technique successfully applied to improving fatigue performance of metallic materials. The fatigue strength and fatigue life of the laser peened material can be significantly improved by deep compressive residual stresses being introduced into the material. The compressive residual stress distribution along the depth of the material is attributed to a high amplitude stress wave induced by a high energy laser pulse. The present paper describes a finite element method for simulating the residual stress distribution in a metal alloy 35CD4 50 HRC steel in single and multiple LSP processes. The process used a three-dimensional dynamic finite element model impacted by a square laser spot. The predicted results for single LSP were well correlated with the available experimental data. Meanwhile, the effects of multiple LSP processes, pressure magnitude and duration, and laser spot sizes on the compressive stress field in the metal alloy were evaluated for the purpose of optimising the process.