Fabrication and finite element analysis of micro dents using μ-laser shock peening

Laser shock peening (LSP) is an innovative surface treatment developed to improve surface integrity. This study explores the feasibility using LSP to direct-write surface micro dents for lubricant retention. Since LSP is a highly transient process with a pulse duration of 10 - 100 ns, a real time in-situ measurement of laser/material interaction such as transient stresses/strains is challenging. Therefore, a 3D finite element simulation of micro-scale laser shock peening was developed to determine the effect of laser pulse duration and peak pressure on the transient material behaviors of titanium Ti-6A1-4V. The simulated dent geometry is similar to the measured dent geometry in terms of morphology. The results suggested there is an optimal peening time that produces the deepest dent. The maximum transient stress in peening direction occurred at a certain laser pulse time. However, the stress along the depth and radius were drastically affected by the peak pressures.