2D Simulations of the NS-Laser Shock Peening

Abstract

Laser shock peening (LSP) is a widely known technique, which is used in industry to improve the properties and performance of metallic components. Laser induced compressive residual stresses (RS) allow to enhance the fatigue life of aircraft structures. Due to deeper depth and higher magnitude of RS in the target material, this technique is a potential substitute of the conventional methods applied in industry, e.g. shot peening. In LSP short laser pulses (fs-, ps- and ns-ranges) with high intensity (usually > 1 GW/cm2) are used to vaporize and ionize the thin surface layer of the target material. The fast expansion of this plasma plume induces a mechanical shock wave propagation, which causes microstructure changes and results in compressive residual stress generation. Plasma formation and shock wave propagation are nonlinear processes with extremely short time scales. Due to that, it is very difficult to optimize the LSP process based on experiments alone. Thus, simulation models are required. In this manuscript, a 2D simulation of a laser ablation of gold is performed with the open source code MULTI2D as a first step towards ns-LSP simulation of different materials. The temporal and spatial distributions of plasma and shock wave are determined to prove that the code is applicable for a nanosecond laser peening and to understand the plasma formation and the shock propagation within a target material.