Shock-wave pressure decay in aluminum: model development

A laser shock wave is a pressure wave in a gigapascal range propagating at speeds above the speed of sound in a medium, induced by a high-power density laser pulse. Its duration is of the order of magnitude of nanoseconds. When the shock wave propagates in a solid, some materials characteristics in the area where laser beam is incident, change due to the application of compressive residual stress. These may be hardness, corrosion resistance, stress-fatigue resistance, to name a few. The shock wave has been found useful for working materials in diverse application fields such as aeronautics, defense, material science, and micro-components. The shock wave pressure decreases drastically as it propagates inside the solid, making it difficult to obtain experimental data when the shock wave propagates in solids with a thickness greater than one millimeter. We employ finite element method for the solution of shock wave propagation problems. Its primary benefit is that wave pressure and velocity may be determined upon modeling for thicknesses greater than one millimeter. We demonstrate a non-linear relationship between the material thickness and the shock wave that decreases with increasing slab thickness. In addition, the relationship between thickness and shock wave velocity is found. We estimate the material thickness by obtaining the attenuation ratio of the shock wave pressure.