Micro-scale Laser Shock Processing – Modeling, Testing, and Microstructure Characterization

This paper reports modeling improvements for micro-scale laser shock processing (LSP), fatigue testing of shock processed copper samples, and microstructure characterization of shock processed materials (Cu and Ni). Plasma expansion is modeled as laser supported combustion wave, in which radial and axial expansions are considered. Stress/strain analysis is extended to three-dimensional and takes into account of finite geometry, which is important for micro-scale LSP. Tests are designed to demonstrate that micro-scale LSP can improve fatigue performance of the materials while offering a level of flexibility. The influence of LSP on the microstructures of the materials is studied quantitatively using Orientation Imaging Microscope (OIM) technique, and grain size and subgrain structures are analyzed.