Abstract
This paper describes recent advances in the observation and modeling of laser peening phenomenon. Laser peening changes the stress field in metallic materials from tensile to compressive by the impulsive effect of laser-induced plasma. The plasma, generated by the irradiation of the second harmonic of a Nd: YAG laser on an SUS304 test piece, was directly observed by imaging the plasma luminescence. Comparing the observed image to the plasma expansion velocity calculated using an analytical model, we calibrated the time evolution of the calculated plasma pressure. The propagation of a shock wave induced by laser irradiation and the dynamic response of the material was simulated by an elasto-plastic analysis with a finite element program using the plasma pressure as an external load. The calculated residual stress was compared to the results of corresponding laser peening experiments.
