Experimental study on the pressure characteristics of laser-induced shock waves under different energy distribution

Laser shock peening has been widely used in anti-fatigue strengthening of metals. The different types of lasers (Flattop laser and Gaussian laser) used have influence on the pressure characteristics of shock wave and the strengthening effect. In this work, using PDV (photonic doppler velocimetry) system, the difference of peak pressure of Flattop laser-induced shock wave and Gaussian laser-induced shock wave is studied experimentally and theoretically. Research shows that the peak pressure of shock wave induced by Gaussian laser is higher than that of Flattop laser, because of the infinitesimal power density in the center of Gaussian laser spot is higher than that of Flattop laser. Furthermore, at the same power density, Gaussian laser can implant a larger and deeper residual stress field in the material.