Influence of high strain rate on the transient transmission of laser shock waves

Laser shock peening (LSP) is an effective surface treatment method used to regulate residual stress and surface roughness of treated materials. In this research, the effect of high strain rate on the velocity of plastic shock waves was analyzed by the Johnson–Cook constitutive model. The transient transmission of a shock wave having different laser-shock-peening parameters was investigated with a three-dimensional finite element method. Firstly, the model validity was experimentally verified, and then, the process parameters were analyzed. In order to determine the effect of high strain rate on the laser shock attenuation, the LSP saturation phenomenon was investigated. The velocity of the plastic shock wave was significantly affected by a high strain rate during the laser peening process. The plastic shock wave velocity was inversely proportional to plastic strain. At the initial stage, the plastic strain increased, the plastic shock wave velocity decreased with the laser power density, and the attenuation gradient of the shock wave pressure increased. When the power density was kept unchanged, the plastic strain and attenuation gradient of the laser shock wave decreased with the number of impacts, and when the number of impacts increased to 3 and 4, the attenuation rate was found to be similar.