Laser Saw And The Role Of Surface Defects Of Finite Element Simulation,

Finite element method has been employed to simulate the generation of ultrasonic guided wave generated by the pulsed laser. The numerical model has been constructed, which represents the laser line source illumination on the aluminum plate. In addition, the interaction of laser-generated surface acoustic wave and the surface defect with various depths have been simulated in detail.Based on the theoretical model of plane strain, line source irradiation on the aluminum plate has been polarized in two dimensional plane, and the plane strain finite element model have been established to simulate line source generated surface acoustic wave. Numerical results demonstrate that laser generated surface acoustic wave is comprised with three components, namely surface skimming longitudinal wave, surface shear wave and Rayleigh wave.The interaction of laser induced surface acoustic wave and surface defects with varied depths have been simulated by the plane strain finite element method. The relation between temporal interval of the reflected surface waves and the depth of surface defect have demonstrated that the first echo pulse is reflected from the tip of defect, and the second echo come from the mode conversion taken place on the bottom of surface defect.The returns in this paper may provide theoretical base for laser ultrasonic theory and numerical simulation research, as well as crack inspection technology and widening its application scope.