Simulation of laser-generated single-mode lamb wave by finite element method

In order to improve the intensity of ultrasound signal, a Laser-ultrasonic excited by ring array laser source is simulated using finite element method based on the theoretical model of Laser-ultrasonic generated in aluminum plate. The optimum load model with the high signal strength and the high signal to the noise ratio is obtained through the adjustment of the number of excitation source and spacing. Then, the frequency of ultrasonic signals is extracted by using FFT transform and the group velocity of ultrasonic packet is calculated. Results indicate that the Laser-ultrasonic generated by the ring array laser source is the A0mode of Lamb wave. It has high energy and small dispersion, and always keeps sufficient vibration energy in the entire internal board. The simulation result can provide some useful reference data for selecting laser excitation source and optimizing models in Laser-ultrasonic nondestructive test.