2023 Volume 79 Issue 15 Article ID: 22-15004
The pulsed laser beam irradiation of a material induces the rapid rise of the thermal stress, and then the stress wave generates and propagates into the material’s interior. This phenomenon is known as the photoacoustic effect, and the generation of the elastic waves in the ultrasonic frequency range has been confirmed experimentally. This study aims to develop a numerical model to simulate the generation and propagation of ultrasonic waves due to the photoacoustic effect. Here, the heat conduction and the elastic wave problems are solved in a coupled manner using the discretization by the finite integration method. For the water immersion non-destructive inspection, a propagation simulation in the wave field, including the interface between solid and liquid, must be considered. The simulation result showed that the intensity of longitudinal waves toward the bottom of the material from the laser irradiation through water was higher than the one through the air. The validation by an experimental measurement was conducted, and the same phenomenon was observed.
