Mixed stress-displacement finite element method for laser-generated ultrasound

In order to study the generation and propagation of laser-generated ultrasound in isotropic semi-infinite aluminum material, a laser-generated ultrasound in an arbitrary elastic semi-infinite medium model was established by using mixed stress-displacement finite element method and perfectly matched layer(PML). The transient wave snapshots and surface normal displacement waveforms in semi-infinite aluminum materials were obtained. The surface normal displacement waveforms were compared with the same geometrical finite element model. The results show that the mixed stress-displacement finite element method can effectively eliminate reflection waves from truncated boundary, and simulate the generation and propagation of ultrasound in semi-infinite solid material accurately. The simulation results provide an effective method for research of the laser-generated ultrasound waves in micro-nanostructure by picosecond or femtosecond laser irradiation.