Ultrasonic field modeling in plates immersed in fluid

Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calculate the ultrasonic field (pressure, velocity and displacement fields in a fluid, or stress and displacement fields in a solid) generated by ultrasonic transducers. So far the technique has been used to model ultrasonic fields in homogeneous and multilayered fluid structures, and near a fluid–solid interface when a solid half-space is immersed in a fluid. In this paper, the method is extended to model the ultrasonic field generated in a homogeneous isotropic solid plate immersed in a fluid. The objective of this study is to model the generation of guided waves in a solid plate when ultrasonic beams from transducers of finite dimension strike the plate at different critical angles. DPSM results for a solid half-space problem are compared with the finite element predictions to show the superiority of the DPSM technique. The predicted results are also compared with the experimental visualization of the mode patterns of Lamb waves propagating in a glass plate obtained from stroboscopic photoelastic method. Experimental and theoretical results show good qualitative agreement. The DPSM technique is then applied to study the mode patterns in aluminum plates immersed in water.