Ultrasounds Excited by a Laser Line Pulse in a Liquid-Filled Tube

Abstract

In this paper, a physical model is proposed to describe the propagation of ultrasounds, which are excited in a homogeneous, isotropic, and liquid-filled tube by a laser line source under either the ablation or thermoelastic regime. Since a metal tube is considered, the thermal diffusion and the optical penetration depth are neglected in this modeling. The Fourier series expansion is introduced for a spatial coordinate to provide the transient response of the structure. Theoretical displacements are obtained for aluminum tubes filled with glycerol or air. The corresponding displacements are observed experimentally by the laser ultrasonic technique. Good agreement is found in the arrival time, shape and relative amplitude of various longitudinal and shear bulk waves propagating in the solid and liquid media. These ultrasonic waves are further identified by the ray trajectory analysis.