The Propagation Trajectory of Lamb Waves on Thin Plates with Circular Thickness of Linear Variation

摘要

In this paper, the propagation trajectory of Lamb waves on thin plates with circular thickness of linear variation is studied by using laser ultrasonic technology. Based on the thermoelastic mechanism, three-dimensional finite element model of Lamb wave excited by laser line source and laser point source is established, respectively. The Lamb wave excited by laser line source propagates into the area of thickness variation, and focuses at the bottom boundary. The sound wave propagates along the bottom boundary; part is strong, while the other parts are relatively weak. The Lamb wave generated by laser point source propagates along the radius into area of thickness variation. The acoustic accumulates continuously at the bottom boundary and the amplitude increases gradually. Moreover, the Lamb wave propagates along two opposite directions of the circle with the same amplitude and frequency. The results of this paper can be used to detect and evaluate thin plates with circular thickness of linear variation.