Lamb波在抛物线型声黑洞薄板结构中的传播特性

Study the Propagation Characteristics of Lamb Waves on Parabolic Acoustic Black Hole Thin Plate Structures

摘要: 本文利用激光激发的超声Lamb波，对抛物线型声黑洞结构薄板上Lamb波的传播特性及轨迹进行了研究。基于在金属材料中激发超声的热弹机制，建立了激光在抛物线型声黑洞结构薄板上激发Lamb波的三维有限元模型。声波以激发区域为中心向外扩散传播，且大部分的声波能量形成平行于激光线源的波振面，并沿垂直于激光线源方向向外传播。当声波开始进入声黑洞的结构中时，向着厚度减小的方向传播，同时波束宽度会变小，振幅逐渐变大。最后，研究声黑洞底部中心点的位移变化，结果表明峰值位移随着时间稳步上升，具有比较明显的声波聚焦现象。本论文研究成果可用于声黑洞薄板结构的检测与评估。

Abstract: In this paper, the propagation characteristics of Lamb waves on thin plate structure with parabolic acoustic black hole are studied by using laser ultrasonic technology. Based on the thermoelastic mechanism, a three-dimensional finite element model of laser excitation of Lamb wave in thin plate structure with parabolic acoustic black hole is established. Then, the acoustic wave propagates outward as the excitation region is the centre; the wave is parallel to the laser line source; and its propagation direction is perpendicular to the laser line source. When the sound wave encounters the acoustic black hole, it will propagate along the thickness decreasing direction. Meanwhile, the acoustic beam width decreases, and the amplitude gradually increases. Finally, the acoustic amplitude at the lowest point of the acoustic black hole increases gradually, which present the sound wave focusing phenomenon. The results of this paper can be used to detect and evaluate the thin plate structure with acoustic black hole.