声表面波在圆弧处反射及透射的数值研究*

为了研究直达表面波在圆弧过渡面处传播性能的变化,采用有限元方法模拟了热弹机制下,线性脉冲激光辐照金属铝块表面时激发的表面波在近表面传播过程中,在不同曲率半径的圆弧处发生的反射及透射现象,建立了圆弧半径与反射表面波以及透射表面波时域信号特征之间的联系。计算结果表明:曲率半径与表面波中心波长的数值关系对表面波在圆弧处的传播有显著的影响;同时证明了根据透射表面波信号的到达时间可以反演圆弧半径的大小,为之后利用表面波信号定量检测材料表面圆弧凹痕的深度提供了理论依据。

Numerical study on reflection and transmission of surface acoustic waves at circular arc

In order to study the change of propagation performance of the surface acoustic wave at circular arc transitional surface. The finite element method (FEM) is used to simulate the reflection and transmission phenomena of the surface acoustic waves excited by the linear pulse laser on the circular arc surface of the aluminium block with various radius during the near-surface propagation, and the relationship between circular arc radius and time domain signal characteristics of reflected and transmitted surface acoustic waves is established. The results show that, the numerical relationship between the radius of curvature and the central wavelength of the surface acoustic wave has a significant influence on the propagation of the surface acoustic wave at the circular arc. Furthermore, it is proved that the radius of the circular arc can be inverted according to the arrival time of the transmitted surface acoustic wave signal, which provides a theoretical basis for quantitatively detecting the depth of the circular arc notch on the surface of the materials.