Nonlinear phenomenon in laser-induced finite-amplitude acoustic waves propagating along cracks
Nonlinear phenomenon in laser-induced finite-amplitude acoustic waves propagating along cracks
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DOI：
10.1063/5.0040491
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发表时间：
2021-03-28
影响因子：
3.2
通讯作者：
Ni, Chenyin
中科院分区：
文献类型：
--
作者：
Li, Mengmeng;Shen, Zhonghua;Ni, Chenyin
研究了纵波和表面波沿板中沿着裂纹的传播。用Q开关激光辐射，在沉积在平板表面的一层液体悬浮碳颗粒中吸收，可以产生应变高达5 × 10~（-3）的波。纵向和表面瑞利波平行于和断裂表面上，分别传播，并从板的自由表面反弹。据观察，纵向回波脉冲表现出的形状，这是依赖于激光激发的幅度，因此，对激光产生的声波的振幅。在一定的光激发水平，领先的拉伸部分的第一纵向回波消失，并再次出现在更高的激发水平。这种效应没有发生在无裂纹的地区的板，是振幅依赖性，因此，它可以归因于纵向和表面瑞利波与裂纹的非线性相互作用。
The propagation of the longitudinal and surface waves along cracks in the plate was studied. Waves with strain up to5 x10- 3 could be generated by radiation of a Q-switched laser absorbed in a layer of liquid suspended carbon particles deposited on the surface of the plate. The longitudinal and surface Rayleigh waves traveled parallel to and on the fracture surfaces, respectively, and bounced from the free surfaces of the plate. It was observed that the longitudinal echo pulses exhibited shapes, which were dependent on the magnitude of the laser excitation and, thus, on the amplitudes of the laser-generated acoustic waves. At a certain photo-excitation level, the leading tensile part of the first longitudinal echo vanished and reappeared again at higher excitation levels. This effect did not occur in the crack-free areas of the plate and was amplitude-dependent; therefore, it could be attributed to the nonlinear interaction of the longitudinal and surface Rayleigh waves with the crack.