Institute of Crystallography, Russian Academy of Sciences, Leninskii pr. 59, Moscow 119333, Russia.
Leibniz Institute for Solid State and Materials Research Dresden, P.O. 27 00 16, D-01171 Dresden, Germany; InnoXacs, Am Muehlfeld 34, D-01744 Dippoldiswalde, Germany.
Ultrasonics. 2014 Sep;54(7):1999-2005. doi: 10.1016/j.ultras.2014.05.010. Epub 2014 May 24.
The paper numerically studies the harmonic Rayleigh wave scattering at the 90-degree corner of isotropic substrate. The finite element method is used. The main attention is paid to two cases. The first one is the apex of the substrate corner is rounded off. The second one consists in that a layer of foreign material is deposited on the face which scatters the Rayleigh wave. The dependence of the reflection and the transmission coefficients on the Poisson ratio, the angle of incidence, the fillet radius, and the layer thickness are obtained. It is found that if the Rayleigh wave is incident perpendicularly to the substrate border, then the fillet of small radius as compared to the wavelength increases the reflection coefficient and decreases the transmission coefficient by factors 1.3-1.8. At normal incidence, the Poisson ratio does not change qualitatively the dependence of the reflection and transmission coefficients on the fillet radius. But the Poisson ratio can substantially affect the angle dependence of these coefficients if the wave is incident obliquely on the corner rounded off. It is also found out that a layer can modify the conditions of scattering such that the incident wave is totally reflected without transmission and conversion into bulk waves in a wide interval of angle of incidence, although, in principle, the bulk wave generation is allowed within a part of this angle interval.
本文数值研究了各向同性基底 90 度角处谐和瑞利波散射。采用有限元法。主要关注两种情况。第一种情况是基底角的顶点是圆形的。第二种情况是在散射瑞利波的面上沉积一层外来材料。得到了反射和透射系数对泊松比、入射角、圆角半径和层厚度的依赖关系。发现如果瑞利波垂直于基底边界入射，则与波长相比，小半径圆角会将反射系数增加 1.3-1.8 倍，并将透射系数减小。在正入射时，泊松比对反射和透射系数对圆角半径的依赖关系没有定性影响。但是，如果波斜入射到圆角上，泊松比会显著影响这些系数的角度依赖性。还发现，一层可以改变散射条件，使得入射波完全反射而没有透射，并将其转换为体波，在宽入射角范围内，尽管原则上在该角度范围内的一部分允许产生体波。
