On the long-wave onset of dispersion of the surface-wave velocity in coated solids

被引:15
作者
Shuvalov, A. L. [1 ]
Every, A. G. [2 ]
机构
[1] Univ Bordeaux 1, Mecan Phys Lab, CNRS, UMR 5469, F-33405 Talence, France
[2] Univ Witwatersrand, Sch Phys, ZA-2001 Johannesburg, South Africa
关键词
surface wave; thin coating; dispersion; elastic anisotropy;
D O I
10.1016/j.wavemoti.2007.12.002
中图分类号
O42 [声学];
学科分类号
070206 ; 082403 ;
摘要
A linear-dispersion coefficient K describing the slope of the Rayleigh-Love velocity branch at its long-wave onset is subjected to analysis. For the case when the sagittal plane is a symmetry plane for both the layer and the substrate (plane strain deformations), it is found that the sign of K is that of the difference between the beam velocities of the layer and substrate materials. A simple approximant of K is obtained for the case of isotropic layer and substrate. In the 3D phase space of isotropic layer and substrate material parameters, the surface K = 0 is established, and the subspace where K is positive/negative for the Rayleigh velocity of a layer smaller/greater than that of a substrate (which is contrary to their commonly encountered correspondence) is identified. The consideration is extended to the case of a functionally graded layer on a homogeneous substrate. It is shown that the sign of K remains being given by the sign of a difference of layer and substrate beam velocities; at the same time, the impact of layer density on this sign can no longer be eliminated through passing to the density-normalized elastic moduli as for a homogeneous layer. (C) 2008 Elsevier B.V. All rights reserved.
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页码:857 / 863
页数:7
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