Resonance theory of elastic shear‐wave scattering from spherical fluid obstacles in solids
作者:
D. Brill,
G. Gaunaurd,
H. Überall,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1980)
卷期:
Volume 67,
issue 2
页码: 414-424
ISSN:0001-4966
年代: 1980
DOI:10.1121/1.383927
出版商: Acoustical Society of America
数据来源: AIP
摘要:
The vector potential for an arbitrarily polarized shear wave in an elastic (lossless) medium incident on, and scattered by, a spherical fluid occlusion is expanded in vector spherical harmonics. The boundary conditions are dealt with for this incident vector potential in terms of two (scalar) Debye shear potentials ψ and χ giving rise to what we have termed ’’sandtwaves,’’ respectively. Theswave scatters into both anotherswave and also mode‐converts into a compressionalpwave. Thetwave scatters only into anothertwave with no mode conversion. Scattering amplitudes are cast in a series of resonance terms. The scatteredpandswaves exhibit resonances; however, thetwave does not. We exhibit monostatic and bistatic plots of the first few partial‐wave amplitudes (n=1,2,3,...) for thesp,ss, andttscattering modes. When the background amplitude corresponding to scattering from anevacuatedspherical cavity is removed from each partial‐wave contribution, the remaining portion of the amplitudes is a clear series of liquid‐sphere resonances. We display these resonances as functions of the acoustic sizekdaof the cavity,andof the ordernof each mode. This work completes the determination of the scattering matrix elements for a fluid sphere in an elastic medium which was commenced by us earlier with the study of resonance effects inppandpsscattering.
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