Acoustic scattering from a strained region

Allwright, David and Jones, Gareth and Parnell, William (2006) Acoustic scattering from a strained region. European Study Group with Industry > 53rd ESGI [Manchester 21/3/2005 - 24/3/2005].

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Abstract/Summary

Item Type:	Study Group Report
Study Group:	European Study Group with Industry > 53rd ESGI [Manchester 21/3/2005 - 24/3/2005]
Company Name:	Thales Underwater Systems
Industrial Sector:	Materials Aerospace and defence
Additional Contributors:	Abrahams, David and Bell, Chris and Bodai, Tamas and Bond, Philip and Hazel, Andrew and Novokshanov, Roman and Parker, David and Perrey-Debain, Emmanuel and Veitch, Ben
ID Code:	67
Deposited By:	Gordon White
Deposited On:	19 June 2006

Problem Statement

A composite material consists of a rubber filled with gas-filled microspheres. In underwater applications it is compressed hydrostatically by a pressure that may be not insignificant compared with the shear modulus of the rubber, so large strains are produced around each spherical inclusion. When these spherical inclusions scatter an incident acoustic wave, the strained region around an inclusion has had its elastic properties altered by the large static strain, and the Study Group was asked to address the question of how this strained region affects the elastic scattering, bearing in mind that the dynamic shear modulus differs from its static value. The acoustic wavelength is large compared with the diameter of the spherical inclusions and, for the purposes of the Study Group, scattering by just a single microsphere was considered. The Study Group showed that for the monopole scattering strength it was enough to use the dynamic shear modulus in place of the static value in the existing approach, and also obtained the equations that would have to be tackled for finding the dipole and other scattering strengths.

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