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THE ALTERNATIVE KIRCHHOFF APPROXIMATION IN ELASTODYNAMICS WITH APPLICATIONS IN ULTRASONIC NONDESTRUCTIVE TESTING

Published online by Cambridge University Press:  23 April 2020

L. J. FRADKIN*
Affiliation:
Sound Mathematics Ltd., CambridgeCB4 2AS, UK; e-mail: l.fradkin@soundmathematics.com
A. K. DJAKOU
Affiliation:
Sound Mathematics Ltd., Cambridge CB4 2AS, UK. Now at GEFCO, Courbevoie Cedex, France; e-mail: noelleaudrey@yahoo.fr
C. PRIOR
Affiliation:
Sound Mathematics Ltd., Cambridge CB4 2AS, UK. Now at Department of Mathematical Sciences, Durham University, Durham, UK; e-mail: christopher.prior@durham.ac.uk
M. DARMON
Affiliation:
CEA, LIST, Department of Imaging and Simulation for NDT, F-91191Gif-sur-Yvette, France; e-mail: Michel.DARMON@cea.fr, Sylvain.CHATILLON@cea.fr, Pierre.CALMON@cea.fr
S. CHATILLON
Affiliation:
CEA, LIST, Department of Imaging and Simulation for NDT, F-91191Gif-sur-Yvette, France; e-mail: Michel.DARMON@cea.fr, Sylvain.CHATILLON@cea.fr, Pierre.CALMON@cea.fr
P.-F. CALMON
Affiliation:
CEA, LIST, Department of Imaging and Simulation for NDT, F-91191Gif-sur-Yvette, France; e-mail: Michel.DARMON@cea.fr, Sylvain.CHATILLON@cea.fr, Pierre.CALMON@cea.fr

Abstract

The Kirchhoff approximation is widely used to describe the scatter of elastodynamic waves. It simulates the scattered field as the convolution of the free-space Green’s tensor with the geometrical elastodynamics approximation to the total field on the scatterer surface and, therefore, cannot be used to describe nongeometrical phenomena, such as head waves. The aim of this paper is to demonstrate that an alternative approximation, the convolution of the far-field asymptotics of the Lamb’s Green’s tensor with incident surface tractions, has no such limitation. This is done by simulating the scatter of a critical Gaussian beam of transverse motions from an infinite plane. The results are of interest in ultrasonic nondestructive testing.

Type
Research Article
Copyright
© 2020 Australian Mathematical Society

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