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Electro-elastic coupled fields of the general line source in infinite multilayered piezoelectric medium

Nowacki J. P.

Archives of Mechanics

2012

Vol. 64, nr 1

3-3

Electro-elastic coupled fields excited by a general line source in a multilayered anisotropic piezoelectric medium are expressed in an analytical form. The general line source represents a combination of a straight 4D dislocation with the force and charge, distributed along the same line. The results are obtained in the form of well-convergent Fourier integrals. They can be considered as Green’s functions describing electro-elastic fields created in the given medium by arbitrary 2D bulk distributions of dislocations, forces, charges and electro-potential. The analysis is accomplished in terms of the propagator matrix which is equally applicable to both the stratified and graded layered media.

Ultrasonic scattering from compressible cylinders including multiple scattering and thermoviscous effects

Hasheminejad S. M., Alibakhshi M. A.

Archives of Acoustics

2006

Vol. 31, No. 2

243-263

This paper presents a study of acoustic scattering by a pair of parallel circular thermoviscous fluid cylinders submerged in an unbounded viscous thermally conducting medium. The translational addition theorem for cylindrical wave functions, the appropriate wave field expansions and the pertinent boundary conditions are employed to develop a closed-form solution in the form of infinite series. The analytical results are illustrated with a numerical example in which two identical thermoviscous fluid cylinders are insonified by a nearby parallel acoustic line source at broadside/end-fire incidence. The backscattered pressure amplitude is numerically evaluated and discussed for representative values of the parameters characterizing the system. The effects of source position, transmission frequency and proximity of the two cylinders are examined. Particular attention has been focused on multiple scattering interactions as well as thermoviscous effects. The imperative influence of thermoviscosity on the analysed phenomena is revealed by notable reduction of backscattering amplitude at intermediate and high frequencies. The numerical results also show that the multiple scattering interaction effects are of great (moderate) consequence for end-fire (broadside) incidence at small separations of the cylinders. A limiting case involving a pair of ideal compressible fluid cylinders is considered and a fair agreement with preceding solutions is established.