4aSA3. First circumferential wave in the low-frequency scattering by a viscoelastic cylinder.

Session: Thursday Morning, May 16

Time: 8:45

Author: Farid Chati
Author: Fernand Leon
Author: Gerard Maze
Location: Lab. d'Acoust. Ultrason. et d'Electron., LAUE URA CNRS 1373, Univ. du Havre, Pl. Robert Schuman, 76610 Le Havre, France


Acoustic scattering from an absorptive cylinder (Lucite) of infinite length excited by a normal plane acoustic wave is investigated in low frequencies. This one is assumed to be homogeneous and isotropic in its viscoelastic properties. The experimental results are obtained with a method of isolation and identification of resonances (MIIR). The resonance spectra are particularly studied. In the given frequency range, the presence of six families of circumferential waves labeled l[inf w] (1(less than or equal to)l[inf w](less than or equal to)6) was noted. The resonances of these families, except l[inf w]=1, are wide compared to those of aluminum or steel cylinders. Nevertheless, the resonances of the first family are easily detected in the Lucite cylinder, contrary to aluminum or steel cylinders. The scattering of a plane-wave pulse can be represented by the Fourier integral in order to determine a theoretical resonance spectrum without choosing the background. A good agreement is obtained for the studied frequency range between experimental and theoretical results. In the case of aluminum or steel cylinders, the computed calculus in vacuum are in good agreement with the experimental results. In the case of the Lucite cylinder, that is not verified, particularly with the first family. Moreover, the effect of the external fluid density on the resonances is analyzed.

from ASA 131st Meeting, Indianapolis, May 1996