4aSA4. Acoustic scattering by a fluid-loaded cylindrical shell with an internal plate.

Session: Thursday Morning, May 16

Time: 9:00

Author: Aleksander Klauson
Author: Jaan Metsaveer
Location: Dept. of Mechanics, Tallinn Tech. Univ., Ehitajate tee 5, EE-0026 Tallinn, Estonia
Author: Andre Baillard
Author: Dominique Decultot
Author: Gerard Maze
Location: Univ. du Havre, 76610 Le Havre, France


An experimental and theoretical study of acoustic scattering from a fluid-loaded circular cylindrical shell with an axially attached internal plate is presented. The normally insonified stainless-steel shell has an outer to inner radius ratio b/a=0.98. A stainless-steel plate of the same thickness is diametrically soldered, inside the shell, at both edges along the axis. The object is closed by two flat circular endcaps and is vertically immersed in a water tank (6 mx4 mx3 m). The aim of the study is to separate the effects of the shell and those of the plate and to interpret different sound generation mechanisms of the structure. The numerical simulation is done by the modal expansion method using the unstiffened cylindrical shell eigenmodes. The shell is taken as infinitely long. The internal plate is considered as a line constraint with the frequency-dependent impedance. The comparison between theoretical and experimental results is achieved by an analysis of backscattered spectra and of arrival times of backscattered echoes. The scattering from the structural joints, the generation and transmission of flexural waves through the internal plate, and the interaction between different vibration forms are observed and analyzed. [Work supported by NATO.]

from ASA 131st Meeting, Indianapolis, May 1996