A unique coupled boundary element/finite element method for the elastoacoustic analysis of fluid-filled thin shells

Abstract

A coupled boundary element/finite element technique originally developed for the analysis of open thin-shell problems, such as propeller blades, is used in this paper for the analysis of the fluid-filled elastic structures. For open thin-shell problems the question of nonuniqueness does not arise, however, it was thought at the time that such a formulation would prove to be nonunique for the analysis of closed fluid-filled submerged bodies. The work presented in this paper will demonstrate that, for submerged fluid-filled closed elastic bodies, this coupled formulation is unique throughout the entire frequency range. An advantage in implementing the variational form of the acoustic integral operator is that the resulting fluid matrix is symmetric. As such, the fluid/structural coupling is simplified, and the computational efficiency enhanced.

Acoustic signature of a submarine hull under harmonic excitation

“…Chen and Stepanishen [11] proposed a new method based on an in vacuo modal expansion to solve fluid loaded shells. Coupled finite element/boundary element methods have been presented by Jeans and Mathews [12][13][14] to study the vibrations of structures in an infinite acoustic medium. A variety of techniques to examine the sound radiation from slender bodies of revolution and spheroidal shells have often been developed with application to submarine hulls [15][16][17][18][19][20][21][22][23][24][25][26].…”

Faster Calculation of the Low-Frequency Radiated Sound Power of Underwater Slender Cylindrical Shells

“…A good review on the evolution of boundary element techniques is given by Chien et al [15]. Coupled finite element/boundary element methods (FEM/BEM) have been presented by Jeans and Mathews [16][17][18] to study the vibrations of structures in an infinite acoustic medium. Caresta and Kessissoglou [19] studied the vibroacoustic behaviors of stiffened conicalcylindrical-conical shells.…”

A Reciprocity Relation for Fluid-Loaded Elastic Plates That Contain Rigid Defects

“…These results are particularly useful for checking numerical or analytical results that involve complicated subsidiary calculations, say, the evaluation of Green's functions and solution of coupled integral equations for scattering by sub-surface cracks [7]. In structural acoustics there are several numerical techniques available, some based upon solving integral equations [8,9] and others based upon coupled boundary and "nite elements (for instance, see reference [10]) and that could be used to tackle problems for which the reciprocity relations provide a checking mechanism. As the reciprocity formula arise from "nding equivalences between two di!erent scattering problems, this can also substantially reduce the number of calculations in a parametric study.…”