Keywords: acoustic, fluid-structure, transient.

In this paper a study of static and dynamic load transfer between flexible structures connected to each other by an acoustic medium is realized. The solid is modelled as linear and elastic and the fluid characterized by an acoustic hypothesis. Dynamic and static acoustic coupling is performed through a formulation that uses velocity potential and static pressure to describe the acoustic fluid behaviour [1,2,3,4]. In the solid domain displacements are the working variables, that makes necessary the use of compatibility equilibrium conditions at the interface.

The solution through the finite element method delivers symmetrical linear systems. The numerical results of the code FEDYFE are compared with the results of a similar scalar formulation, based on pressures, implemented in a commercial finite-element code (ANSYS). Analytical comparison is realized whenever possible. The study case is an acoustic cavity with a flexible bottom and an immersed body supported by springs. This cavity is analyzed completely closed and than opened at the top to observe the system in a predominantly incompressible condition. For each study-case a detailed dynamic analysis is carried out, which includes a previous full modal analysis of both uncoupled and coupled systems and then transient analysis of the coupled system with several loading conditions.

1

Everstine G.C., "A Symmetric potential formulation for fluid-structure interaction problems", Journal of Sound and Vibration, letter to the editor, vol.79, 157-160, 1981.

2

Olson L.G., Bathe K.J., "Analysis of fluid-structure interactions. A direct symmetric coupled formulation based on the fluid velocity potential", Computer & Structures, vol. 21, n. 1/2, 21-32, 1985. doi:10.1016/0045-7949(85)90226-3

3

Barbosa A.N., "Uma formulação potencial simétrica para o cálculo estático e dinâmico de problemas de interação fluido-estrutura", Dissertação de Mestrado em Estruturas - UnB-FT/EnC, E.DM 008A/98, julho, 1998.

4

Barbosa A.N., Pedroso L.J., "A study for fluid-structure interaction based on the displacement and fluid velocity potential respectively in solid and fluid domain, Computational Mechanics - New trends and applications", Proceedings of the 4th World Congress on Computational Mechanics, Buenos Aires, Argentina, 1998.

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