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Changes in Coupled Vibration Frequencies and Modes of Wall-Cavity Systems Induced by Stiffness Variation in the Structure



Author(s)

Soraya Mendes de Souza1, Lineu José Pedroso1 and Paulo Marcelo Vieira Ribeiro2

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DOI:10.17265/1934-7359/2013.09.006

1. College of Technology, University of Brasilia, Brasilia 70904-108, Brazil
2. Civil Engineering Department, University of Pernambuco, Recife 50740-530, Brazil

Problems of fluid structure interactions are governed by a set of fundamental parameters. This work aims at showing through simple examples the changes in natural vibration frequencies and mode shapes for wall-cavity systems when the structural rigidity is modified. Numerical results are constructed using ANSYS software with triangular finite elements for both the fluid (2D acoustic elements) and the solid (plane stress) domains. These former results are compared to proposed analytical expressions, showing an alternative benchmark tool for the analyst. Very rigid wall structures imply in frequencies and mode shapes almost identical to those achieved for an acoustic cavity with Neumann boundary condition at the interface. In this case, the wall behaves as rigid and fluid-structure system mode shapes are similar to those achieved for the uncoupled reservoir case.

Fluid-structure, finite element, vibration modes, acoustic cavities.