Reduced models for structures in the medium-frequency range coupled with internal acoustic cavities

Abstract : This paper concerns the development of a method adapted for constructing reduced models in the medium-frequency range to a general three-dimensional dissipative structure consisting of an anisotropic, inhomogeneous, viscoelastic bounded medium coupled with an internal acoustic cavity. The reduced models are obtained using the Ritz- Galerkin method for which the projection subspace corresponds to the dominant eigensubspace of the energy operator of the structure in the medium- frequency band of analysis. Two fundamental cases are considered: 1) both the structure and the internal acoustic cavity have a medium-frequency behavior in the frequency band of analysis; 2) the structure has a medium-frequency behavior in the frequency band of analysis while the internal acoustic cavity has a low-frequency behavior.