Structural-Acoustic Vibration Problems in the Presence of Strong Coupling

Free vibrations of fluid-solid structures are governed by unsymmetric eigenvalue problems. A common approach which works fine for weakly coupled systems is to project the problem to a space spanned by modes of the uncoupled system. For strongly coupled systems, however, the approximation properties are not satisfactory. This paper reports on a framework for taking advantage of the structure of the unsymmetric eigenvalue problem allowing for a variational characterization of its eigenvalues and structure preserving iterative projection methods. We further cover an adjusted automated multilevel sub-structuring (AMLS) method for huge fluid-solid structures. The reliability and efficiency of the method are demonstrated by the free vibrations of a structure completely filled with water. [DOI: 10.1115/1.4007251]