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The vibration behavior of thin elastic structures is noticeably influenced by the surrounding water, which represents a heavy fluid. In this case, the feedback of the fluid pressure onto the structures cannot be neglected and a strong coupling scheme between the structural domain and the fluid domain is required. In this paper, a coupled finite element and boundary element (FE-BE) solver is developed for the modal analysis of three-dimensional submerged elastic structures. The structures are modeled by means of the finite element method (FEM). The compressibility of the surrounding fluid is taken into consideration, and thus the Helmholtz equation is used as the governing equation and solved by using the boundary element method (BEM). The resulting nonlinear eigenvalue problem (NEVP) is converted into a small linear one by using a contour integral method. A numerical example is finally given to demonstrate the effectiveness and applicability of the developed method.

Fluid-structure interaction; Modal analysis; Coupled FE-BE method; Nonlinear eigenvalue problem; Contour integral method