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Based on the wave propagation method and improved Fourier series, the coupled vibration model of double-sided immersion (DI) cylindrical shell under arbitrary boundary conditions is established, and its coupled vibration characteristics are solved. The coupling vibration characteristic experiment of a cylindrical shell under the DI condition is carried out for the first time. The calculated natural frequency and vibration acceleration are compared with the model experimental results, which not only verifies the reliability of the theoretical method but also proves the effectiveness of the experimental results. Finally, the coupled vibration characteristics of DI cylindrical shells with arbitrary boundary conditions are analyzed. The results show that the natural frequency and acceleration of underwater immersed cylindrical shells are consistent with those of liquid filling cylindrical shells. The natural frequency and peak acceleration of the single-sided submerged cylindrical shell are greater than that of the DI cylindrical shell. The spring stiffness at both ends of the DI cylindrical shell can be divided into three sections: free boundary, elastic boundary, and rigid boundary. [ABSTRACT FROM AUTHOR]

The vibration properties of the submerged sandwich cylindrical shell with a viscoelastic core are investigated in this paper. Considering the acoustic-structure coupling, the analytical model of the submerged sandwich cylindrical shell that can handle three medium conditions including fluid-filled, fluid-loaded, and fluid-filled and -loaded is derived based on the wave propagation approach and the Flügge thin-shell theory. The vibration properties of the sandwich cylindrical shell under different medium and boundary conditions are analyzed, followed by a comparison of the damping effect of the constrained damping layer. Finally, an analysis is conducted on the influence of thicknesses of viscoelastic and constrained layers on vibration spectrum and natural frequency under fluid-filled and -loaded conditions. An experimental platform was established to conduct relevant experiments. Several important conclusions can be drawn. [ABSTRACT FROM AUTHOR]