Analytical and experimental studies for the vibration transmission of the double-plated structure containing the inner fluid and elastic connections

The vibration transmission of the double-plated structure containing the inner fluid and elastic connections are researched by the analytical and experimental techniques. An analytical method is firstly proposed to predict vibration responses of the double-plated structure. The improved Fourier series are used to describe the transverse displacements of the plates and the sound pressure of the acoustic cavity. The elastic connections are regarded as springs. Motion equations are derived by the energy method and vibration results are gained via the Rayleigh–Ritz technique. Meanwhile, a test sample of the double-plated structure is manufactured. Four vibration isolators are utilized as the elastic connections. The inner fluid is air or water. Forced vibration tests are conducted with a random white-noise force. The results from both experiments and the finite element method (FEM) are well consistent with ones calculated by the analytical method. Then the effects of important parameters on the vibration transmission are studied by the analytical and experimental analyses, including the stiffness of elastic connections, the height of the inner fluid, the boundary condition of plates, the spring position, the inner fluid loading and the coating damping layer. It is found that the inner water acts as a short circuit in the vibration transmission, and the inner air leads to the less vibration transmission from the upper plate to the lower one. Some other new phenomena are also observed and analyzed in this paper.