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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]

In order to study the vibration isolation characteristics in water, based on the Flügge theory, a double-walled cylindrical shell model with spring connection is established using the wave propagation method. The fluid inside the inner shell is considered in the model. The reliability of the theoretical method is verified by comparing the calculation results of the mean square velocity with those of the finite element method. The effects of spring stiffness, spring number, fluid load, and inter-shell fluid thickness on vibration transmission of inner and outer shells are studied. The results show that the fluid loading effect of the water medium inside the inner shell can act on the inner shell and the outer shell simultaneously, while the fluid loading effect of the outboard fluid only acts on the outer shell. Under the condition of keeping the total spring stiffness unchanged, increasing the number of springs can reduce the vibration transmission from the inner shell to the outer shell, especially the vibration transmission from the inner shell to the outer shell at low frequencies. The "vibration short circuit" effect easily occurs in the inter-shell water, which is independent of the thickness of inter-shell water. When the elastic connection stiffness is small, the inter-shell water plays a leading role in vibration transmission in the whole frequency range. When the stiffness of elastic connection is large, the inter-shell water plays a leading role in vibration transmission at low frequencies, while the elastic connection plays a leading role in vibration transmission at high frequencies. [ABSTRACT FROM AUTHOR]

Based on the Flügge theory and orthotropic theory, the acoustic vibration coupling model of ring-stiffened cylindrical shell is established by using the wave propagation method and virtual source method. And the effects of water immersion on both sides, free surface, and hydrostatic pressure on the cylindrical shell are considered in the coupling model. Muller three-point iterative method is used to solve the coupling frequency. The calculation results of degradation theory are compared with COMSOL's calculation results and experimental results, respectively, which verifies the reliability of the theoretical method. Finally, the influence of fluid load, ring rib parameters, boundary conditions, hydrostatic pressure, and free surface on the coupled vibration of ring-stiffened cylindrical shell is analyzed by an example. [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]

This paper aims to clarify the behaviour and mechanism of electromagnetic vibration in long sheet secondary tubular linear induction motors (LSS‐TLIMs). Firstly, the spatial and temporal characteristics of electromagnetic force acting in the stator are analysed. Secondly, based on the wave propagation method, an analytical model is established to calculate the vibration response of the stator, which is simplified as a finite cylindrical shell. The accuracy of the proposed model, as well as the rationality of the simplification, are verified by 3D FEM simulation. It is indicated that the electromagnetic vibration response of LSS‐TLIMs mainly depends on the "axial breathing mode" (ABM) and corresponding "modal participation factor". Moreover, the influences of the spatial distribution of electromagnetic force and the structural dimensions on the vibration are investigated. Finally, the "static vibration test" is performed to validate the above analysis. It is concluded that, compared with a rotary motor, the low‐frequency vibration of LSS‐TLIMs can be easily controlled since the natural frequency of ABMs tends to be much higher than that of the circumferential mode. [ABSTRACT FROM AUTHOR]