Abstract
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.
Highlights
The double-walled cylindrical shell structure with elastic connection generally appears in large generators, aero generators, and other equipment
Ye et al.8 calculated the natural frequency of double-walled cylindrical shells based on the Donnel shell theory and wave propagation method, and they compared the analytical calculation results of natural frequency with the finite element calculation results, which proved the accuracy of the wave propagation method in solving the natural frequency of doublewalled cylindrical shells
It can be seen from the figure that when the axial stiffness and tangential stiffness of the spring are 1 × 105 N/m, the mean square velocity (MSV) of the inner and outer shells is almost the same as that of the spring with 0 N/m
Summary
The double-walled cylindrical shell structure with elastic connection generally appears in large generators, aero generators, and other equipment. Wang and Yu14 established a two-dimensional acoustic solid coupling model of vibration and sound radiation of liquid tanks between the sides by the analytical method and studied the influence of the plate and the inter-shell water on vibration transmission characteristics. The vibration isolator is simplified as a spring, and considering the influence of fluid filling in the inner shell, a coupled model of liquid filled doublewalled cylindrical shells with elastic connection and inter-shell fluid is established. It has great practical value and strong application background
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