The Numerical Analysis Of Sound And Vibration From A Ring-Stiffened Cylindrical Shell By FEM

The uppermost character of submarine is the flexibility and the stealth, which have decided its advantage of sudden strike and its effects of terrorizing. So that it is the key point of reducing submarine's acoustic for hiding its body in naval battle to ensure the combat effectiveness. The vibration and the sound radiation from the structure have important effect on the stealth of submarine. Reducing the vibration and the sound radiation of a submarine can not only improve its conceal, but also can enhance its sonar properties, improve its undersea antagonism ability thereby greatly. Therefore, the research of underwater monolayer or bilayer shell structure is very valuable.The paper was focused on the submerged cylindrical shell vibration and radiated sound power. The finite length stiffened cylindrical shells is the main structure style in hull part of vessel both in air and water, and the structure noise of these vessels comes from the vibration of shell which was causes by the exciting force of internal machine and the acoustic radiation in the surrounding media.A theoretical analysis of the combination of vibrational energy flow and the sound radiation and dispersion of underwater model of infinite cylindrical shell structure, detailed analysis of the model to consider the effects of hydrostatic pressure on the structural vibration were given, which can be used to the reference of reducing the noise of underwater vibration-shell structure.In the thesis, the numerical analyses of vibration and sound radiation from a submerged elastic ring-stiffened have been carried out by the FEM software ANSYS. It discussed the influence to structure nature frequency, radiation efficiency and acoustic pressure at surface by changing the parameter of longitudinal rib, rings rib, longitudinal-ring rib. In four working conditions, the radiated sound power and radiation efficiency of sound power are analyzed. It can easily get that cylindrical shell with longitudinal-ring rib have larger influence than others condition. According to the research of the radiated sound power, it has supplied reference to reducing and controlling vibration an acoustic radiation of the structure template .