The structural and acoustic responses of a submarine hull to fluctuating propeller forces are investigated in the low frequency range. The fluctuating forces are caused by operation of the propeller in a non-uniform wake, and are transmitted to the submarine hull through the shaft and also via the fluid, because of the resulting dipole field of the propeller. Numerical models have been developed to simulate the strongly coupled fluid-structure interaction of the submerged vessel in the frequency domain. The hull is modelled using the finite element method (FEM), which allows for structural complexities such as the ring-stiffeners, bulkheads, end closures and the propeller-shafting system. A simple, passive vibration attenuation system known as a resonance changer (RC) is included in the model of the propeller shafting system. The fluid is modelled using the boundary element method (BEM) in which the radiation damping and added mass effect of the water are taken into account. It is demonstrated that the performance of the RC is influenced greatly by the effects of forces transmitted to the hull via the fluid. Propeller vibration is taken into account in determination of the fluid and structural excitation of the hull. The effect of changing the propeller mass is demonstrated.
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