Tranferred boundary similarity method and application to the prediction of ship vibration and radiated noise

Abstract

Based on principle of structural dynamics, the utility of excitation force and transferred boundary condition method is demonstrated by the vibration analysis of an equipment-base system. By constructing a “virtual force” while maintaining the consistency of transferred boundaries of structure with dynamic parameters locally unknown, transferred boundary similarity method (TBSM) is proposed to obtain the structural dynamic response with given transferred boundary conditions with structural dynamic parameters locally unknown. The effectiveness of TBSM is also verified. On that basis, TBSM is applied to the prediction of a ship's underwater vibration and sound radiation. The underwater sound radiation characteristic of a ship is analyzed. Result shows that the underwater vibration and sound radiation of a ship are highly related with location and frequency of excitation. On one hand, sound radiation from the ship is mainly concentrated in the vicinity of excitation of the middle and aft region of the ship, followed by aft and bow. On the other hand, the underwater sound radiation is more uniformly distributed along the ship length at low frequency band, while the inhomogeneity and directivity gradually increase as the excitation frequency increases.