Abstract：Based on principle of structural dynamics analysis, the unitary of force and moving boundaries is proved by using the “equipment-base” vibration system as an example. By constructing “virtual force” to keep the consistency of moving boundaries of structure with dynamic parameters locally unknown, moving boundary similarity method (MBSM) is thus proposed to solve structural dynamics prediction problem of given moving boundary conditions with structural dynamic parameters locally unknown. The effectiveness of MBSM is also verified. On that basis, MBSM is applied to the research of ship structural underwater vibration and noise radiation. The underwater noise radiation characteristic of a ship is analyzed. Result shows that the underwater vibration and sound radiation of a ship are highly related with the location and frequency of excitations and other factors. On the one hand, ship structural borne noise radiation is mainly concentrated in the vicinity of excitation source in the middle and aft region of ship hull, followed by the aft of ship hull, and the underwater noise radiation of bow has the minimum effect. On the other hand, the underwater noise radiation is more uniformly distributed along the ship length in low frequency band; however, the inhomogeneity and directivity of the underwater noise radiation gradually increases as excitation frequency increases.
2014, Vol. 33 
