| Ship is a complex flexible structure.In the proeess of operating,the ships will be affected byengine, Propeller, waves and so on.The role of these external incentives will Lead to different degrees of the ship vibration even harmful vibration.These exeessive vibration may lead to fatigue damage,influencing work effieiency and even physical health, but will also affect the equipment Normal using.Therefore, in the stage of ship designing, we must predict the iltherent vibration characteristics of the ship structure,Accurately to avoid resonance,especially the resonance of superstructure.Wih the fast development of computer sotfware and hardware, it does not have diffieulty in principle to do ship structural dynamics direct calculation and analysis to the whole hull's structral dynamics characteristics by the finite elment mesh model based on the hull frame and longitudinal stiffener spna.But, this method involves many factors and large amount of work.So its applieation is still not extensive, especially in the domestie.This thesis takes a 89m sand dump carrier as an example to have a study on the direct calclation of dynamic characteristics to the whole hull structure through FEM.The ship superstructure vibration seriously. In this thesis, using MSC/Patran, Nastran to establish full-dimensional finite element model of the ship steel structure. Base on loading condition to determine the accurate distribution of eqipment, oil-water and other non-steel hull vessels in the whole ship range.Determine the additional water quality and the wet surface distribution. With Lanzos method to solve the free oscillation frequencies and modes of the ship in the case of normal displacement,static water and freedom.Analysis and assess why the hull vibration strong.And provide a reference of ships in this series for design of dynamic characteristicsThe results show that the direct calculation method of the whole ship's dynamic characteristics is feasible and reliable.
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