船舶上层建筑整体纵向固有频率算法研究

Research on Calculation Method Predicting Natural Frequency of Longitudinal Vibration of Whole Ship Superstructure

将上层建筑视为弹性固定在主船体上的阶梯形变断面高腹梁 ,采用力学方法推导出了上层建筑整体纵向振动固有频率公式。推导中 ,仍将上层建筑整体纵向固有频率视为由下述两部分串联合成 :上层建筑根部刚性固定在主船体上的剪弯振动固有频率 fs;上层建筑根部弹性固定在主船体上的刚体转动固有频率 fr。本文重点研究了上层建筑刚体转动固有频率算法。经实船振动测试 。

In this paper, ship superstructure is simplified to a non nuiform deep cantilever beam with elastic fixation at its root, and the formula predicting the natural frequency of longitudinal vibration of whole superstructure is derived by means of mechanics analysis. The formula put together the natural frequency f s of shearing bending vibration of superstructure rigidly fixed on the hull and the natural frequency f r of rigid rotating vibration of superstructure elastically fixed on the hull, in which the calculating method of the frequency f r is studied in detail. Calculational results of full scale ships show that the formula presented here is of high accuracy in longitudinal vibration prediction of whole superstructure.