船体总振动固有频率实用计算方法

Pratical Approach to Calculation of Natural Frequency of Ship Hull Vibration

将船体视为梁，当梁的长度与横向尺度之比大于５时，按梁的弯曲振动理论建立 固有频率近似计算模型；当梁的长度与横向尺度之比小于５时，按梁的剪切振动理论 建立固有频率近似计算模型。在精确计算中，考虑剪切迟滞，用有限元法或迁移矩阵 法计算船体梁固有频率，在计算中同时还考虑上层建筑对总体振动影响。经实船激振 试验验证，上述方法计算结果与实验值相吻合。

The ship hull is regarded as a girder in this paper. In the case of the ratio over 5 of the length against the transverse dimension, the approximate calculation model for natural frequency is set up based upon vibration theory of Beam Bending; while in the case of the ratio smaller than 5 the model for natural frequency set up based on vibration theory of Beam's Shear. The detailed calculation of the hull's natural frequency utilizes Finite Element Method or Transfer Matrix Method with shear retardation taken into consideration. Accounting for superstructure's effects on ship hull vibration in terms of correction coefficients reduces computer time dramatically, lessening the difficulty to determine the superstructure's influences on ship hull vibration. The results of the excitation experiment of the real-scale ship show their good agreement with those given by the above calculation method.