Studies on Methods of Calculating Accurate Natural Frequencies of Vertical Vibration of Ships

为了准确地估计船舶垂直振动的固有频率，必须考虑船体与大型局部结构（如底部结构和甲板架）的耦合振动影响。对具有两个侧壳板、两个横向舱壁板和一个底壳板的单舱模型进行了垂直振动试验，研究了底部结构的振动特性。考虑船体与弹性船底结构耦合振动的影响，对船舶的垂直振动进行了理论研究，并通过水中模型船的振动试验对结果进行了验证。并对不同尺寸甲板的模型船进行了垂直振动试验。从理论上考虑了船体与甲板结构耦合振动的影响。理论结果与实验结果吻合较好。

In order to estimate accurately the natural frequencies of vertical vibration of ships, it is necessary to consider the effect of coupled vibration of ship hull and the large local structures such as bottom structure and deck errection.Vertical vibration experiments were made on single-hold models having two side shell plates, two transverse bulkhead plates and a bottom shell plate, and the vibration characteristic of the bottom structure was investigated. Taking into account the effect of coupled vibration of ship hull with elastic bottom structure, the vertical vibration of a ship was studied theoretically and the results were verified by vibration tests of model ships in water.Vertical vibration experiments were also made on model ships having deck errections of various size. Theoretical consideration was made on the effect of coupled vibration of ship hull and deck errection. Theoretical results showed good agreement with the experimental results.