The vibration of a container ship has been studied with a chief attention to the horizontal and the torsional vibrations. Some checks on the problems of structural behaviour and of the added virtual mass of water have been made. Centre of virtual mass of water is calculatedfor the Lewis form sections. The model experiment has been carried out to check the behaviour of coupled vibration. At the last the experiments in a full scale container ship have been made, using the vibration generator and in the sea trials. It is found that the problem is pretty complicatedand many investigations are necessary in order to clarify the mechanism of coupled vibration and therigidities in the torsional vibration. Horizontal vibration, though it is complicated due to the coupling with torsional vibration, is more accessible. The characteristics of the vertical vibration of the container ship are qualitatively the same as those of conventional types of ships. The bottom vibration is significant in the vertical vibration of higher modes which is likely to reduce the natural frequencyof the vertical vibration.
As the analyzing system on the total hull girder stress on open ships such as container ships, open bulkers, etc., has been developed and structural behaviours of longitudinal members were investigated on four container ships, the outline of the system and the results of calculations are reported in this paper. This system consists of many programs which compute ship motions, dynamic loads, structural responses and response amplitudes in regular and irregular waves. The following knowledge about the stress on the upper deck in the irregular waves was obtained. (1) Maximum total hull girder stress which is composed of vertical bending stress, horizontal bending stress and warping stress, occurs at the midship or in front of the engine room. (2) At the midship, the total stress is slightly larger than the vertical bending stress. (3) In front of the engine room, the total stress is comparatively larger than the component stresses of that section, and is nearly the same level as the total stress at the midship. The further discussion concerning these results, will be presented together with the simple method to evaluate the total hull girder stress on the open ship, in the next paper.
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