大型バラ積貨物船のスラミングとAxial Forceの影響について

抄録

Slamming responses and the effects of axial force on deck stress are discussed regarding a large bulk carrier. Axial force may not be neglected in full-formed ship like bulk carriers particularly in rough seas, because of the high wave height and her large pitching and/or heaving motions. In rough seas, moreover, slamming may occur, so the deck stress is raised due to both the whipping vibrations and the axial force.
In order to clarify the characteristics of slamming responses of a large bulk carrier in rough seas, model tests and numerical calculations are carried out : A series of tank tests for slamming is conducted in regular high waves with the use of an elastic model ship, and the deck strains are measured using strain gauges. On the other hand, numerical calculations are performed by virtue of a computer program for nonlinear ship responses in waves called TSLAM, to which a routine for calculation of axial force is newly added in the present paper.
Comparing the results of experiments with the calculations and performing the numerical calculations for an actual bulk carrier, following conclusions are obtained : The effects of axial force on deck stress cannot be neglected for large bulk carriers in rough seas and are significant in the fore-body. Pressure force due to pitching motion is dominant in the axial force.