As the size of container ships increases, springing and whipping phenomena have been one of important design considerations due to its significant effect on wave loads and fatigue analysis. Therefore needs of reliable model test data is increasing for validation of state of the art analysis tools for springing and whipping. In the present study, a model system for measurement of torsion springing and whipping which is composed of a backbone and segmented container ship model in which natural frequencies of bending and torsion are matched using an open section beam. A series of model tests have been carried out for selected cases of springing and whipping in regular and irregular waves. Discussions are focused on physics of torsion springing and whipping observed in model tests, and technical difficulties associated with interpreting torsion moment from measured strains from backbone model.
As the size of container ships increases, springing and whipping phenomenon has been one of important design considerations due to its significant effect on wave loads and fatigue analysis. Almost 15,000 TEU class container ships are already in service, and the appearance of very large container ships much bigger than 15,000 TEU is expected in near future. Therefore, needs of experimental investigation of springing and whipping have been arisen from classification societies as well as ship builders because model test data are most reliable references for validation of the state of the art analysis tools. A systematic experimental study on wave induced vibrations (springing and whipping) has been conducted by Storhaug (2007), the model was made of four segments and flexible joints to meet design structural stiffness. They showed higher-harmonic resonant behaviors of bending moment are observed in irregular sea states. Oka et al.(2009) investigated springing and whipping phenomena experimentally in regular and irregular waves.