Lloyd's Register joined WILS II (Wave Induced Loads on Ships) Joint Industry Project. The aim of this JIP was to investigate the hydroelastic responses of on a large container ship and to provide reliable experimental data of the global loads acting on the ship. In this study Fluid Structure Interaction (FSI) models are used to investigate nonlinear wave actions and wave induced global loads acting on a 10,000 TEU class container ship. The results from the computational analyses have been correlated with those from model tests undertaken by MOERI (Maritime and Ocean Engineering Research Institute, Korea). Finally the global effects of springing and whipping acting on large container ships are discussed and commented upon.
The demand for larger container ships has increased dramatically in the last few years as world trade continues to grow and with the marine industry requirement for more energy efficient ships. Currently the largest of these ships have capacities of 14,000 TEU and designs of 18,000 TEU or more are currently being prepared. Due to the large deck openings of these ships springing and whipping phenomena can be critical for the design and operation of large container ships. Springing of a ship is the continual hull girder vibration as a consequence of the waves exciting resonant hull girder frequencies. The flexing of the hull girder due to springing may continue for a significant period once initiated. Springing is an issue for ships which have low natural vibration frequencies of bending or torsion modes, typically when the lowest natural frequency is less than 3 rad/sec (≈ 0.5 Hz) and the ship operation speed is above 20 knots. The magnitude of the springing moments (stresses) is usually low and hence springing is not normally a strength issue.
