Nonlinear effects in ship dynamics and capsizing

摘要

A better understanding of ship stability is necessary to prevent losses of ships due to unstable motions, particularly in high seas. We analyze the stability of ship motions using a hydrodynamic model accounting for all the rigid body motions of a ship, as well as memory effects in the fluid. A comparison with model tests shows that the computer model provids reasonable results. The influence of the steady wave pattern is assessed for a container ship. Simulations show that ship's dynamics depend strongly on the nonlinearities of the ship-fluid-system. When wave heights increase we notice a bifurcation before the ship capsizes. A path following method is employed to determine in a systematic manner the stability limits. The application for a simplified system shows the importance of the nonlinearities of the mathematical model.