Numerical Investigation Of Ship’s Uncoupled Roll, Heave And Pitch Motion In Irregular Sea
The mathematical modeling of uncoupled motions of a ship is described in this paper. The dynamics of ships in extreme waves include strong nonlinearities, transient effects, and some additional physical phenomena, which may lead to a ship capsize. It is quite often that roll motion is treated as a single degree-of-freedom (DOF) dynamic problem, whereas heave and pitch are solved in a coupled two degree of freedom system. The analysis and investigation of resonance due to ship motion in wave is important with respect to the vessels stability in the beginning of design stages. In this paper, a mathematical model has been developed with the aim to describe the behavior of uncoupled pitch, heave motion and roll motions of a ship when the influences of irregular waves are dominant. There will be a great effort if the prediction instrument has been validated to a great extent by model experiments for a ship in irregular waves. Time-domain simulations are performed for ship at different encounter frequencies. The dynamic effect in wave and parametric resonance are investigated using analytical treatment to obtain roll, pitch and heave motions. In the future the experimental studies demonstrate that the motion of ship in wave acting on the concept ship is a tug.
Keywords—Uncoupled Motion, Roll Amplitude, Irregular Sea Wave, Dynamic Stability and Capsizing Probability.