Research On Mathematical Model Of Ship Rolling Motion In Irregular Waves

For ship6degree-of-freedom motions, rolling motion is the most dangerous one. In order to improve the precision of shiphandling simulator’s mathematical model, the azimuth tug of Delta Linda’s rolling model in irregular waves is detailed studied. Essentially, ship sails in irregular waves. Studying the mathematical of ship rolling motion in irregular waves satisfies the DET NORSKE VERITAS standard about shiphandling simulator. So the thesis has carried out the following works:Firstly, ship model data is used to determine the coefficient of damping and restoring moment. According to the free rolling decay curve of Delta Linda tug, the damping moment is determined by energy method. The restoring moment is determined by restoring arm formula. Free rolling decay test is simulated by utilizing The validity is verified by comparing simulation data and experiment data.Secondly, the random rolling moment model is established. Wave amplitude is determined by the frequency equalization of the P-M spectrum. Random phase is determined by producing the uniform distribution pseudo-random number within0～2π. Random rolling moment is realized through the sub-waves’superposition. The validity is verified by comparing simulation data and experiment data.Thirdly, the testing platform of nonlinear ship rolling in irregular waves is established by using Visual C++and real-time simulation is described. Simulation test is classified into two categories. One is to analyze the rolling motion of Delta Linda tug in different sea states, course and speed. The other is to verify the model validity by comparing simulation results with experiment results when Delta Linda tug sails in significant wave height3meters at13.6knots speed.