MANOEUVRABILITY ANALYSIS OF AN ICEBREAKER BASED ON DISCRETE ELEMENT METHO

This paper presents a numerical solution to the prediction of ice resistance and maneuverability of an ice breaker in ice regions, which was solved in the time domain by the discrete element method (DEM) and the maneuvering equation. The breaking process of an intact ice sheet by an advancing ice breaker was investigated by a bonded particle model in the discrete element method. The bonded elements can be broken in the process of the interaction between the ice sheet and the ship hull. The ship hull is constructed with triangular elements and treated as a six degrees of freedom system to simulate maneuvering in level and floe ice. The equations of motion for maneuvering including propeller force, rudder force and hydrodynamic force were adopted in this simulation. The influences of the ice thicknesses (1.2 m~1.7 m) and ice concentrations (40%, 60%, 80%) for floe ice and ice thickness (0.8 m~1.2 m) for level ice on the ice resistance and maneuverability of the ship were numerically established. The simulation results by the present method indicate that the ice resistance of the ice breaker in floe ice region has lower value than that in level ice region. The diameters of turning circle in the floe ice region basically coincide with that in open water. The ship has poorer maneuverability in the level ice region, and the diameters of turning circle are two to six times that in open water. This study can aid the prediction of ice resistance and maneuverability of ice breakers in ice-covered fields.