Investigation On The Calculation Method For Motion Of Icebreaker And Icebreaking Loads

The thesis mainly focuses on the theoretical analysis of continuous icebreaking processes and ship motions in six degrees of freedom.A numerical model is introduced to simulate ship-ice interaction,and a numerical method is established to predict ice loads and ship motions of icebreakers.The effect on icebreaking capacity of bow shapes is investigated as well.The main research contents are as follows:1.The Newmark's method is applied to solve the motion equations of icebreakers,and the coupling problem between continuous ice forces and ship motions is solved.Semi-empirical formulas are applied to determine the forces and moments,and the Euler force induced by a non-uniformly rotating frame is derived.2.The mode of ship-ice interaction is investigated,and a geometrical model is established.Continuous icebreaking processes can be idealized as a sequence of contact-crushing-bending cycles.The numerical theories in these three stages are studied and derived,and ice forces and ice edge shape are obtained at every time step.3.Based on the numerical theory,a program is written in Fortran language to establish a numerical model of ship-ice interaction,and simulate the transiting and turning operations.Then the instantaneous ice forces are calculated in the simulation program.The numerical program is validated by comparison with the data from other papers.4.The effect on icebreaking capacity of bow shapes is investigated through altering different parameters of bows,including the stem angle and the camber angle.