A Numerical Simulation Method for Prediction of Ice Resistance and Ship Motion in Level Ice

Estimating ice resistance and ship motion in ice-covered region is important for the planning of operations and transport routes. This paper proposes a numerical simulation method for predictions of ice loads and ship motions in level ice. The dynamic interaction between ship and level ice is considered on basis of nonlinear finite element method. Numerical simulations between level ice and a ship are carried out by LS-DYNA software. The ice material model which can simulate ice crushing and bending failure modes is used. To consider the net thrust during ship-ice interaction, the user-defined load subroutine LOADSETUD that provides a means to apply nodal loads as a function of velocity is used. In addition, the water effect on the level ice model is taken into account by using a nonlinear discrete spring model. The model tests of an icebreaker navigating in level ice is used to test the presented method. The predicted results including ice resistance, net thrust and attainable speeds for given ice conditions are compared with the model test data. The comparison shows a generally good agreement, which indicates that the presented method is able to give reasonable predictions. Furthermore, the comparison between the numerical results obtained by the rigid ship and the deformable ship is made. The ship structural response during ship-level ice interaction is investigated.