A six-degrees-of-freedom numerical model for level ice–ship interaction

•A six-degrees-of-freedom numerical model for ship–ice interaction is developed.•A Swedish icebreaker is modeled to validate the numerical model with full-scale data.•Icebreaking pattern plays an important role in determining ships' performance in ice.•Ship speeds are in most cases slightly higher in the 6-DOF model than the planar model.

A new numerical model simulating ship–ice interaction is proposed in this paper. Since icebreaking is in its nature a three-dimensional nonlinear dynamic problem, the numerical model is developed to look into the intricate interaction process by considering ship motions in 6 degrees of freedom (DOFs). The effect on the icebreaking pattern and ship's performance of ship motions in heave, roll and pitch is investigated. Moreover, pressure–area relation is included in calculating the contact force. Semi-empirical method is used in developing the numerical model and the results are validated by comparing with full-scale data from an icebreaker.