STUDY OF CONTINUOUS ICEBREAKING PROCESS WITH COHESIVE ELEMENT METHOD

Accurate simulation of the continuous icebreaking process in level ice is crucial for the design of icebreakers. The crushing and bending failures of ice sheet, as well as the rotating, sliding and accumulating of ice cusps broken from the ice sheet constitute a complex system for the icebreaking process. In this paper, cohesive element method is combined with an elastoplastic softening constitutive model to simulate continuous icebreaking process in level ice. Firstly, the elastoplastic softening constitutive model in modelling ice local crushing is calibrated by simulating the ice cone crushing tests. Three different softening laws are proposed and their effects on simulation results are evaluated by comparing with the experimental data. Then, the continuous icebreaking process in level ice is simulated by cohesive element method. The regular tri-prism mesh is applied to ice bulk elements to realize the random propagation of crack. The mesh dependency study is carried out, and the simulation results are validated by comparing with model test results in both of time domain and frequency domain. The ice failure patterns during continuous icebreaking process are also compared between the simulated and experimental results. Finally, the influences of ship velocity on ice resistance and ice failure patterns are investigated by numerical methods and semi-empirical formulas.