Numerical Simulation And Ice Resistance Prediction During Continuous Icebreaking Of Icebreakers In Level Ice

During the last decade,with the global warming,ice melts increasingly in Arctic,the Arctic route linking Europe,East Asia and North America appeals to more and more countries for in-depth exploration.Navigation,scientific investigation and exploration for natural resources rely on breaking ice and developing voyage by icebreakers.Therefore,simulation of continuous icebreaking process of icebreakers and accurate prediction of ice resistance during icebreaking are of important theoretical and practical significance.In this thesis,finite element numerical model of an icebreaker and level ice is set up,the continuous icebreaking of an icebreaker in level ice is simulated and the ice resistance is predicted with the nonlinear finite element software LS-DYNA.The classification of sea ice is introduced.Some significant physical and mechanical properties of sea ice are summarized as well.Depending on the properties of sea ice as well as crushing and bending failure of level ice during icebreaking process,two numerical models of ice material are established,including hexahedron ice model and cohesive element model.Hexahedron ice model performs well when simulating interaction with icebreakers and crushing failure of level ice during ship-ice collision.Cohesive element model can simulate crushing and bending failure of level ice effectively.The numerical model is validated by comparing the numerical simulation results with measured data from compressive cone-shaped ice experiments.The hexahedron ice model is applied to numerical simulation of continuous icebreaking in infinite level ice.The ice resistance obtained from numerical simulation is compared with that of empirical formula.Numerical simulations with different shape of bow and different ice thickness are implemented.The influences of the shape of bow and level ice thickness on continuous icebreaking process are analyzed and the applicability of the numerical simulation method is certified.Cohesive element method is applied for modelling finite element numerical model of level ice.Using this model,the continuous icebreaking of an icebreaker in level ice is simulated and the ice resistance is predicted.By implementing numerical simulation with different icebreaker speeds,the influence of the speed is analyzed.Meanwhile,various empirical and analytical formulas are applied to predict the ice resistance.By comparing the prediction results with experimental data,the applicability and accuracy of the numerical simulation and various formulas are validated.