| In recent years,with the warming of the global climate,the glaciers of the North and South poles have been melting,and the opening of a "legendary channel",the Arctic Channel,has gradually turned from a dream to a reality.The ice ships are facing unprecedented opportunities for development.The ice-breaking principle,navigation characteristics and ice load of ice ships have become research hotspots.The interaction between ice ships and level ice/broken ice is a common situation during navigation,which is also the focus of this paper.The work of this paper mainly includes the following five aspects:(1)Studying the navigation characteristics of ice ships.Based on the MMG separation modeling theory,the MMG icebreaking motion equation set including ice loads,inertial hydrodynamic forces,viscous hydrodynamic forces,propeller thrust and rudder forces is established.(2)Studying the failure mode of sea ice.The influence of the inclination angle of ship-ice contact surface on the failure mode of sea ice is analyzed.The dynamic bending failure model and the crushing failure model of sea ice are established.The timing,location and conversion relationship of the two failure modes in the ship-ice contact process are determined.Finally,a more realistic ship-ice contact model is proposed.(3)Studying the fracture process of sea ice.The effects of elastic bending and secondary fracture on icebreaking force are analyzed.Dynamic bending failure criterion and crushing failure criterion are introduced to analyze the influence of loading rate on extreme bending load.Finally,a more perfect numerical method for prediction of ice load is proposed.(4)Simulating the navigation of ice ships in level-ice zone.MATLAB is used to simulate the free direct sailing and free turning motions of ice ships in level-ice zone,and the accuracy of the numerical simulation method is verified.On this basis,the effects of failure criterion and secondary fracture on numerical simulation results are studied,and the influence of the bow parameters on icebreaking ability is analyzed.(5)Simulating the navigation of ice ships in broken-ice zone.Based on the discrete element theory,PFC and MAXSURF are used to simulate the uniform direct sailing motion of ice ships in broken-ice zone,and the existing broken-ice resistance model test is used to verify the accuracy of the numerical simulation method.On this basis,the effects of speed and ice condition on ice resistance are studied. |
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