Study On Quadrilateral Block Discrete Element Model Of Level Ice Bending Failure

The bending failure of level ice is one of the most important failure modes of level ice in the polar region.In this paper,the quadrilateral discrete element model is used to study the interaction process of level ice bow and the bending fracture process of ice plate under wave action.Firstly,the contact algorithm between quadrilateral discrete elements and the neighbor retrieval algorithm based on mesh search are established by using the overlapping area algorithm of convex polygons.Based on the quadrilateral element contact algorithm,a discrete element bonding model with bonding breaking characteristics is introduced to simulate the failure process of level ice.The sensitivity of the number of discrete elements to the calculation accuracy is studied through the numerical test of the load on the end of the cantilever beam.Then,based on the quadrilateral element bonding model,the interaction process between icebreaker and level ice is simulated.The calculation results show that in the interaction process with icebreaker,the breaking of level ice is random,and the average breaking length of level ice will decrease with the increase of ship speed and increase with the increase of ice thickness.The ice force curve between bow and ice shows a strong "pulsating" characteristic,and the ice resistance increases with the increase of ice thickness and speed.Finally,the one-way coupling model of ice plate and wave is established,the fracture characteristics of floating ice plate and ice plate fixed at one end under wave action are analyzed,and the fracture wave height and its influencing factors of ice plate fracture are discussed.It is found that the breaking limit wave height of floating ice plate decreases with the increase of relative ice length.For floating ice with relative ice length less than 1,the breaking limit wave height decreases with the increase of relative ice length;When the relative ice length is greater than 1,the breaking limit wave height of floating ice block increases slightly with the increase of relative ice length;When the ice length ratio is equal to 1,the ultimate breaking wave height of the floating ice plate is the smallest,and the ice plate is most prone to fracture.For the ice plate with one end fixed,the change of the ultimate wave height with the relative ice length is not obvious.For a floating ice plate with one end fixed,under the same relative ice length,the ultimate fracture wave height increases with the increase of ice thickness.