The Study Of The Numerical Simulation Method Of Peridynamic Based On The Bending Fracture Of Sea Ice

Due to the dramatic melting of a large amount of glaciers in the Arctic under the tendency of global warming in the recent years,the demands of opening the sailing route through the Arctic and the exploitation of oil and gas resource in the cold region keep increasing continuously.Thus,currently,the research about the polar ocean engineering has become the hot spot area around world.However,since the ice load is regarded as the major factor that influences the safety of polar ship and marine-structure,it is one of most important research area in the polar ocean engineering.During the interaction between sea ice and marine-structure,the calculation of the ice load is mainly related to the failure mode of sea ice.For the finite element method based on continuum mechanics which is regarded as the major method for the calculation of ice load,when coming across discontinuous issue,remesh process always result in the decrement of computational efficiency.Nevertheless,the peridynamics which is a nonlocal lagrangian particle method based on integral equation of displacement field,has huge advantage on handling with discontinuity.Therefore,in this paper,based on the peridynamics,combining with the properties of sea ice,the simulation of the bending fracture of sea ice and the interaction between level ice and marine-structures have been studied.The main work is listed as following,In this paper,initially,both bond-based and state-based peridynamic theory and its numerical method have been introduced in detail,including their advantages and limitations of the application which are described respectively.Based on the bond-based peridynamic model,the micro beam with six-freedom between the particles is introduced to substitute the bar in order to overcome the restriction of poisson ratio.For the application of state-based peridynamics,the polar decomposition is utilized when coming across large deformation problems with the material of non-linear behavior,so that the constitutive model could satisfy the frame indifference during the simulation.Besides,to build a foundation for numerical computation,the decomposition of states is described as well.Besides,combining with mechanical properties of sea ice,for the three-point bending test under high loading rate,the constitutive model of elastic-brittle material is introduced with maximum principle strain regarded as the failure criterion to establish the peridynamic model for the simulation of the ice beam.The distribution of the stress and the local damage are analyzed during the simulation.In addition,the results attained from the simulation will be compared with the one obtained from the experiment to testify the accuracy of numerical model.In addition,due to the definition of spherical horizon during the three-dimensional discretization,the numerical model is required to contain two layers of particles at least.Thus,in order to improve the efficiency of computation,the less dimensional peridynamic model is proposed for the simulation of Bernoulli beam and Kirchhoff plate.By introducing a factor which contains the thickness of the structure and other material parameters,the bending of thin structure can be calculated.The calculated deflection will be compared with the analytical result to verify the accuracy of the peridynamic model.Finally,the two-dimensional and three-dimensional ice-sloping interaction is simulated respectively.The factors which influence the radius of the fracture like ice thickness,ice velocity,and angel of slope are discussed in detail.The initiation and the propagation of the crack during the ice-sloping interaction are described specifically as well.At last,the horizontal ice force attained from the stimulation is compared with the analytical one to verify the accuracy of the numerical model.