Simulating Ice-structure Interaction With The Material Point Method

7The process of ice-structure interaction is a complex problem which is influenced by the properties of both ice and the structure.Considering the shortage of existing methods in this problem,the material point method(MPM)is employed to simulate the interaction between an ice sheet and a structure in this paper,which provides new research idea for simulating this issue.Firstly,the physical and mechanical properties as well as factors which influence the ice load are briefly introduced in this work.Then,the fundamental principal of the MPM is described.MPM is efficient in solving history dependent and large deformation problems and has shown advantage in hyper-velocity impact and landslide issues,etc.Before conducting of the simulation,some hypotheses are delivered.In the simulation,the ice follows elasto-viscous-plastic model at low strain rate and elasto-brittle model at high one.In order to manifest the effectiveness of the MPM,a preliminary test is given by comparing the results with the references obtained using experiments and the software of LS-DYNA.And the simulated results of MPM are closer to the experiment data when compared with the results of LS-DYNA.Afterwards,the influence of ice temperature,penetration speed of structure,structure width and ice thickness on ice load is emphatically studied through numerical simulations.By comparing the simulated results with a series of empirical formulas,the MPM model has been found to be able to provide reasonable solutions with similar tendency and lying in the middle range of formulas' results.However,the fracture of ice has not been considered in the above simulations.Motivated from the fact that the MPM has difficulties in solving cracks and the traditional methods display low efficiency in crack problems,a combination of singular cell-based smoothed radial point interpolation method(CS-RPIM)and finite element method(FEM)is proposed for fracture simulation in the final part of this thesis,where some numerical examples are used to verify the validity of the combination method.It can be found that the combination method shows high precision when the node number is small,and preserves distinct advantage.Based on the current study,the MPM has been preliminarily proved to be a promising numerical method in ice-structure or ice-ship interaction problems.And it will be applied to more sophisticated ice engineering issues when combining MPM with other numerical methods,which,obviously,has a long way to go.