Research On Numerical Simulation Of Ice Breaking By Under Ice Explosion Based On Peridynamics

In the background of global warming,the exploration and utilization of polar area have been becoming possible,no matter in the aspects of natural resources,shipping or military strategy.In addition,ice flood has been occurred frequently in high altitude alpine regions of China.Such disasters not only pose great threat to the property security of people,but also endanger the personal safety of people.As an effective ice-breaking method,under ice explosion can remove the large ice sheets effectively.It has a good effect on the user of the rivers such as river dredging and the opening of Arctic channel.Therefore,the research on under ice explosion to break ice has a great meaning in economics,politics and safety.As for the research in this field,experimental methods and numerical simulation method are mainly used for this research.The numerical simulation is low in cost and high in safety,so it is favored by researchers at home and abroad.However,the traditional Finite Element Method,a widely used numerical simulation method has some shortages in dealing with fracture problems which limits the research on under ice explosion.The peridynamics is an emerging meshless method,which is a kind of reconstruction of continuum mechanics,which can solve the continuous problem well.More importantly,unlike the traditional finite element method,the peridynamic adopted the form of integral to express its basic equation which makes it have great advantages in solving the fracture problem and the crack propagation.In this paper,based on the merits of peridynamics in fracture problems.the peridynamics is applied to the study of under ice explosion.The main contents of the study are as follows:Firstly,the peridynamics theory and its numerical calculation method are elaborated.The method is validated from static and dynamic problems respectively.The tensile deformation of isotropic two-dimensional plate and the deformation of plate collided by a rigid ball are simulated by peridynamics.The results are compared with analytical solution and the solution of FEM for verification.Then the physical and mechanical properties of ice material and its characteristics are analyzed.According to the characteristics of the ductile-brittle transition,the ice material exhibits brittleness when subjected to high strain rate and toughness at low strain rate.Aiming at the high loading rate of ice under ice explosion,the constitutive model of the brittleness of ice materials in pridynamics is obtained,and the related peridynamics numerical discrete model is established to prepare for the study of ice explosion under ice.The process of the under ice explosion was described,and the form of the load involved in this process was analyzed.At present,there are some shortcomings in the research on ice-breaking using under ice explosion at home and abroad.Most of the research only considers the shock wave and does not consider the bubble pulse.Several bubble loading methods such as spherical bubble load and mirror bubble are proposed.Bubble load combined with the shock wave,so that the study of the explosion load under the ice is more completed and comprehensive.This type of load is loaded into the peridynamics model for numerical simulation to obtain the dynamic response and damage effects of the ice layer.By comparing the results obtained by these load simulations with the experimental results,the optimal load mode is obtained.The applicability of the method to the ice-breaking ice-breaking study is also verified.Finally,the ice failure modes and laws were explored and analyzed from the two factors of ice thickness and explosion distance.