| Ice flood disasters,which happen frequently in the north China,cause great harm to the life and property security of people on both sides of the river in the high latitude and cold regions.The implementation of underwater explosion is the fast and effective measure to prevent and control ice flood disasters.At the same time,the Arctic with the value of the military,energy and shipping has received more and more attention from all over the world in recent years.Deploying the strategic underwater vehicle in the Arctic is of great significance for the maintenance of the overall security and lawful rights of our country.Ice cover is the key factor to affect the rapid launching of vehicle in the arctic region.Breaking appropriate range of ice cover by underwater explosion is an effective way to ensure vehicle launched successfully under the ice cover.Therefore,the research on underwater explosion to ice breaking has high economic,social and safety significance.For the study of underwater explosion to ice breaking problem,domestic and foreign scholars always use the method of numerical simulation.However,the numerical methods based on classical continuum mechanics,which suffer from a lot of troubles in resolving the problem of ice cover damage,have restricted the progress of research in this area.Peridynamics,which employs integral form of the equations of motion,is an emerging meshless method based on the nonlocal theory and has huge advantage on handling with problems of damage and crack propagation.Therefore,in this paper,based on the improved bond-based peridynamics,the process of underwater explosion to ice breaking has been studied.The main research content is as follows,Initially,the bond-based peridynamic theory and its numerical method have been introduced in detail.As for the problem that the traditional constant micromodulus function appeared jumping and discontinuous,a continuous form of micromodulus function was introduced.It can reflect the weakening of the stiffness of a bond when the distance between two particles increases and the stiffness of a bond is reduced to zero at last.At the same time,continuous form of bond stiffness functions for one-dimensional,two-dimensional and three-dimensional model were derived.As for the problem that measuring the energy release rate when material fractured was very difficult in the experiment,a more reasonable method was introduced to derive the critical stretch based on the K criterion for brittle fracture in the linear elastic fracture mechanics.In order to better simulate the damping effect and avoid the natural phenomenon such as material points dislocation and embedded,the viscous damping and short-range repulsive force were introduced into the peridynamics.As for the mechanical properties of ice under high loading rate,a reasonable elastic-brittle constitutive model of ice for the bond-based peridynamic theory was put forward considering different compressive and tensile strength of ice.According to the problem of underwater explosion to ice breaking,the load problem was analyzed in detail and then the load of shock wave was identified as the computation load.The problem of fluid–solid coupling was analyzed based on the Taylor’s plate theory and the additional water mass was also discussed.In addition,the peridynamics numerical model of underwater explosion to ice breaking was established.Furthermore,the process of underwater explosion to ice breaking and the characteristics and regularity of ice cover’s cracks formation,propagation and branch were also analyzed.The numerical simulation results were compared with experimental data to verify the accuracy of the numerical model.Finally,the effect of the material parameters(density,fracture toughness,elastic modulus),the size of the hole in the ice cover,the distance of charge migrated,the complete ice cover and the model parameters(the mass of the explosive,the thickness of the ice cover,the depth of the explosive underwater)on the ice cover broken and the characteristics and regularity of ice cover’s cracks formation,propagation and branch were analyzed qualitatively and quantitatively. |
