Numerical Simulation Of Sea Ice Damage Based On Peridynamics

With the global warming and gradual opening of the Arctic waterway, interests of polar region ocean transportation and energy utilization make Polar Ocean Engineering Research becomes hotspot all over the world. Sea ice is the main factor affecting the safety of the polar ocean engineering. But currently, it is short of a numerical method to simulate the complex failure process of sea ice. At the same time, the numerical methods derived from classical continuum mechanics, which has difficulties in resolving discontinuity, have also restricted the research progress of the polar ocean engineering. Peridynamics is a meshless method to solve the equations of motion by using integral form. Therefore, it has obvious advantages for the simulation of complex material damage. This thesis uses peridynamics to study failure process of sea ice including:Theory of peridynamics and relevant numerical methods are introduced. The main factors affecting the mechanical properties of sea ice were discussed in details. Considering the main mechanical properties of sea ice, a bond-based peridynamic material model was constructed to meet the different tensile and compressive strength and brittle-ductile transition. On the basis of the original bond-based peridynamic elastic-brittle material model, considering the stress-strain relation of the ideal elastic-plastic model,bond-based peridynamic ductile material model was conducted. Rate of elongation of bond length is used to control ductile-brittle transition. At the meantime, different critical elongations were set up for tensile and compressive strength.Peridynamic models of two dimensional and three dimensional bond-based with pre-existing cracks were conducted. The crack path and stress distribution in the simulation process were studied. The simulation results are compared with the extended finite element method and the experimental results, which verify the correctness of the peridynamic simulation results. Furthermore,selecting the level ice - reinforced plate interaction and level ice - rigid cylindrical structure interaction as the calculation model, the crushing process of ice-structure interaction was simulated by bond-based peridynamics. The failure phenomena,ice force distribution and total ice force characteristics of the numerical simulation were analyzed. The numerical simulation results were compared with the experimental results to the reliability of applying peridynamics on Arctic Ocean Engineering.Due to the lack of the concept of stress/strain and the inability to directly introduce the constitutive model in bond-based peridynamic method, state-based peridynamics was proposed recently. This thesis introduced the theory of state-based peridynamics and numerical methods. Regarding with the advantage of state-based peridynamics, using state-based near peridynamics to simulate plate under tension. The stress distribution was compared with the result of corresponding finite element model and calculation error was analyzed. Elastoplastic theory was introduced and, furthermore, linear reinforced plastic material model was introduced in state-based peridynamics. Based on the uniaxial tension calculation model of elastic-plastic materials, the correctness of the material model was verified by the stress-strain relationship during loading and unloading process. In addition,failure phenomena and characteristics of reaction force were analyzed.