Simplified Calculation Method Of Ship Ice Collision In Water And Study On Failure Mode Of Hull Structure

With the rising of global temperature,most of the ice in the Arctic waters is melting away.The rich resources and valuable Arctic waterways in the polar regions have become the focus of many countries.Therefore,the demand for polar ships has increased significantly.What represents the level of a country’s shipbuilding industry,restricts a country’s voice and affects the new world is the polar transport ship.There is still large promotion space in the R&D and construction capacity of polar ships in China.The government and academia have emphasized that the key research targets for polar ships in the future are polar crude oil carriers and polar deck carriers.As an important water transportation vehicle,ships are inevitably affected by the surrounding waters when they encounter collision during their nevigation.At present,most scholars use the attached water quality method to replace the role of water medium in the study of ship-ice collision,and ignore the influence of water pressure change during of ship-ice collision.To sum up,it’s important for improving the structural safety of polar ship that conduct the research on water-ice coupling technology of ships and carry out the syudy on failure mode and load prediction under collision load of hull slab,and it’s also the core and the key basic problem to be solved urgently for polar transport ships.The main works of this paper are as follows:(1)Introduce the theoretical and numerical methods used in the ship-ice encounter.Describe the basic governing equations for three-dimensional viscous fluid motion and control equations and parameter settings of RNG k-ε model in two-equation model and free surface-VOF model.After that,the numerical solution of the flow field and the dynamic mesh technique are introduced.Finally,the numerical wave pool is briefly described.(2)The hydrodynamic interaction in ship-ice encounter and the simplified calculation method of ship ice collision in water medium is studied.Using the FLUENT software combined with the sliding mesh and the moving mesh method,the RNG k-ε model is used to solve the unsteady RANS equation.Numerical simulation of the viscous flow field of ship ice under sea ice-wave and ship coupling is carried out.The water pressure distribution and wake field information of the side outer plate are analyzed.Through the numerical simulation under different design conditions,the pressure changes of each monitoring surface under different projection areas and ship velocities can be predicted in real time,and the pressure prediction formula of the monitoring surface at the moment of collision contact(when ship ice has not yet contacted)can be regressed,so that the calculation of ship ice collision can be simplified quickly and it lays the foundation for the later study of the failure mode of the side structure.(3)The numerical simulation technology of ship-ice collision and the failure mode of side structure under ice load are studied.Taking the side structure of the polar navigation oil tanker as the research object,the ship-ice collision numerical model under different scenes is established.Based on the simplified calculation method of the pre-watering pressure in this paper,the finite element analysis software LS-DYNA was used to analyze the failure mode of the structure under the collision with the cube iceberg ridge.(4)The simplified analytical calculation of the wedge-shaped striker impact plate is studied.The basic theory of simplified analysis is briefly introduced,and the basic flow of analytical solution is given.Then an analytical model of a wedge-shaped striker impacting t plate is proposed.In order to consider the coupling of the width direction and the length direction,the deformation of the plate is simplified by dividing it into three regions,which makes the analytical method simple and feasible.The validity of the analytical model is verified by numerical simulation and experimental data.On this basis,the analytical calculation of the impact of the side outer plate on the ridge of the ice body is proposed,and the numerical simulation of the hull side of the ice body is used for comparison verification.