Ship’s Side And Ice Floes Collide Multiple Times At Low Temperature Response Research

With the increase in global temperature caused by the greenhouse effect,meteorologists predict that there will be a large reduction in summer ice floes in the Arctic Ocean,which means the full opening of the Arctic waterway.Once the Arctic waterway is opened,it will have a significant economic effect,forming the Arctic Ocean economic circle,and there will also be many ship ice collision incidents.For metal materials,its mechanical properties are related to strain rate,and the constitutive relationship of materials is directly related to the accuracy of collision,impact and other phenomena simulation.In order to accurately predict the structural deformation and damage modes of ship structures under collision,it is particularly important to study the dynamic mechanical properties of ship steel under impact loads and to establish a constitutive model.This paper has carried out a comprehensive and in-depth study on the impact of the collision response of the ship structure,analyzed the collision scenarios of the ship’s side and the floating ice,and carried out the numerical simulation study of the ship ice collision on the typical marine stiffened plate structure and the side structure through the finite element technology.The dynamic response of the structure under different working conditions is presented,which provides a reference for the crashworthiness design of ships sailing in ice areas.The specific research content is as follows:(1)Propose a dynamic constitutive model of EH36 steel with engineering practical value considering the effect of low temperature.According to the quasi-static tensile test results of EH36 steel at five typical temperatures,the relationship of the influence of temperature drop on the yield strength of EH36 steel is fitted.According to the results of the tensile test of EH36 steel at low strain rate and the impact compression test of EH36 steel at high strain rate,it is found that EH36 steel is a strain rate sensitive material,and its viscosity parameters and strain rate are fitted based on the Cowper-Symonds model.Hardening parameters.On this basis,a dynamic constitutive model of EH36 steel considering the low temperature effect is proposed.Numerical simulation of the experiment was carried out using finite element software,and the comparison and analysis with the experimental results verified the accuracy of the constitutive model.(2)Describe possible collision scenarios,consult data to define the constitutive model of ice material,and use LS-DYNA to establish a finite element ice block numerical model,combined with the ISO recommended pressure-area theoretical curve and the experimental data of related scholars,select reliable Numerical model with high performance.Choose a suitable material model to establish a double-span stiffened plate structure considering material properties,and explain in detail the meshing,element types,and collision contact definitions in the modeling process.Analyze the influence of the speed,temperature,shape,position and ice size changes on the stiffened plate during ship ice collision.Compare and analyze ice row damage and outer plate dent damage,give the impact stress,strain,and system internal energy changes with time,analyze and explore the performance of the structure.(3)Describe the scenario where multiple collisions may occur,and establish the finite element model of the tanker’s double bottom and double hull cargo area and the non-angular ice sheet,and define the mesh division,element type,and collision contact during the modeling process.Detailed description.Select a classic working condition to analyze in detail the ice row damage during the multiple collisions between the ship’s side and the ice row,the attenuation of the ice row speed,the energy absorption of the components,the total energy change of the system,the time history curve of the outer plate collision stress and the time history curve of the outer plate unit.Subsequently,the four factors of collision speed,ice sheet thickness,friction coefficient and temperature are considered on the ship ice multiple collision response,and the damage,the outer plate stress-strain time history curve and the total energy during the multiple ice movement processes of different ships are analyzed.The change.(4)By combining the initial conditions of the simulation in this thesis,the rationality of the theoretical derivation of the collision force and deformation of the stiffened plate structure is verified.According to the calculation results and the simulation results,the empirical formula suitable for this scenario is summarized and fitted for verification.