| Most of icebreakers in world were built in northern Europe,Russia,and U.S.A,etc.China constructed the ice breaking ship is based on Bohai and Heilongjiang ice situation,and China has not got enough experience on designing or constructing professional polar icebreakers.But nowadays,ice in polar area is abating in a steady speed,so countries in Europe,North America,Europe and other countries have opened Arctic coastal routes.Because of the extreme environment in the polar regions,either professional icebreakers or ice transporters,severe challenges brought by sea ice are unable to avoid.Once accidents occurred,not only ship owners and sailors will suffer huge losses,but also more critically,it is a great disaster to polar environment.So people must pay more attention in polar ships design and construction to raise the safety.In this paper,an ice oil tanker as the research object,through the simulation of ship ice interaction to analyze the extrusion pressure and the damage situation of the ship.Two kinds of working conditions are considered: dynamic extrusion and rotary extrusion.Study on the influencing factors of speed,extrusion velocity,ice thickness,steering speed and obtain the extrusion pressure,residual velocity and damage of the ship structure.Specific research contents are as follows:In order to study the interaction between ship and ice body,this paper briefly introduces the classification and properties of sea ice,and analyzes the properties of steel materials.Established isotropic visco-plastic finite element numerical model by LSDYNA.Then made combination between simulation results and ISO recommended pressure-area curve and ice impact experiments results respectively,to evaluate the accuracy of numerical model.Secondly,the two scenarios of the occurrence of the ice and the ship are described,and the causes of the extrusion are introduced.Comparison of two kinds of different extrusion collision in ice and ship,analysis the plastic deformation of ship side,and found that the plastic deformation is larger when the ship meets the sea ice with sharp edges and corners,so the behind analysis of ship ice extrusion choose this great harm of the ice sheet.Friction is a great impact on ship ice extrusion,this paper compares three different friction coefficients,the extrusion pressure and the plastic deformation of ship side effects of various friction coefficient,finally combined with previous experience obtained the friction coefficient is 0.1.Again.Establish a finite element model of double bottom double hull oil tanker cargo area and the edge of the ice sheet.Analyzing the variation of the extrusion pressure and velocity and the energy absorption on the side of the ship.Through the analysis of the three factors,we obtain the influence of different factors on the ice extrusion of the ship.The first is the speed of the ship's navigation,the different speeds corresponding the different navigation time.It is not obvious that the influence of the size of the navigation speed on the extrusion,and the damage to the ship is not too large,but with the increase of the speed,the damage is increased.Secondly,the extrusion speed,with the increase of extrusion speed,contact area is increased rapidly,and the ship side-ice extrusion increased,causing pressure increased relatively faster and the ship extrusion speed reduce faster,the ship side damage seriously.The last is the ice thickness,the greater of the ice thickness,caused by the effect of extrusion is greater on the ship,and the extrusion damage is greater.Finally,Establish a finite element model of double bottom double hull oil tanker's cargo area and the square of the ice sheet.Analyzing the variation of the extrusion pressure and the energy absorption on the side of the ship.The paper analyzed the influences of different rotary extrusion factors on the rotary extrusion.The first is the impact of ice thickness,due to the increase of ice thickness,ice-ship area will increase and the pressure will increase.The thick ice's damage to the ship is more serious.Secondly is the steering speed.Due to the increase of steering speed,speed of rotation of the ship has correspondingly increased,and the contact of the ship side and ice will increase,thus increasing the steering speed will increase the ship side damage.The last is the ice bound.Through analysis when the vessel encountered in the floating ice,extrusion is not very serious,but when meet the head-on speed and fixed ice,ship side damage is more serious. |
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