Research On Calculation Method And Numerical Simulation Of Rotational Motion Of Ship In Ice-covered Region

Along with the gradual melting of Arctic ice,more and more scholars pay attention to the problem of polar ship navigation.Unlike sailing in conventional waters,the movement of the ship in ice area is more complex and the risk is greater.So,the prediction and simulation of maneuverability of the ship is of great significance.On the basis of existing research,the ice loads of ships moving in ice region are calculated by empirical method,finite element method and probability method,and the motion and maneuverability of ships are simulated.Firstly,a three-degree-of-freedom(3DOF)motion model of ship sailing in ice area is established by using MATLAB language.The ship's motion in open water is simulated,and the results are validated by comparing with the test data.Then,the ice force and moment are calculated by empirical formula method and added into the 3DOF motion model,and the simulation results are compared with the data of test and those of Discrete Element Method model,respectively,which validates the proposed method.Finally,the law of ship's rotational motion in ice area under different parameters is analyzed.Secondly,based on the non-linear finite element method,the collisions between ship and ice in straight and rotational motions are simulated.The accuracy of the finite element simulation results is verified by comparing with the ice load calculated by empirical formula.On this basis,the influences of various parameters on the ship motion are analyzed.Then,the fluid-structure interaction method is used to simulate the ship ice interaction with the presence of fluid field,and the change of ship rotation characteristics is analyzed considering the effect of water.Finally,combined with the finite element method and maneuverability theory,referring to the solution method of hydrodynamic derivatives,the maneuvering coefficients of a ship in level ice are obtained by simulating some specific forms of motion.The approximate relationship between ice resistance and speed is obtained by data fitting.A 3DOF motion model including the maneuvering coefficient in ice is established.On this basis,the probabilistic ice loads calculation method is introduced.The random ice force function method and the ice force spectrum method are used to generate the probabilistic ice loads on ships,and the motion of ships under the probabilistic ice loads is analyzed.