Research On The Damage Mechanism Of Hull Structures Under Multiple Ice Floes Collision

The arctic region is rich in oil,gas,coal,minerals,hydropower,and other resources.At the same time,the arctic channel is the shortest channel connecting the Pacific Ocean and the Atlantic Ocean.With the gradual consumption of land resources and global warming,the resources of the arctic region have gradually become exploited by countries.The goal is that the arctic channel will also be fully opened shortly.As a near-arctic country,my country is of great significance in terms of energy reserves,maritime transportation,and international trade.However,the navigation of ships in the arctic channel is directly affected by the climate,which is a new challenge for all countries.It can be seen from the statistical navigation time that climate change determines the change of the channel opening time.Due to the low-temperature in winter,sea ice freezes and extends to each other,making it difficult for polar sailing ships to sail in this season.As the temperature in summer increases,the sea ice continues to melt and shrink,the number of ice floes increases significantly,and the navigability of the ship also greatly improves.The opening time is mainly concentrated between July and September in the summer.When the polar sailing ship sails in the open waters of the arctic channel during the opening time,the collision between the polar sailing ship and the ice floes will be inevitable.However,due to the regional and wave environment,the size and distribution of the ice floes are also the same and have been changing,which brings certain challenges to the collision analysis of ships and ice floes.Therefore,scientific and reasonable simulation of the distribution of ice floes is the prerequisite for the analysis of the collision between polar sailing ships and ice floes.Although the collision between the ship and the ice floes will not directly cause damage to the hull structures,multiple impacts at its low energy level will also cause certain cumulative damage to the hull structure,which needs to be paid attention to in the design stage to strengthen the ship structures in the ice area.However,the damage mechanism of the hull structures under multiple ice floes is still unclear,which brings certain challenges to the structural strengthening design.Therefore,it is of great significance to carry out research on the multiple collision performance of polar navigation ships and ice floes and to clarify the characteristics of multiple impact loads of ice floes and related structural damage and deformation mechanisms,which is of great significance for the strengthening design of polar navigation hull structures and ensuring the safety of ships.This paper mainly focuses on the problem of multiple collisions between polar sailing ships and ice floes,and carries out a study on the probability distribution of ice floes,forming a method for generating the probability distribution of ice floes under different parameters,and analyzing the hull structures of ships and ice floes under the coupling of ship-ice-water The damage and deformation characteristics and the effects of the ice field and navigation parameters on the hull structures response are discussed.On this basis,a method for determining the continuous impact load of ice floes and structural response analysis is proposed,which can provide a reference for the design of the ship structure in the ice area.The main research contents are as follows:(1)The basic principle of ship collision is introduced.The ice material constitutive model is discussed and the rationality of the constitutive model applied in the finite element software LS-Dyna is verified.On this basis,the ship-ice-water coupling analysis technology was established to solve the constitutive model of ice materials and low-temperature steel materials,which laid the foundation for the subsequent analysis of multiple collisions between ships and ice floes.(2)The number,size and regional distribution characteristics of Arctic ice floes are analyzed,the probability function of ice floes distribution is determined,and the data of ice floes distribution under different observation methods are summarized.On this basis,the parametric generation method of the shape,size,and distribution of the ice floes was determined,and the corresponding subroutines were written through the APDL language,and the automatic generation of ice floes was realized in the ANSYS software.(3)Taking polar sailing ships as the research object,it is based on the generation method of the probabilistic model of ice floes and the simulation analysis technology of ship-ice-water coupling collision.The research on the damage mechanism of hull structures under multiple ice floes was carried out,and the damage deformation mechanism,energy absorption mechanism,impact load and ice floes motion response of hull structures were obtained.On this basis,the effects of different ice floes and navigation parameters(ice floes density,ice floes thickness,and ship speed)on the damage and deformation of the hull structures,energy absorption,impact load,and the typical movement of ice floes are discussed.(4)Based on the IACS rules and combined with the above simulation results,the calculation method of the limit ice loading size and the ice loading area was given,and the direct calculation method of the hull structures response under the continuous impact load of the ice floes on the long route was formed.On this basis,the damage and deformation of polar navigation ship bow structure under the action of continuous impact load is analyzed,and compared with the results of ship-ice-water coupling analysis method,the compatibility of the method is discussed.