Ice Load Calculation And Structure Strength Research Of Icebreaker Bow

In recent years,with the global climate warming,the Arctic permafrost is constantly melting.In order to shorten the distance between the Asian countries and the Europe and America countries and reduce the cost of transportation,all countries in the world are actively exploring the arctic channel.However,ship navigation in the Arctic waters will inevitably encounter the problem of ice,polar icebreakers play an important role in ensuring the continuity and patency,icebreakers are also essential for polar exploration.During polar navigation,ice load has become an important factor affecting the hull structure and operation safety.However,there is little research on the ice load of icebreakers under normal operating conditions at home and abroad,the structure response of icebreakers under ice load is also not available.Based on the above reasons,this paper carried out the ice load calculation of icebreaker bow and structural strength assessment research.The ice load and hull structure response of the icebreaker under continuous and cash ice breaking modes were studied.According to the hull structure damage under extreme conditions,the structure of the bow collision area was strengthened,and new crashworthy structures were designed.The main works of this paper are as follows:(1)The main physical and mechanical properties of Arctic sea ice were introduced,and the ice material parameters were selected.According to the pressure-area curve recommended by the International Committee for Standardization(ISO)and the previous ice-rigid wall test,the feasibility of the ice material was verified.(2)The finite element model of icebreaker and ice were built by pre-processing software PATRAN.Simplification,meshing and the contact definition were introduced in detail.The large nonlinear finite element software LS-DYNA was used to study the ship and ice model.Simulating different working conditions of the icebreaker under the continuous ice breaking modes,the maximum collision force,deformation and energy absorption of the icebreaker under different working conditions were studied.(3)According to the principle of energy conservation in ship-ice collision process,the theoretical method of ice load in continuous ice breaking mode was established by energy method,and the ice load theoretical formula was given.At the same time,the ice load results in the numerical simulation were compared with the calculated results of the ice load theoretical formula and the ice load calculation results in the DNV specification and Russian standard,the feasibility of the ice load theoretical calculation formula and the numerical simulation method were verified.(4)The nonlinear finite element software LS-DYNA was used to simulate the different working conditions of the icebreaker under the cash ice breaking modes,the maximum collision force,deformation and energy absorption of the icebreaker under different working conditions were studied.The structural response of the icebreaker under extreme operating condition was studied in this paper.(5)The thickness of the outer plate and the size of the frame were calculated according to the DNV specification,the structure was strengthened by different schemes to study the deformation and energy absorption.In order to optimize the structure of the icebreaker bow,four new types of crashworthy structures were designed.The dynamic response of the hull structure under the traditional strengthening method and the new structure strengthening method were analyzed and compared,then put forward a better crashworthiness hull structure.