Research On Dynamic Response Of Bow Structure Under Combined Action Of Ice Breaking And Ice Layer

In recent years,with the rapid development of social industry,the Arctic ice has gradually melted and the area of the ice cover has decreased sharply,which greatly increases the sailing time of shipping vessels in the Arctic region and improves the social and economic benefits.Due to the complex ice situation in the Arctic region and the distribution of a large number of irregular floating ice,it is inevitable that the polar transport ship will collide with the floating ice in the ice region in the process of sailing,which will cause the response of the hull structure,damage the hull,and damage to the personnel and equipment on board.During the ice-breaking voyage of polar ships,the collision area of the hull is mostly located near the water plane of the bow,and the structural stress of the bow part is large.Therefore,this paper studies the deformation and damage of the bow structure,energy absorption,collision force and a series of problems during the voyage of transport ships in the ice area.The structure damage and deformation,energy absorption and collision force distribution and their change rules of the bow and regular ice layer,the bow and irregularly shaped ice layer and the bow under the combined action of broken ice and irregularly shaped ice layer are analyzed and discussed.Two research conditions,ice thickness and ship speed,are mainly considered,and the comparative analysis has certain reference value for the route selection of polar transport ships and the optimization of ship bow structure design.The full work content is as follows:(1)The ship ice collision finite element method was studied,and the ship 3D model was established by Patran software.Based on the theoretical experimental research of ice materials at home and abroad,the properties of sea ice and several constitutive models of ice materials are collected and sorted,and the relevant parameters of ice materials are determined.The ice materials are selected as the isotropic elastic fracture failure model for finite element analysis.(2)Simulate the collision process between the bow structure of polar transport ship and regular layer ice.Firstly,the mesh refinement of the regular layer ice was carried out,and the air domain and water area were established.Secondly,the coupled model of ship-regular layer ice and water was established by using the nonlinear finite element software LS-DYNA.Through the stress analysis of the regular layer ice under the ship-ice interaction,the breaking mode and crack propagation mechanism of the regular layer ice were obtained.The effects of ice thickness and ship speed on the ship-ice interaction are obtained by analyzing the structural response rules of bow structure,such as damage and deformation,energy absorption and collision force.(3)The collision process between the bow structure of a polar transport ship and the irregular shape layer ice is simulated.The ship-irregular layer ice-water coupling model was established,and two different conditions of ice thickness and sailing speed were considered respectively.The structural response rules such as structural damage and deformation,energy absorption and collision force in the ship-regular layer ice-water coupling model were compared and analyzed,and the effects of different shapes of layers of ice on ship-ice interaction were obtained.(4)The ice collision process of polar transport ship under the combined action of broken ice and irregular shape layer ice load is simulated.The solid model of broken ice was built by using the cellular machine technology and the parametric design plug-in Grasshopper in Rhino software,and the coupled model of ship-ice-broken ice-irregular layer ice-water was established.The damage and deformation,energy absorption and collision force of the bow structure under ice thickness and speed were analyzed,and the bow structure response rules were compared with those of polar transport ships under regular and irregular ice loads,which provided some reference for the route selection and structure optimization of polar transport ships.