The Analysis Of Ultimate Strength Of Ice Ship Structure Subjected To The Extrusion Ice Load

With the exploitation of hydrocarbon resources in the polar ice region,researches focus on the ice ships continuously increase.Generally,all that designed to sail in the ice region are called ice ship.Compared with the regular ships,ice ships face to a great challenge because of the environment of these region is much more complex,especially the extrusion ice load.Therefore,it is necessary to evaluate the ultimate strength of an ice ship when it is under the design and evaluation period.The influence of the extrusion ice load,however,has not been considered in the traditional ship ultimate strength methods.In order to study the influence of the extrusion ice load on the ultimate strength of ice ship,a nonlinear finite element method was used to analyze the extrusion ice load,further,the ultimate strength of stiffened panel under the extrusion ice load and under both the extrusion ice load and the axial compression load were analyzed in this paper.On the basis of the above,the ultimate strength of ice ship were performed under the extrusion ice load.The following works are included:(1)A nonlinear finite element method was proposed to analyze the extrusion ice load.By compared with the empirical formula and experiment,the numerical results show that it is in good agreement with the empirical formula and experiment results.(2)A nonlinear finite element method was used to calculate the ultimate strength of stiffened panel under the extrusion ice load,which means the stiffened panel is subjected to the ice extrusion load only.The influence of plate length,plate thickness,flange thickness,web thickness,loading area,length and width of the loading area,loading position were investigated on the ultimate strength of stiffened panel under the extrusion ice load.The results show that the ultimate strength of stiffened panel will be reduced by increasing the plate length.With the increasing the plate thickness,the flange thickness and the web thickness,the ultimate strength of stiffened planes also increases.The increase of loading area will increase the ultimate strength of stiffened planes.As the loading position close to the stiffened panel boundary,the ultimate strength will be large compared with other location.(3)A nonlinear finite element method was used to calculate the axial compression ultimate strength of stiffened panel under the extrusion ice,which means the stiffened panel is subjected to both the extrusion ice load and the axial compression load.The influence of force,loading area and loading position of ice load were investigated on the axial compression ultimate strength of stiffened panel subjected to the extrusion ice load.The results show that the axial compressive ultimate strength of stiffened planes is decreased by increasing the ice force.When the loading area is increasing gradually as the total force is the same,the axial compression ultimate strength of stiffened planes is increasing.The axial compression ultimate strength of stiffened planes is increasing gradually as the distance between the location of the ice load and the center point of the stiffened planes increasing.(4)An ice ship compartment structure was established to study the ultimate moment of ice ship structure subjected to the extrusion ice load in sagging and hogging conditions.The extrusion ice load was calculated by the formulas in “Requirements concerning-Polar Class” by IACS and finite element method.The results show that the ultimate strength of ice ship is reduced a little by the extrusion ice load,but a serious influence on the local structure which directly undertake the ice load.