Strength And Buckling Analyses Of Ship Girders With Cutout

The longitudinal girders and floors in the double bottom of a ship hull are the main structural components of the ship structures; and their strength and stability have significant influence on the carrying capacity of the ship. Usually the cutouts are inevitably made in the web of the components to provide access for fabrication, inspection or maintenance. The size of such cutouts, to the extent of 60% or more of the girder height, will obviously result in great changes in stress distribution within the members, as well as a reduction of strength and variations in the buckling characteristics of the components.The main research work of this thesis is to study the variations of strength and stability concerning girders of ships, under the circumstances of different thickness, opening scale of the cutouts etc. by using the finite element method. The main research works are as follows:1)Calculate strength and stability for an intact plate under uniaxial compression or shear load, and then compare the results with the theoretical formula to ensure the applied load and boundary conditions of the finite element model are correct. After that, continue the research work on girders with cutout and stiffeners.2)Calculate strength and stability for isolated girder webs with two forms of cutouts under uniaxial compression or shear load. Discuss the influence of thickness, type and scale of cutouts on the strength and buckling characteristics of girder webs. And from mechanical performances, appraise which kind of cutout shall be better.3)Base on the previous work, calculate strength and stability for isolated girder webs with two forms of cutouts and two vertical web stiffeners under uniaxial compression or shear load. Discuss the influence of thickness, type and scale of cutouts on the strength and buckling characteristics of girder webs. And from mechanical performances, appraise which kind of cutout shall be better.4)Discuss ship girders of perforated web with or without vertical stiffeners. Compare the behaviors of strength and stability for different thickness, hole size and shape, appraise the mechanical characteristics of ship girders of perforated web.Through the comparisons among the results from FEM calculations for ship girders of perforated web, the comments and conclusions presents by the thesis could be used as the reference in practical ship structural design.