Algorithm Study And An Assessment System Development For The Advanced Bucking Of Stiffened Plates Of Ship

The development of science and technology, and the application of high-strength steel make the tensile stress no longer the main problem to be solved in structural field. Buckling, which is characterized by compressive stress, has become the principal issue of structural design, more and more Classification Societies pay close attention to the advanced bucking of the stiffened plates with initial defect.December 2005, through broad consultation and deep study the International Association of Classification Societies General Assembly announced:Common Structural Rules, should be enforced on April 1,2006.Common Structural Rules for Double Hull Oil Tanks introduced "ultimate strength" concept to the specification of technical standards. With this introduction, it could be more realistic to assess the ultimate bearing capacity of stiffened panels so as to promote the modern ships technology. It pointed out that the ultimate strength of stiffened plates of ships could be calculated by both nonlinear finite element method and non-linear advanced buckling analysis, but no details is offered in CSR.For this problem, this thesis can be divided into two parts:(1) Calculate the ultimate strength of stiffened plate by FEM; (2) Develop an assessment system for the advanced bucking analysis of stiffened plates.The first part of this thesis is aimed to calculate ultimate strength in a more reasonable way with considering the initial deformation of stiffened plate structures by the Patran/Marc's PCL language.The second part is focus on developing an assessment system for the advanced bucking of stiffened plates, which need to consider the theory of nonlinear buckling in the CSR as well as material non-linearity, geometric non-linearity, initial imperfections and so on. The new system can offer efficient and relatively accurate calculation of the "ultimate bearing capacity" of the stiffened plates, through the incremental Galerkin method.In this thesis, the main works are as following:(1) To find a suitable semi-analytical method to solve the affection by the large deflection to the ultimate strength of the stiffened plates.(2) To consider the affection of initial imperfections (mainly refers to the initial deflection), plastic materials to the ultimate strength of the stiffened plates.(3) To calculate the ultimate of the stiffened plates under axial compression/tension, lateral compression and shear load combination cases in theory.(4) To develop an assessment system for the ultimate of the stiffened plates according to above.(5) To compare and analyze the results calculated by the program in this thesis with the results calculated by Patran/Marc and Ansys.