Residual Ultimate Strength Of Stiffened Plates With Cracks

Ship structures are prone to suffering various types of accidents and damages, which may cause ultimate strength decrease. Attention has been given to estimate reasonably the residual ultimate strength of cracked ship structures for the assurance of service safety. Cracks may be one of the most important types of damages in ship structures. Due to the complexity of stress distribution of cracks in structures, the strength assessment methods of cracked structures are of great difference comparing to those for integrated ones.So this thesis presents that the residual ultimate strength assessments of cracked ship structures are studied, the analysis methods are discussed, the effects of crack damages on the ultimate strength of ship structures are investigated. To achieve this purpose, the following efforts and contributions have been made in this thesis:(1) The study methods on residual ultimate strength of cracked ship structures are summarized systematically based on existing research conclusions.(2) Non-dimensional parametric FE analyses on cracked plates are conducted considering the parameters including material properties as yield stress and Poisson's ratio, crack length, crack angle and crack position represented by two eccentric ratios, the plate's thickness and aspect ratio, the boundary conditions of uniform stress and constant displacement.(3) Numerical analyses on residual ultimate strength of stiffened panels have been investigated considering the effects of several parameters such as flexible factor of plates, flexible factors of stiffened plates and characteristics of stiffeners.(4) The analyses of container ships have also conducted by the FEM package ABAQUS and some useful conclusions have been drawn.