Thin sections fracture

基于断裂力学的评估含有缺陷的结构完整性的程序依赖于断裂韧性测量的可用性。这些测量都是使用含有裂纹的试样进行的，试样的尺寸和几何形状通常是根据公认的断裂韧性测试标准选择的，以便在断裂过程中在裂纹前缘局部产生高强度的拉伸静水应力。然而，这种方法可能会导致过于保守地低估裂纹部件的破坏载荷，因为在这种情况下，结构中局部裂纹前沿的拉伸静水应力的大小低于用于确定断裂韧性的实验室样品中的应力。本项目的目的是开发一种方法，用于确定包含贯穿壁裂纹或半椭圆/扩展表面裂纹的给定薄壁钢构件的失效载荷的准确估计。这将需要考虑的方式，其中应力状态变化沿裂纹前缘的各种组件厚度。将考虑在线弹性和全塑性行为的极端之间的一系列负载水平。

Fracture mechanics-based procedures for assessing the integrity of structures containing defects rely on the availability of fracture toughness measurements. Each of these measurements is made using a test specimen containing a crack, with the specimen size and geometry generally being chosen, in line with accepted fracture toughness testing standards, to generate high-magnitude tensile hydrostatic stresses local to the crack front during fracture. However, this approach can result in an excessively conservative underestimate of the failure load of a cracked component of interest being made in cases where the tensile hydrostatic stresses local to the crack front in the structure are lower in magnitude that those in the laboratory specimen used to determine the fracture toughness. The aim of the present project is to develop a method for determining an accurate estimate of the failure load of a given thin-walled steel component containing either a through-wall crack or a semi-elliptical/extended surface crack. This will entail considering the way in which the stress state varies along the crack front for a variety of component thicknesses. A range of load levels will be considered between the extremes of linear-elastic and fully-plastic behaviour.