Thin sections fracture

断裂力学为基础的程序，用于评估结构的完整性，包含缺陷依赖于断裂韧性测量的可用性。这些测量中的每一个都是使用含有裂纹的试样进行的，其中通常根据公认的断裂韧性测试标准选择试样尺寸和几何形状，以在断裂期间在裂纹前缘局部产生高量级的拉伸静水应力。然而，这种方法可能会导致一个过度保守的低估的情况下，局部的拉伸静水应力的结构中的裂纹前端的破坏载荷的破坏载荷是在那些在实验室样本用于确定断裂韧性较低。本项目的目的是开发一种方法，用于确定一个给定的薄壁钢构件的破坏载荷的准确估计包含一个贯穿壁裂纹或半椭圆形/扩展表面裂纹。这将需要考虑应力状态沿不同部件厚度的裂纹前缘沿着变化的方式。荷载水平的范围将被视为介于线弹性和完全塑性行为的极限之间。

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.