FATIGUE CRACK PROPAGATION OF SURFACE CRACK BEND AND COPMACT TYPE SPECIMEN UNDER DIFFERENT TYPES OF RANDOM LOADING

摘要

The aim of this study was to evaluate differences in the behaviour of two types of LEFM specimens. The investigation of fatigue crack propagation was performed on BS4360-50D steel frequently used in offshore oil platforms and other large structures. The tests were conducted on compact-type and surface-crack bend specimens. Because the majority of tests was done in pure bending of surface-crack bend specimens, the results apply to all part-through crack geometries. The data were analysed using linear elastic fracture mechanics (LEFM). Almost all the tests were conducted under random loading; the random-load signals having a normal distribution but differing by their power-spectrum shapes, which were double-peaked, triple-peaked, and broad band type.