Development of inspection techniques for non-sharp defects

The science of fracture mechanics assume a sharp crack is present. This approach is conservative, sometimes overly so, for real defects such as porosity, mechanical or corrosion damage, weld defects, or certain design features including crevices in partial penetration welds. These defects have non-sharp defect tips and an increased resistance to fracture compared to an equivalent component containing a sharp crack.
To take advantage of this increased toughness in operating components it is necessary to measure the radius. This poses a significant challenge as it is not currently possible to distinguish between sharp (e.g. fatigue) cracks and non-sharp defects and to produce accurate shape descriptions. Recent developments show promising opportunities for creating new capabilities for improved structural efficiency of safety-critical assets. These methods were pioneered at the University of Bristol (UoB) and have yet to be exploited for design and structural integrity applications and therefore further experimental testing and validation is required.