The use of the theory of critical distances in fracture and structural integrity assessments

There are many situations where the structural integrity of a given component or structure is determined by the presence of defects acting as stress risers. Moreover, these defects are not necessarily cracks, which can be analysed using fracture mechanics concepts, but they may be notch-like defects (e.g., mechanical damage, fabrication defects, corrosion defects, holes…). In such cases, the application of ordinary fracture mechanics assessments may lead to overconservative results, so that it is important to define methodologies for the fracture and structural integrity assessment of components containing notches or any other kind of stress riser. This paper presents the capacities of the Theory of Critical Distances (TCDs) for the assessment of this kind of situations, gathering and summarising the results obtained by the authors in a wide range of materials. The results show how the TCDs provides reasonable results for the prediction of both the apparent fracture toughness and the load-bearing capacity. It also increases the accuracy of the structural integrity assessments performed using Failure Assessment Diagrams.