Handbook of Nondestructive Evaluation (NDE) Capability and Reliability
Nondestructive inspection (NDI) is often the primary basis for establishing the initial flaw size that is used as the basis safe life analysis of components, structures and systems. It is often desirable to use a small initial flaw size for purposes of fatigue and fracture analysis, thus the capability of applied the nondestructive inspection procedure often becomes a primary design constraint. The introduction of fracture mechanics analysis in design applications has established requirements to quantify the capabilities of applied nondestructive inspection procedures for purposes of determining the “largest flaw that might be missed”. That flaw size, in turn, becomes the starting point for fracture mechanics analysis and for crack growth in fatigue life analyses. It is clearly desirable to start with a very small flaw size. In recent years, considerable effort has been expended in both meeting “attainable” flaw requirements and in improving NDI procedures capabilities to detect smaller flaws. Such efforts have identified uncertainties in fracture mechanics analysis procedures in predicting the behavior of small flaws and have greatly increased the complexity and sophistication of NDI procedures being applied.