Prediction of the Probability of Eddy Current Flaw Detection

Abstract

The validity of a nondestructive inspection method can be measured by two quantities, the probability that a given flaw size will be detected, and the probability that background noise will give rise to a false indication of the presence of a flaw. Unfortunately, experimental determination of the probability of detection (POD) and the probability of false alarm (PFA) requires a rather extensive set of measurements to obtain statistically sound estimates. Furthermore, if one or more of the parameters that define the method, such as the scan track spacing or probe configuration, are changed, then the full set of measurements must be repeated to obtain new estimates of the POD and PFA, thus adding to the time and expense of test validation. In some situations, where one is designing an inspection for a part or flaw size that is not yet available for testing, there is no way that the validity of a proposed inspection can be evaluated beforehand.