Demonstration of probability of detection taking consideration of both the length and the depth of a flaw explicitly

This study proposes the construction of the probability of detection (POD) as a function of both the depth and length of a flaw. In addition, this study discusses how to censor signals in constructing the POD. The general effects of the flaw parameters on signals are evaluated by numerical simulations, and the scattering of signals, which is critical to the POD, is estimated by signals obtained in experiments. A new likelihood function is introduced, and the proposed method is demonstrated using eddy current signals caused by various artificial flaws on a flat type 316L stainless steel plate obtained in a laboratory test. The demonstration confirms that the proposed method can provide a reasonable POD with a small amount of experimental signals, and reveals that proper censoring significantly decreases the detrimental effect of noise on the POD.