Numerical Evaluation of the Depth of Branched-Off Cracks Using Eddy Current Testing Signals

Numerical simulation shows that eddy current testing (ECT) signal of a branched-off crack is much larger than that of a same deep, single crack. To avoid the overestimation of the depth of a branched-off crack, a depth sizing index, which is designed to have maximum sensitivity to crack depth, is constructed based on an optimization approach, and the depths of branched-off cracks are estimated using this index. This depth sizing approach is numerically and experimentally validated.