Classification of pulsed eddy current GMR data on aircraft structures

An experimental comparison of multi-frequency and chirp excitations for eddy current testing on thin defects

“…Similarly to the (ii) case, it can be useful to analyze the instant at which the impulse response reaches its maximum since it is related to the characteristics of defects [4,7,15,16]. To this aim, an image is formed by considering IM CH mTðx; yÞ ¼ t à where jĥ x;y ðt à Þj ¼ max t ðjĥ x;y ðt à ÞjÞ.…”

“…To mitigate the effect of noise, and also to avoid calibration, several signal processing techniques for time signals from PEC have been developed. For instance features extraction by Principal Component Analysis revealed a useful tool for defect classification [15,16].…”

Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

“…Other examples of work where PCA has been used are introduced in Refs. [14], [28], [48], [52], [55][56][57][58][59][60].…”

“…For unsupervised methods, K-means has been used for estimation of the size the cracks, also in aircraft structures [28]. Another report by Qiu, et al [61] included both supervised and unsupervised methods, namely LDA and Bayes.…”

“…Stress-induced cracks that occur under a fastener and between fasteners in multi-layered structures of the wings are crucial to be detected early for the safety of the aircraft during its flights. Works related to these issues can be found in the following works about PEC [1], [14], [15], [18], [28], [58], [60], [89], among others.…”