Interpretation of pulsed eddy current signals for locating and quantifying metal loss in thin skin lap splices

PEC defect automated classification in aircraft multi-ply structures with interlayer gaps and lift-offs

“…(1). Differential time response is also named as balanced signal in another PEC work [15], which can represent the perturbations of the reflected field due to flaws or other abnormal conditions.…”

“…To reduce the liftoff effect, Giguere and Dubois conducted intensive investigations of lift-off and proposed the Lift-off point of Intersection (LOI), representing a lift-off independent point in the time-domain pulsed eddy-current signals [13] to eliminate the lift-off effects in multilayer structures [14,15]. In 2006, Lefebvre and Mandache investigated the characteristics of lift-off via theory and experiment [16] and proposed LOI slope to accurately measure the non-conductive layer thickness on a conductive substrate [17].…”

Transient Eddy Current Response Due to a Subsurface Crack in a Conductive Plate

“…However, it is found that variations of lift-off and inter-layer gap can cause noise which may overwhelm the material loss signature. Giguère et al [23], [24], [25], [26]…”

Pulsed Eddy Current Nondestructive Testing for Defect Evaluation and Imaging of Automotive Lightweight Alloy Materials

“…This technique holds the potential of becoming the primary means of detecting corrosion in multilayered structures [25]. In 2002, Lepine et al used the lift-off intersection (LOI) and gap point of time response to eliminate the lift-off effect and interlayer gap effect in the twolayer structures [26]. In recent years, some features from frequency response have been used to reduce these effects; He et al used some FFT amplitude from PEC frequency response as a feature to classify the first-layer defects and second-layer defects in two-layer structures in 2010 [27,28].…”