| Corrosion in aircraft lap splices is a costly and dangerous problem for military and civilian aircraft fleets. Due to hidden nature of crevice corrosion, detecting and quantifying the material loss can be challenging. A further complication to detecting hidden corrosion occurs when corrosion in one layer overlaps or superposes the corrosion in another layer. Separating the defects into layers can better contribute to corrosion stress models and help in the assessment of fatigue life and repair processes.; Through the combination of ultrasonic and pulsed eddy current testing, superposed defects were separated into bottom of top (BOT) and top of bottom (TOB) defects. To separate the defects, the proposed pulsed eddy current reference technique was employed. The technique relies on a determined relationship between ultrasonic and pulsed eddy current response that is later used, along with superposed pulsed eddy current information, to subtract the BOT defects. With the ultrasonic data providing the BOT assessment and the reference technique revealing the TOB defects, it is possible to separate superposed defects. |
