Detection of fatigue damage cracks in aircraft skin structures is an ongoing NDT challenge. Cracks growing rate is difficult to predict, and for this reason, it is important to detect them as soon as possible to avoid a catastrophic break. Eddy current methods are known and well-accepted techniques which are relatively simple to carry out. However, with conventional inspection of airframe structures using standard driver-pickup eddy current probes, it is difficult to detect small fatigue cracks initiated in the second layer of the skin and in the shadow region at fastener holes. Such difficulty is related to fasteners length and their spacing which reduces test sensitivity. This report explains the development of improved eddy current probe/technique to detect and visualize fatigue cracks in fasteners. In this study, an eddy current array probe was evaluated and new coil design was suggested. Several tests were conducted on an A-300 circumferential joint sample with simulated fatigue cracks. With the investigated improved coil design, the results showed great potential and enhanced detection capabilities of relatively small fatigue cracks in the fasteners. Modeling tools were also investigated to optimize the new probe design configuration and to improve inspection results.
Fatigue crack detection in aircraft skin structures using eddy current array technique
Nachweis von Ermüdungsrissen in Luftfahrtaußenhaut-Strukturen mittels Wirbelstrom-Arraytechnik
CINDE Journal (Canada's National NDT Magazine) ; 25 , 6 ; 14-17
2004
4 Seiten, 7 Bilder
Aufsatz (Zeitschrift)
Englisch
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