The use of flat coil sensors and impedance spectroscopy for fatigue crack monitoring of Al 2024-T3 plates

Flat coil sensor based on eddy-current technology has been developed for the Non-Destructive Testing (NDT) of aluminium plate-like structures for aerospace applications. The critical points for crack initiation and development can be found primarily around small holes or rivets present in plate-like aluminium parts. In this study, high-cycle fatigue tests were performed in order to monitor cracks in thin Al 2024-T3 plates using a flat coil sensor. For the initiation of the cracks, a hole was artificially created in the middle of the plate. Results showed that this type of sensor was able to detect the crack growth by electromagnetic impedance measurements, and due to its flexible and thin design it can be used as an embedded sensor between the primer and top-coating of the aluminium plate like structures.