Crack detection in aluminium plates for aerospace applications by electromagnetic impedance spectroscopy using flat coil sensors

A flat coil sensor based on eddy current technology has been developed in K.U. Leuven for the purpose of structural health monitoring (SHM) of critical aircraft components. SHM is an upcoming technology and the implementation of those techniques receiving a high level of interest from the aviation industry. Aircraft manufacturers and airline companies nowadays are concerned with constant structural monitoring of their aircrafts. It is crucial not only for safety reasons but also for a faster maintenance and a healthy ready-to-operate fleet. Nowadays, eddy current sensors are already used as the main detection system for cracks on various critical points of an aircraft. These critical points can be found primarily on plate-like aluminium parts where small holes or rivets are present. In this study, a high-cycle fatigue test using the flat coil sensor was performed in order to monitor cracks in thin aluminium 2024-T3 plates. Results showed that this type of sensor was able to detect crack growth by impedance measurements and due to its flexible design it could be used as an embedded sensor for online monitoring.