Mutual interference effect of a rosette eddy current array sensor for quantitative crack monitoring in metallic structures

The in-situ monitoring of crack damage due to fatigue in metallic bolted-joint aircraft structures is a critical challenge for structural health monitoring (SHM) systems to achieve active control of aircraft safety. In order to analyse the mutual interference effect of a rosette eddy current array sensor, a crack monitoring system and an equivalent sensor model were established. The sensor output transimpedance was analysed under conditions where only a single channel worked and where multiple channels worked simultaneously. As the drive current frequency increased, the amplitude of the transimpedance also increased, whereas the phase of the transimpedance decreased initially before then increasing. The results obtained from the model indicate the existence of mutual interference between the channels, which changes the amplitude and phase of the transimpedance, but there is little effect on the trends in the corresponding parameters that vary with the drive frequency condition. Thereafter, a crack monitoring experiment was performed to validate the sensor capability of crack propagation monitoring.