Rosette eddy current sensor and its experimental research on aircraft metallic structure fatigue damage monitoring

Fatigue damage monitoring of aircraft metallic structure is critical to flight safety. Based on the previous work of ref.[13], a kind of rosette eddy current sensor is proposed, and monitoring experiment of 2A12-T4 aluminum alloy under constant load based on constructed fatigue-crack monitoring system is carried out, which intends to validate the quantitative crack-monitoring capability of rosette eddy sensor through comparison between experimental result and fractographic quantitative analysis result. The comparison result shows that amplitude ratio of sensing-channel signal is sensitive to the crack propagation, and has step feature. When the crack extends from the position of sensing-channel to adjacent channel position, the amplitude ratio of sensing-channel signal increases sharply, and then increases slowly after the adjacent channel position. Viewing the changing-point as indication of crack position, the quantitative-monitoring capability of fatigue crack is achieved by rosette eddy current sensor with precision of 1 mm, and the sensing-channels near fatigue source are capable of qualitative-monitoring of accumulated fatigue damage. © 2013 Journal of Mechanical Engineering.