Rosette Eddy Current Sensor for Structural Health Monitoring

Abstract

To monitoring of the crack damage located at the bolt hole of metallic bolted-joint structure in real-time, a fatigue crack monitoring scheme based on rosette eddy current sensor is put forward. The characteristics of sensor are analyzed via semi-analytic model, and feasibility of proposed scheme is verified through monitoring experiment using constructed fatigue crack monitoring system. The result of semi-analytic model shows that the magnitude of transimpedance is more sensitive to changing of conductivity and liftoff than phase of transimpedance, and the sensitivity of magnitude increases with the frequency. The result of fatigue crack monitoring experiment of 2A12-T4 aluminum alloy under constant load indicates that viewing the break point as indication of crack position, the rosette eddy current sensor achieves quantitative-monitoring capability of fatigue crack with precision of 1mm and the sensing-channels near fatigue source are capable of qualitative-monitoring of accumulated fatigue damage.