Electrical resonance eddy current sensor for submillimeter defect detection

Electrical resonance based eddy current methods are being investigated and developed for the detection of sub-millimeter surface defects in low conductivity material such as superalloy in aircraft. The probe has high sensitivity due to the noise elimination by evaluate the relative resonance shift on the impedance change cause by material properties variance. This method has reported analytically with experimental validation recently. In this paper, the detecting system includes the coil sensor and the coaxial connection is modelled using full wave electromagnetic simulation with integration of the circuit co-simulator. The finite element simulation is to study the probe behavior while the circuit model simulator is used to investigate the influence of the component such as capacitance and resistance in the detection system. With our model, further investigation on the sensitivity of the detection system due to the variation of sensor parameters, such as ferrite core and liftoff as well as and capacitance and effective resistance from the electronic component, is performed. This study not only contributes to the optimization and sensitivity enhancement of the detecting system, but also provide accurate detection of submillimeter defect.