Modeling of the Change of Impedance of an Eddy Current Probe Due to Small Changes in Host Conductivity

Two different approximation techniques for predicting the response of an eddy current coil in the presence of small changes in conductivity were developed. The small changes in conductivity are the result of changes in the orientation of individual anisotropic crystals in a polycrystalline aggregate. Orientation information from electron backscatter diffraction was imported directly into the modeling domain and the simulations were run to map orientations into an approximated eddy current response. These approximated responses were compared with experimental data obtained with commercially available eddy current equipment, and the approximations were found to be in good agreement with experiment. Further verification was performed with other existing numerical and analytical models to demonstrate the accuracy of the approximations made in deriving the eddy current response. This paper shows these results and demonstrates the viability of using low-fidelity approximations in predicting the eddy current response when the change in conductivity is low.