Eddy-Current Lift-Off Effect Compensation for 3-D Printed Ti-6Al-4V Components With Various Electrical Conductivities

In this study, the effect of lift-off distance variation in the eddy-current measurement is compensated by estimating the zero-lift-off phase value based on the modified theoretical derivation of the phase value and lift-off distance measurement. The theoretical model shows that the phase value variation from 0 to an arbitrary lift-off distance can be expressed as a simple exponential function. Based on this observation, the phase value at an arbitrary lift-off distance is normalized to the zero-lift-off phase value. Finally, the experimental validation is performed using 3-D printed Ti-6Al-4V specimens with various electrical conductivities.