Impact of Lift-Off on Detected Current Time Signal on Harmonic Analysis Method on the 3MA Prototype NDT Technique

This research investigates the impact of the liftoff on the harmonic analysis of induced and detected current around a yoke magnetization coil. The study focuses on two magnetic material grades, D04 and C15E. The finite element method (FEM) is utilized to solve the two-dimensional (2D) electromagnetic equations in a transient step-by-step manner. The non-linear behavior of the ferromagnetic components is modeled using vector hysteresis and also considers the presence of eddy currents. Simulation results of both soft and hard material enable the calculation of total current and magnetic field amplitude across various liftoff states under a fixed voltage amplitude supply. Subsequently, the harmonic analysis of the current signal is performed. Finally, a comparison between simulation and experimental results for both magnetic materials shows a match between FEM simulation and experimental findings.