A finite element model for three-dimensional Eddy current NDT phenomena

The defect detection mechanism for eddy current nondestructive testing (NDT) probes is related to the interaction of induced eddy currents in the metal test specimen with flaws and the coupling of these interaction effects with the moving test probe. To date, numerical modeling of these phenomena has been limited to two-dimensional and axisymmetric geometries. A three-dimensional magnetic vector potential finite element formulation for the modeling of eddy current NDT phenomena is described, and the technique is illustrated by predicting differential eddy current probe impedance plane trajectories for flaws in PWR steam generator tubing.