Abstract
The remote-field eddy current effect refers to a low frequency eddy current nondestructive testing (NDT) phenomenon in tubular conductors (magnetic or nonmagnetic) in which the behavior of both amplitude and phase of induced magnetic field are in apparent contradiction to the conventional eddy current theory. Equal detection sensitivity across the wall thickness, linear relationship between the output signal phase-lag and the wall thickness, and absence of the lift-off problem are some of the attractive and contradicting features of this technique. Despite its early recognition and useful application in down-hole inspection of oil-well casing, no development of adequate scientific base that could explain this phenomenon has been reported. This paper describes modeling of this phenomenon using the finite element numerical analysis technique. Amplitude and phase of the sensor coil output have been predicted using this model for different axisymmetric test geometries, material properties, and excitation frequencies.
