MOTION-INDUCED REMOTE FIELD EDDY-CURRENT EFFECT IN A MAGNETOSTATIC NONDESTRUCTIVE TESTING TOOL - A FINITE-ELEMENT PREDICTION

A hitherto unobserved phenomenon - motion induced remote field eddy current effect is presented in this paper. A numerical study of the non-destructive in spection of tubing with conducting walls, using a DC electromagnetic probe led to the detection of this interesting effect. This paper describes a bi-directional transmission of the electromagnetic field energy through the tube wa.Us, similar to the phenomenon responsible for the Remote Field Eddy Current (RFEC) effect in eddy current (an AC electromagnetic non-destructive testing tool) inspection of tubing. Thus far it was considered that the RFEC effect by the nature of its physics was possible only in the presence of AC excitation in tubular geometries. However, it is shown in this paper that currents induced by magnetic flux moving over conducting material produce a RFEC effect even when a DC probe is used. This phenomenon may enable extraction of valuable information regarding the entire thickness of the tube wall from measurements made on the same side as the excitation source.