Layered and Truncated Conductors

Abstract

The subject of this chapter is the eddy-current inspection of test-pieces that are coated, layered, or truncated. It is presumed that various surfaces of the test-piece significantly perturb the induced eddy currents and that the effect of those surfaces must be taken into account to properly interpret the observed eddy-current probe coil impedance. The discussion includes a description of impedance-plane diagrams for surface coils, encircling coils, and bobbin coils in relation to coated, layered, or truncated test-pieces with planar or cylindrical surfaces. The effect of the test-piece edge on the observed probe coil impedance is also described.