Defect characterization in multi-layered conductive components with pulsed eddy current

Abstract

Capabilities of the Pulsed Eddy Current (PEC) method to perform in-depth scanning have been successfully demonstrated for hidden corrosion detection. In the present work, a drive pulse and the response is analyzed in terms of Fourier Transform to understand the scope of material penetration with PEC. Variations of the drive pulse shape can be an effective technique to control the depth of penetration of conductive materials. An observation time interval and a sampling rate are the components that can be used for “in-depth slicing” of conductive media. Two-dimensional scanning of multi-layered structures such as aircraft skin structures with a PEC probe provides detection of subsurface defects. Experiments have been performed on aluminum panels with flat bottom holes. An image processing routine is applied to reconstruct geometry of the component from a series of eddy current images obtained with a two-dimensional scanner. A problem of accurate reconstruction of the internal geometry of the component under test is considered. The advantages and limitations of the technique are discussed.