The capabilities of the pulsed eddy current technique to extract depth related information have been successfully demonstrated for hidden corrosion detection. In the present work, the drive pulse and the transient response are analyzed in terms of the Fourier transform to understand the depth of material penetration with pulsed eddy current. A multifrequency analysis of the transient response that allows information to be selectively chosen from different layers is described. An observation time interval and a sampling rate are the components that define high- and low-frequency resolution of a pulsed eddy current system. An example of 'in-depth slicing' of a multilayer structure is provided. The use of solid state sensors to acquire transient response is discussed. Examples of pulsed eddy current imaging with arrays of giant magneto resistors are given. Recently developed two-dimensional arrays enable instant imaging of the structure under the probe without mechanical scanning. They also provide the fastest surface coverage for large area testing when used with 2D scanners. Experiments have been performed on aircraft aluminum skin with a portable prototype system. The advantages and limitations of the technique are discussed.
Enhanced corrosion detection in airframe structures using pulsed eddy current and advanced processing
Verbesserter Korrosionsnachweis in Flugzeugzellen mittels Impuls-Wirbelstromprüfung und moderner Signalverarbeitung
Materials Evaluation ; 65 , 4 ; 403-410
2007
8 Seiten, 10 Bilder, 9 Quellen
Article (Journal)
English
Buried corrosion detection in multi-layer airframe structures using pulsed eddy current
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