Eddy-current testing

Eddy-current testing uses electromagnetic induction to detect flaws in conductive materials. There are several limitations, among them: only conductive materials can be tested, the surface of the material must be accessible, the finish of the material may cause bad readings, the depth of penetration into the material is limited, and flaws that lie parallel to the probe may be undetectable.

However, eddy-current testing can detect very small cracks in or near the surface of the material, the surfaces need minimal preparation, and physically complex geometries can be investigated. It is also useful for making electrical conductivity and coating thickness measurements.

This form of testing relies on the attraction of magnetic particles to the flux leakage when an eddy current is passed through the material, this is an indication of the flaws existence, this flux leakage is caused by the flaw in the ferromagnetic material for which is being tested.

The testing devices are portable, provide immediate feedback, and do not need to contact the item in question.Recently tomographic notion of ECT has been explored see for example:

M. Soleimani, W. R.B Lionheart, A. J. Peyton, and X. Ma, S. Higson, A 3D inverse finite element method applied to the experimental eddy current imaging data, IEEE Trans Magnetics Vol. 42, No. 5, pp. 1560-1567, May 2006.

ee also

*Eddy current
*Nondestructive testing
* [http://www.ndt-ed.org/EducationResources/CommunityCollege/EddyCurrents/Introduction/IntroductiontoET.htm An introduction to eddy current testing from the NDE/NDT resource center]
* [http://www.ndt.net Database of NDT and Eddy Current Testing]
* [http://www.geocities.com/raobpc/EC-Def.html Eddy Current Non-Destructive Testing - B.P.C. Rao]
* [http://www.joe.buckley.net/papers/eddyc.pdf Intro to Eddy Current Testing] by Joseph M. Buckley (pdf, 429 kB)
* [http://eddycation.de/41265.html EddyCation - the Eddy Current System for Education]
* [http://www.dci-meettechniek.nl EC testing worldwide]