A non-uniform model for alternating current field measurement of fatigue cracks in metals

Article type: Research Article

Authors: Zhou, Jianwei^a | Lugg, Martin C.^{a; *} | Collins, Roy^b

Affiliations: [a] Technical Software Consultants Ltd, 6 Mill Square, Featherstone Road, Wolverton Mill, Milton Keynes MK12 5RB, UK | [b] NDE Centre, Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK

Correspondence: [*] Corresponding author. Fax: +44 1908 220959; E-mail: martinl@tscuk.demon.co.uk.

Abstract: The ACFM technique has been proved to be an extremely practical NDE method for crack detection and sizing. Its original mathematical model is based on a uniform interrogating surface current field. In this paper, the theoretical aspects of the ACFM technique are re-examined. The thin-skin theory of electromagnetic perturbation due to a surface-breaking crack has now been generalised to allow non-uniform interrogating current fields and has then been combined with the theory of electromagnetic induction in a half-space to produce a non-uniform ACFM model. More realistic simulations of many types of ACFM probes are obtained from the new theoretical model.

DOI: 10.3233/JAE-1999-142

Journal: International Journal of Applied Electromagnetics and Mechanics, vol. 10, no. 3, pp. 221-235, 1999