NDTnet 1998 Aug, Vol.3 No.8

Abstract

A new electrical and magnetic method for sizing of surface flaws was proposed in [1]. The sizing is based on a regression between the distribution of the intensity of the leakage field measured at a constant distance above the surface of the sample along the line which is parallel to the applied field and positioned over the centre of a flaw and the corresponding theoretical distribution of the intensity of the leakage field. It was demonstrated in [2] that the method allows precise sizing of surface cracks with known shapes of their relatively simple cross-sections and arbitrary orientations with respect to the applied field. An algorithm based on the method [1] was developed in [3] for sizing of cracks with complex cross-sections and unknown shapes when the cracks are oriented perpendicularly to the applied field. The algorithm computes the width and the depth of a crack at six equidistant points of its cross-section, and the surface density of charge at the crack walls, and contains five minimisation procedures which are performed the same way as in the method [1].

In this paper, computations are performed for sizing of surface cracks with different orientations with respect to the applied field, complex cross-sections, and unknown shapes by using the algorithm from [3] It is shown that the algorithm allows to perform sizing of cracks with complex cross-sections independent of the shape of the crack for orientation angles not exceeding 45°. The crack width and surface charge density are always computed perfectly. The error in the computation of the depth profile of the crack is less than 20%.

REFERENCES
1) Minkov,D. and Shoji,T., Accepted for publication in NDT&E International
2)Minkov,D. and Shojij., Third International Workshop E'NDE '97, Workshop Digest, pp.76-77
3) Minkov,D. and Shoji,T., To be presented at the 1998 Annual Spring Meeting of JSME in Tokyo

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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