The Quantitative Measurement Model of ACFM Based on Swept Frequency Method


Article Preview

The alternative current field measurement (ACFM) technique is a new non-destructive testing (NDT) method to evaluate the surface flaws, and in contract to other methods it has advantages of non-contacting and non-calibrating. Precise locating and crack length measurement can be easily achieved. But it is rather difficult to measure the crack depth with the complicated mathematic model. Its application is thus limited. On this ground, the swept frequency method is introduced to make up of this shortage. The penetration depth of eddy current that is theoretically different for different operational frequencies is the principle of crack depth measurement of the swept frequency method. By means of measuring the switching-frequency of the characteristic curve, the information of flaw depth is achieved by sweeping frequency. The paper introduced the physical model of ACFM and assayed the errors of measurement. Some methods were introduced to decrease the errors. The crack depth is proportional to the interval of the switching-frequency of flaw and of no-flaw, which is detected at the position of minimum value of Bz.



Key Engineering Materials (Volumes 353-358)

Edited by:

Yu Zhou, Shan-Tung Tu and Xishan Xie




Z. W. Kang, "The Quantitative Measurement Model of ACFM Based on Swept Frequency Method", Key Engineering Materials, Vols. 353-358, pp. 2273-2276, 2007

Online since:

September 2007





[1] S. K Burke: in: The 10 th APCNDT, Austrilia, (2000).

[2] Information on http: /www. ndt. net.

[3] Francisco Carlos R and Marques: Marcus Vinicius M. Martins, in: The 15th WCNDT, Roma, (2000).

[4] Alan Raine: in: the 15 th WCNDT, Roma , (2000).

[5] Zhong-wei Kang, Fei-lu Luo and Di-xiang Chen: Electrical Measurement & Instrumentation, 2004, 41 (3): 44-47.

[6] Zhong-wei Kang, Meng-chun Pan, Fei-lu Luo et al: Journal of Test and Measurement Technology, Vol. 18 (2004), pp.263-268.

[7] Z. Mottl: NDI international Vol. 11(1990), pp.11-18.

[8] Mirshekar-Syahkal Dariush: IEEE Transactions on instrumention and measurement, Vol. 51(2002), pp.374-382.