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Evaluation of the lift-off robustness of eddy current imaging techniques

Lookup NU author(s): Ibukun Adewale, Professor Gui Yun TianORCiD


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The development of lift-off invariant strategies is one of the main goals in Eddy Current Non-Destructive Testing research. In the present work, from the analysis of amplitude and phase signals of magnetic field sensors under Multi-Frequency Eddy Current excitation, two imaging procedures are analyzed and compared with respect to their ability to retrieve reliable results even in presence of huge changes of lift-off. A figure of merit based on the Signal to Noise Ratio evaluated on the 2D reconstructed images allows the comparison of the different strategies in terms of the quality of the image to show the defect. The numerical and the experimental tests realized show that the imaging procedure relying on the analysis of the phase-lag is quite insensitive to changes in the lift-off with respect to that based on the amplitude analysis. In detail the former guarantees good results even when the probe lift-off is randomly changed during the test with variations up to 3 mm, while the latter is able to tolerate only lift-off fluctuation lower than 1 mm.

Publication metadata

Author(s): Ricci M, Silipigni G, Ferrigno L, Laracca M, Adewale ID, Tian GY

Publication type: Article

Publication status: Published

Journal: NDT & E International

Year: 2017

Volume: 85

Pages: 43-52

Print publication date: 01/01/2017

Online publication date: 07/10/2016

Acceptance date: 06/10/2016

ISSN (print): 0963-8695

ISSN (electronic): 1879-1174

Publisher: Elsevier Science Ltd.


DOI: 10.1016/j.ndteint.2016.10.001


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FCTR10MRFondazione Carit "Tecniche elettromagnetiche per il controllo di saldature in strutture metalliche complesse"