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Sensors 2015, 15(7), 17420-17432; doi:10.3390/s150717420

A New Method to Evaluate Surface Defects with an Electromagnetic Acoustic Transducer

1
School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074, China
2
School of Life Science & Technology, Huazhong University of Science & Technology, Wuhan 430074, China
*
Author to whom correspondence should be addressed.
Academic Editor: Vittorio M.N. Passaro
Received: 31 May 2015 / Revised: 7 July 2015 / Accepted: 8 July 2015 / Published: 17 July 2015
(This article belongs to the Section Physical Sensors)
View Full-Text   |   Download PDF [1517 KB, uploaded 17 July 2015]   |  

Abstract

Characterizing a surface defect is very crucial in non-destructive testing (NDT). We employ an electromagnetic acoustic transducer (EMAT) to detect the surface defect of a nonmagnetic material. An appropriate feature that can avoid the interference of the human factor is vital for evaluating the crack quantitatively. Moreover, it can also reduce the influence of other factors, such as the lift-off, during the testing. In this paper, we conduct experiments at various depths of surface cracks in an aluminum plate, and a new feature, lift-off slope (LOS), is put forward for the theoretical and experimental analyses of the lift-off effect on the receiving signals. Besides, by changing the lift-off between the receiving probe and the sample for testing, a new method is adopted to evaluate surface defects with the EMAT. Compared with other features, the theoretical and experimental results show that the feature lift-off slope has many advantages prior to the other features for evaluating the surface defect with the EMAT. This can reduce the lift-off effect of one probe. Meanwhile, it is not essential to measure the signal without defects. View Full-Text
Keywords: lift-off slope; surface defect; EMAT lift-off slope; surface defect; EMAT
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Zhang, K.; Yi, P.; Li, Y.; Hui, B.; Zhang, X. A New Method to Evaluate Surface Defects with an Electromagnetic Acoustic Transducer. Sensors 2015, 15, 17420-17432.

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