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

Zhang K, Yi P, Li Y, Hui B, Zhang X - Sensors (Basel) (2015)

Bottom Line: Moreover, it can also reduce the influence of other factors, such as the lift-off, during the testing.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.Meanwhile, it is not essential to measure the signal without defects.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074, China. zhangkang@hust.edu.cn.

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.

No MeSH data available.


Related in: MedlinePlus

The schematic diagram of the experiment.
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sensors-15-17420-f003: The schematic diagram of the experiment.

Mentions: Figure 3 illustrates the schematic diagram of the experiment. As shown in Figure 3, the RPR4000 is a high power pulsed generator and receiver. A high power pulsed current is sent through the transmitting probe T, and the wave propagating in the aluminum plate interacts with the crack. At first, the receiving probe R, whose structure is the same as the transmitting probe T, acquires the signal and sends the signal to the RPR4000. Then, the signal is filtered and amplified by the RPR4000. The processed data are saved and displayed in the oscilloscope. Finally, the data are processed on the PC.


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

Zhang K, Yi P, Li Y, Hui B, Zhang X - Sensors (Basel) (2015)

The schematic diagram of the experiment.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541941&req=5

sensors-15-17420-f003: The schematic diagram of the experiment.
Mentions: Figure 3 illustrates the schematic diagram of the experiment. As shown in Figure 3, the RPR4000 is a high power pulsed generator and receiver. A high power pulsed current is sent through the transmitting probe T, and the wave propagating in the aluminum plate interacts with the crack. At first, the receiving probe R, whose structure is the same as the transmitting probe T, acquires the signal and sends the signal to the RPR4000. Then, the signal is filtered and amplified by the RPR4000. The processed data are saved and displayed in the oscilloscope. Finally, the data are processed on the PC.

Bottom Line: Moreover, it can also reduce the influence of other factors, such as the lift-off, during the testing.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.Meanwhile, it is not essential to measure the signal without defects.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074, China. zhangkang@hust.edu.cn.

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.

No MeSH data available.


Related in: MedlinePlus