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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

(a) The structure of the probe; (b) the schematic diagram of the coil.
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sensors-15-17420-f004: (a) The structure of the probe; (b) the schematic diagram of the coil.

Mentions: Figure 4 shows the geometric parameters of the probes. The probe consists of the magnet and the meander coil, which is made of printed circuit board. The x-direction length c, the y-direction length b and the z-direction length of the magnet are 40 mm. The remnant magnetic flux intensity is 1.21 T. Figure 4b shows the details of the meander coil. The thickness of the printed circuit board is 0.6 mm. The coil includes 10 bends, and every bend consists of 6 conductor wires. The width of the conductor wire a is 0.15 mm. The interval s1 of the adjacent conductors is 0.3 mm. The height g of the coil is 0.035 mm. The interval s2 of the adjacent bends is 3.0 mm.


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)

(a) The structure of the probe; (b) the schematic diagram of the coil.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-17420-f004: (a) The structure of the probe; (b) the schematic diagram of the coil.
Mentions: Figure 4 shows the geometric parameters of the probes. The probe consists of the magnet and the meander coil, which is made of printed circuit board. The x-direction length c, the y-direction length b and the z-direction length of the magnet are 40 mm. The remnant magnetic flux intensity is 1.21 T. Figure 4b shows the details of the meander coil. The thickness of the printed circuit board is 0.6 mm. The coil includes 10 bends, and every bend consists of 6 conductor wires. The width of the conductor wire a is 0.15 mm. The interval s1 of the adjacent conductors is 0.3 mm. The height g of the coil is 0.035 mm. The interval s2 of the adjacent bends is 3.0 mm.

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