scholarly journals A Longitudinal Mode Electromagnetic Acoustic Transducer (EMAT) Based on a Permanent Magnet Chain for Pipe Inspection

Sensors ◽  
2016 ◽  
Vol 16 (5) ◽  
pp. 740 ◽  
Author(s):  
Ming Cong ◽  
Xinjun Wu ◽  
Chunqiao Qian
Keyword(s):  
Permanent Magnet ◽  
Longitudinal Mode ◽  
Pipe Inspection ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer

scholarly journals Characteristics of T(0, 1) Guided-Wave Point-Focusing Electromagnetic Acoustic Transducer for Pipe Inspection

2020 ◽  
Vol 20 (6) ◽  
pp. 2895-2903 ◽  
Author(s):  
Songling Huang ◽  
Hongyu Sun ◽  
Gongtian Shen ◽  
Baoxuan Wang ◽  
Qing Wang ◽  
...  
Keyword(s):  
Guided Wave ◽  
Pipe Inspection ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer

scholarly journals Influence of Magnetostriction Induced by the Periodic Permanent Magnet Electromagnetic Acoustic Transducer (PPM EMAT) on Steel

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7700
Author(s):  
Cong Zhu Sun ◽  
Anthony Sinclair ◽  
Tobin Filleter
Keyword(s):  
Permanent Magnet ◽  
Signal Amplitude ◽  
High Signal ◽  
Sh Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Generation Mechanisms ◽  
Semi Empirical ◽  
Operating Points ◽  
Shear Horizontal

The periodic permanent magnet electromagnetic acoustic transducer (PPM EMAT) is a sensor that can generate and receive shear horizontal (SH) waves without direct contact with the inspected medium using the Lorentz mechanism. However, the PPM EMAT experiences high signal variance on ferromagnetic steel under specific conditions, such as a change in signal amplitude when the sensor is moved in the direction of SH wave propagation. Magnetostriction effects are hypothesized to be the cause of these anomalous behaviors; the objective of this paper is to determine the relative strengths of the magnetostriction and Lorentz wave generation mechanisms for this type of EMAT on steel. This goal is accomplished through the use of a second EMAT, which induces only magnetostriction (MS-EMAT), to calibrate a novel semi-empirical magnetostriction model. It is found that magnetostriction effects reduce the amplitude of the SH wave generated by this particular PPM EMAT transmitter by an average of 29% over a range of input currents. It is also determined that magnetostriction is significant only in the investigated PPM EMAT transmitter, not the receiver. In terms of practical application, it is shown that the MS-EMAT is less sensitive to changes in the static and dynamic fields than PPM EMATs at specific operating points; this makes the MS-EMAT a viable alternative for nondestructive evaluation despite lower amplitudes.

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