scholarly journals Optimization of a Focusable and Rotatable Shear-Wave Periodic Permanent Magnet Electromagnetic Acoustic Transducers for Plates Inspection

Sensors ◽  
2017 ◽  
Vol 17 (12) ◽  
pp. 2722 ◽  
Author(s):  
◽  
Keyword(s):  
Permanent Magnet ◽  
Shear Wave ◽  
Electromagnetic Acoustic Transducers ◽  
Acoustic Transducers

Electromagnetic Acoustic Resonance To Assess Creep Damage In 2.25Cr-lMo Steel

1997 ◽  
Vol 503 ◽  
Author(s):  
M. Hirao ◽  
H. Ogi ◽  
T. Ohtani ◽  
T. Morishita
Keyword(s):  
Shear Wave ◽  
Attenuation Coefficient ◽  
Creep Test ◽  
Creep Deformation ◽  
Wave Attenuation ◽  
Creep Damage ◽  
Acoustic Resonance ◽  
Noncontact Measurement ◽  
Electromagnetic Acoustic Transducers ◽  
Acoustic Transducers

ABSTRACTMethod of electromagnetic acoustic resonance (EMAR) was applied to the noncontact measurement of the shear wave attenuation during the creep test of 2.25Cr-1Mo steels. Two electromagnetic acoustic transducers were manufactured for this purpose, which generate the polarized shear waves through the magnetostriction effect. The attenuation coefficient increased with the creep deformation. The evolution range of the attenuation was beyond 0.1 μs−1 before the failure, which was much larger than the attenuation variation among the samples.

scholarly journals Pure SH1 Guided-Wave Generation Method with Dual Periodic-Permanent-Magnet Electromagnetic Acoustic Transducers for Plates Inspection

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 3019 ◽  
Author(s):  
Gongzhe Qiu ◽  
Xiaochun Song ◽  
Xu Zhang ◽  
Jun Tu ◽  
Tao Chen
Keyword(s):  
Permanent Magnet ◽  
Guided Waves ◽  
Simulation Analysis ◽  
Guided Wave ◽  
Enhancement Effect ◽  
Large Area ◽  
Suppression Effect ◽  
Electromagnetic Acoustic Transducers ◽  
Positioning Errors ◽  
Acoustic Transducers

High frequency guided-waves offer a trade-off between the high sensitivity of local bulk ultrasonic thickness measurements and the large area scanning of lower frequency guided-waves, so it has been a growing interest for corrosion inspection with the dispersive SH1 mode. However, according to the dispersive curve, it is hard to generate the pure SH1 mode since the non-dispersive SH0 mode will be excited simultaneously. Thus, this paper investigates a transducer design method to generate a pure SH1 guided-wave, where the dual periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs) are placed on exactly opposite positions either side of the plate symmetrically. The suppression effect for SH0 and the enhancement effect for SH1 of the dual PPM EMATs are mainly discussed by theoretical analysis and simulation analysis, and the influence of positioning errors of PPM EMATs placed on opposite sides of the plate on its performances are analyzed. Employing the proposed dual PPM EMATs, some experiments are performed to verify the reliability of finite element simulation. The results indicate that the dual PPM EMATs can suppress the SH0 mode and generate the pure SH1 mode effectively. Moreover, the longitudinal and lateral positioning errors can affect the dual PPM EMATs performances significantly.

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