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.

Oil-Tank Weld Detection Using EMAT

2017 ◽  
Vol 14 (02) ◽  
pp. 1750008 ◽  
Author(s):  
Li Chen ◽  
Wang-Rim Choi ◽  
Jeong-Gu Lee ◽  
Yi-Gon Kim ◽  
Hong-Sik Moon ◽  
...  
Keyword(s):  
Elastic Waves ◽  
Guided Waves ◽  
Ferromagnetic Material ◽  
Transduction Efficiency ◽  
Sh Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Oil Tank ◽  
Non Destructive ◽  
Shear Horizontal

Tanks are typically used for the storage of oil by the petrochemical industry, and the storage quality is largely determined by the safety of the equipment. Recently, Electromagnetic Acoustic Transducer (EMAT) technology has been the focus of many non-destructive examinations, as EMATs can generate elastic waves without contact, thereby making it easy to carry out the process of detection. The Shear Horizontal (SH)-guided waves that are generated by an EMAT are modeled in a plate made of ferromagnetic material, and this is of particular interest regarding the testing of welded structures. This paper provides an EMAT-sensor design that can be used to find cracks in the welds of a tank whereby the need for people to climb onto the tank is removed; furthermore, regarding cases where the amplitude signal of the SH-wave EMATs is too low, a simulation is used in this paper to propose a method that improves the transduction efficiency.

scholarly journals High Temperature Shear Horizontal Electromagnetic Acoustic Transducer for Guided Wave Inspection

Sensors ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 582 ◽  
Author(s):  
Maria Kogia ◽  
Tat-Hean Gan ◽  
Wamadeva Balachandran ◽  
Makis Livadas ◽  
Vassilios Kappatos ◽  
...  
Keyword(s):  
High Temperature ◽  
Guided Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Temperature Shear ◽  
Shear Horizontal

Development of the ISI Device for Fast Breeder Reactor MONJU Reactor Vessel

2006 ◽  
Author(s):  
Akihiro Tagawa ◽  
Masashi Ueda ◽  
Takuya Yamashita
Keyword(s):  
Test Performance ◽  
Cooling System ◽  
Ccd Camera ◽  
Fast Breeder Reactor ◽  
Test Results ◽  
Sh Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Acoustic Transducer ◽  
Main Components ◽  
Service Inspection

In-service inspection (ISI) is carried out to confirm the integrity of the main components of the Fast Breeder Reactor (FBR) “MONJU”. The weld-joints are examined by using an inspection device which has a glass fiber scope for visual examination and a horizontally polarized shear (SH) wave electromagnetic acoustic transducer (EMAT) for volumetric testing. The ambient temperature during the inspection is 200°C and the irradiation field is 10 Sv/hr. A new inspection device has been developed in order to improve the visual test performance, volumetric test performance and controllability of the inspection device reflecting the experience of the original test. In this paper, detail of the new inspection device and the test results of sensors such as the CCD camera, EMAT and bead sensor are reported. The paper also reports on the CCD camera cooling system and other components.

An improved design of shear horizontal guided wave electromagnetic acoustic transducer

2020 ◽  
Vol 62 (8) ◽  
pp. 494-497
Author(s):  
Xu Zhang ◽  
Sheng Feng ◽  
Jun Tu ◽  
Xiaochun Song
Keyword(s):  
Guided Waves ◽  
Cost Effective ◽  
Guided Wave ◽  
Experimental Investigations ◽  
Electromagnetic Acoustic Transducer ◽  
Rectangular Array ◽  
Acoustic Transducers ◽  
Acoustic Transducer ◽  
Improved Design ◽  
Shear Horizontal

This work proposes the use of a Halbach magnet structure to enhance the generation efficiency of shear horizontal (SH) guided waves on a plate. SH waves are normally generated using periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs). Two PPM configurations are designed using a Halbach magnet array and the enhancements of the static magnetic fields of the two magnet arrays are validated by the finite element method, indicating that these configurations can increase the peak flux density compared with the conventional configuration. Numerical analysis and experimental investigations indicate that a racetrack coil combined with either a rectangular or triangular Halbach magnet array can enhance the amplitude of the SH guided wave by factors of ∼1.2 and ∼1.1, respectively, and that the rectangular array performs better and is more cost effective.

Development of a SH Wave Single Unit Electromagnetic Acoustic Transducer (EMAT) for MONJU Reactor Vessel In-Service Inspection

2009 ◽  
Author(s):  
Yang Xu ◽  
Akihiro Tagawa ◽  
Kazunari Fujiki ◽  
Masashi Ueda ◽  
Takuya Yamashita
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Detection Sensitivity ◽  
Magnetic Flux Density ◽  
Sh Wave ◽  
Electromagnetic Acoustic Transducer ◽  
Signal Processing Method ◽  
Acoustic Transducer ◽  
Main Components ◽  
Service Inspection

In-service inspection (ISI) is carried out to confirm the integrity of the main components of a Fast Breeder Reactor (FBR) “MONJU”. The ambient temperature during the inspection is 200 degree C and the irradiation field is about 10 Gy/hr. A Periodic Permanent Magnet (PPM) structure has been used for electromagnetic acoustic transducer (EMAT). The PPM structure is the structure of putting in order alternately the S pole and N pole laterally magnetized magnets. A Halbach magnet structure is the structure which sandwiched the longitudinally magnetized magnets between each magnet of PPM structure. Thereby, magnetic flux density is improved to 1.4 times. Moreover, it is also shown that the detection sensitivity increased to 4 times by using a new signal processing method. The magnetic flux density of a SH wave EMAT with a Halbach magnet structure is calculated from room temperature up to 240 degree C. The characteristics and durability at elevated temperature for Halbach type EMAT in 200 hours under the 200 degree C are reported. Twenty to thirty percents of sensitivity reduction can be observed but this is enough for MONJU ISI.

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