Electromagnetic acoustic transducers for in- and out-of plane ultrasonic wave detection

Jian, X.; Dixon, S.; Quirk, Kevin J.; Grattan, K. T. V.

doi:10.1016/j.sna.2008.07.004

Cited by 38 publications

(18 citation statements)

References 16 publications

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“…The generation mechanism of an EMAT may be via the Lorentz force, magnetization-force, and/or magnetostriction, depending on the sample properties [17][18][19]. The samples used in these experiments are aluminium, with the top 3 mm of aluminium removed [20].…”

Section: Methodsmentioning

confidence: 99%

“…For detection, the directional sensitivity is determined by the magnetic field and coil design arrangement [19]. In all experiments the transmitter and receiver EMATs are held 150 mm apart in a "pitch-catch" arrangement, as illustrated in Figure 2.…”

Section: Scanned Emat Systemmentioning

confidence: 99%

“…EMATs are velocity sensors [19]. The particle velocities for a Rayleigh wave in the in-plane, V x , and out-of-plane, V z , components can be calculated from the displacements (U x and U z ) given in Viktorov [5] as follows;…”

Section: Velocity Components Of the Rayleigh Wavementioning

confidence: 99%

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In-plane and out-of-plane measurements of Rayleigh waves using EMATs for characterising surface cracks

Rosli

Edwards

Yang

2012

NDT & E International

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Electromagnetic acoustic transducers (EMATs) have been used to measure the properties of Rayleigh waves in the vicinity of defects propagating at different angles to the sample surface, which are more representative of real defects than slots machined normal to the surface. Transmission measurements show that one must consider the angle of the defect when choosing a depth calibration curve. We propose a procedure for crack characterisation (depth, angle) that considers transmission alongside measurements of both the in-plane and out-of-plane velocity components of the Rayleigh wave in the near-field of a defect, where the signal is enhanced due to constructive interference of incident and reflected wavemodes, and/or mode conversion.This procedure uses image analysis of B-Scans alongside the ratio of the enhancement in the in-plane to the out-of-plane components to characterise the angle. Once this is known the correct transmission depth calibration curve can be used. The procedure shows very good agreement between the measured and the actual slot characteristics on test samples.

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Section: Methodsmentioning

confidence: 99%

Section: Scanned Emat Systemmentioning

confidence: 99%

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In-plane and out-of-plane measurements of Rayleigh waves using EMATs for characterising surface cracks

Rosli

Edwards

Yang

2012

NDT & E International

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“…The receiving coil used is the same as the transmitting coil; the induced voltage in the receiving coil can be calculated from the receiving velocity fields [41]. In this work, receiving signals calculated are in millivolts.…”

Section: Combination Of Electromagnetic Simulation Andmentioning

confidence: 99%

Simulation of an Electromagnetic Acoustic Transducer Array by Using Analytical Method and FDTD

et al. 2016

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Previously, we developed a method based on FEM and FDTD for the study of an Electromagnetic Acoustic Transducer Array (EMAT). This paper presents a new analytical solution to the eddy current problem for the meander coil used in an EMAT, which is adapted from the classic Deeds and Dodd solution originally intended for circular coils. The analytical solution resulting from this novel adaptation exploits the large radius extrapolation and shows several advantages over the finite element method (FEM), especially in the higher frequency regime. The calculated Lorentz force density from the analytical EM solver is then coupled to the ultrasonic simulations, which exploit the finite-difference time-domain (FDTD) method to describe the propagation of ultrasound waves, in particular for Rayleigh waves. Radiation pattern obtained with Hilbert transform on time-domain waveforms is proposed to characterise the sensor in terms of its beam directivity and field distribution along the steering angle, which can produce performance parameters for an EMAT array, facilitating the optimum design of such sensors.

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“…EMATs are particle velocity sensors, which can be designed to have sensitivity to in-plane and out-of-plane ultrasonic displacements, by suitably arranging the magnetic field in the receiving EMATs [13,20,21]. A specially designed EMAT is used to receive the surface waves excited by the meander-line-coil EMAT under study.…”

Section: Methodsmentioning

confidence: 99%

3-D modeling and analysis of meander-line-coil surface wave EMATs

Wang

Kang

et al. 2012

Mechatronics

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Electromagnetic acoustic transducers for in- and out-of plane ultrasonic wave detection

Cited by 38 publications

References 16 publications

In-plane and out-of-plane measurements of Rayleigh waves using EMATs for characterising surface cracks

In-plane and out-of-plane measurements of Rayleigh waves using EMATs for characterising surface cracks

Simulation of an Electromagnetic Acoustic Transducer Array by Using Analytical Method and FDTD

3-D modeling and analysis of meander-line-coil surface wave EMATs

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