Enhancement of ultrasonic signal using a new design of Rayleigh-wave electromagnetic acoustic transducer

Kang, Lei; Zhang, Chao; Dixon, Steve; Zhao, Hui; Hill, Samuel; Liu, Menghan

doi:10.1016/j.ndteint.2016.11.008

Cited by 48 publications

(24 citation statements)

References 21 publications

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“…The magnetic flux density near the edges on both sides of the magnet is larger and the middle is lower relatively. This nonuniformity is higher than the results when the sample is aluminum [5]. The magnetic flux density distribution near upper surface in the specimen is plotted as a curve, as shown in Fig.…”

Section: Discussionmentioning

confidence: 63%

“…Obviously, the simulation result is inconsistent with these arguments. The eddy current density is approximately proportional to the derivative of the excitation current in the coil, merely with a phase difference, which can be also deduced from equations (4)(5). This has been explained in more detail by other workers [17].…”

Section: Eddy Current and Dynamic Magnetic Field In Specimenmentioning

confidence: 62%

“…where is the electrical conductivity of the specimen. Equations (1)(2)(3)(4)(5) show how the Lorentz force is related to , and . The magnitude of is proportional to the magnitudes of and , and the magnitude of is proportional to the magnitudes of and .…”

Section: Theorymentioning

confidence: 99%

See 2 more Smart Citations

Enhancement of EMAT’s efficiency by using silicon steel laminations back-plate

Ren

Dixon

et al. 2018

Sensors and Actuators A: Physical

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Section: Discussionmentioning

confidence: 63%

Section: Eddy Current and Dynamic Magnetic Field In Specimenmentioning

confidence: 62%

See 1 more Smart Citation

Enhancement of EMAT’s efficiency by using silicon steel laminations back-plate

Ren

Dixon

et al. 2018

Sensors and Actuators A: Physical

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“…The ultrasonic guided wave testing technique is more sensitive, economical, and convenient than conventional non-destructive testing (NDT) techniques [1][2][3][4][5]. The testing methods of ultrasonic guided waves can be divided into piezoelectric ceramics, magnetostriction, piezoelectric thin films, and electromagnetic ultrasonic testing according to different excitation modes [6][7][8].…”

Section: Accepted Manuscript I Introductionmentioning

confidence: 99%

Improvement of unidirectional focusing periodic permanent magnet shear-horizontal wave electromagnetic acoustic transducer by oblique bias magnetic field

Sun

Huang

Wang

et al. 2019

Sensors and Actuators A: Physical

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“…EMATs have poor electro-mechanical efficiency as either generators or detectors and can have complicated coupling mechanisms for ferromagnetic materials, where both magnetoelastic and Lorentz mechanisms contribute to transduction. Research has been undertaken in an attempt to improve the efficiency of the EMAT and better understand the physics behind the coupling mechanisms involved [7,8,[19][20][21][22][23]. In operating on non-ferromagnetic materials, the EMAT has only Lorentz force mechanisms to consider.…”

mentioning

confidence: 99%

A study of magnetostriction mechanism of EMAT on low-carbon steel at high temperature

Ren

Dixon

et al. 2019

NDT & E International

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The Electromagnetic acoustic transducer (EMAT) is used in a number of non-destructive testing applications [1][2][3][4][5]. The EMAT's operation is principally based on one of two mechanisms; the Lorenz force and magnetostriction mechanism [6-9]. The magnetostriction mechanism of an EMAT at elevated temperatures is reported in this paper. An optimized model is developed to describe the magnetostriction of polycrystalline iron, which is based on Brown's magnetic domain wall movement model [10] and Lee's magnetic domain rotation model [11]. The magnetostriction curves of polycrystalline iron for the temperature range 300 K to 900 K are predicted, which reveal that the saturated magnetostriction coefficient changes from to approximately . A non-linear, isotropic magnetostriction, finite element model is developed to simulate the Lamb waves generated in 4 mm thick steel plate by an EMAT, and the results show that the amplitude of S0 Lamb wave is greatly enhanced with an increase of temperature. In the experiments, a magnetostriction-based EMAT is used to generate Lamb waves in 4 mm thick steel plate. Experimental measurements verify that the contribution of the magnetostriction mechanism on steel rises as temperature increases in the range 298 K to 873 K, while the contribution to ultrasonic generation from the Lorenz force mechanism decreases, as expected. Key wordsElectromagnetic acoustic transducer, magnetostriction mechanism, high temperature, finite element model, low-carbon steel 1. IntroductionElectromagnetic acoustic transducers (EMATs) are used in non-destructive testing (NDT) as they offer several benefits including their non-contacting nature and their ability to generate and detect a range of wave modes [7,12,13] that are difficult to achieve using conventional transducers. The non-contact nature of EMATs makes them suitable for NDT applications where the object under test is at an elevated temperature or is moving [14][15][16][17][18]. EMATs have poor electro-mechanical efficiency as either generators or detectors and can have complicated coupling mechanisms for ferromagnetic materials, where both magnetoelastic and Lorentz mechanisms contribute to transduction. Research has been undertaken in an attempt to improve the efficiency of the EMAT and better understand the physics behind the coupling mechanisms involved [7,8,[19][20][21][22][23]. In operating on non-ferromagnetic materials, the EMAT has only Lorentz force mechanisms to consider. In ferromagnetic materials, magnetostriction and magnetisation mechanisms must also be considered [7,8]. Research on the quantization of the Lorentz force mechanism and magnetostriction mechanism has shown that, for the conventional EMAT that can operate via both mechanisms, the Lorentz force is usually the main contributor [24,25] to the

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Enhancement of ultrasonic signal using a new design of Rayleigh-wave electromagnetic acoustic transducer

Cited by 48 publications

References 21 publications

Enhancement of EMAT’s efficiency by using silicon steel laminations back-plate

Enhancement of EMAT’s efficiency by using silicon steel laminations back-plate

Improvement of unidirectional focusing periodic permanent magnet shear-horizontal wave electromagnetic acoustic transducer by oblique bias magnetic field

A study of magnetostriction mechanism of EMAT on low-carbon steel at high temperature

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