A New Electromagnetic Acoustic Transducer Design for Generating and Receiving S0 Lamb Waves in Ferromagnetic Steel Plate

He, Jianpeng; Dixon, Steve; Hill, Samuel; Xu, Ke

doi:10.3390/s17051023

Cited by 22 publications

(21 citation statements)

References 31 publications

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“…A configuration of a coil with a bias magnetic field is usually applied in conventional EMATs, whose mechanisms mainly include Lorentz force and magnetostriction (for magnetic materials). Previous work shows that magnetostriction becomes the main contributor and the Lorentz force could be ignored when the lift-off of a coil-only transducer is more than 7 mm [26]. The coil-only transducer is employed as the excitation transducer in these experiments with a 10 mm lift-off.…”

Section: Methodsmentioning

confidence: 99%

“…10. Lamb waves are usually generated in the plate sample, and the simulated S0 Lamb wave is the first wave to reach the detection point, followed by the A0 Lamb wave [26], as shown in the Fig. 10.…”

Section: Simulationsmentioning

confidence: 99%

“…The function of an EMAT receiver is to convert the vibration of the sample's surface into a voltage signal. For a traditional EMAT receiver, Faraday's law of electromagnetic induction is considered to be the main contributor to this transduction process [39], although it also includes the magnetoelastic effect [26]. The magnitude of the voltage signal is proportional to the eddy current density below the probe, which is defined by the following formula [39]:…”

Section: S0 Lamb Wavesmentioning

confidence: 99%

“…generation or detection of ultrasonic waves. Certain EMAT designs can also make magnetostriction the major contributor [26] to ultrasonic generation by increasing the lift-off of a coil-only generator.…”

mentioning

confidence: 99%

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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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Section: Methodsmentioning

confidence: 99%

Section: Simulationsmentioning

confidence: 99%

Section: S0 Lamb Wavesmentioning

confidence: 99%

mentioning

confidence: 99%

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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 results showed that the phase velocity and amplitude changes of Lamb waves obtained by simulation were in good agreement with experiment. He et al [31] designed two electromagnetic acoustic transducers to generate and receive S 0 Lamb waves in ferromagnetic steel plates, which were kept within 5 and 19 mm from the sample surface, respectively. This allowed the electromagnetic acoustic transducer to interact with the sample with less force and facilitated easier scanning.…”

Section: Transducers For Lamb Wavesmentioning

confidence: 99%

The Rapid Detection Technology of Lamb Wave for Microcracks in Thin-Walled Tubes

Wang

Yang

2019

Applied Sciences

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Thin-walled tubes are a kind of pressure vessel formed by a stamping and drawing process, which must withstand a great deal of sudden pressure during use. When microcrack defects of a certain depth are present on its inner and outer surfaces, severe safety accidents may occur, such as cracking and crushing. Therefore, it is necessary to carry out nondestructive testing of thin-walled tubes in the production process to eliminate the potential safety hazards. To realize the rapid detection of microcracks in thin-walled tubes, this study could be summarized as follows: (i) Because the diameters of the thin-walled tubes were much larger than their thicknesses, Lamb wave characteristics of plates with equal thicknesses were used to approximate the dispersion characteristics of thin-walled tubes. (ii) To study the dispersion characteristics of Lamb waves in thin plates, the detection method of the A 0 mode was determined using the particle displacement-amplitude curve. (iii) Using a multi-channel parallel detection method, rapid detection equipment for Lamb wave microcracks in thin-walled tubes was developed. (iv) The filtering peak values for defect signal detection with different depths showed that the defect detection peak values could reflect the defect depth information. (v) According to the minimum defect standard of a 0.045-mm depth, 100,000 thin-walled tubes were tested. The results showed that the missed detection rate was 0%, the reject rate was 0.3%, and the detection speed was 5.8 s/piece, which fully meets the actual detection requirements of production lines. Therefore, this study not only solved the practical issues for the rapid detection of microcracks in thin-walled tubes but also provided a reference for the application of ultrasonic technology for the detection of other components. Appl. Sci. 2019, 9, 3576 2 of 15 quantitatively, which can easily lead to misjudgment [10]. Magnetic particle testing is more suitable for surface defect detection, and it is difficult to quantitatively detect the depth of a flaw [10]. The X-ray method is mainly used to detect the volume of the defect inside the object. For an area defect, there will be an overlap of the front and back, and the angle between the ray beam and the orientation of the crack cannot exceed 10 • ; otherwise, it cannot be detected [10]. Penetration detection is limited to the defects of the surface opening. The penetrating liquid pollutes the parts and the environment and is not suitable for on-line detection [10]. Ultrasonic testing is sensitive to the area of the defect inside the object and can locate the relative size and location of the defect. The detection depth is much greater than other detection methods, and thus, it has been widely used [10]. For thin-walled tubes, ultrasonic Lamb waves are usually used for testing [11].The ultrasonic detection principle of thin-walled tubes is the same as that of pipe, and there are many studies on the principle, method, and application of Lamb wave detection of pipe for reference. Therefore, based...

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Ultrasonic Analysis of Lorentz Force for Gas Density Monitoring Using EMAT Sensor

Das,

Mohanty,

Panigrahi

et al. 2024

Lecture Notes in Electrical Engineering

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A New Electromagnetic Acoustic Transducer Design for Generating and Receiving S0 Lamb Waves in Ferromagnetic Steel Plate

Cited by 22 publications

References 31 publications

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

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

The Rapid Detection Technology of Lamb Wave for Microcracks in Thin-Walled Tubes

Ultrasonic Analysis of Lorentz Force for Gas Density Monitoring Using EMAT Sensor

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