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

Sun, Hongyu; Huang, Songling; Wang, Qing; Wang, Shen; Zhao, Wei

doi:10.1016/j.sna.2019.03.003

Cited by 47 publications

(15 citation statements)

References 27 publications

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“…To obtain the characteristics of focusing T (0, 1) mode pipe-waves, the drive frequency of the burst signal is set to 1MHz in accordance with the dispersion curves and our previous study [30], and corresponding simulations have been done. The lift-off distance is set to 1 mm in both simulation and experiment, the remanence magnetism of the PPM is 1.21 T and the focal length is 30 mm.…”

Section: Resultsmentioning

confidence: 99%

“…The wall thickness of the pipe is much smaller than its radius, and the T (0, 1)wave has the same dispersion curves and wave structures as the SH0-wave mode [29]. The design method of the focusing transducer can be therefore related to our previous studies on plate focusing [30,31], while necessary changes must be made for a pipe. Fig.…”

Section: A Geometric Modelmentioning

confidence: 99%

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Characteristics of T(0, 1) Guided-Wave Point-Focusing Electromagnetic Acoustic Transducer for Pipe Inspection

et al. 2020

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Section: Resultsmentioning

confidence: 99%

Section: A Geometric Modelmentioning

confidence: 99%

Characteristics of T(0, 1) Guided-Wave Point-Focusing Electromagnetic Acoustic Transducer for Pipe Inspection

et al. 2020

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“…The excitation process of the SH guided wave includes the coupling of two physical fields: an electromagnetic field and a dynamic elastic field. The electromagnetic field mainly describes the distribution of eddy currents in an aluminum plate, and Maxwell's equations can be used to describe this physical process as [23].…”

Section: A Theoretical Methodsmentioning

confidence: 99%

Point-Focusing Shear-Horizontal Guided Wave EMAT Optimization Method Using Orthogonal Test Theory

et al. 2020

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As a class of devices used in sound detection, electromagnetic acoustic transducers (EMATs) have been widely used in the field of nondestructive testing (NDT) owing to their advantages such as contact-free operation, wide applicability, and high performance. However, their low energy-conversion efficiency is the main drawback that limits usage in industrial testing. In this work, we report the effect of different parameters of the point-focusing shear-horizontal EMAT (PFSH_EMAT) on the signal intensity of the receiving transducer. The impact factors of the focusing transducer are as follows: number of magnets in a row m, fan-shaped periodic permanent magnet (FPPM) remanence magnetization Br, coil width w, coil winding number n, aperture angle , focal length IF, life-off distance h1, excitation current frequency fc and current amplitude Ic. To improve the analysis efficiency, and L32(4 9) orthogonal table is used to investigate the nine different factors at four levels, which can be calculated through finite element simulations. The effect of each factor on the signal intensity is obtained by range analysis, and the influence degree of each factor is obtained, and the parameter combination is optimized by analyzing the test results to improve the PFSH-EMAT's performance. The experimental results show that the optimized PFSH-EMAT is 170% more efficient than the average of the top-three signal intensities in the orthogonal test, which proves the effectiveness of the proposed optimization method.

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“…Ribichini et al use a linear coil wrapped around an array of magnets [16]. Focusable SH wave EMATs have been developed using cooperation of two rotatable transducers [19], or a fan-shaped PPM array with an oblique angle [20]. All of these designs require a large number of magnets.…”

Section: A Emat Design Considerationsmentioning

confidence: 99%

Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

et al. 2021

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Electromagnetic acoustic transducers (EMATs) are well suited to generating and detecting a variety of different ultrasonic wavemodes, without the need for couplant, and they can be operated through some coatings. EMATs can be used to generate shear horizontal (SH) waves, which show promise for fast screening of wall thinning and other defects. However, commercial SH-wave EMATs are not suitable for robotic implementation on ferritic steel due to the large magnetic drag force from the magnets. This paper describes the design and characterisation of miniaturised SH guided wave EMATs, which significantly reduce the magnetic drag and enable mounting onto a small crawler robot for sample scanning. The performance of the miniaturised EMATs is characterised and compared to a commercial EMAT. It is shown that signal to noise ratio is reduced, but remains within an acceptable range to use on steel. The bandwidth and directivity are increased, depending on the exact design used. Their ability to detect flat bottomed holes mimicking wall thinning is also tested.

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

Abstract: (2019) 'Improvement of unidirectional focusing periodic permanent magnet shear-horizontal wave electromagnetic acoustic transducer by oblique bias magnetic eld.', Sensors and actuators A : physical., 290. pp. 36-47.

Cited by 47 publications

References 27 publications

Characteristics of T(0, 1) Guided-Wave Point-Focusing Electromagnetic Acoustic Transducer for Pipe Inspection

Characteristics of T(0, 1) Guided-Wave Point-Focusing Electromagnetic Acoustic Transducer for Pipe Inspection

Point-Focusing Shear-Horizontal Guided Wave EMAT Optimization Method Using Orthogonal Test Theory

Miniaturised SH EMATs for Fast Robotic Screening of Wall Thinning in Steel Plates

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