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Journal ArticleDOI

Numerical Decoupling Study of EMAT Testing Signal for Ferromagnetic Materials

01 Apr 2020-IEEE Sensors Journal (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 20, Iss: 7, pp 3476-3486
TL;DR: In this article, a single detection of an electromagnetic acoustic transducer (EMAT), where ultrasonic waves were generated based on the coupling of the magnetostriction effect and the Lorentz force mechanism, when the EMAT was used to detect ferromagnetic materials was proposed.
Abstract: To improve the efficiency and robustness of electromagnetic ultrasonic testing, magneto-acoustic compound inspection for ferromagnetic materials is proposed. Both ultrasonic waves and pulsed eddy current (PEC) could be obtained by the single detection of an electromagnetic acoustic transducer (EMAT), where ultrasonic waves were generated based on the coupling of the magnetostriction effect and the Lorentz force mechanism, when the EMAT was used to detect ferromagnetic materials. In this study, three simulation models of the EMAT were built by coupling different physics fields while keeping the geometry of the models unchanged and the other parameters of the EMAT constant. Transverse wave could be generated by magnetostriction force, and longitudinal wave could be generated by Lorentz force. Based on time-frequency analysis of the simulation results, the energies of ultrasonic waves and PEC were concentrated in different frequency ranges. Through the filtering strategy and by separating the time-domain signal, magnetostriction force ultrasonic wave (MFUW), Lorentz force ultrasonic wave (LFUW), and PEC could be decoupled from the EMAT testing signal. Multiple parameters can be extracted by a single detection of the EMAT, and the ability of the electromagnetic ultrasonic testing can be improved.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a differential coil EMAT was used to measure both the in-plane and out-of-plane components of the displacement or velocity of a surface-breaking defect.
Abstract: Surface acoustic waves, such as Rayleigh or Lamb waves, can be used to characterise the geometry of surface-breaking defects. For accurate measurement of defect length and depth, the in-plane (IP) and out-of-plane (OP) components of the displacement or velocity can be measured and compared. Electromagnetic acoustic transducers (EMATs) offer a simple, non-contact method of doing this, as it is possible to design detection EMATs such that they are sensitive predominantly to either the IP or the OP velocity component. Here we present a new design of differential coil EMAT which measures both components simultaneously, and through simple processing gives the IP and OP velocities. This is compared to previous designs, showing that these components are obtained accurately. The system is used to characterise three artificial surface-breaking defects in aluminium and one thermal fatigue crack in 10 mm thick steel plate under thin coating.

12 citations

Journal ArticleDOI
TL;DR: In this paper, an advanced magneto-acoustic compound inspection method, in which pulsed eddy current and ultrasonic waves were obtained from a single electromagnetic acoustic transducer (EMAT) testing signal, was adopted.
Abstract: The performance degradation of 12CrMoV steel generally occurs under a long-term working period in a high-temperature environment. In order to improve the reliability of a single nondestructive testing method for the performance degradation analysis of 12CrMoV steel, an advanced magneto–acoustic compound inspection method, in which pulsed eddy current (PEC) and ultrasonic waves were obtained from a single electromagnetic acoustic transducer (EMAT) testing signal, was adopted. The magneto–acoustic compound inspection method was carried out on 12CrMoV steel plates heat-treated at different temperatures and times. New parameters, including the slope and peak value of PEC, and the amplitude and attenuation of ultrasonic waves, were introduced to evaluate the performance degradation of 12CrMoV steel. It was found that ultrasonic waves manifested higher sensitivity than eddy current when the microstructure changed significantly. Therefore, the magneto–acoustic compound inspection method is advantageous for evaluating the performance degradation of 12CrMoV steel.

7 citations

Journal ArticleDOI
TL;DR: In this article , an advanced magnetoacoustic compound inspection method for a high-order Lamb waves mode electromagnetic acoustic transducer (EMAT) was proposed, which can achieve the excitation and reception of the A 1 mode EMAT.
Abstract: In this study, an advanced magnetoacoustic compound inspection method for a high-order Lamb waves mode electromagnetic acoustic transducer (EMAT) was proposed. The proposed EMAT can achieve the excitation and reception of the A 1 mode which is the first-order Lamb waves mode. According to the characteristics of the A 1 mode EMAT testing signal, a signal processing method for obtaining the pulsed eddy current signal by curve fitting was developed to extract the information for the pulsed eddy current. The voltage of the ultrasonic waves was carried on the pulsed eddy current voltage, and it was obtained by removing the pulsed eddy current voltage and extracting the time-domain testing signal of the A 1 mode EMAT. Through A 1 mode EMAT single detection that was used to obtain the pulsed eddy current and A 1 mode, the multi-parameter from the magnetoacoustic compound testing signal of the A 1 mode EMAT could be used to characterize the aluminum plate performance degradation. The detection accuracy of aluminum plate performance degradation was improved by the magnetoacoustic compound inspection compared with a single detection method.

4 citations

Journal ArticleDOI
01 Nov 2022-Sensors
TL;DR: In this article , the authors investigated the impacts of the backplate position on the pulse width and amplitude of thickness-measurement signals, using EMATs and showed that the output impedance of the receiving coil is strongly influenced by the coil-backplate gap.
Abstract: Nondestructive testing (NDT) is an essential method for assessing structural integrity in the oil and gas industry. Electromagnetic acoustic transducers (EMATs) have been extensively used to detect the wall-thickness reduction of plate-like structures, because they do not require direct contact. The pulse intervals of echoes are used to calculate the remnant thickness of structures. If the width of a single pulse is too large, multiple pulses will be superimposed, making it more difficult to extract the pulse interval. Thus, the width of a single pulse affects the resolution of measurements. This paper investigates the impacts of the backplate position on the pulse width and amplitude of thickness-measurement signals, using EMATs. By means of impedance modeling and measurement, it can be shown that the output impedance of the receiving coil is strongly influenced by the coil-backplate gap. With the increment in the coil-backplate gap, the signal amplitude and damping coefficient increase, while the self-resonant frequency decreases. By means of signal measurements on the specimen, it is shown that the pulse width and the signal amplitude can be significantly influenced by the backplate position. By reducing the coil–backplate gap, the pulse width can be reduced by over 80%, and by increasing the gap, the signal amplitude can be increased by over 300%. These research results can be used to optimize EMAT design, thereby suppressing the superposition of pulse echoes.

1 citations

Journal ArticleDOI
TL;DR: In this paper , a magnetoelectric-ultrasonic hybrid transducer and multimodal system for quantitative non-destructive evaluation (NDE) of solid metal materials is presented.

1 citations

References
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BookDOI
01 Jan 2017

75 citations

Journal ArticleDOI
TL;DR: This type of generation source provides a robust, non-contact and inexpensive means of ultrasonic generation without worrying the permanent magnet attracting ferromagnetic particles that can prevent from practical on-line application of EMATs.

59 citations


"Numerical Decoupling Study of EMAT ..." refers methods in this paper

  • ...As the coupling between the EMAT and the sample is electromagnetic [1], [6], [7], EMATs can generate or detect ultrasonic waves in electrically conductive materials through the Lorentz force mechanism for non-magnetic metal materials [3]....

    [...]

Journal ArticleDOI
Zenghua Liu1, Fan Junwei1, Yanan Hu1, Cunfu He1, Bin Wu1 
TL;DR: In this article, a modified planar solenoid array (MPSA) coil-MPTs array was proposed to generate and receive the torsional mode in pipes.
Abstract: In recent investigations, the application of the transducers used in plates has been extended to pipe inspection with circumferential arrays because of the similar particle displacement patterns of some modes between plate and pipe, such as SH and torsional modes. Motivated by the configuration of magnetostrictive patch transducer (MPT), in which a planar solenoid array (PSA) coil was adopted to generate SH waves in plates, we proposed a MPTs array employing a modified planar solenoid array (MPSA) coil, i.e. MPSA coil-MPTs array, for generating and receiving the torsional mode in pipes. The configuration of the MPSA coil modified from PSA coil is suitable to be arranged on the pipe surface and can generate high-power waves. In the suggested configuration of MPT, because the direction of the actuating dynamic magnetic field produced by the MPSA coil is orthogonal to the direction of the static magnetic field produced by the permanent magnets in the magnetostrictive patch, the shear deformation induced by the magnetostriction in the patch will be delivered to the pipe, thus generating the torsional mode. First, it was experimentally verified that the fundamental torsional mode, T(0,1), could be effectively generated and received in pipes with the developed MPSA coil-MPTs array. Then, we studied the relationship between the frequency response characteristic of the developed MPSA coil-MPTs array and the interval defined by the distance of adjacent solenoids in the MPSA coil. Simultaneously, the circumferential crack defects in pipe were successfully identified. Finally, the performance of the MPSA coil-MPTs array was compared with that of previous meander coil-MPTs array. The comparison results demonstrated that the developed MPSA coil-MPTs array could enhance the power of the torsional mode.

54 citations


"Numerical Decoupling Study of EMAT ..." refers background in this paper

  • ...2959601 a range of ultrasonic waves, such as transverse wave, longitudinal wave, and Lamb waves [9]–[12]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the frequency dependence of the propagation direction of ultrasonic shear and longitudinal waves generated by a meander-line electromagnetic transducer at MHz frequencies has been determined.
Abstract: The frequency dependence of the propagation direction of ultrasonic shear and longitudinal waves generated by a meander‐line electromagnetic transducer (EMAT) at MHz frequencies has been determined. The results are found to agree well with theory and demonstrate that electronic beam steering is possible using EMAT’s. The relative efficiency of generation in aluminum was also studied and, for a specific meander‐line geometry with a permanent magnet providing the necessary static magnetic field, it was found to be relatively flat versus frequency. Efficiency for shear‐wave generation (frequency range, 5–9 MHz) was about 4 dB per conversion less than the Rayleigh‐wave generation efficiency at 4.6 MHz, and for longitudinal waves (frequency range, 10–24 MHz) about 10 dB less.

42 citations


"Numerical Decoupling Study of EMAT ..." refers methods in this paper

  • ...ELECTROMAGNETIC Acoustic Transducers (EMATs) offer a non-contact, non-destructive evaluation (NDE) method [1], [2]....

    [...]

Journal ArticleDOI
TL;DR: A non-destructive method for measurements of DoS in aluminum alloys with an electromagnetic acoustic transducer (EMAT) is described and it is found that the longitudinal wave velocity was almost a constant, independent of the sensitization, which suggests that theitudinal wave can be used to determine the sample thickness.

38 citations