中国物理B ›› 2011, Vol. 20 ›› Issue (6): 68104-068104.doi: 10.1088/1674-1056/20/6/068104

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    下一篇

Circuit-field coupled finite element analysis method for an electromagnetic acoustic transducer under pulsed voltage excitation

郝宽胜, 黄松岭, 赵伟, 王珅   

  1. State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
  • 收稿日期:2010-09-05 修回日期:2011-01-09 出版日期:2011-06-15 发布日期:2011-06-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 10974115).

Circuit-field coupled finite element analysis method for an electromagnetic acoustic transducer under pulsed voltage excitation

Hao Kuan-Sheng(郝宽胜), Huang Song-Ling(黄松岭)†, Zhao Wei(赵伟), and Wang Shen(王珅)   

  1. State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
  • Received:2010-09-05 Revised:2011-01-09 Online:2011-06-15 Published:2011-06-15
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 10974115).

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摘要： This paper presents an analytical method for electromagnetic acoustic transducers (EMATs) under voltage excitation and considers the non-uniform distribution of the biased magnetic field. A complete model of EMATs including the non-uniform biased magnetic field, a pulsed eddy current field and the acoustic field is built up. The pulsed voltage excitation is transformed to the frequency domain by fast Fourier transformation (FFT). In terms of the time harmonic field equations of the EMAT system, the impedances of the coils under different frequencies are calculated according to the circuit-field coupling method and Poynting's theorem. Then the currents under different frequencies are calculated according to Ohm's law and the pulsed current excitation is obtained by inverse fast Fourier transformation (IFFT). Lastly, the sequentially coupled finite element method (FEM) is used to calculate the Lorentz force in the EMATs under the current excitation. An actual EMAT with a two-layer two-bundle printed circuit board (PCB) coil, a rectangular permanent magnet and an aluminium specimen is analysed. The coil impedances and the pulsed current are calculated and compared with the experimental results. Their agreement verified the validity of the proposed method. Furthermore, the influences of lift-off distances and the non-uniform static magnetic field on the Lorentz force under pulsed voltage excitation are studied.

Abstract: This paper presents an analytical method for electromagnetic acoustic transducers (EMATs) under voltage excitation and considers the non-uniform distribution of the biased magnetic field. A complete model of EMATs including the non-uniform biased magnetic field, a pulsed eddy current field and the acoustic field is built up. The pulsed voltage excitation is transformed to the frequency domain by fast Fourier transformation (FFT). In terms of the time harmonic field equations of the EMAT system, the impedances of the coils under different frequencies are calculated according to the circuit-field coupling method and Poynting's theorem. Then the currents under different frequencies are calculated according to Ohm's law and the pulsed current excitation is obtained by inverse fast Fourier transformation (IFFT). Lastly, the sequentially coupled finite element method (FEM) is used to calculate the Lorentz force in the EMATs under the current excitation. An actual EMAT with a two-layer two-bundle printed circuit board (PCB) coil, a rectangular permanent magnet and an aluminium specimen is analysed. The coil impedances and the pulsed current are calculated and compared with the experimental results. Their agreement verified the validity of the proposed method. Furthermore, the influences of lift-off distances and the non-uniform static magnetic field on the Lorentz force under pulsed voltage excitation are studied.

Key words: electromagnetic acoustic transducer, nondestructive testing, circuit-field coupling, finite element method

中图分类号:  (Nondestructive testing: ultrasonic testing, photoacoustic testing)

  • 81.70.Cv
81.70.Ex (Nondestructive testing: electromagnetic testing, eddy-current testing) 41.20.-q (Applied classical electromagnetism)