基于空间域谐波控制的电磁超声Lamb波模态抑制方法

doi:10.19595/j.cnki.1000-6753.tces.200467

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摘要电磁超声换能器（EMAT）激励的Lamb波中经常存在多种模式,给波形分析造成困难,甚至会干扰对缺陷信息的判断,从而导致误判。常规的EMAT线圈空间波数谱中含有谐波,谐波是造成多模式现象的重要原因。该文提出试件涡流密度分布（洛伦兹力分布）相当于对线圈电流密度分布的空间低通滤波,通过对线圈空间域进行有效设计从而抑制空间域谐波,进而实现激发单波数正弦形式的涡流密度分布。结合正弦脉冲宽度调制（SPWM）技术的特点,提出将时域中的SPWM技术应用于空间域以实现线圈参数设计。通过建立有限元仿真模型,仿真证明了正弦形式的涡流密度空间分布可以被激励。该文以激励S0模态Lamb波为例进行实验,实验结果表明,由波数谱中的3次谐波激励的A0模态被极大地抑制,抑制比为21dB。

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	翟国富
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关键词 ：电磁超声换能器, Lamb波, 模态抑制, 空间域谐波控制, 正弦脉冲宽度调制

Abstract：Lamb waves excited by electromagnetic acoustic transducers (EMAT) often have multiple modes, which make waveform analysis difficult and even interfere with the judgment of defect information, leading to misjudgment. Harmonics of conventional EMAT coils in the space wavenumber spectrum are the important cause of the multi-mode phenomena. This paper proposes that the eddy current density distribution (or the Lorentz force distribution) in the specimen is equivalent to the spatial low-pass filtering of the coil current density distribution. By effectively designing the coil, the harmonics in the space domain can be suppressed, and the sinusoidal (that is, single wavenumber) eddy current density distribution can be excited. Combining the characteristics of sinusoidal pulse width modulation (SPWM) technology, it was proposed to apply the time domain SPWM technology to the space domain to design the coil parameters. A finite element simulation model was established, and the simulation proved that the sinusoidal eddy current density distribution can be excited. The experiment was conducted by taking the S0 mode Lamb wave as an example. It is shown that the A0 mode excited by the third harmonic in the wavenumber spectrum is greatly suppressed, and the suppression ratio is 21dB.

Key words： Electromagnetic acoustic transducers (EMAT) Lamb mode suppression spatial harmonic control sinusoidal pulse width modulation (SPWM)

收稿日期: 2020-05-07

PACS:

TM15

基金资助:国家自然科学基金（51977044）和民用航天技术预先研究（JZKGJ20190004）资助项目

通讯作者: 李永虔男,1991年生,博士研究生,研究方向为电磁超声无损检测技术。E-mail: 15B906029@hit.edu.cn

作者简介: 翟国富男,1964年生,教授,博士生导师,研究方向为高可靠电器设计理论与技术、产品质量一致性稳健设计理论与技术、电子系统及装备可靠性和可测性设计及健康管理、电磁超声无损检测技术。E-mail: gfzhai@hit.edu.cn

引用本文:

翟国富, 李永虔, 刘玥怡, 秦伊人. 基于空间域谐波控制的电磁超声Lamb波模态抑制方法[J]. 电工技术学报, 2021, 36(16): 3467-3473. Zhai Guofu, Li Yongqian, Liu Yueyi, Qin Yiren. Mode Suppression Method of Lamb Wave Excited by Electromagnetic Acoustic Transducers Based on Spatial Harmonic Control. Transactions of China Electrotechnical Society, 2021, 36(16): 3467-3473.

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https://dgjsxb.ces-transaction.com/CN/10.19595/j.cnki.1000-6753.tces.200467 https://dgjsxb.ces-transaction.com/CN/Y2021/V36/I16/3467