【摘要】：針對電磁超聲換能器(electromagnetic acoustic transducer,EMAT)轉(zhuǎn)換效率低、信號微弱、信噪比低的問題,設(shè)計(jì)開發(fā)了包括電磁超聲換能器在內(nèi)的,由低噪前置放大器、寬帶接收器以及基于虛擬儀器的正交鎖相放大等構(gòu)成的電磁超聲檢測系統(tǒng)。對比了傳統(tǒng)EMAT結(jié)構(gòu)與新的EMAT結(jié)構(gòu)磁通密度的不同,通過提高偏置磁場的強(qiáng)度提高EMAT的換能效率;分析了前置放大器、寬帶接收器、電磁超聲換能器的頻率響應(yīng)特性;研究了相敏檢波器中低通濾波器的階數(shù)、濾波器類型以及截止頻率對電磁超聲回波信號檢測的影響,并對鋁板進(jìn)行了缺陷檢測實(shí)驗(yàn)。實(shí)驗(yàn)結(jié)果表明:該系統(tǒng)能夠?qū)崿F(xiàn)電磁超聲信號的實(shí)時(shí)采集、分析和存儲(chǔ),同時(shí)能夠提高信號的信噪比和分辨率。
[Abstract]:Aiming at the problems of low conversion efficiency, weak signal and low signal-to-noise ratio (SNR) of electromagnetic ultrasonic transducer (electromagnetic acoustic transducer,EMAT), a low-noise preamplifier, including electromagnetic ultrasonic transducer, is designed and developed. The electromagnetic ultrasonic detection system is composed of wideband receiver and quadrature phase locked amplifier based on virtual instrument. The difference of flux density between the traditional EMAT structure and the new EMAT structure is compared, the conversion efficiency of the EMAT is improved by increasing the intensity of the bias magnetic field, the frequency response characteristics of the preamplifier, the broadband receiver and the electromagnetic ultrasonic transducer are analyzed. The influence of the order of low-pass filter, filter type and cut-off frequency on the detection of electromagnetic ultrasonic echo signal in phase sensitive detector is studied, and the defect detection experiment of aluminum plate is carried out. The experimental results show that the system can realize the real-time acquisition, analysis and storage of electromagnetic ultrasonic signals, and improve the signal-to-noise ratio and resolution of the signals.
【作者單位】： 河北工業(yè)大學(xué)電磁場與電器可靠性省部共建重點(diǎn)實(shí)驗(yàn)室;天津工業(yè)大學(xué)電工電能新技術(shù)天津市重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金(51307043) 河北省自然科學(xué)基金(E2016202260) 天津市自然科學(xué)基金(16JCYBJC19000)
【分類號】：TG115.28

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