电磁超声特征信号检测系统的设计

发布时间：2018-09-19 19:18

【摘要】：针对电磁超声换能器(electromagnetic acoustic transducer,EMAT)转换效率低、信号微弱、信噪比低的问题,设计开发了包括电磁超声换能器在内的,由低噪前置放大器、宽带接收器以及基于虚拟仪器的正交锁相放大等构成的电磁超声检测系统。对比了传统EMAT结构与新的EMAT结构磁通密度的不同,通过提高偏置磁场的强度提高EMAT的换能效率;分析了前置放大器、宽带接收器、电磁超声换能器的频率响应特性;研究了相敏检波器中低通滤波器的阶数、滤波器类型以及截止频率对电磁超声回波信号检测的影响,并对铝板进行了缺陷检测实验。实验结果表明:该系统能够实现电磁超声信号的实时采集、分析和存储,同时能够提高信号的信噪比和分辨率。
[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.
【作者单位】：河北工业大学电磁场与电器可靠性省部共建重点实验室;天津工业大学电工电能新技术天津市重点实验室;
【基金】：国家自然科学基金(51307043) 河北省自然科学基金(E2016202260) 天津市自然科学基金(16JCYBJC19000)
【分类号】：TG115.28

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