仅线圈式电磁超声检测方法与提离特性研究  

Study on Coil-Only Electromagnetic Ultrasonic Testing Method and Its Lift-Off Characteristics

作　　者：石文泽[1] 胡力萍 卢超[1] 胡博[1] 沈功田[2] 张路根 张琦 SHI Wenze;HU Liping;LU Chao;HU Bo;SHEN Gongtian;ZHANG Lugen;ZHANG Qi(MOE Key Laboratory of Nondestructive Testing,Nanchang Hangkong University,Nanchang Jiangxi 330063,China;China Special Equipment Inspection&Research Institute,Beijing 100029,China;Special Equipment Inspection&Testing Research Institute,Jiangxi General Institute of Testing and Certification,Nanchang Jiangxi 330036,China)

机构地区：[1]南昌航空大学无损检测教育部重点实验室,江西南昌330063 [2]中国特种设备检测研究院,北京100029 [3]江西省检验检测认证总院特种设备检验检测研究院,江西南昌330036

出　　处：《传感技术学报》2024年第10期1681-1691,共11页Chinese Journal of Sensors and Actuators

基　　金：国家自然科学基金项目(52065049,12064001);江西省杰出青年基金项目(20212ACB214010);江西省主要学科学术和技术带头人培养计划项目(20204BCJL22039,20225BCJ23023);江西省重点研发计划项目(20212BBE51006,20223BBE51034);国家市场监督管理总局科技计划项目(2021MK056);江西省检验检测认证总院计划项目(ZYK202202);南昌航空大学研究生创新专项资金项目(YC2021-081)。

摘　　要：针对传统永磁体式或脉冲电磁铁式电磁超声换能器(Electromagnetic Acoustic Transducer,EMAT)易吸附铁磁性颗粒导致换能效率下降甚至功能性损坏、难与铁磁性金属材料实现快速分离或移动、探头体积大、难以实现狭小区域等探头不可达区域的检测等难题,提出了一种仅线圈式电磁超声检测的技术实现与建模方法。建立了集仅线圈式EMAT的激励等效电路和检测过程的场路耦合分析有限元模型,分析了仅线圈式EMAT的纵波激励和接收机理,研究了提离对EMAT线圈的等效阻抗、放电电流的高频成分和类直流成分、检测回波的幅值和中心频率的影响。研制了仅线圈式EMAT检测电路,验证了提离的影响规律。研究结果表明:所研制的仅线圈式电磁超声检测系统可以在80 mm厚的铝合金试样中激励和接收纵波,且在0.1 mm提离时,一次底波的信噪比为28.10 dB。当提离由0.1 mm增加至1.0 mm时,二次底波的信噪比由22.21 dB减小至8.01 dB,其中心频率由1.35 MHz下降为1.27 MHz。Traditional permanent magnet or pulse electromagnet electromagnetic acoustic transducer(EMAT)has some problems,such as being easy to absorb ferromagnetic particles,resulting in the reduction of energy conversion efficiency and even functional damage,difficul ty in achieving rapid separation or movement with ferromagnetic metal materials,a large volume of the probe,and being challenging to achieve the detection of the inaccessible areas of the probe such as small narrow areas.A technique realization and modeling method of coil-only electromagnetic ultrasonic testing is proposed to solve the above problems.A finite element model for field-circuit coupling analy sis of the excitation equivalent circuit and the detection process of the coil-only EMAT is established.The mechanism of longitudinal wave excitation and reception of the coil-only EMAT is analyzed,and the effect of lift-off on the equivalent impedance of the EMAT coil,the high-frequency and DC-like components of the discharge current,and the amplitude and center frequency of the detection echo is also studied.A coil-only EMAT detection circuit is developed,and the lift-off effect is verified.The results show that the coil-only electromag netic ultrasonic testing system can excite and receive longitudinal waves in an 80 mm thick aluminum alloy sample.The primary bottom wave's signal-to-noise ratio(SNR)is 28.10 dB at 0.1 mm lift-off.When the lift-off increases from 0.1 mm to 1.0 mm,the SNR of the second bottom wave decreases from 22.21 dB to 8.01 dB,and its center frequency decreases from 1.35 MHz to 1.27 MHz.

关 键 词：超声检测 仅线圈式EMAT 场路耦合分析 提离 纵波 

分 类 号：TB552[理学—物理] TH878[理学—声学]