电工技术学报  2024, Vol. 39 Issue (11): 3270-3279    DOI: 10.19595/j.cnki.1000-6753.tces.231764
电工理论与新技术 |
高纯度横波蝶形线圈电磁超声换能器优化设计
董明1,2, 李航辉1, 马宏伟1,2, 陈渊2, 曹现刚1,2
1.西安科技大学机械工程学院 西安 710054;
2.西安科技大学陕西省矿山机电装备智能检测与控制重点实验室 西安 710054
Optimization Design of High-Purity Shear Wave Electromagnetic Acoustic Transducer with Butterfly Coil
Dong Ming1,2, Li Hanghui1, Ma Hongwei1,2, Chen Yuan2, Cao Xiangang1,2
1. School of Mechanical Engineering Xi’an University of Science and Technology Xi’an 710054 China;
2. State Key Laboratory of Mine Electromechanical Equipment Intelligent Detection and Control of Xi’an University of Science and Technology Xi’an 710054 China
全文: PDF (10601 KB)   HTML
输出: BibTeX | EndNote (RIS)      
摘要 蝶形线圈电磁超声换能器(EMAT)能够在铝块中同时激发出超声横波和纵波,接收信号中存在横波反射回波和纵波反射回波,纵波回波会影响缺陷检测的准确性。该文设计了一种变尺寸蝶形线圈EMAT,通过改变线圈不同位置导线的宽度与间距,改变不同位置的换能效率,以实现横波的增强和纵波的抑制。首先,考虑永磁体的空间磁场分布,分析蝶形线圈EMAT不同位置导线所受洛伦兹力与激发超声波类型的关系,结合有限元声场云图,得到EMAT接收信号中存在多个回波的原因;其次,研究线圈参数对换能效率和横波纵波幅值比的影响规律,利用有限元仿真确定变尺寸EMAT的设计参数;最后,制备常规与变尺寸蝶形线圈EMAT,采集无缺陷铝合金试块的回波,结果表明,当永磁体直径与线圈中心宽度比为1.92时,纵波幅值削弱了66.1%,横波幅值增大了36.3%,横纵波幅值比从5.8升至23.1。该文设计的变尺寸蝶形线圈EMAT实现了对纵波的削弱和横波的增强,提升了横波电磁超声内部缺陷检测的可靠性。
服务
把本文推荐给朋友
加入我的书架
加入引用管理器
E-mail Alert
RSS
作者相关文章
董明
李航辉
马宏伟
陈渊
曹现刚
关键词 横波电磁超声换能器高纯度横波变尺寸蝶形线圈缺陷检测    
Abstract:The electromagnetic acoustic transducers (EMATs) are electromagnetically coupled ultrasonic transducers which can generate and detect ultrasonic waves on electrically conducting media. Compared with spiral coil, butterfly coil EMAT has the highest eddy current and pressure at the central axis, which has significant advantages in detection of inner defects and thickness measurement. The butterfly coil EMAT is easy to generate shear waves and longitudinal waves in an aluminum block. The echo of longitudinal wave will be judged as a defect echo, which brings a big challenge to defect identification. To improve the detect ability, an optimization design method for high-purity shear wave electromagnetic acoustic transducer with butterfly coil is prosed.
Firstly, the spatial magnetic field distribution of the permanent magnet was taken into account, and the relationship between the Lorentz force and the type of excitation ultrasonic waves at different positions of the butterfly coil EMAT was analyzed. The propagation characteristics of the ultrasonic waves were examined in a 2D finite element simulation model, and the causes of multiple echoes were analyzed. The echo of the longitudinal wave will be judged as a defect echo, which can lead to inaccurate detection results. Secondly, a butterfly coil with varied size was proposed, where the wire width and spacing of the butterfly coil varies with the position, simultaneously, the transduction efficiency was altered. The longitudinal waves were suppressed while shear waves were enhanced, and high-purity shear waves were achieved. The influence of butterfly coil parameters on the excitation efficiency and the amplitudes ratio of shear and longitudinal wave was studied, and the optimized parameters were determined through finite element simulation. Finally, the equal-size and varied-size butterfly coil EMAT were prepared for the comparison experiment involving shear wave excitation and defect detection.
The experimental results showed that when the magnet-to-coil width ratio reached approximately 1.92, the longitudinal wave was weakened by 66.1%, while the shear wave was enhanced by 36.3%. Consequently, the shear-to-longitudinal amplitude ratio increased from 5.8 to 23.1. A flat bottomed hole with a diameter of 5 mm was inspected using the optimization EMAT transducers, the amplitude of the longitudinal echo reflected by the bottom and the converted echo have been suppressed, and both echoes were almost submerged in the noise signal. The amplitude of the shear echo reflected by the flat bottomed hole has been enhanced, making it easier to detect defects. The varied-size butterfly coil EMAT designed in this paper can weaken the longitudinal wave and enhance the shear wave, thereby improving the reliability of shear wave electromagnetic ultrasonic internal defect detection.
The following conclusions can be drawn from the analysis: (1) Butterfly coil EMAT is easy to generate shear waves and longitudinal waves in an aluminum block. The receiving signal include echo of longitudinal wave, shear wave and converted wave. The longitudinal wave echo will be judged as a defect echo, which brings a big challenge to defect identification. (2) Reducing the wire width and spacing of the butterfly coil in the middle part can improve the energy transfer efficiency and enhance the shear wave amplitude, while increasing the wire width and spacing of the butterfly coil in the side part can weaken the energy transfer efficiency and weaken the longitudinal wave amplitude. The ratio of shear wave amplitude and longitudinal wave amplitude varies with the magnet-to-coil width ratio.
Key wordsShear wave electromagnetic acoustic transducers (EMATs)    high-purity shear wave    varied-size butterfly coil    defect detection   
收稿日期: 2023-10-23     
PACS: TB552  
  TM93  
基金资助:国家自然科学基金(51705418,52175518,52274158)和陕西省自然科学基础研究计划—陕煤联合基金(2021JLM-07)资助项目
通讯作者: 董 明 男,1984年生,副教授,硕士生导师,研究方向为超声无损检测与评价、机械测试理论与技术等。E-mail:jesunatg@hotmail.com   
作者简介: 李航辉 男,1998年生,硕士研究生,研究方向为电磁超声无损检测。E-mail:953160592@qq.com
引用本文:   
董明, 李航辉, 马宏伟, 陈渊, 曹现刚. 高纯度横波蝶形线圈电磁超声换能器优化设计[J]. 电工技术学报, 2024, 39(11): 3270-3279. Dong Ming, Li Hanghui, Ma Hongwei, Chen Yuan, Cao Xiangang. Optimization Design of High-Purity Shear Wave Electromagnetic Acoustic Transducer with Butterfly Coil. Transactions of China Electrotechnical Society, 2024, 39(11): 3270-3279.
链接本文:  
https://dgjsxb.ces-transaction.com/CN/10.19595/j.cnki.1000-6753.tces.231764          https://dgjsxb.ces-transaction.com/CN/Y2024/V39/I11/3270