New Combination of Magnet and Coil of Electromagnetic Acoustic Transducer for Generating and Detecting Rayleigh Wave
New Combination of Magnet and Coil of Electromagnetic Acoustic Transducer for Generating and Detecting Rayleigh Wave
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DOI：
10.1109/tuffc.2019.2956711
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发表时间：
2020-04-01
影响因子：
3.6
通讯作者：
Takagi, Toshiyuki
中科院分区：
文献类型：
--
作者：
Sun, Hongjun;Uchimoto, Tetsuya;Takagi, Toshiyuki
用于识别金属材料表面缺陷的无损检测对于工业和基础设施非常重要。瑞利波广泛用于检测这些表面缺陷。为了用电磁声换能器（EMAT）代替压电换能器进行金属材料的表面检测，本文提出了一种新的磁体和线圈组合，由周期永磁体（PPM）和返回位错曲折线线圈组成。返回位错曲折线线圈是在传统曲折线线圈的基础上发展起来的，其导线从一侧返回到另一侧并移动一定的距离。通过二维有限元模拟来分析所提出的瑞利波 EMAT 的性能。仿真结果表明，与大型常规磁体相比，PPM提高了最大磁通密度，并使磁通密度分布更加集中在样品表面，特别是线圈下方。在线圈的中部，PPM大大增加了水平磁场的强度。另外，返回位错曲折线线圈充分利用了每个小磁体中心下方和相邻磁体处的强磁场。设计的瑞利波EMAT被制作出来，实验结果表明，与传统瑞利波EMAT相比，新设计的瑞利波EMAT接收信号提高了57.9%。
Nondestructive testing for identifying defects on the surface of metal materials is important for industries and infrastructures. The Rayleigh wave is widely used for detecting these surface defects. For replacing piezoelectric transducers with electromagnetic acoustic transducers (EMATs) for the surface inspection of metal materials, this article proposes a new magnet and coil combination consisting of a periodic-permanent-magnet (PPM) and a returned dislocation meander line coil. The returned dislocation meander line coil was developed using a traditional meander line coil, whose wires return from one side to another and shift for a certain distance. A 2-D finite-element simulation was conducted to analyze the performance of the proposed Rayleigh wave EMAT. The simulation results revealed that, compared with a large conventional magnet, the PPM increased the maximum magnetic flux density, and made the magnetic flux density distribution more concentrated on the specimen's surface, particularly below the coil. In the middle part of the coil, the PPM greatly increased the intensity of the horizontal magnetic field. Additionally, the returned dislocation meander line coil made full use of the strong magnetic field below the center of each small magnet and at the adjacent magnets. The designed Rayleigh wave EMAT was fabricated, and the experimental results revealed that the new design of the Rayleigh wave EMAT increased the received signal by 57.9% compared with the conventional Rayleigh wave EMAT.