基于电磁超声换能器的兰姆波单一模态激励方法研究  

Research on single mode excitation method of Lamb wave based on electromagnetic ultrasonic transducer

作　　者：郭中会 李松松 何慧敏 杨莹 张琦 Guo Zhonghui;Li Songsong;He Huimin;Yang Ying;Zhang Qi(School of information engineering,Dalian Ocean University,Dalian 116023,China)

机构地区：[1]大连海洋大学信息工程学院,大连116023

出　　处：《仪器仪表学报》2021年第5期253-260,共8页Chinese Journal of Scientific Instrument

基　　金：国家自然基金项目(51778104);辽宁省教育厅科学研究项目(DL202005)资助。

摘　　要：针对电磁超声换能器(EMAT)激发的超声兰姆波存在多模态的问题,提出一种通过换能器结构优化来激励兰姆波单一模态的方法。首先根据毕奥萨伐尔定律和麦克斯韦方程组研究了永磁铁形状与磁场分布的关系,设计了一种新型可聚磁的"拱桥"式永磁铁结构。然后对优化前后的EMAT进行了仿真实验和实测实验对比,实验结果表明:优化后的EMAT激励出兰姆波的S0模态幅值均有所增加,仿真与实测增加的幅值分别为优化前的1.05倍和1.1倍;而优化后的A0模态幅值均明显下降,分别为优化前的0.22倍和0.12倍;优化后的S0模态与A0模态的比值,也分别由优化前的2.60倍和1.82倍增加到12.48倍和16.17倍。由此可见,优化后的EMAT相比于优化前的普通EMAT,能够很好地激励S0模态抑制A0模态,因此验证了新型EMAT可以有效激发兰姆波的单一S0模态。Aiming at the problem that the ultrasonic Lamb wave excited by the electromagnetic ultrasonic transducer(EMAT)has multiple modes,a method is proposed to excite a single mode of the Lamb wave by optimizing the structure of the transducer.First,according to Biot Savart‘s law and Maxwell’s equations,the relationship between the shape of the permanent magnet and the magnetic field distribution is studied,and a new type of magnetizable"arch bridge"permanent magnet structure is designed.Then,the simulation experiment and the actual measurement experiment were performed on the EMAT before and after the optimization.The experimental results show that the S0 modal amplitudes of the Lamb wave excited by the EMAT after optimization are 1.05 and 1.1 before the optimization,and the A0 modal amplitudes are respectively It is 0.22 and 0.12 before optimization;the ratio of S0 mode to A0 mode is also increased from 2.60 and 1.82 before optimization to 12.48 and 16.17 respectively.It can be seen that,compared with the ordinary EMAT before optimization,the optimized EMAT can excite the S0 mode and suppress the A0 mode well,thus verifying that the new EMAT can effectively excite the single S0 mode of the Lamb wave.

关 键 词：EMAT 单一模态 兰姆波 有限元仿真 永磁铁结构 

分 类 号：TB552[理学—物理] TH878[理学—声学]