中文摘要：

电磁超声兰姆波换能器由于其激发的兰姆波具有多模式、频散性和信号较弱的特点，在一定程度上限制了其发展及应用。针对增强电磁超声兰姆波信号强度问题，提出了一种优化设计方法。通过在永磁铁和线圈之间加入超微晶叠片来减小永磁铁表面的涡流，增加试件中的涡流，同时改善静磁场的分布，从而增强铝板中的信号强度。重点研究了超微晶对电磁超声信号的影响，采用有限元软件进行仿真分析，并进行了实验验证。实验结果表明，该优化方法能够有效增强兰姆波信号强度。

英文摘要：

The electromagnetic acoustic transducers （EMATs） possess the capability of generating Lamb waves. The waves manifest the characteristics of multi-mode, dispersion and weak singal, which limit the development and application of EMATs. To enhance the signal of Lamb wave EMATs, we proposed an optimal design method. By adding super-microcrystals between the permanent magnets and the coils, the eddy current in the surface of the permanent magnet was reduced and the eddy current in the specimen was increased. Meanwhile, the distribution of the static magnetic field was improved, and the signal intensity in the aluminum plate was enhanced. In this paper, the effect of ultra crystallite on electromagnetic ultrasonic signal was mainly studied. The finite element software was used to simulate and analyze the experiment. The experimental results show that the method can effectively enhance the intensity of Lamb wave signal.