基于洛伦兹力机制的电磁超声发射换能器的建模与优化

doi:10.3901/JME.2016.06.012

摘要/Abstract

摘要： 电磁超声换能器(Electromagnetic acoustic transducer, EMAT)是电磁超声检测技术的核心部件,具有非接触、不受工作环境影响、易于激发多种类型的超声波等优点。但与传统的压电式超声换能器相比,电磁超声发射换能器的换能效率较低,导致超声回波信号较弱,检测结果不理想。现阶段,在完善对EMAT建模分析的基础上,通过对换能器参数的优化和结构的改进设计以及与其他新技术相结合的方式,EMAT的换能效率已经有了明显的提高,但仍存在解析、半解析建模方法不完整,数值建模方法计算时间长,以及换能效率仍然不够理想等问题。对此,综述近十几年来基于洛伦兹力机制的电磁超声发射换能器的数学建模方法,包括解析法、数值法和半解析法,给出较为完整的耦合方程和建模过程。并在此基础上,分析了偏置磁场、激励线圈、提离距离等参数对换能效率的影响规律以及换能器的优化设计方法,为今后电磁超声换能器的模型完善和改进提高提供参考。

关键词: 电磁超声换能器, 换能效率, 激励线圈, 建模, 偏置磁场, 提离效应, 优化设计

Abstract: Electromagnetic acoustic transducer(EMAT) is the core component of the electromagnetic acoustic technique, which has many advantages such as non-contact, not affected by the environment and easy to excite various types of ultrasonic wave etc. However, compared with the traditional piezoelectric transducer, the transduction efficiency of EMAT transmitter is lower, which causes the weak ultrasonic echo signal. At present, on the basis of the mathematic model of EMAT, through the optimization of parameters and structural design of EMAT, as well as combined with other new technologies, the transduction efficiency of EMAT transmitter has been obviously improved. But there are still some problems, for example the analytical method and semi-analytical method are not complete, and it takes long time to compute by numerical method, also, the transduction efficiency is not ideal. Based on the papers published during recent years, the mathematical modeling methods of EMAT transmitter working on Lorentz principle including analytical method, semi-analytical method and numerical method are systematically reviewed. Then the effect of bias magnetic field, exciting coil and lift-off on transduction efficiency are analyzed and the optimum design methods of EMAT are reviewed, providing a foundation for EMAT improvement.

Key words: bias-magnetic field, electromagnetic acoustic transducer(EMAT), exciting coil, lift-off effect, modeling, optimum design, transduction efficiency

中图分类号:

TB552

孙斐然, 孙振国, 张文增, 陈强. 基于洛伦兹力机制的电磁超声发射换能器的建模与优化[J]. 机械工程学报, 2016, 52(6): 12-21.

SUN Feiran, SUN Zhenguo, ZHANG Wenzeng, CHEN Qiang. Review of Modeling Method and Optimum Design of EMAT Transmitters Based on Lorentz Principle[J]. Journal of Mechanical Engineering, 2016, 52(6): 12-21.

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