电磁超声换能器三维有限元分析及优化设计

3-D Finite Element Analysis and Optimum Design of Electromagnetic Acoustic Transducers

电磁超声换能器(electromagnetic acoustic transducer,EMAT)设计理论的不足严重限制了电磁超声检测技术的进一步发展。为了从根本上解决该问题,对用于铝板表面检测的电磁超声表面波换能器进行了三维有限元建模和仿真分析,发现换能器的几何参数对EMAT的换能效率具有重要影响。为此,在所建模型基础上,利用正交试验设计方法选取了影响换能效率的关键参数,确定EMAT设计的基本准则,并依次对EMAT线圈和永磁体进行了优化设计。实验表明,优化后的电磁超声信号幅值增长为优化前的2.99倍,在三维有限元模型基础上利用正交试验设计方法能够有效地对EMAT进行优化设计。

The deficiency of designing theories of electromagnetic acoustic transducers （EMATs） severely confines the further expansion of their scope of application. To thoroughly solve this problem, this paper built a 3-D finite element model of an surface wave EMAT used for the surface inspection of aluminum plates. Simulation analysis of the model revealed that transduction efficiency of the EMAT was greatly affected by EMAT parameters. As a consequence, based on the established model and by utilizing orthogonal test method, this paper extracted EMAT＇s key parameters that significantly influenced the transduction efficiency of the transducer; obtained the basic designing principle of the EMAT; and accomplished the optimum design of the EMAT by studying the coil and the magnet individually. Experiment indicated that after optimization the amplitude of the EMAT-received signal increased by 2.99 times. The transduction efficiency of EMATs can be effectively improved by utilizing orthogonal test method based on 3-D finite element model.