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电磁超声换能器(electromagnetic acoustic transducer,EMAT)接收信号十分微弱,限制了电磁超声无损检测技术的应用。通过对表面波电磁超声换能器进行发射–接收过程多物理场有限元的建模与分析,发现换能器几何参数对其接收性能具有重要影响。为此,在所建有限元模型基础上,利用正交试验设计方法提取了影响EMAT接收性能的关键参数并对EMAT几何参数进行了优化设计。优化后电磁超声接收电压峰峰值增长为优化前的1.41倍。设计了一种同向6根导线结构的曲折线圈,又将接收电压提高至优化后的3.83倍,大大提高了EMAT的接收性能。最后,实验验证了模型和优化设计方法的有效性。
Electromagnetic acoustic transducer (EMAT) receiving signal is very weak, limiting the application of electromagnetic ultrasonic non-destructive testing technology. Through the modeling and analysis of the multiphysics finite element of the transmission-reception process of the surface-wave electromagnetic ultrasonic transducer, it is found that the geometric parameters of the transducer have an important influence on the receiving performance. Therefore, based on the finite element model, the key parameters that affect EMAT reception performance were extracted by using orthogonal experimental design method and the geometric parameters of EMAT were optimized. After optimization, the peak-to-peak value of electromagnetic ultrasonic reception voltage is 1.41 times of that before optimization. A twisted coil with 6 conductors in the same direction was designed, which in turn improved the receiving voltage to 3.83 times of the optimized one, which greatly enhanced the receiving performance of EMAT. Finally, the effectiveness of the model and the optimization design method are verified experimentally.