电磁超声表面波换能器发射过程的精确建模与分析

摘要

To increase the accuracy of the model of the meander-line-coil surface wave EMATs used for the inspection of surface layer of aluminum plates,this paper established a novel 3D accurate model by combining numerical calculations and analytical solutions with special attention to the influence of the dynamic magnetic field.Simulation and analysis indicated that the frequency of the surface waves due to the dynamic magnetic field was twice of that due to the static magnetic field;the double-frequency surface wave component could effectively improve the sensitivity of the transducers;both increasing transmitting current and decreasing lift-off distance could significantly enhance the component.The validity and accuracy of the established model was verified by experiment.%针对具有曲折线圈结构的电磁超声表面波换能器模型精度较低问题,以铝合金板材表层缺陷检测为背景,在考虑交变磁场影响前提下,通过将有限元方法与解析法相结合,建立了一个精确描述电磁超声表面波换能器发射过程的三维模型。仿真分析表明,换能器在发射过程中产生的交变磁场可激发出两倍频率成分的表面波;该表面波分量能够有效提高换能器的缺陷敏感度;增加发射电流、降低提离距离均可显著增强该分量。试验验证了所建模型的有效性和精确性。