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基于适当的假设和近似 ,通过分析电涡流的分布、洛伦兹力、磁致伸缩力和磁化力 ,研究了在铁磁材料中用电磁声换能器 (EMAT)的方法产生超声的耦合机理 ,并针对有实用意义的结构参数进行了数值计算以解释换能器的性能 .结果表明 :对于铁磁性材料 ,在磁场强度较低、材料磁化未达到饱和时 ,磁致伸缩效应在EMAT超声波的产生中起主导作用 ;但是 ,随着偏置磁场的逐渐增强而使材料达到磁化饱和时 ,磁致伸缩逐渐消失 ,对产生超声不再有贡献作用 ,洛伦兹力变成是激发超声的惟一原因 .因此 ,为获得优化的设计 ,计算洛伦兹力和磁致伸缩力以及选择合适的工作方式变得尤为重要 .
Based on the appropriate assumptions and approximations, the coupling mechanism of ultrasonic wave generated by using EMAT in ferromagnetic materials was studied by analyzing the distribution of eddy current, Lorentz force, magnetostriction force and magnetizing force , And the practical structural parameters were numerically calculated to explain the performance of the transducer.The results show that for ferromagnetic materials, when the magnetic field strength is low and the material magnetization does not reach saturation, the magnetostriction effect in the EMAT ultrasound Production; however, as the bias magnetic field is gradually increased so that the material reaches the magnetization saturation, the magnetostriction disappears, no longer contribute to the generation of ultrasound, Lorentz force becomes the only excitation ultrasound Therefore, in order to obtain an optimized design, it becomes particularly important to calculate the Lorentz force and the magnetostriction as well as to choose the proper working method.