电磁超声电声转换效率的影响因素分析  

Analysis of Influencing Factors in Electromagnetic Acoustic Electro-acoustic Conversion Efficiency

作　　者：黄凤英[1] 郭犇[1] 高东海[1] 范振中[1] 

机构地区：[1]中国铁道科学研究院金属及化学研究所,北京100081

出　　处：《工程与试验》2013年第4期1-6,共6页Engineering and Test

摘　　要：电磁超声是一种非接触超声检测方法,因不需要耦合剂,在一些常规超声无法实施的特殊检测领域发挥着重要作用。但是,由于电磁超声电声转换效率低,制约着电磁超声的广泛应用。分析了几种参数对电磁超声电声转换效率的影响,包括探头的提离、激励信号的电流幅值、频率、周期个数和仪器的输出功率等几个因素。研究表明:随着探头提离的增大,电磁超声的信号几乎成指数衰减;通过优化激励信号的电流幅值、周期个数和激励频率以及在探头两端增加阻抗匹配单元,可以提高电磁超声的电声转换效率。EMAT is a non-contact ultrasonic testing method,with no need coupling,and plays an important role in a number of special routine ultrasonic testing fields.However,the lower elec-tro-acoustic conversion efficiency restricts the usage of electromagnetic acoustic.The influences of several parameters on the electro-acoustic conversion efficiency are analyzed,such as the probe lift-off,the current excitation signal amplitude,frequency,cycle number,output power of in-strument,and so on.The results show that with the increase of probe lift-off,the electromagnet-ic acoustic signal decreases almost exponentially,and the electromagnetic acoustic electro-acoustic conversion efficiency can be improved by optimizing the current excitation signal amplitude,the cycle number,the excitation frequency,and adding the impedance matching unit in the probe ends.

关 键 词：电磁超声 无损检测 电声转换效率 

分 类 号：TM914.4[电气工程—电力电子与电力传动]