曲折线圈折线角度对EMAT换能效率的影响

Effect of Different Line Angle of Meander Coil on EMAT Energy Transfer Efficiency

针对曲折线圈型电磁超声换能器的换能效率,分析了不同折线角度曲折线圈对EMAT(电磁超声换能器)换能效率的影响。根据声束指向原理,通过改变载流导线的角度,设计了0°、30°、60°、90°曲折线圈激励产生电磁超声导波,并采用收发分离式换能器结构在钢板上进行检测试验。结果表明,曲折线圈载流导线角度为0°时,EMAT激发的声波能量集中,方向性好,回波信号幅值强,为钢板的长距离检测提供了可能;曲折线圈载流导线角度增加为30°、60°、90°时,EMAT激发的声波信号纯净,简化了模态分析,对工程中钢板检测的信号简化处理具有重要意义。

By studying the energy transfer efficiency of the meande coil electromagnetic ultrasonic transducer, the impact of meande coils with different line angles on the energy transfer efficiency of the EMAT was analyzed. According to the principle of acoustic beam pointing in the direction and by changing the angle of the current- carrying conductor, 0 degrees, 30 degrees, 60 degrees, and 90 degrees meander coils were designed for the excitation of ultrasonic guided wave, and the transceiver separation transducer structure on the steel plate was adopted for experimental research. The results have shown that when the current-carrying conductor angle of the meander coil is 0 degree, the excitation acoustic energy of EMAT is focused, owing high directivity and strong echo signal amplitude, which provides the possibility for the long distance detection in the steel plate; when the current- carrying conductor angle of meander coil increased to 30 degrees, 60 degrees and 90 degrees, the EMAT inspires pure acoustic signal of being easy to identify and simplify the modal analysis, which has great significance for the signal processing in steel plate detection of the engineering.