Single SH guided wave mode generation method for PPM EMATs  

作　　者：Guo-Fu Zhai Yong-Qian Li 翟国富;李永虔(Institute of Reliability in Electrical Apparatus and Electronics,Harbin Institute of Technology,Harbin 150001,China)

机构地区：[1]Institute of Reliability in Electrical Apparatus and Electronics,Harbin Institute of Technology,Harbin 150001,China

出　　处：《Chinese Physics B》2020年第5期326-332,共7页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant No.51977044).

摘　　要：Using periodic permanent magnet(PPM)electromagnetic acoustic transducers(EMATs),different shear horizontal(SH)guided wave modes can form simultaneously in some situations,which can interfere with the inspection.The main cause of this phenomenon(typically named multiple modes)is related to the frequency bandwidth of excitation signals and the transducer spatial bandwidth.Simply narrowing the frequency bandwidth cannot effectively limit the number of different SH modes.Previous researches showed that unnecessary SH wave modes can be eliminated by using dual EMATs.However,in practical applications,it is more convenient to change the excitation frequency than to use dual EMATs.In this paper,the stress boundary conditions of the PPM-EMAT are analyzed,the analytical expression of SH guided wave is established,and the magnitude of SH guided wave mode under continuous tone and tone-burst input is obtained.A method to generate a single SH mode by re-selecting an operating point is proposed.Furthermore,the influence of the frequency bandwidth of the tone-burst signal is analyzed.Finally,a single SH mode excitation is achieved with tone-burst input.

关 键 词：operating point multiple modes SH guided waves electromagnetic acoustic transducer(EMAT) 

分 类 号：TB55[理学—物理]