基于吸盘式脉冲电磁铁的EMAT实验研究

电磁铁式电磁超声传感器较永磁体式具有接触和移动性好、不易粘附杂物等优点,工程应用潜力巨大,然而目前对其研究开发较少.提出了一种基于吸盘式脉冲电磁铁的EMAT,能更好地适应环形线圈,实现超声波的激励与接收.建立了通用的脉冲电磁铁式电磁超声传感器检测实验系统,在铁磁性材料和非铁磁性材料上进行了脉冲回波式检测实验,验证了传感器的有效性.研究了主要影响因素(被检材料、励磁电流和提离距离)对此种传感器检测信号的影响规律,结果表明此种传感器在铁磁性材料上的换能效率远大于非铁磁性材料上的换能效率;一定范围内传感器检测信号幅度随励磁电流线性增加,随提离距离呈反比函数关系衰减.

Electromagnetic Acoustic Transducer with Sucker Type Pulsed Electromagnet

Electromagnetic Acoustic Transducer with Electromagnet has the advantages of good contacting and moving convenience than that with permanent magnet. However,the research and develop work was much less until now. This paper proposed an electromagnetic ultrasonic sensor with sucker type pulsed electromagnet,which can better adapt to the planar coil and realize the excitation and reception of ultrasonic wave. For verifying the validity of the sensor,a common experiment system for pulsed electromagnet EMAT was established. The effectiveness was proved by a pulse-echo test on ferromagnetic and non-ferromagnetic materials. And the effects of tested material,ex-citation current and lift-off distance on inspection signal was studied. The results show that the energy conversion ef-ficiency of the sensor on the ferromagnetic material is much greater than that on the non-ferromagnetic material. The amplitude of the sensor detection signal increases linearly with the excitation current and decays with the lift-off dis-tance by inverse proportional function relationship.