Electromagnetic acoustic transducer(EMAT)has been widely used in the field of nondestructive testing due to its advantages of non-contact and designability.At present,most EMATs can only excite ultrasonic waves at a fixed frequency,which limits the application range of the transducer.To address this issue,this article proposes a new type of phase-controlled frequency-conversion EMAT(PC-FC-EMAT),which can achieve the purpose of variable-frequency excitation by adjusting the phase-control time delay of the transducer's excitation signal.Firstly,the design scheme of PC-FC-EMAT is proposed,the frequency domain response model of PC-FC-EMAT is formulated,and the mechanism of the phase-controlled time delay on the frequency domain response under the spatial response of the Lorentz force is revealed.Secondly,a multi-physics field coupling simulation model of PC-FC-EMAT is established to study the role of the phase-controlled delay on the PC-FC-EMAT time and frequency domain response,and simulate the modulation effect of the phase-controlled delay on the frequency response of PC-FC-EMAT.Finally,PC-FC-EMAT is developed,and experimental research is carried out.The experimental results show that the developed PC-FC-EMAT can achieve wavelength regulation in the range of 4～12 mm,and the frequency band covers 252～687 kHz,which meets the design requirements.
关键词
电磁声传感器/相控变频/表面波/时间延迟
Key words
electromagnetic acoustic sensor/phase-controlled frequency conversion/surface wave/time delay
维普
万方数据