Analysis of influencing factors of EMAT equivalent impedance of racetrack coil
Electromagnetic ultrasonic transducer(EMAT)is a transducer that can ultrasonically detect the test piece without the need for a coupling agent,and plays an important role in areas that are difficult to detect with conventional ultrasound.However,the problems of low transduction efficiency and poor signal-to-noise ratio of electromagnetic ultrasonic transducers are restricting the development of electromagnetic ultrasonic transducers.This paper mainly studies the impedance characteristics of the sensor from the perspective of equivalent impedance,analyzes the influencing factors affecting the impedance characteristics of the sensor,optimizes the design of the sensor according to the impedance characteristics of the sensor,and impedance matches the sensor under different operating conditions,and investigates the impact of the impedance matching network on the amplitude of the sensor signal and the signal-to-noise ratio under different operating conditions.The results show that the magnet-to-coil spacing and lift-off distance have a significant effect on the equivalent impedance of the sensor,and the sensor designed according to the lift-off distance of 0.5 mm and magnet-to-coil spacing of 1 mm can meet the purpose of detecting the optimal signal amplitude of the detected materials of different properties,and the attenuation of signal amplitude with the change of the lift-off distance is different in different materials,and the addition of impedance matching network is conducive to the improvement of signal-to-noise ratio under large lift-off.
NETL
NSTL
万方数据
维普
