The Characteristics Of Electromagnetic Acoustic Transducer Receiving System Is Analyzed

The electromagnetic Acoustic Transducer technology is a new type of nondestructivetesting, the testing technology without coupling agent, high precision, non-contact, broadscope, can accurately detect quickly whether the surface of the aluminum plate and internaldefects. So the EMAT technology get the attention of people more and more, to be one ofthe important means of detection in industrial production. In this paper the EMATtechnology was applied to emphasis on the study of defect detection in aluminum platesurface wave excitation.In this paper, analyzing the mechanism of EMAT and researching the transmissionmechanism of the EMAT surface wave system and basic principle of excitation andreceiving. According to the type of the test, it is necessary to produce different types ofwave type, choose different shapes excitation coil and magnet configuration inspire thewave of testing required. In this paper, detecting the integrity of the aluminum plate withsurface wave, the choice of the rectangular permanent magnets and winding coil withstimulating surface wave, for testing defects.On the basis of theoretical research, the electromagnetic ultrasonic transducerdetection system is analyzed and designed. The EMAT is three parts by the magnet, coiland tested specimen，Paper analyzed the influence of the parameters of the transducer forreceiving signals, parameters including pulse number and the receive coil number of turnsand the width of the wire diameter and separation, selection of magnets and magnetcross-sectional area. Produced by the EMAT surface wave directional flaw detection andpositioning plays an important role, pointing angle through experimental research on theinfluence of electromagnetic ultrasonic signals, and analyze the parameters of thetransducer, improve the detection sensitivity. Due to the low efficiency of electromagneticultrasonic transducer can change, the received echo signal is weak, in order to improve theefficiency of conversion, the coil impedance matching, improving the received power.The surface of the received wave shape is analyzed, and analyzing characteristic valueof each wave packet and researching the wave propagation process in aluminum plate. Bycomparing the received waveform, judging whether aluminum plate is flawed, and fixingthe defect. In this paper through the waveform analysis can make the EMAT testingtechnique is applied to defect inspection.