The Design Of Electromagnetic Acoustic Transducer Based On Non-ferromagnetic Material

The electromagnetic ultrasonic transducer is a new type of ultrasonic transmitting andreceiving device. Compared with the conventional piezoelectric ultrasonic transducer, it avoidthe pre-process and acoustic couplant on the surface of the measured specimen, and it couldexcite a variety of types of ultrasonic wave, such as transverse wave, longitudinal wave, surfacewaves and Lamb waves, therefore the superiority is prominent. But the shortcoming is also veryobvious, compared with piezoelectric ultrasonic transducer, the conversion efficiency is low, so itneed a good data acquisition and analysis system.According to the strengths and weaknesses of electromagnetic ultrasonic detectiontechnology, this paper researched the electromagnetic ultrasonic detection technology by thefinite element simulation method.The work process of electromagnetic acoustic transducer can be divided into two stages: theprocess which electromagnetic acoustic transducer generates Lorentz force, and the processwhich it excites ultrasonic. The first stage was electromagnetic field model, it included coil,aluminum plate, permanent magnet and air. Through simulation, the distribution law and mainfeatures of electric field, magnetic field, and force field were given. The second stage was soundfield model, it only had aluminum plane. Through simulation, the radiation field, directivity,trajectory and attenuation law of ultrasonic were analyzed. The simulation results match thetheoretical analysis well.According to the problem of ultrasonic signal strength weak, simulation was done bychanging the winding coil shape, the magnet base area size, the number of turns of the windingcoil and excitation power waveform. Then this paper made a comparative analysis of differentsituations to determine which is better.