Numerical analysis of ultrasonic inspection using electromagnetic acoustic transducer

摘要

This paper analyses ultrasonic inspection of defects using an Electro-Magnetic Acoustic Transducer of Lorentz type. This type of EMATs can be applied to many structural materials without contact, and they can easily excite various wave modes by arranging the coils and the magnets. The eddy current induced by a coil generates the Lorentz force under the static bias magnetic field by permanent magnets. The excited ultrasonic wave is reflected from the boundary or the defects and reaches the boundary surface faced to the EMAT. The eddy current induced by the reflected wave under the bias magnetic field generates the dynamic magnetic field, which is received by the coil through the electromagnetic induction. This paper simulates such transmission and reception processes by the EMAT and attempts to identify an inside crack by scanning the probe over the surface of the specimen.