パルス磁場 EMAT の開発と構造材料を対象とした状態監視への適用
Development of EMAT with pulse electromagnet applied to condition based maintenance for constructive materials condition based maintenance for constructive materiais
大塚 裕介 Yusuke OHTSUKA 西川 雅弘 Masahiro NISHIKAWA
Electromagnetic Acoustic TransducerSH WaveUltrasonic Wave
A pulse electromagnetic acoustic transducer (pulse EMAT), with an induction coil replacing the conventional magnet, has been developed in order to increase transmission amplitude of ultrasonic waves. Us ing a pulse generator, a current of approximately 100 A was passed through the induction coil for 25 us, and a surface SH wave was transmitted during induction. As a result, the observed detection sign al for the pulse EMAT was 20% of that of an EMAT with a periodic permanent magnet (PPM) structure. The time taken to reach the receiver was the same for the pulse EMAT and PPM structure EMAT, and the re ceived wave had equivalent profiles when normalized. Furthermore, the magnetic field magnitude ratio of pulse EMAT and PPM structure EMAT were found to match the magnitude ratio of the received fields.