軟鋼ワイヤの縦波用電磁超音波センサの送受信特性

概要

論文の詳細を見る
Electromagnetic acoustic transducers (EMATs) are made for exciting and receiving longitudinal wave in ferromagnetic steel wires. The EMAT consists of a coil wound around the wire and an electromagnet to apply a static magnetic field in the axial direction. Ferromagnetic materials show a dimensional change, called magnetostriction, when an external magnetic field is applied. If the dynamic magnetic field is induced by the coil, the resultant dynamic magnetostriction launches the longitudinal wave, which propagates along the wire. In this study, we investigated the generation and detection mechanisms of the EMATs by studying the amplitude response to the bias field and pulse intensity. The results are compared with the magnetostriction curve, ensuring that the magnetostriction is the dominant mechanism for this type of EMAT. We find that the optimum static magnetic field is different for transmitter and receiver. Thus, the use of the dual-EMAT configuration is recommended to improve the signal to noise ratio for detecting flaws in wires.
社団法人日本機械学会の論文
1999-05-25