Author(s)

Riichi Murayama¹, Masayuki Kobayashi¹, Kenshi Matsumoto¹, Makiko Kobayashi²

¹Department of Intelligent Mechanical Engineering, Fukuoka Institute of Technology, Fukuoka, Japan.
²Department of Computer Science and Electrical Engineering, Kumamoto University, Kumamoto, Japan.

The nondestructive inspection of a high temperature structure is required in order to guarantee its safety. However, there are no useful sensors for high temperature structures. Some of them cannot work at temperatures over 50°C. Another concern is that they are too expensive to use. A sensing system, which can transmit and receive an ultrasonic wave that travels a long distance using a long waveguide, has been studied. We confirmed that the optimal guided ultrasonic wave could travel more than 10 m using an electromagnetic transducer (EMAT) with a thin Ni-sheet surrounded on the surface of the bar and a 2-mm diameter bar as the waveguide. However, we had the difficult problem of receiving the reflected ultrasonic wave from the inside of a test specimen. We tried to improve the trial inspection system using an acoustic horn. An experiment in which the temperature of the test block was heated to about 500°C has now been completed. Finally, the condition of the bend in the waveguide to pass without reflection was confirmed.

Guide Wave, Waveguide, Acoustic Horn, NDI, Thickness Measurement

Murayama, R. , Kobayashi, M. , Matsumoto, K. and Kobayashi, M. (2014) Ultrasonic Inspection System Using a Long Waveguide with an Acoustic Horn for High-Temperature Structure. Journal of Sensor Technology, 4, 177-185. doi: 10.4236/jst.2014.44017.