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Proceedings Paper

Crack propagation testing using a YCOB acoustic emission sensor
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Paper Abstract

Piezoelectric crystals are popular for passive sensors, such as accelerometers and acoustic emission sensors, due to their robustness and high sensitivity. These sensors are widespread in structural health monitoring among civil and industrial structures, but there is little application in high temperature environments (e.g. > 1000°C) due to the few materials that are capable of operating at elevated temperatures. Most piezoelectric materials suffer from a loss of electric properties above temperatures in the 500-700°C range, but rare earth oxyborate crystals, such as Yttrium calcium oxyborate (YCOB), retain their piezoelectric properties above 1000 °C. Our previous research demonstrated that YCOB can be used to detect transient lamb waves via Hsu-Nielsen tests, which replicate acoustic emission waves, up to 1000°C. In this paper, YCOB piezoelectric acoustic emission sensors were tested for their ability to detect crack progression at elevated temperatures. The sensor was fabricated using a YCOB single crystal and Inconel electrodes and wires. The sensor was mounted onto a stainless steel bar substrate, which was machined to include a pre-crack notch. A dynamic load was induced on the bar with a shaker in order to force the crack to advance along the thickness of the substrate. The obtained raw data was processed and analyzed in the frequency domain and compared to the Lamb wave modes that were evaluated in previous Hsu-Nielsen testing for the substrate.

Paper Details

Date Published: 9 March 2014
PDF: 8 pages
Proc. SPIE 9063, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2014, 906307 (9 March 2014); doi: 10.1117/12.2045091
Show Author Affiliations
Joseph A. Johnson, North Carolina State Univ. (United States)
Kyungrim Kim, North Carolina State Univ. (United States)
Shujun Zhang, The Pennsylvania State Univ. (United States)
Xiaoning Jiang, North Carolina State Univ. (United States)


Published in SPIE Proceedings Vol. 9063:
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2014
H. Felix Wu; Tzu-Yang Yu; Andrew L. Gyekenyesi; Peter J. Shull, Editor(s)

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