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Proceedings Paper

Influence of process route on mechanical and sensing performance of fiber Bragg grating optical sensors
Author(s): Cathy Y. Wei; Stephen W. James; Chen-Chun Ye; Ralph P. Tatam; P. E. Irving
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Paper Abstract

Fiber Bragg gratings were fabricated in commercially available photosensitive optical fiber, using a phase mask and UV irradiation at 245.6 nm and 266 nm. Prior to irradiation, the acrylate buffer coating was removed from the fiber using different stripping methods: chemical solvent, hot-acid and heat. The tensile strength of the fiber was measured at various stages of the fabrication process: with buffer coating intact, with the buffer coating chemically removed, and following UV irradiation. A Fabry-Perot demodulation system monitored the wavelength shift of the reflected peak from the FBG during the tensile loading, from which the strain to failure of FBG sensors has been determined. Each set of strength data has been plotted by applying the Weibull statistics. The results indicate that the removal of the buffer coating degrades the strength of optical fibers. The Weibull analysis indicates two failure mechanisms. Bare fibers show a high Weibull modulus, above 24, if no mechanical flaws have been introduced, while the fibers with surface flaws fail at low stress with the Weibull modulus as low as 2.78. UV irradiation has been found to further reduce the fiber strength. Most irradiated fibers fractured within the sensor gauge length. It is believed that a stress concentration or surface stress is induced by the UV energy, which results in mechanical degradation.

Paper Details

Date Published: 31 May 1999
PDF: 7 pages
Proc. SPIE 3670, Smart Structures and Materials 1999: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials, (31 May 1999); doi: 10.1117/12.349727
Show Author Affiliations
Cathy Y. Wei, Cranfield Univ. (United Kingdom)
Stephen W. James, Cranfield Univ. (United Kingdom)
Chen-Chun Ye, Cranfield Univ. (United Kingdom)
Ralph P. Tatam, Cranfield Univ. (United Kingdom)
P. E. Irving, Cranfield Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 3670:
Smart Structures and Materials 1999: Sensory Phenomena and Measurement Instrumentation for Smart Structures and Materials
Richard O. Claus; William B. Spillman Jr., Editor(s)

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