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Proceedings Paper

Examination of reliability of fibre optic sensors embedded in carbon/epoxy composites
Author(s): Klas Levin; Soren Nilsson
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Paper Abstract

One of the most important tasks in achieving a reliable performance of embedded optical fiber sensors in aircraft health monitoring and usage systems is to clarify their function reliability. In this study the limit of reliable sensor function is addressed for a number of loading conditions at room temperature. For static tensile loading the function strain limit for EFPI- sensors was approximately 0.20%, whereas the function limit of embedded Bragg grating sensors was above the strain level (0.4 - 0.5%) for initiation of matrix cracking in the laminate. In compression the function of the EFPI-sensor was unimpaired to a strain level which was about four times larger than that in tension. In constant amplitude fatigue loading the function strain limit of the EFPI-sensor was similar to that in static tensile loading, i.e. 0.20% at 105 cycles. The silica glass/polyimide coating interface in the EFPI-sensor was identified as the sites where failure was initiated. The finite element analysis showed that the effects of curing stresses and moisture in laminates have significant influence on the function reliability of sensors. The stress concentrations on the interface caused by the cavity in the EFPI-sensor are the main reason for the lower reliability obtained for the EFPI-sensor than for embedded Bragg grating sensors.

Paper Details

Date Published: 26 April 1996
PDF: 8 pages
Proc. SPIE 2779, 3rd International Conference on Intelligent Materials and 3rd European Conference on Smart Structures and Materials, (26 April 1996); doi: 10.1117/12.237116
Show Author Affiliations
Klas Levin, FFA-Aeronautical Research Institute of Sweden (Sweden)
Soren Nilsson, FFA-Aeronautical Research Institute of Sweden (Sweden)


Published in SPIE Proceedings Vol. 2779:
3rd International Conference on Intelligent Materials and 3rd European Conference on Smart Structures and Materials
Pierre Francois Gobin; Jacques Tatibouet, Editor(s)

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