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Proceedings Paper

Embedded optical fiber Bragg grating sensors for the measurement of crack-bridging forces in composites
Author(s): Michel Studer; Kara J. Peters; John Botsis
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Paper Abstract

Fiber reinforced composites offer increased resistance to fracture as compared to isotropic materials. In addition, they have demonstrated great potential to support embedded sensor systems. However, to develop a truly reliable, embedded sensor for composites, the failure modes of such materials, including the influence of the embedded fiber sensor, must be known. Crack bridging by intact fibers is considered to be one of the most efficient mechanisms to slow down transverse crack propagation in a fiber reinforced composite. This paper presents non-invasive, direct measurements of bridging fiber stresses in a model epoxy/glass composite, using long gage length optical fiber Bragg gratings. Several central crack specimens, containing artificially bridged cracks, were fabricated and tested. The Bragg grating gage length of 12 mm permitted measurement of the force distribution in the reinforcing fiber extending from the crack surface to the far field region. A T-matrix simulation was used to model the grating response. Results from specimens involving both a strong and mixed interface are presented. The measured strain distribution in the bridging fibers compared well with previous analytical models. Discussion of the application of these results to structurally embedded sensors for damage detection is also presented.

Paper Details

Date Published: 27 June 2002
PDF: 12 pages
Proc. SPIE 4694, Smart Structures and Materials 2002: Smart Sensor Technology and Measurement Systems, (27 June 2002); doi: 10.1117/12.472607
Show Author Affiliations
Michel Studer, Swiss Federal Institute of Technology (United States)
Kara J. Peters, North Carolina State Univ. (United States)
John Botsis, Swiss Federal Institute of Technology (Switzerland)

Published in SPIE Proceedings Vol. 4694:
Smart Structures and Materials 2002: Smart Sensor Technology and Measurement Systems
Daniele Inaudi; Eric Udd, Editor(s)

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