Failure of nano-structured optical fibers by femtosecond laser procedure as a strain safety-fuse sensor for composite material applications

As shown in a previous paper (Delobelle et al. (2013)) if synthetic flaws are generated on the surface or in the core of optical fibers thanks to single-shot femtosecond laser procedure, the rupture strength of these modified fibers can be controlled. In this paper, numerous new experiments have been conducted to show the potentialities of the embedded structured fibers within composite materials to act as a strain safety fuse sensor. The choice of a multimode optical fiber with polyimide coating has been validated. New Weibull's statistics on short fibers have been determined for two kinds of structuration, flaws on the surface or in the core of the silice fibers and in the failure strains range consistent with sensor applications on composite materials. Long structured fibers have been embedded within plane specimens of two components materials (glass fibers composite (16-20 plane sheets, 0 degrees) and carbon fibers composite (4 sheets,+/- 45 degrees)) and the comparison between the failure strains of these fibers with those issued from the Weibull's statistics of short fibers shows, at least for the superficial structuration, the possibility to use these structured fibers as strain fuse sensor. A very simple phenomenological model has been proposed. (C) 2014 Elsevier B.V. All rights reserved.