Composites with Embedded Optical Fibers at Structural Details with Inherent Stress Concentrations

A recurring issue relating to composites with embedded optical fibers is the concern that optical fibers will act as unintended crack initiators leading to untimely failure of the host structure. Previous studies have shown that there is little or no reduction in load-carrying ability as long as an optical fiber is embedded between similar plies and the optical fiber is, predominantly, in the fiber direction of these plies. However, most composite structures also contain structural details with inherent stress concentrations, and a need exists to investigate whether the introduction of embedded optical fibers into these regions will affect the load-carrying ability. In the present study, one composite lay-up containing ply-drops and one bolted joint configuration were studied. Results indicate that embedded optical fibers will not in general affect the structural integrity, as they did not initiate failure.