Optical fibre sensor for monitoring flow and resin curing in composites manufacturing

An optical fibre has been used as an intensity-based, dual-purpose sensor for the monitoring of the progress of fluid front infiltrating a reinforcing fibre mat and the curing of an epoxy resin in composites manufacturing. The sensor length comprised the fibre core, initially surrounded by air or vacuum and subsequently covered by the infiltrating fluid. Two configurations were tested for flow sensing, where a step-change or a continual output signal was obtained, respectively. The sensor was also used to monitor the curing of resin, where the power output was falling as the surrounding resin was curing. The sensor was successful at determining the gel point, which was in agreement with rheological data.