Abstract
In the present paper, process monitoring of GFRP laminates during a hot-press molding was conducted by fiber-optic index sensors. From the measured optical power, it appeared that the transverse molding pressure of 0.5MPa applied to optical fibers did not affect the sensor outputs. It was also found that resin flow which covered the sensing part was clearly indicated as sudden fall of the reflected optical intensity. The refractive index curves obtained from the sensor outputs showed that large fluctuation existed in the sensor signal due to scattering from air-voids in resin. The fluctuation disappeared within 20 minutes because the voids were vacuumed. The trend of index curve turned from decrease to increase because of proceeding of cure reaction and then became constant when cure reaction finished. From these results, it appeared that the embedded refractive index sensor could detect resin flow and void vacuuming as well as degree of cure.
