A Fiber Optic Ultrasound Sensor for Monitoring the Cure of Epoxy

Epoxy is a common matrix material in fibrous composites and is frequently used with: kevlar, glass, carbon, and boron fibers. Composite materials with an epoxy matrix are processed in an autoclave which applies temperature and pressure to the part during cure. Temperature and pressure facilitate the crosslinking of epoxide groups which react with amine groups present in the epoxy resin. Current methods of hardening fiber/epoxy composites utilize predetermined values of temperature and pressure in the cure cycle. These values are specified by the manufacturer and do not account for batch to batch variations in the epoxy resin which affect the cure. Possible variations in the epoxy resin include: chemical composition, water content, resin fiber content, temperature history, and humidity [1].