Monitoring the effects of planar constraint on strain accumulation during epoxy resin curing process using fibre Bragg gratings

The control and monitoring of epoxy resins' curing process is crucial for ensuring product quality and minimizing production times. The curing of epoxy resin involves changes in temperature, strain, and refractive index. Strain accumulates during the curing process as a result of several factors, including changes in temperature and resin crosslinking. We report an experimental investigation on strain accumulation during the epoxy curing process using fibre Bragg gratings sensors. We studied strain accumulation in resin samples that were either unconstrained or constrained in a plane, similar to how resin hardens in a mould. The results show that strain primarily accumulates during the cooling of the cured epoxy. The sample with a planar constraint develops anisotropic strain, which causes changes in the spectrum profile of the fibre Bragg gratings.