Molding strain of glass fibers of model GFRP

Abstract

In order to evaluate strain induced by shrinkage of resin during cure process, model specimen of glass optical fiber-reinforced polymers were manufactured. Single FBG sensor was embedded in the specimen for measuring molding process-induced strain. From the experimental results, it was found that cure shrinkage strain as well as thermal strain should be considered for evaluating residual stress in reinforcing fibers. An viscoelastic FEM analysis was conducted to evaluate the molding strain of reinforcements. Mechanical and thermal properties of resin as functions of degree of cure were measured and used for the simulation. It appeared that the calculated results agreed well with experimental results. Therefore, it was found that viscoelastic property, thermal expansion and curing shrinkage of resin play significant roles for cure processinduced strain of reinforcing fibers of FRP. The ratio of cure process-induced strain by curing shrinkage of the resin to whole molding process-induced strain was 17.7%. This fact indicates that the effect of curing shrinkage of the resin should be taken into account for evaluation of molding process-induced strain of the reinforcements.