12. Experimental and Analytical Study of Process-induced Stress in Reinforcement Fibers of FRP

Abstract

In the present study, the evaluation method for process-induced stress of thermosetting FRP has been developed by in-situ strain evaluation using an FBG sensor and an viscoelastic FEM analysis. A model specimen of glass optical-fiber reinforced polymers where the FBG sensor were embedded, was manufactured for the evaluation. 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. The mechanical properties of resin used for the simulation were represented as functions of degree-of-cure and tempeature. Since the FEM results agreed well with experimental result, it was found that viscoelastic properties, thermal expansion and curing shrinkage of resin play significant roles for generating process-induced strain of fibers. In addition, simulated results show that the process-induced strain decreases when heating rate is smaller.