Characterization of Curing Stress Effects on Fracture Behavior of FRP Laminated Composites with Embedded Delaminations

Abstract

A detailed study on the effect of curing stresses on interlaminar delamination crack growth behavior in fiber-reinforced polymeric (FRP) composites is presented. At a given applied load or displacement, the strain energy release rate distribution along the delamination front with and without considering the effects of curing stresses are compared. In this analysis, results are presented for elliptical delaminations embedded between plies of different orientations in the laminate. A full three-dimensional coupled-field finite element analysis has been conducted to study the delamination crack growth behavior due to curing stress effects. A superposition procedure along with the modified crack closure integral technique based on the concepts of linear elastic fracture mechanics is employed to evaluate the individual modes of strain energy release rates during delamination propagation. It has been observed that the residual thermal stresses developed during the curing stages in manufacturing of FRP laminated composites significantly affect the onset and growth of delamination. The asymmetric behavior of interlaminar fracture energy along the delamination front is found to depend upon the stacking sequence, neighboring ply orientation, thermoelastic anisotropy, and material heterogeneity at the interface of laminated composites.