Investigation of the Interfacial Failure Criterion at Glass Fiber/Epoxy Matrix by the Cruciform Specimen Method Considering the Debonding Initiation Location

Abstract

This paper evaluates interfacial failure criterion under combined stress state and precise location along the fiber circumference of interfacial failure (debonding) initiation at glass fiber fiber/epoxy interface by the cruciform specimen method. The effects of both thermal residual stress occurred during specimen preparation and inelastic stress-strain constitutive relationship of matrix resin on the evaluation of interfacial failure criterion are considered. The interfacial stresses distribute along with fiber circumference. In this study, the location of interfacial failure initiation is specified and the interfacial failure criterion is evaluated. By changing the cruciform arm angle (the angle between the fiber and the loading directions), various combined stress states are obtained which make it possible to evaluate the interfacial failure criterion. Both the quadratic and parabolic criteria are assumed and discussed.