Comparison of glass-epoxy interface strengths examined by cruciform specimen and single-fiber pull-out tests under combined stress state

A cruciform specimen test and a single-fiber pull-out test are used to examine two glass-epoxy interface-failure envelopes under a combined stress state. A single fiber embedded in various off-axis directions for the cruciform specimen test creates various combined stress states. Finite-element analysis considering an inelastic constitutive equation of matrix resin and thermal residual stress is implemented for both tests. For the single-fiber pull-out test, a resin cone serving as the fiber entrance part, called the resin meniscus in this study, is modeled in finite-element analysis. This enables more precise calculation of interface stress around the interface failure point than calculations not considering the resin meniscus. The interface failure strengths obtained using the cruciform specimen and single-fiber pull-out tests show good agreement for both interfaces.