FEA simulation and experimental validation of mode I and II delamination at the carbon/glass/epoxy hybrid interface: Physical-based interpretation

The aim of this study was to carry out simulations and perform experimental quasi-static delamination tests in modes I and II to characterize the mechanical behavior at a hybrid interface. For that purpose, contact angle, infrared spectroscopy, and energy balance model results were obtained to characterize the physical interfacial energy behavior. The simulations and experimental tests presented similar values and trends, indicating that this is a viable method for predicting the critical fracture toughness of hybrid laminated composites. The low interfacial energy of the stitching (PS) and the epoxy matrix showed a decrease in the experimental strain energy release. The hybrid interface (carbon/glass/epoxy) showed an improvement in fracture toughness, which was physically elucidated through the synergy of high CF/epoxy interfacial energy strain combined with the toughness interaction via organosilane in GF/epoxy interface. In addition, the directional change in the micro-cracks generated between the two interfaces (rough fracture) requires an increase in energy to propagate the delamination as a result of the synergy between the CF and GF stiffness, also confirmed by the physical-based model.