A novel micromechanical model to study the influence of cure process on the in-plane tensile properties of z-pinned laminates

This paper proposes a novel micromechanical model to study the curing effects on the in-plane tensile properties and failure mechanisms of carbon/epoxy laminates reinforced with z-pins. The microstructures including fiber distortion and resin-rich pockets caused by z-pins are characterized. The results indicate that cure-induced residual stresses greatly exist with increasing z-pin density. Thermal expansion and volume shrinkage mismatch between z-pins and resin-rich regions attribute to the high stress concentration. The existence of interfacial stress concentration and resin-rich channels produce a loss of tensile strength and lead to an initial pathway for crack growth under tension. The failure mode changing from the interfacial cracking to softening and damages of both interface and resin-rich regions is also revealed with increasing z-pin density.