Multiscale modelling of curing-induced z-pin/composite interfacial cracks

The curing process generates thermal residual stress in z-pinned composites, leading to partial or complete cracking along z-pin/composite interfaces. In this study, we applied a novel multiscale framework to evaluate the delamination behaviors of z-pinned composites considering the effects of z-pin/composite interfacial cracks. Unit cell models were used to represent the typical microstructures and micromechanisms of z-pinned composites with diverse interfacial conditions and to predict z-pin pullout behaviors. The derived z-pin bridging laws are then used to simulate the behaviors of individual z-pins in macroscale models. The load-versus-displacement relationships of z-pinned composites under mode-Ⅰ loading conditions are predicted using macroscale models and then verified experimentally. A parametric study reveals that interfacial cracks can affect the failure behaviors of z-pinned composites by changing the microscale bridging mechanisms of individual z-pins. It is theoretically feasible to customise z-pin/composite interfacial bonding properties, z-pin surface roughness, and curing temperature to optimise the delamination properties of z-pinned composites.