High-fidelity modelling of damage mechanisms in through-thickness reinforced composites

A high-fidelity model of a composite through-thickness reinforced with a z-pin was generated in order to study and characterise the increase in damage tolerance brought by this type of reinforcement. A coupled cohesive-friction interface model was developed and implemented to characterise the frictional behaviour between the z-pin's surface and the composite during the different stages of damage propagation. A thermo-visco-plastic constitutive model is used to model the epoxy behaviour. Failure of the z-pin is captured considering a maximum tensile failure and maximum longitudinal shear failure criteria. High-fidelity of the geometry of the model is achieved thanks to an automated script capable of reproducing all geometrical features of the reinforcement. Different mixed mode loading conditions (tension and/or shear) were applied to the model and the apparent increase in toughness, as well as the different phenomena leading to this increase were captured. The study was repeated for different stacking sequences next to the delamination plane so that a more reliable design of experiments could be performed, especially in a high-rate testing regime.