Transverse tensile properties of laminar unidirectional carbon fiber-reinforced polymers enhanced with multiscale fiber-interleaving: Experiments and modeling

In this study, a micromechanics model, based on a hierarchical/gradient interface design, for predicting randomly hybrid carbon nanotube (CNT)/aramid pulp (AP) micro/nano-fibers interleaved in a laminar unidirectional carbon fiber-reinforced polymer (UD-CFRP) is proposed. The model emphasizes the gradient interfaces that are formed in situ because of the graded penetration mechanisms of the CNT and AP. Additionally, via an experimental study, it is analytically verified that CNT/AP-interleaving enhances the transverse tensile strength and modulus of the UD-CFRP. The modeling and experimental results show a strong correlation. The increase in transverse tensile strength and modulus of the UD-CFRP with CNT/AP hybrid interleaving and the associated hierarchical toughening mechanism are confirmed theoretically and experimentally. Furthermore, new insights into the multiscale toughening mechanisms of transverse tensile properties are obtained via systematic analysis. The hierarchical gradient interfacial structure formed by the penetration of CNT/AP-interleaving and multiscale fiber-bridging results in a transformation of the failure mechanism. Finally, the effects of the failure mechanism on model predictions and the applicability of micromechanical models are further discussed.Highlights A micromechanics modeling of UD-CFRP with CNT/AP-interleaving is proposed. The enhancements of CNT and AP are confirmed theoretically and experimentally. The contribution of CNT and AP to the properties of CFRP is theoretically verified. The effect of the hierarchical fiber-bridging toughening mechanism is revealed. The transverse tensile properties of UD-CFRP are enhanced by CNT/AP-interleaving and a micromechanical model is developed to predict the properties. image