▎ 摘　　要

This work evaluates the effects of modified-graphene oxide (M-GNs) loading and graphene nanoplatelets (GNs) modification on the low-velocity and high-velocity impact (LVI and HVI) behaviors of aramid fiber/epoxy composites. Aminopropyltrimetoxysilane compound was used to modify the surface of the GNs. The epoxy resin was incorporated with 0.1, 0.3, and 0.5 wt%M-GNs to fabricate the multiscaleM-GNs/aramid fiber/epoxy composites via the hand lay-up route. The obtained results from the LVI and HVI tests revealed that the highest impact resistance was related to the multiscale specimen having 0.3 wt%M-GNs. For example, under LVI conditions (impact energy of 60 J), the addition of 0.3 wt%M-GNs enhanced the force peak and absorbed energy of the composite by 44% and 95%, respectively. The addition of 0.3 wt%M-GNs increased the ballistic limit and absorbed energy of the composite (exposed to the HVI) by 23% and 52%, respectively. The fracture surface of the specimens was evaluated by scanning electron microscopy to find the dominant mechanisms. It was also found that the incorporation of theM-GNs reduced the damaged area and enhanced damage tolerance. The results demonstrated that modification of the GNs enhanced the LVI and HVI properties of the multiscale composites.