Synergistic toughening modification and finite element analysis of carbon fiber/epoxy resin‐reinforced composites

Abstract In this work, the poor fracture toughness of carbon fiber‐reinforced composites (CFRPs) was improved by the introduction of a graphene oxide/nanosilica (GOS) hybrid, and short carbon fibers (SCFs) were investigated through experimental and modeling methods. The effects of the SCF content, number of SCF layers, and introduction position on the mode I fracture toughness (G_IC) and mode II fracture toughness (G_IIC) of the composites were considered for epoxy resin (EP) modified by GOS. The results showed that GOS and SCF exhibited a synergistic toughening effect on CFRP. The G_IC and G_IIC of CFRP laminate with GOS content of 0.2 wt% and SCF content of 0.4 wt% reached 0.506 and 2.15 kJ/m², increased by 72.2% and 53.6% compared to the unmodified composite, respectively. The number of layers and the lamination mode of GC10S5‐B specimens exhibited the optimal improvement of interlaminar fracture toughness. Similarly compared with those of the original. The G_IC and G_IIC of the CFRP laminates reached 0.662 and 0.506 kJ/m² (enhanced by 125.9% and 95%, respectively). In addition, the stress propagation path and distribution, and progressive damage of the CFRP composites were obtained to further reveal the toughness mechanism. Highlights Synergistic toughening of resin modification and short carbon fiber on modes I and II fracture toughness of composites were considered. Content of short carbon fiber and lay‐up methods on toughness performance were investigated thoroughly. Finite element models were established to reveal the stress progress and distribution and toughness mechanism.