Enhancing tensile performance and CFRP/steel interface properties of CFRP plates with nano-SiO2 and MWCNTs

The mechanical performance of carbon fiber reinforced polymer (CFRP) is a crucial parameter influencing the effectiveness of CFRP reinforcement. The addition of nano-toughening agents to the resin matrix can effectively enhance the mechanical properties of CFRP. This paper investigates the influence of nano-SiO2 and MWCNTs content (0.2, 0.4, and 0.6 wt%) as well as their blending ratios (1:3, 1:1, 3:1) on the tensile properties of CFRP plates using the vacuum assisted resin infusion molding (VARIM) process. Additionally, an assessment is conducted to evaluate how the tensile performance of CFRP plates affects the CFRP plate/steel interface performance.The results indicate that the resin viscosity increases with the addition of nano-toughening agents, with the resin viscosity experiencing a respective increase of 32.9% and 92.7% when incorporating 0.6 wt% nano-SiO2 or MWCNTs compared to pure resin. The inclusion of nano-toughening agents enhances the tensile strength of CFRP plates, with a more pronounced effect observed when adding 0.4 wt% nano-SiO2 or MWCNTs, resulting in respective increases of 41.5% and 31.5% compared to pure CFRP plates. When nano-SiO2 and MWCNTs are mixed, the tensile performance of the CFRP plate is inferior to that of plates with the same individual nanotoughening agents content. This is attributed to the excessively high viscosity of the resin matrix during mixing, hindering complete infiltration of carbon fibers. Therefore, in the manufacturing process of CFRP plates using the VARIM technique, it is advisable to consider resins with lower viscosity. Additionally, the utilization of CFRP plates with superior tensile performance contributes to enhanced CFRP/steel interface properties, although the tensile performance of CFRP plates does not alter the bonding slip curve of CFRP/steel double-lap joint specimens.