High-strain-rate Response of GFRP Composites Impregnated with Multiwalled Carbon Nanotube Reinforced Shear Thickening Fluid

This study investigates the high-strain-rate impact performance of glass-fiber-reinforced polymer (GFRP) fabric that is impregnated with a shear thickening fluid (STF) and reinforced with multiwalled carbon nanotube (MWCNT) particles. Impact tests were conducted on four GFRP-STF and twelve GFRP-MWCNT/STF composite specimens under four strain rates using a split Hopkinson pressure bar apparatus. The MWCNT/STF specimens were synthesized by dispersing 0.4 wt%, 0.8 wt%, and 1.2 wt% MWCNT nanoparticles in silica-based STF (20.0 wt%). Scanning electron microscopy images confirmed that multiple silica and MWCNT nanoparticles adhered to GFRP fibers and filled the spaces between the fibers. In addition, MWCNT improved the peak viscosity of silica-based STF and degraded the elastic and storage moduli at high strain rates. Split Hopkinson pressure bar testing revealed that GFRP-MWCNT/STF had a significant strain-rate-dependent effect on the peak stress and energy absorption, which was most significant before the failure of the specimen. Compared with GFRP-STF, 0.8% MWCNT/STF improved the peak stress and energy absorption of GFRP by up to 99.4% and 57.1%. Increasing the MWCNT mass fraction improved the peak stress and energy absorption of GFRP-MWCNT/STF and significantly improved the secondary energy absorption capacity, especially when the strain rate was small. In particular, the maximum increase was 41.2%.