Investigation on the High-velocity Impact Resistance in Grid Composite Plates Containing Carbon Nanotubes

Grid composite structures are a new generation of composite materials which due to their unique design (consist of network of stiffeners which have been located upon a skin) possess high specific strength and stiffness, as well as excellent energy absorption. In this study, the effect of addition of multi walled carbon nanotubes in various weight percentages (0, 0.1, 0.25 and 0.4) on the high-velocity impact properties of grid composite plates was investigated. Multi-walled carbon nanotubes by using mechanical stirrer and ultrasonic waves were dispersed into the polymeric matrix. Grid composite plates with hexagonal geometry were fabricated by hand lay-up method and then high velocity impact test by cylindrical projectile with conical nose was performed on these plates. Experimental results showed that the presence of network of ribs which reinforced with carbon fibers restricts the damaged area and increases the energy absorption. For grid composite plates, the best high-velocity impact behavior was obtained with the addition of 0.4 wt. % of carbon nanotubes which in this case, the ballistic limit velocity and absorbed energy during highvelocity impact was increased by 11 and 22%, respectively. Also with the addition of multi walled carbon nanotubes, the damage size of grid composite plates was decreased.