Effect of velocity variation on carbon/epoxy composite damage behavior

In this paper, the damage mechanism for carbon fiber-reinforced polymers composites was studied from low- to high-velocity impact for different velocity ranges. Initially, the composites were manufactured by using CU125NS prepreg in quasi-isotropic 16 layers pattern [0/±45/90]_2s in autoclave by adopting standard procedures. Specimens were also exposed to the simulated LEO environment and 0.42% total mass loss occurred due to out-gassing. Afterwards, the specimens were impacted with Al2017-T4 spherical projectiles of 5.56 mm in diameter, 0.25 g in weight for different velocities ranging from 500 m/s to 2200 m/s. With the impact velocity increase, the energy absorption was found to increase in the composite specimens, while the ratio of energy absorbed to total impact energy remains the same on average. Mainly, the fiber breakage and matrix fracture play a critical role in energy absorption, but delamination contribution also found increasing trend with the increase of impactor velocity. Afterwards, C-SCAN analyses were conducted to investigate the damage patterns, and it was found that the damage area increased with higher velocities. The delamination contribution increased on average by 12.7% for the velocity range of 2200 m/s in comparison to that for 502 m/s. On the basis of these findings, it was concluded that the contribution of fiber breakage, matrix fracture and delamination towards the damage mechanism of composites is greater for higher velocities.