Epoxy-based fiber-reinforced composites are widely utilized in aerospace applications due to their mechanical properties, thermal stability, and chemical resistance. However, it is known that materials become brittle, and poor crack resistance restricts their applications in cryogenic engineering. The purpose of this paper is to experimentally investigate the effect of cryogenic temperatures on the low-velocity impact (LVI) behavior of composite laminates. Additionally, the effect of matrix modification in the studied composites was investigated. The LVI tests were conducted at RT (room temperature), 0 °C, -50 °C, -150 °C, and -196 °C (liquid nitrogen temperature) on the composite laminates to measure the influence on their energy absorption capacity. LVI tests were performed according to ASTM-D-7136 standard under 10, 20, and 30 J impact energy levels. The results show that the contact forces and energy absorption capacities are improved by adding SiO2 nanoparticles into the epoxy matrix. The absorbed energy at cryogenic temperatures increased by 24.87%, from 18.1 J for pure epoxy resin to 22.7 J for modified epoxy. For comparison, the LVI properties of composites at RT were also investigated. It is noted that the energy absorption capacity is not higher at cryogenic temperatures than at RT for both modified and neat epoxy composites. Moreover, the peak contact forces are reduced under low-temperature conditions.
