Effect of cryogenic temperature on the fracture toughness of graphite/epoxy composites

The research presented in this paper is an effort to better understand the interlaminar fracture behavior of graphite/epoxy composite laminates in cryogenic conditions. Double cantilever beam tests were performed on different types of specimens, at room and cryogenic temperatures, and the fracture toughness was calculated from their load-displacement diagram. Additionally, the fracture toughness of some plain-weave textile composite specimens and specimens treated with nanoparticles (38 nmAl(2)O(3)) were also measured. It was observed that all specimens, with the exception of woven composites, showed deterioration in fracture toughness at the liquid nitrogen temperature. Nanoparticle treated specimens showed an improvement in fracture toughness, both at room and cryogenic temperatures compared to the control specimens. The woven composite specimens showed an increase in fracture toughness at cryogenic temperature. The results indicate that woven fiber composites may have potential in lightweight cryogenic storage systems.