Cryogenic mechanical properties of CF/polymer composites for tanks of reusable rockets

Cryogenic properties of different types of CFRPs are experimentally evaluated to survey the basic applicability of different material systems to the cryogenic propellant tanks for future reusable launch vehicles. Temperature dependent material constants, tensile strength and interlaminar fracture toughness are experimentally obtained, together with detailed observations of matrix cracks and delaminations. Up to about 20% reduction in cryogenic static tensile strength is observed for most of the material systems tested. The damage initiation stresses also decreased under cryogenic conditions. The results indicate that matrix cracks may be one of the major critical issues when current material systems are applied to cryogenic propellant tanks. Numerical predictions of the delaminations and matrix cracks are conducted to theoretically support the experimental consequences.