Effect of cryogenic environments on failure of carbon fiber reinforced composites

The present study is concerned with damage and failure of CFRP composites under isothermal mechanical loads in the ambient and cryogenic thermal regimes. In an experimental study, the mechanical failure behavior of unidirectionally carbon fiber reinforced materials is investigated at ambient temperature and in a liquid Helium environment at 4.2 K under a variety of loading conditions. The effect of thermally induced damage is investigated on specimens exposed to cryogenic temperature without external mechanical load and subsequent testing till failure at ambient temperature. Three different materials including high modulus and intermediate modulus high strength fibers as well as epoxy and thermoplastic (PEEK) matrix systems are considered. The results are employed to investigate the applicability of different standard composite failure criteria in the cryogenic regime.