Cryogenic Compression Properties and Failure Mechanism of Lightweight 3D MWK Carbon Fabric Reinforced Epoxy Composites

Lightweight 3D MWK carbon fabric reinforced epoxy composites are fabricated successfully. The compressive experiments on the 3D MWK carbon/epoxy composites with different fiber architecture are performed in three directions (longitudinal, transverse and in-plane) at room and liquid nitrogen temperature (low as -196 °C). Macro-Fracture morphology and SEM micrographs are examined to understand the deformation and failure mechanism. The results show 3D MWK carbon/epoxy composites have extremely compression properties at cryogenic temperature. The stress-strain curves and compression properties at liquid nitrogen temperature are improved significantly than those at room temperature. Meanwhile, the properties decrease with the increase of fiber orientation angle at room and cryogenic temperatures. Moreover, the compression properties are different in the longitudinal, in-plane and transverse direction. The results also show matrix is solidified and fiber/matrix interface adhesion is enhanced at cryogenic temperature and the main failure modes of material behave as fiber layers delaminating, fibers and bulk matrix shear fracture. In addition, the failure mechanism can be significantly affected by the temperature, fiber architecture and load mode.