Experimental investigation on the compression properties and failure mechanism of 3D braided composites at room and liquid nitrogen temperature

The compressive experiments on the 3D braided composites with different braiding parameters are performed in three directions (longitudinal, in-plane and transverse) 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 that the stress-strain curves and the compression properties are significantly different in the longitudinal, in-plane and transverse direction. Meanwhile, the compression properties at liquid nitrogen temperature are improved significantly than that at room temperature. Moreover, the damage and failure patterns of composites vary with the loading directions and test temperature. At liquid nitrogen temperature, the brittle failure feature becomes more obvious and the interfacial adhesion capacity is enhanced significantly. In addition, the compressive properties and failure mechanism at room and liquid nitrogen temperature can be significantly affected by the braiding angle and the fiber volume fraction.