A novel mechanical behavior and failure mechanism analysis of 3D six-directional braided composites in liquid nitrogen subjected to compression

The influence of temperature, braiding angle, and braided structure on compressive mechanical properties and failure mechanisms of three-dimensional six-directional braided composites (3D6DBCs) were comprehensively analyzed. At low temperature, the out-of-plane and transverse strength increased by 16.2% and 50.1%, respectively. Interfacial damage caused a 25.3% decrease in longitudinal strength. The increase in braiding angle leads to a decrease in longitudinal and transverse strengths. At room temperature, the failure of the yarn-matrix interface and the deformation of the composites are the main reasons for the failure of 3D6DBCs. At low temperature, 3D6DBCs exhibits brittle fracture and shear failure modes. The braiding angle affects the deformation of 3D6DBCs. The composites with different braided structures have significant property differences. The addition of axial and transverse yarns significantly improves the longitudinal and transverse properties of 3D6DBCs.