Modeling and Experimental Study of Off-Axis Tensile Properties in 3D Braided Composites

This work explores the off-axis tensile behaviour of three-dimensional braided ceramic matrix composites through a combined experimental and theoretical approach. Uniaxial tensile tests were performed at different off-axis angles (0°, 45°, 60° and 90°) to evaluate the anisotropic mechanical performance of the composites. The results show a clear degradation in tensile strength and stiffness with increasing off-axis angle, reflecting a strong directional dependence. Strain field evolution and failure morphology analyses indicate a transition in damage mechanisms from fibre dominated fracture at low angles to matrix cracking and interfacial debonding at higher angles. A theoretical model that integrates yarn orientation and microstructural characteristics was established to accurately predict the off-axis tensile modulus, demonstrating consistency with both experimental data and finite element simulations. These findings offer critical understanding of the failure mechanisms in 3D braided ceramic matrix composites and serve as a practical guide for their use in anisotropic structural settings.