The effect of fiber orientation on failure behavior of 3DN C/SiC torque tube

In this paper, the 3DN C/SiC torque tubes were fabricated by chemical vapor infiltration (CVI) combined with silicon melt infiltration (SMI) method with different fiber orientations (0°/90° and ± 45°) which leads to different density, torsional behaviors and failure behaviors. CT test was implemented to characterize the density heterogeneity. Using the density measured from Archimedes drainage method, FEM software was implemented to simulate the stress distribution of the tubes and calculate the failure stress. A good agreement with analytical model was obtained which helps a lot to failure analysis. Torsional tests were conducted using special attachments to a universal material test machine, the shear strain was calculated from the strain gauge, the shear strength was calculated by simplified formula, different torsional behaviors of two different fiber orientations were represented in the stress-strain curves. The fracture morphologies were observed by SEM, and the predominant factors of failure were analyzed. Torque tubes with fiber orientations of ± 45° have a higher torque capacity, modulus, and reasonable fracture morphologies, which is in good agreement with simulation results.