Torsional failure analysis of C/SiC and SiC/SiC combined CMC torque tube

To overcome the inherent limitations of the ceramic matrix composite (CMC) process and increase the torque capacity of CMC torque tubes, this study investigated the failure causes of 2D woven chemical vapor infiltration (CVI) C/SiC and SiC/SiC combined CMC torque tubes. The CT test was used to describe the non-homogeneous density distribution of the CMC torque tubes. Using the Archimedes drainage method to evaluate density and porosity, we simulated the stress distribution and failure strength of CMC torque tubes using an FEM model. Fixtures suitable for universal material testing apparatuses were used for CMC torque tube torsional tests. The stress-strain curves showed that two distinct fiber types of CMC torque tubes displayed different torsional tendencies, and we examined the main causes of failure. The SiC fiber in the CMC torque tube increased maximum shear stress and modulus. Additionally, the strength of the SiC/SiC torque tube, rather than the interface between the C/SiC and SiC/SiC torque tubes, was the primary cause of combined CMC torque tube failure.