Thermo-elastoplastic behavior prediction of CMCs considering the effects of the temperature and off-axis angle

Aerospace applications require advanced thermal protection systems to withstand increasingly extreme conditions. Ceramic matrix composites (CMCs) have become crucial materials owing to their outstanding thermostructural performance. Nevertheless, CMCs display intricate mechanical responses under multi-axial thermomechanical loads. Temperature variations combined with off-axis loading from 0° to 90° result in unpredictable strengthening or degradation mechanisms of the material. The experiments performed are not only costly but also technically demanding. In this study, a 3D thermo-elastoplastic constitutive model considering the effects of temperatures and off-axis angles is developed to predict the stress–strain behavior of the ceramic matrix composite. Kinematic hardening and isotropic hardening are considered to describe plastic deformation. The off-axis angle is considered a state variable in the model to characterize the effect on the mechanical behaviors. The material parameters in the model are identified from experiments at different temperatures and off-axis angles. The mechanical behaviors of the C/SiC composite are predicted by the theoretical model without further adjusting the parameters. The comparison of the prediction results with experimental data shows good agreement, indicating that the model can accurately capture the mechanical behaviors of the ceramic matrix composite. By using the proposed constitutive model, the effects of temperature and off-axis angle on mechanical behavior are discussed.