Mechanical behavior of unidirectional SiC/Ti composites subjected to off-axis loading at elevated temperatures

A micromechanical approach is used to study the damage initiation and nonlinear behavior of SiC/Ti composites subjected to a general complicated off-axis loading at elevated service temperatures. The effects of stress relaxation, interface damage together with fiber coating are considered. A cohesive zone model is applied to define the imperfect interface between the fiber and matrix. Introducing a unique failure criterion for all loading angles at different elevated service temperatures may be considered as the main contribution of this study. In order to simultaneously apply a combination of mechanical loadings and thermal residual stresses, appropriate periodic boundary conditions are imposed on the model. Predictions of the presented model show acceptable correlation with the reported experimental data at elevated temperatures. Results reveal that by increasing the service temperature, the strength of the composite is linearly degraded at fast rate especially at loading angles of 20° and 30°.