Damage initiation and collapse behavior of unidirectional metal matrix composites at elevated temperatures

A two-dimensional micromechanical finite element model is developed to investigate the transverse behavior of SiC/Ti-6Al-4V metal matrix composite (MMC) at elevated service temperatures with a square representative volume element (RVE). The effects of various parameters such as manufacturing process thermal residual stress, fiber coating and interface damage are considered. Proper interface elements between fiber/coating (f/c) and coating/matrix (c/m) together with appropriate failure criteria are introduced to include interface damage in the model. A user defined subroutine is employed to implement interface failure. Predicted results show good agreement with the available experimental data at various elevated temperatures. Results reveal that initiation of f/c interface damage is the first failure mode and its sensitive to temperature mainly due to different residual stress states at higher temperatures. Furthermore, due to lower strengths of c/m interface and matrix at elevated temperatures, collapse stress of the composite decrease critically at elevated temperatures.