Micromechanical consideration of interface damage in fiber reinforced Ti-alloy under various combined loading conditions

Initiation and propagation of interface damage of a unidirectional SiC/Ti-6Al-4V metal matrix composite (MMC) subjected to biaxial loading is investigated using a three-dimensional finite element micromechanical model. The model includes effects of manufacturing process thermal residual stress, fiber coating and interface bonding. The model consists of SiC fibers, titanium matrix, fiber coating and two distinct interfaces. The two interfaces are employed to investigate effects of various bonding levels of the interfaces. Different failure criteria, which are combinations of normal and shear stresses across the interface, are used to predict initiation and propagation of damage in fiber/coating (f/c) and coating/matrix (c/m) interfaces. Results show that the presented model provides more accurate results when compared with experimental data in uniaxial loadings beyond the yield point. Furthermore, failure modes during biaxial tension/compression loading in the presence of residual stresses are discussed in details.