Micromechanically based continuum damage mechanics material laws for fiber-reinforced ceramics

A micromechanically based continuum damage mechanics material law is developed for fiber-reinforced ceramics. Its parameters and internal variables are obtained from micromechanical models rather than from macroscopic experiments. Micromechanical models are derived for the damage and failure mechanisms observed in 2D C/C–SiC composite samples loaded by tension, shear and compression. In specimens subjected to tension, the early stage of damage is characterized by transverse cracking. Further load increase induces fiber failure in the longitudinal plies, what leads to fracture. Shear loading initiates cracks oriented at 0°/90° and 45° to the fiber axes, the latter causing fracture. Specimens loaded in compression exhibit catastrophic failure due to microbuckling of fiber bundles. Simulation results show the ability of the developed model to describe the observed failure mechanism in experiments.