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

A micromechanically based continuum damage mechanics material law is develo ped for fiber-reinforced ceramics. Its parameters and internal variables ar e obtained from micromechanical models rather than from macroscopic experim ents. Micromechanical models are derived for the damage and failure mechani sms observed in 2D C/C-SiC composite samples loaded by tension, shear and c ompression. 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 in itiates cracks oriented at 0 degrees /90 degrees and 45 degrees to the fibe r axes, the latter causing fracture. Specimens loaded in compression exhibi t catastrophic failure due to microbuckling of fiber bundles. Simulation re sults show the ability of the developed model to describe the observed fail ure mechanism in experiments. (C) 2001 Elsevier Science Ltd. All rights res erved.