Damage development under gradual loading of composites

We present a theoretical investigation of damage development in Ceramic Matrix Composites (CMC's) before catastrophic failure under gradual loading conditions. The aim of the work is to give a theoretical interpretation of the experimental results on the development of damage in the C/C-SiC composite obtained by cyclically loading, unloading, and reloading a planar specimen. Our approach is based on statistical, micromechanical models of the failure of CMC's in the framework of global load sharing, where the failure mechanism includes quasi-periodic matrix cracking, gradual breaking of fibers, and sliding of broken fibers with respect to the matrix. It is demonstrated that the non-linear characteristics of the constitutive behavior and the potential drop measured under uniaxial loading of a planar C/C-SiC specimen can be described with reasonable accuracy in the framework of statistical, micromechanical models. (C) 2000 Kluwer Academic Publishers.