Damage development under gradual loading of composites

We present a theoretical investigation of damage development in Ceramic Mat rix Composites (CMC's) before catastrophic failure under gradual loading co nditions. The aim of the work is to give a theoretical interpretation of th e experimental results on the development of damage in the C/C-SiC composit e obtained by cyclically loading, unloading, and reloading a planar specime n. Our approach is based on statistical, micromechanical models of the fail ure of CMC's in the framework of global load sharing, where the failure mec hanism includes quasi-periodic matrix cracking, gradual breaking of fibers, and sliding of broken fibers with respect to the matrix. It is demonstrate d 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.