A geometry-invariant fracture law for ceramic matrix composites

Abstract

This paper reports the development of a generalized fracture law that can assess the mechanical behavior of ceramic matrix composites (CMCs). The established law differs from conventional bridging laws in that it accounts not only for the bridging effect but also for all major energy dissipation mechanisms including matrix cracking and fiber pull-out. As such, the formulation can be used to directly assess the original, experimentally recorded, fracture behavior of the material in the load-extension domain. The established expression successfully approximated the experimental load versus beam deflection (P-u) curves of a SiC-fiber reinforced glass-ceramic matrix composite tested under the single-edge-notched beam (SENB) configuration. The fracture law was found to be geometry-invariant by comparison with results from tensile specimens with radically different damage zone geometries. A parametric analysis is presented which demonstrates the potential of the model in the a priori prediction of the fracture behavior of hypothetical CMCs with similar fracture characteristics.