Modeling the effects of stress concentrations on the initiation of matrix cracking in woven CMCs

Abstract

In this study, we employ detailed three-dimensional (3D) finite element models of plain and satin weave ceramic matrix composites (CMCs) as needed to establish the stress concentration around existing voids and their effect on the elastic response of these complex material systems. Fundamental 3D elasticity boundary value problems addressing the response of these materials under a combination of remote biaxial tension, in-plane shear, and thermal loading are utilized to characterize the matrix micro-stresses in the vicinity of large-scale macroscopic voids. The combined stress fields are then used to assess the conditions for the initiation of matrix cracking in such regions of high-stress concentration. Comparison of model results with available experimental data is discussed. Extensive parametric studies have yielded broad matrix cracking loci, which may be critical for the reliable use of woven CMCs in engineering applications.