SLIP AND FRICTIONAL SHEAR STRESSES IN CERAMIC-MATRIX COMPOSITES

Ceramic materials reinforced by continuous ceramic fibres show enhanced toughness in the case of weak conditions of load transfer at the Fibre/Matrix interface. Load transfer in these materials mainly takes place through interfacial friction. The corresponding shear stresses are investigated in the present work with the aid of both an analytical and a finite element analysis of the thermomechanical stresses in a microcomposite consisting of one fibre surrounded by a cylindrical outer tube. The applied method is able to describe the non-homogeneous field of frictional shear stresses induced by the presence of a matrix crack. Stresses are analysed for two different material systems (SiC/Glass and SiC/SiC) and compared with experimental data for SiC/SiC reported elsewhere. Comparison between the analytical and experimental results has revealed the necessity to consider the effect of roughness of the created slip planes on the frictional shear stress.