AN APPROACH TO THE MECHANICAL-BEHAVIOR OF SIC/SIC AND C/SIC CERAMIC MATRIX COMPOSITES .2. THEORETICAL APPROACH

A model is proposed for the mechanical behaviour of continuous fibre-reinforced ceramics. This model was applied to the bidirectional SiC/SiC and C/SiC composites examined in Part 1 of the present paper. This model satisfactorily predicted the load-displacement relations for bending specimens, from an intrinsic constitutive law based on data measured in tension. However, the results were weakened by the significant scatter exhibited by experimental data. The constitutive law was also theoretically determined from matrix and fibre properties: matrix cracking was predicted by an approach generalizing the Aveston-Cooper-Kelly theory, predictions of fibre failure used numerical simulations. Theoretical values were significantly over-estimated, which was attributed to the contribution of microstructural flaws to the fracture process.