A predictive study of effective properties and progressive failure of tri-axially woven SiCf-SiC composites

Abstract

Effective properties and progressive failure of SiC matrix composites reinforced by tri-axially woven fabrics of SiC fibres (SiCf) are predicted using micromechanics and the finite element method. Two different orientations (i.e., –55°-0°-55° and –45°-0°-45°) of the woven fabrics are considered in geometrical modelling. Three-dimensional unit cells with the matrix reinforced by the fabrics in such orientations are constructed and used. Homogenisation analyses are carried out using the unit cell-based finite element models. It is found that the –55°-0°-55° fabric orientation provides higher effective elastic moduli and exhibits a response closer to being isotropic than the –45°-0°-45° orientation. The effective properties obtained are then used to conduct a progressive failure analysis of the SiCf-SiC composites subjected to uni-axial tensile loading. The progressive failure analysis incorporates both geometrical and material non-linearities, and describes the progressive damage induced by crack initiation and propagation via a material degradation model. The Tsai-Wu failure criterion is used, and a two-parameter Weibull distribution is employed to account for the changes in strength with increasing specimen volume. Based on this progressive failure analysis, true stress-strain curves for the SiCf-SiC composites are obtained.