Microstructure Modeling and Further Effective Property Prediction for Plain Weave C/SiC Composites Considering Manufacturing Process

Abstract

The aim of this paper is to propose a systemic methodology to predict effective properties of plain weave C/SiC composites based on finite element computational micromechanics (FECM) method. Utilizing photomicrographs taken by scanning electron microscope (SEM), we established an accurate macro representative volume element (macro-RVE) model for plain weave C/SiC composites and a sub-RVE model for their carbon fiber bundles. Four classes of manufacturing porosity were taken into consideration, namely intersection voids; matrix cracks around fiber bundles; inter-fiber micro-voids; and interfacial micro-cracks. The presence of each of these classes of porosity has been confirmed by SEM observations. The undulation equations of carbon fiber bundles have been obtained from measurements of SEM photomicrographs of sectioned C/SiC composites to describe the actual fiber bundle architectures. Mix mode of equilateral triangle and square arrays was adopted to characterize the distributions of carbon fibers in fiber bundles. For the case of void-like porosity, periodicity and volume fraction have been used; and for crack-like porosity, periodicity of the cracks and their lengths have been measured and quantified. Intersection voids and matrix cracks around fiber bundles were implemented into the macro-RVE model and the rest two classes into sub-RVE model. The procedures to determine the elastic moduli using FECM method on the basis of homogenization theory were presented, in which the in situ properties of carbon fiber after manufacturing were used. Comparisons with experimental data show the validity of the proposed methodology.