Numerical studies on modeling heterogeneity in elastic properties of 8HS woven C/C composites

Abstract

The variation in fiber volume fraction and pores developed at the microscale during the manufacturing process is a source of heterogeneity in the elastic properties of woven Carbon/Carbon (C/C) composites. This study investigates the effect of heterogeneity on the elastic properties of Eight Harness Satin (8HS) woven C/C composites using a two-scale (micro–meso) finite element (FE) homogenization method. At the microscale, variations in fiber volume fraction and porosity are incorporated by generating 25 representative volume elements(RVEs) from the reconstructed CT scan images. The RVEs preserve the shape, size, orientation, and spatial distribution of pores that are present in the microstructure. The carbon fibers are virtually generated inside the 25 micro-RVEs using the random sequential adsorption (RSA) algorithm in accordance with the reconstructed microstructure of actual pores. At the mesoscale, the model incorporates warp and weft yarns embedded in a pyrolytic carbon matrix. Yarn heterogeneity is modeled by subdividing the meso RVE into smaller domains, each assigned elastic properties derived from the microscale RVEs. The degree of heterogeneity was varied using different combinations of the microscale RVEs to assign material properties. This approach effectively incorporates the randomness of the microstructure into the computation of the effective elastic properties of woven composites. The on and off-axis elastic properties of 8HS woven C/C composites are computed, and the results determined from the numerical study are compared with experimental tests conducted on 0° and 45° specimens. This study highlights the importance of fiber volume fraction and pores on material heterogeneity in accurately computing the elastic properties of 8HS woven C/C composites. © 2025 Taylor & Francis Group, LLC.