Experimental and numerical analyses on the stiffness of three-dimensional woven carbon preform reinforced cellular matrix composites

Three-dimensional cellular matrix composites (3DCMC) and three-dimensional regular matrix composites (3DRMC) were fabricated and tensile tested. The experimental results showed that the stiffness of 3DCMC was lower than that of the 3DRMC. Because of significant density reduction of 3DCMC, their specific stiffness was found to be 12–19% greater than that of the 3DRMC. Stiffness averaging method was used for prediction of the tensile modulus for both 3DCMC and 3DRMC materials. Reasonable agreement between the computational and the experimental results were obtained for 3DRMC (within 3–6%) but a larger discrepancy (18%) existed for 3DCMC. By treating the whole 3DCMC as a special type of rigid foam material, an empirical correlation between the ratio of the moduli and that of the densities of 3DCMC and 3DRMC was used to accurately predict stiffness of 3DCMC from that of 3DRMC (within +-2–5%).