Effect of needling parameters on the effective properties of 3D needled C/C-SiC composites

For 3D needled C/C-SiC composites, the in-plane fibers are transferred to out-of-plane direction by needling technology to enhance the delamination resistance capacity, while the breakage of in-plane fibers could be observed in needling regions. The distribution of needling regions is dense and disorder in the composites. Based on the observation of microstructures of the composites, four typical representative elements are chosen and established to predict the effective properties of needling and un-needling regions, where the local geometrical characterizations, such as fiber breakage and deflection etc., are taken into account. A periodic unit cell including needling and un-needling regions is constructed according to the needling process to predict the effective properties of the composites and study the effect of needling density, depth and distribution on the material performances further. It is verified that the predicted results are in good agreement with the experimental data and the effective properties of the 3D needled C/C-SiC composites are closely related with the needling parameters, which would be helpful to guide the manufacturing and design of the composites in the engineering.