Numerical and experimental studies on scattered mechanical properties for 3D needled C/C-SiC composites

3D needled C/C-SiC composites show scattered mechanical properties in the experimental tests due to the random needling region distributions in the composites and the variability of microstructures at the needling regions. A specified methodology is developed to predict the scattered mechanical properties of the composites. Meso-scale models of the test specimens are established, in which the random distribution of needling regions and the uncertain properties of needling regions are considered. The predicted coefficients of variation for initial modulus, strength and failure strains of the composite agree well with the experimental results. Size effect of the test specimens on the experimental results is well analyzed by the proposed method. The influence of needling density, depth and distribution on the uncertainty of composite properties are also obtained. The methodology introduced by this work would guide the design of the proper specimen size and manufacturing needled materials with lower scattered mechanical properties.