Microstructure characterization from X-ray micro-tomography and equivalent mechanical properties of carbon matrix of 4D in-plane carbon/carbon composites

The present work uses high-resolution X-ray tomography to measure inner structures characteristics of multi-directional braided carbon/carbon composites so as to obtain probability density function of size distribution of microscopic structure in matrix. Based on the theory of non-homogeneous equivalent inclusion, it is easy to establish mathematical analysis model of effective elastic properties of carbon matrix. Strength theory of porous medium is adopted to deduce strength calculation model. The study shows that there are many holes which are randomly distributing and anisotropic. The size of these holes fit normal distribution. Specifically, they are within the range of 20 μm to 200 μm. We work out the equivalent stiffness and strength by introducing the statistical regularities of characteristics of carbon matrix into equivalent mechanical model .It is clear that find out that the hole can impact mechanical properties of matrix significantly .And when the hole fit normal distribution, the stiffness and strength of matrix can also fit normal distribution.