Characterization and statistical modeling of irregular porosity in carbon/carbon composites based on X‐ray microtomography data

Source abstract

Abstract Statistical analysis procedure is proposed to characterize volume, shape and orientation distribution of pores in chemical vapor infiltrated carbon/carbon composites. The microstructure data is provided by X‐ray microtomography. To characterize orientation distribution of pores, probability distribution functions of pore volume, orientation angles and principal moments of inertia are constructed. Based on this information, a statistically significant range of pore geometry parameters is determined for evaluation of their contribution to the effective elastic properties of the material. Using the design of experiment approach, a subset of 53 pores is selected for the finite element simulations. The results are analyzed to construct a 3‐factor stochastic model of a pore contribution to the overall elastic response based on its geometric parameters. It is determined that the non‐dimensionalized surface to volume ratio factor plays an important role for pores in this type of material. A 4‐factor model incorporating this ratio is proposed. The model is validated by direct finite element simulations for a set of 150 randomly selected pores not included in the initial subset. The accuracy of the proposed approach is compared with the traditionally used approximation of pores by equivalent ellipsoids.