Micro-porosity as damage indicator for characterizing cyclic thermal shock-induced anisotropic damage in oxide/oxide ceramic matrix composites

Ceramic matrix composites display complex mechanical behavior under thermo-mechanical loading conditions. The present work focuses on micro-structural evolution and resultant macroscopic property representation of the composites after cyclic thermal shocks. Micro-structural investigation reveals that variations of the hierarchical porosity in the matrix characterize the collective behavior of micro-structural evolution in the material. Cyclic thermal shocks induce thermo-mechanical damage and lead to increasing matrix porosity. Material damage development is driven by elastic strain energy density which is related to the matrix porosity increment. Experiments confirm that the anisotropic damage can be represented by the porosity increment accurately. The porosity provides a meaningful model for the thermal shock damage evolution in the anisotropic composites.