Analysis of anisotropic thermal conductivity of unidirectional fiber reinforced CMC materials considering mechanical damage

To estimate the equivalent thermal conductivity of Ceramic Matrix Composite （CMC） after mechanical damage， considering the significant anisotropy in the material’s thermal conductivity due to its internal heterogeneity and non-uniformity， the impact of material mechanical damage on its anisotropic thermal conductivity is explored. In the study， a microscale analysis model was established to reflect the mechanical damage characteristics of materials. Under two distinct constant temperature boundary conditions， namely axial and radial， the effects of matrix cracks， interfacial debonding， fiber fracture， and damage rate on the thermal conductivity of materials were analyzed and compared. The results indicate that， the fiber fracture has the greatest impact on the axial thermal conductivity of the material， while interfacial debonding has the greatest impact on the radial thermal conductivity of the material. Additionally， as the damage rate increases， the overall anisotropic thermal conductivity of the CMC material decreases， with the greatest impact on the axial thermal conductivity. In the calculation conditions presented in this article， when the damage degree reaches 5%， both the axial and radial thermal conductivities of the material attain their minimum values among all considered conditions， which are 16.245 6 W/（m·K） and 10.173 3 W/（m·K） respectively. Compared to the undamaged state， the axial and radial thermal conductivities decrease by 34.5% and 5.33%， respectively.