Numerical study of mesoscopic ablation-erosion of C/C composites with inclined fibers

Carbon Carbon (C/C) composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion, and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles. We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers (CCIF). First, a thermochemical ablation model describing the reaction–diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process, and the corresponding surface ablation morphology is obtained. Then, the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis, and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method. Moreover, the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated, and the ablation-erosion behavior is analyzed and discussed. The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different, showing granular and block erosion phenomena respectively. The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow. These results can provide a theoretical basis for the design and optimization of thermal protection system materials.