13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- 4. Numerical results Damage analysis of hexahedron RVE in the ablation process was carried out first. The numerical example was presented to bring out for analyzing the potential ablation damage location. The finite element model was implemented in ABAQUS using a heat transfer element to analyze the ablation property of C/C composites during high temperature radiation of 2000℃. Figure 5 shows the heat flux distribution in a time of 0.13 seconds. The thermal flux magnitude of the 14 nodes along the circumscribed circle radius of the hexahedron is shown in figure 6. Figure 5. Heat flux distribution in micromechanical structure at 0.13seconds The simulation result indicated that the heat flux at the interface between fiber and matrix is maximum, which make the interface damage easily, as shown in red colored area in figure 5. The result in figure 6 demonstrated that because of the mismatch between fibers and matrix, the thermal flux at the interface jumps to a higher value than the values inside the fiber, implying the debonding between fibers and matrix may happen during the ablation process. Figure 6. Variation of heat flux of selected nodes Next, the damage analysis of Cylinder RVE in the ablation process was conducted. The numerical simulation focused on the temperature rise period of cylinder RVE in ultra thermal radiation environment. According to the symmetry of the cylinder RVE of C/C composites, a 3D axisymmetric model was established in software ABAQUS. The heat-transfer element was used to simulation the progress of temperature rising up during the ultra thermal radiation. It was subjected to specified surface radiation interaction with a temperature of 2000℃on the surfaces except the
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