Crack modeling in charring ablation materials

Modern Thermal Protection Systems (TPS) used for planetary exploration missions often utilize light-weight porous materials as its outer isolating layer. The combination of large heat flux and shear force during the atmospheric entry can compromise the TPS overall integrity. Therefore, it is of paramount importance to accurately understand how and when these porous materials fail. In this study, a crack model is developed and implemented into a material response solver for charring ablation problem. The numerical model is validated through comparison with experimental data on FiberForm. Results show that a higher level of scattering in material properties leads to more localized failure, yet it is not a sufficient factor for crack penetration and development. In addition, the developed model show a great capability to capture the thermal-mechanical erosion, which accelerates the energy penetration and result in unexpected failure mode such as tunneling. Three-dimensional modeling also show different results, including the tunneling-like failure on the exposed surfaces.