Numerical investigation of nonlinear structural responses in ablation problem

The ablative Thermal Protection System materials often exhibit nonlinear behaviors during charring ablation. The decomposing virgins often cause a large variation in displacement and stress distributions at early stage; the large temperature and temperature gradient cause the nonlinear thermal expansion at certain locations; and the large non-linearity in material properties often cause the unpleasant large thermal strains and the residual thermal expansion after cooling off. In this study, a nonlinear structure response code is developed to investigate all of the complex behaviors in charring ablation. Detailed mathematical formula and derivations will first be presented. Then, verification and validation will be presented to show the correct implementation of the solver. Finally, the charring ablation test cases will be provided for both a 1D case and an iso-Q sample test case. The 1D case will focus on the stress development during charring ablation while the iso-Q test case will focus on the nonlinear thermal expansion and residual deformations.