Multiscale modeling of thermal ablation in fiber reinforced composites



Journal Title

Journal ISSN

Volume Title



The development of improved numerical methods and physical models of thermal ablation is necessary for reducing uncertainties in the prediction of Thermal Protection System (TPS) performance and hence the reduction of TPS weight and the maximization of aerospace vehicle payloads. Models simulating ablation must address significantly disparate temporal and spatial scales, including molecular scale chemical physics of resin pyrolysis and macroscale resin and fiber ablation. Numerical methods must also be able to account for solid erosion effects and the resulting geometry evolution. This research has developed the first discrete nonholonomic Hamiltonian approach for the multiscale modeling of thermal ablation. The model incorporates three scales of interest, including a reacting molecular dynamics model at the nanoscale and hybrid particle element models at the meso and macro scales. Unlike all previous works in literature, the disparate temporal and spatial scales of the ablation problem are addressed, in part, by incorporating a fully coupled chemical-thermomechanical ablation model at the mesoscale. The research builds on previous work on the hybrid particle element method by the addition of variable mass particles at the meso and macro scales, as well as a description of the resin and fiber composite architecture in the macroscale model. Solid erosion effects and the resulting surface recession are accounted for explicitly in the particle-element kinematics. The presented methodology improves on existing macroscale models in three main respects: first, the solid dynamics is modeled explicitly with full chemical-thermomechanical coupling at the mesoscale and thermomechanical coupling at the macroscale, second mass and energy is rigorously conserved in the formulation of the state space equations, and third a general method of accounting for solid erosion effects and geometry evolution is included. The formulation is validated by comparison with published ablation experiments on fiber reinforced phenolic and cyanate ester composites.


LCSH Subject Headings