Multiscale reactive model for 1,3,5-triamino-2,4,6-trinitrobenzene inferred by reactive MD simulations and unsupervised learning

When high-energy-density materials are subjected to thermal or mechanical aggression at extreme conditions (shock loading), a coupling between the thermo-mechanical and chemical behavior is systematically involved. We develop a reactive model for 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) at the mesoscopic scale where the chemical behavior and thermal transport properties of the system are determined by underlying microscopic reactive simulations.

All-atom reactive MD simulation are conducted and a reduced-order chemical kinetics model for TATB is fitted on isothermal and adiabatic simulations of single crystal chemical decomposition. Isothermal decomposition simulations, along with an unsupervised learning methodology, allow to calibrate a three components analytical formulation for the thermochemistry kinetics of TATB, and adiabatic simulations are conducted to determine the associated heats of reaction.



Finally, this analytical formulation, coupled to a diffusion and temperature evolution terms, is incorporated in a continuum formalism and the model is compared against one-to-one MD simulations of a 1D hotspot. A good agreement is found for both time and spatial evolution of the temperature field.