Solid Propellant Shock to Detonation Modeling and Formulation

The objective of this project is to develop software capable of predicting shock-to-detonation transition (SDT) of solid propellant formulations. SDT is prompted by localized events, occurring at the meso-scale (material) level, and leading to hot spots (e.g., adiabatic shear bands, hydrodynamic hot spots, and void collapse), which trigger violent chemical reactions. However, for the reaction to be able to propagate, the diameter of the propellant must be above a (propellant dependent) critical value for which chemical energy generation exceeds loss processes. A multi-scale finite element based model is employed to simulate SDT in composite solid propellants. This approach permits the incorporation, in a single analysis, of meso-scale structure effects such as void collapse, with the macro-scale characteristics such as the external diameter and bore shape of the solid propellant. A coupled thermal-mechanical-chemical model represents the propellant. The proposed approach will be implemented in a nonlinear finite element code. In order to demonstrate the feasibility of the proposed approach, numerical simulations of the Naval Ordnance Laboratory Large-Scale-Gap-Test will be carried out. The results of these simulations will be validated against data obtained from real experiments.