Implications of reaction chemistry models for multiscale predictions of shock sensitivity of eneregtic materials

The sensitivity of energetic materials depends on molecular and microstructure. The former determines material properties, some of which are fairly well established for widely used energetic species, such as HMX, RDX, TATB etc. However, one primary driver of sensitivity remains quite unsettled, viz. reaction chemistry models for the decomposition and combustion. Traditionally, sensitivity (in Pop-plots/James curves) of these energetic materials have been characterized experimentally or through global, semi-empirical reactive burn models that have not demanded accurate reaction chemistry models. With the recent advances in multi-scale, first-principles models to develop predictive, microsructure-aware energy deposition models, it is now imperative to settle reaction chemistry models for individual energetic molecular species. In this presentation, we will show how uncertainties in reaction chemistry models for popular species such as HMX can significantly influence structure-property-performance predictions for HMX-based heterogeneous EMs. Uncertainties in reaction chemistry models are quantitatively linked to the uncertainties in macro-scale SDT predictions. The physics of hotspots underlying these uncertainties are eluciated. Finally, some insights and guidelines are offered regarding the characteristics of "acceptable" reaction chemistry models from the viewpoint of making reliable SDT predictions.