Structure-property-performance linkages for heterogenous energetic materials through multi-scale modeling

In porous solid energetic materials, the mechanical processing technique (e.g. casting, pressing) creates defects such as voids, cracks, interfaces, and inclusions; these defects in the microstructure strongly influence the sensitivity of the material to imposed loading. Energy localization at defects causes hotspots; the ignition and growth of hotspots in the microstructure (i.e. the meso-scale) play a crucial role in the macroscale initiation of the material. Predictive models of shock response of energetic materials must connect the meso-scale heterogeneities (structure) and hotspot physics (properties) to macro-scale response (performance and safety). To achieve this structure-property-performance (S-P-P) linkage, SEM-imaged samples of neat pressed HMX are obtained, and morphometry is performed to quantify the microstructure. Since the microstructure is stochastic, the aleatory uncertainties in the morphological parameters are quantified. The link between the microstructure and the key meso-scale quantity of interest-the hotspot ignition and growth rates-is established using reactive meso-scale computations to construct meso-informed surrogate models for energy localization. The surrogate models are used to close homogenized macro-scale governing equations. The performance of the HE at the macro-scale, i.e. its sensitivity to shock loading, is measured via run-to-detonation distances (in Pop plots) and the critical energy required for initiation (in James plots). The predicted critical energy for the material is compared with experimental data. The methods established in this paper can be useful not only for establishing structure-property-performance (S-P-P) linkages for pressed energetic materials, but also for other heterogenous reactive composites such as propellants and plastic-bonded explosives.