DETONATION BEHAVIOR OF ENERGETIC MATERIALS WITH NONUNIFORM MICROSTRUCTURES UNDER SHOCK LOADING

The behavior of energetic materials is significantly influenced by the spatial distributions of microstructure heterogeneities and voids. In this study, we explored how the non-uniform spatial distribution of voids influences the detonation behavior of polymer-bonded explosive microstructures designed based on polymer bonded explosive polymer bonded explosive 9501. The microstructures had spatially varying and spatially uniform void densities at different levels. It was found that shock wave propagation from a high void density region (low material mass density) to a low void density region corresponded with shorter run distances to detonation compared to shock loading in the opposite direction. In addition, the run distances of materials with non-uniform void densities were generally different from those of materials with uniform void densities equal to the lowest, average, or highest densities of the non-uniform materials. This result revealed that there are complex interplays in the coupled mechanical-thermal-chemical processes underlying the material response such that the spatial nonuniformity of void density distribution is an additional material attribute that should be considered separately in addition to other microstructure parameters. The computationally predicted Pop plots using a history variable reactive burn model were compared with available experimental data for PBX 9501. The results showed that although the existing reported model parameters did not produce results that fully coincide with the experimental data, proper choices of the model parameters can lead to results that match the experimental data.