A modified Drucker-Prager Cap model for densification behavior of polymer bonded explosives powders

The densification behavior of polymer bonded explosives (PBX) powders during compaction is critical for manufacturing highly reliable PBX. The modified Drucker-Prager Cap (DPC) model is widely employed to characterize the mechanical response during powder compaction. In this work, the densification behavior of HMX-based and TATB-based PBX powders was investigated. The density-dependent elastic and plastic material parameters of the modified DPC model for PBX powders were systematically calibrated through uniaxial die compaction, Brazilian disk, uniaxial compression and radial stress calibration tests. Results from uniaxial die compaction tests and finite element simulations based on the modified DPC model show excellent agreement, demonstrating that the modified DPC model can accurately characterize the compaction behavior of PBX powders and validating the calibrated material parameters. Differences in material parameters between the two PBX powders and other powders were analyzed, and the underlying physical mechanisms were elucidated. The modified DPC model was further applied to investigate non-uniform stress and density distributions during uniaxial die compaction, and to predict the geometry and density distribution of large-scale PBX components after compaction. This study demonstrates that the density-dependent modified DPC model accurately characterizes the mechanical response of PBX powders during compaction.