Quasi-static compaction study of coarse HMX explosive

Abstract

The quasi-static compaction behavior of granular beds of coarse HMX (cyclotetramethylenetetranitramine) explosive has been investigated, in some detail, by simultaneously measuring applied force, transmitted force and porous bed displacement. A narrow sieve-cut of both HMX and Class D HMX was selected for study. These two materials have a similar average particle size (∼900 μm) but differ appreciably in their particle size distribution. The principal difference in the compaction behavior of these two materials was observed in the early stages, below 85% TMD (theoretical maximum density), and is associated with the difference in their initial particle packing efficiency. Above 85% TMD, the difference in behavior was small, suggesting that the physical state of the compacted bed had become very similar for the two materials. Optical examination of recovered sieve-cut HMX samples revealed that the onset of widespread fracture of particles occurred a little above 58% TMD (average initial density was 56.6% TMD) and widespread fracture occurred, in apparently increasing amounts up to 75% TMD. Above 80% TMD, the recovered samples were intact, a condition which precluded direct determination of the extent of fracture.