Reversal of particle size/shock sensitivity relationship at small particle size for pressed heterogeneous explosives under sustained shock loading

Shock initiation of pressed heterogeneous explosives has been reviewed. The key processes of ignition and buildup and their relative importance under sustained and short duration shock are described. Particle size effects on shock sensitivity are shown to depend on both density (ZTMD) and shock duration. A series of RDX samples of narrow particle size range were subjected to sustained shock (gap test). Sensitivity increased over the series 250 < 138 < 100.0 < 21.2 μm median particle size but decreased for a 3.9 μm sample. These results combined with earlier published data support published modelling studies which predict decreased shock sensitivity at small particle size.