Effects of precursor waves in shock initiation of granular explosives

✍ Scribed by R.E. Setchell

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 705 KB
• Volume: 54
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(83)90030-5

✦ Synopsis

The effects of compressive waves propagating ahead of stronger shock waves in a granular explosive have been investigated experimentally. In particular, the propagation and growth of 5.0 GPa shocks preceded by either a 3.2 GPa shock or a 2.0 GPa ramp wave having a 0.6/as rise time were examined in the low porosity explosive PBX-9404. The evolution of a 3.5 GPa shock preceded by a 0.2 GPa precursor wave was also examined in this explosive. The initial waves were generated using planar impact techniques, and laser velocity interferometry (VISAR) was used to measure particle velocity histories after the waves had propagated through explosive samples having different thicknesses. The recorded waveforms for shocks with precursors were compared with similar measurements obtained for single shocks having the same peak axial stresses. These comparisons confirmed that compression by a precursor wave renders the granular explosive less sensitive to initiation by a subsequent shock. For the 5.0 GPa eases, the ramp wave precursor was more effective in retarding the release of chemical energy than the precursor shock. In both cases the propagation distance required to achieve detonation was extended by an amount that depended on the duration of the precursor. The 0.2 GPa precursor was also found to be quite effective in desensitizing the PBX-9404 to the subsequent 3.5 GPa shock. This suggests that desensitization can result from precursor waves just strong enough to reduce the porous microstructure within the granular material.