Ramp-wave initiation of granular explosives

✍ Scribed by Robert E. Setchell

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 930 KB
• Volume: 43
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(81)90025-0

✦ Synopsis

Initiation

processes in granular explosives have been investigated experimentally by observing the propagation and growth of finite-rise-time compression waves. In this study 'ramp" waves having a rise-time of either 0.3 /.ts or 0.8 /AS were transmitted into the explosive PBX-9404, resulting in initial waves having a peak axial stress of 5.1 GPa. Velocity interferometry (VI&AR) was used to measure particle velocity histories after the initial wave had propagated through explosive samples having different thicknesses.

For comparison, similar measurements were made for the case of shock loading to the same peak axial stress. The velocity records indicate that processes for local hot-spot generation and ignition are strongly inhibited by the finite rates of compression.

As the ramp waves propagate they steepen into shocks. with little evidence of chemical energy release prior to shock formation. The waveforms recorded during this nonreactive period provide information on the mechanical properties of the granular material. After shock formation the release of chemical energy results in wave growth toward detonation, although the transition to detonation is delayed considerably compared to the case of initial shock loading. Comparisons of velocity histories from the different loading conditions indicate that chemical energy is being released throughout the compressed explosive, rather than only near the shock front.