Parallel/Oblique Impact on Thin Explosive Samples
Final rept. 1 Jan 1990-30 Sep 1992
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
Pagination or Media Count:
The shearing of explosive materials under pressure is an effective way to produce localized heating by viscoplastic work concentrated in a small region of the deforming explosive. This localized heating can cause the explosive to react releasing additional heat to accelerate the reaction. In an earlier paper, we described the results obtained when a small cylinder of explosive was pressurized within heavy steel confinement and then allowed to slide against the steel confinement Boyle, Frey, and Blake 1989 in a similar arrangement, we investigated explosive on explosive shear by punching a plug from the pressurized explosive cylinder. In those experiments, we demonstrated that the ignition threshold depends on both pressure and shear velocity. Those experiments had a relatively long duration of about 1 ms, a maximum pressure of about 1.0 GPa, and a maximum shearing velocity of about 80 ms the pressure and shear velocity varied during the course of the experiment. The rise time to peak pressure was several hundred microseconds. Also the shear localization was not well defined so the local strain rate could not be determined. In the experiments reported here, we have attempted to study the ignition of several explosives as they were impacted under conditions that would cause the explosive sample to shear in a known manner under the high pressure of the impact. A maximum pressure of 1.3 GPa was reached with a strain rate of about 50,000 per second over an explosive layer 0.6 mm thick.
- Ammunition and Explosives