Shotgun/Drop-Weight Initiation of Energetic Materials

Shotgun impact tests were performed by firing plexiglas projectiles at 6 mm long by 12 mm diameter propellant samples at 150 and 200 ms impact velocities. Three different HTPBAP propellants were tested an Army fielded munition and two research propellants. The feasibility of a new technique, laser obscuration, was evaluated for measuring the pre- and post-impact projectile velocity history. Using less than ideal optical components, the present system is able to measure the pre-impact velocity but does not provide adequate resolution of the crucial post-impact velocity. The limits of even state-of-the- art optical components coupled with the small length of the sample 6 mm precludes using this type of laser system for future testing. A light detection system provided severity of and time to reaction information for the three propellants tested. The performance of PVDF stress gauges for determining critical energy was marginal with calculated values that qualitatively support lower velocity drop-weight results. For two of the three propellants, critical energy density decreased at the higher shotgun impact velocities as expected. Attempts were made to correlate the gono go and severity of reaction response to several stress gauge output parameters, but due to the limited data obtained in this one-year program, no strong correlations were obtained.