A Low Velocity Impact Experiment for Obtaining Ignition Thresholds in Unconfined High Explosives

Many non-shock ignition tests involve impact to explosives that are confined by opaque materials, which precludes direct imaging of the samples and determining the location and timing of ignition. We have recently conducted a series of tests that impact unconfined explosives mounted onto a polycarbonate plate at low velocities (15-40 m/s) using a rounded projectile. Using high speed videography we recorded the impact event from the back side of the plate. This allowed us to determine threshold velocities for ignition, the effects of explosive composition, and a qualitative understanding of the damage evolution prior to any reactions.  These results are used for comparison to threshold velocities for ignition obtained from other tests and inform the development and calibration of the High Explosive Response to Mechanical Stimuli (HERMES) explosive safety model [1]. In this work we introduce and present results of the impact threshold experiment (ITE) and findings from modeling of the impacts with HERMES.

[1] J. E. Reaugh, et al. “A Computer Model to Study the Response of Energetic Materials to a Range of Dynamic Loads,” Propellants, Explosives, Pyrotechnics, 43(7), p. 703-720, 2018.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-844726.