Modeling of the dihedral shear compression (DiSCo) test for for studying non-shock ignition in high explosives

• Main Authors: White, Bradley W., Reaugh, John E., Miller, Christopher M., Ruch, Aaron J., Vandersall, Kevin S.
• Format: Conference Proceeding
• Language: English
• Subjects: Coefficient of friction; Explosive compacting; Explosives; HMX; Ignition; Projectiles; Shearing; Thresholds
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/12.0028523

The Dihedral Shear Compression (DiSCo) test was recently designed to characterize non-shock ignition thresholds for high explosives. While the data this test provides can be used for ranking of mechanical induced reactions thresholds across multiple high explosives (HE), it is primarily being used to calibrate and constrain the HERMES ignition model [1]. During a recent DiSCo test series on HMX-based explosives we observed dependencies of ignition on the projectile impact conditions (tilt and vertical shift) where reactions were preferentially seen in one of the two samples or exhibited varying time delays between ignitions in both samples. In this work we performed HERMES calculations in the ALE3D hydrocode [2] to examine the effects of projectile tilt, vertical shift, and velocity, as well as the friction coefficient between the sample and test assembly parts on the evolution of the HERMES ignition history variable. We found off-center impacts to have the largest effect on the ignition parameter under non-ideal impact conditions while projectile tilt had only a slight influence. Under ideal impacts, lower friction values resulted in less pronounced sample shearing, which decreased the likelihood of the samples to ignite.