A Computational Study to Determine the Critical Velocity Required to Initiate Explosively Loaded Munitions

Report No. ARL-RP-47
Authors: William Lawrence
Date/Pages: January 2002; 19 pages
Abstract: When a fragment (projectile) impacts a stack of munitions, a strong shock can be produced which can initiate/detonate the explosive in the munitions. The critical velocity required to initiate the explosive is principally a function of the diameter of the fragment. However, the shape of its tip also influences the initiation process. A computational study was conducted to aid in understanding these effects and to determine the critical velocities of projectiles. This understanding is important in preventing munitions explosions. The munitions were simulated as explosives with different types of covers, and fragments were simulated as projectiles of different shapes and sizes. Two-dimensional (2-D) simulations of projectile impact on covered explosives were made. The response of the munitions was measured by monitoring pressure at various locations inside the explosive layer. Computational results show that for large (more than 5-mm) diameter projectiles, higher critical velocities than predicted by a well-known model (Jacobs-Roslund) are required to initiate the explosive. But for small diameter projectiles, the velocities calculated using the CTH code and the velocities predicted by Jacobs-Roslund are close.
Distribution: Approved for public release
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Last Update / Reviewed: January 1, 2002