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Simulating accidental explosion of cased and stacked sources in storages

: Ramin, M. von; Grunwald, C.; Riedel, W.; Stolz, A.

Univ. of Florida, Gainesville/Fla.:
16th International Symposium on Interaction of the Effects of Munitions with Structures, ISIEMS 2015. Proceedings : Sandestin, Florida, USA, 9.-13.11.2015
Sandestin/Fla., 2015
10 pp.
International Symposium on the Interaction of the Effects of Munitions with Structures (ISIEMS) <16, 2015, Sandestin/Fla.>
Conference Paper
Fraunhofer EMI ()

The accidental detonation of ammunition stacked inside a storage enclosure can have disastrous effects. Additional to the related blast wave, the potential damage caused by debris throw is significant. Not only is the human body more vulnerable to flying debris than to air-pressure waves, but the unobstructed ejection can extend into distances far beyond the hazardous range of the blast wave. The eight-national Klotz Group (KG) investigates the effects of accidental detonation of high explosive (HE) sources inside storage structures. The present contribution describes recent findings addressing the influence of metal casings and stacking of sources on the break-up process, with the goal to better understand the initial launch conditions for debris originating from the surrounding faces of the enclosure. Based on findings of recent investigations with two different cased sources, additional to the net explosive quantity (NEQ) and thus loading density inside the storage, parameters like number and location of sources, HE mass to hull mass ratio, and the properties of the casing have a significant effect on the structural failure process.
In the event of a simultaneous explosion stacked sources affect each other in two ways: 1. Numerous primary fragments partly collide, resulting in a change of direction, velocity, and mass of the released single distributed fragments. 2. Blast waves of different sources interact, which may cause locally an accelerating jetting effect. Both phenomena influence the initial impulse on the structure, its failure, and the resulting debris launch into the surroundings. Additionally, the casing properties influence the timing and development of the blast wave inside the structure, hence they affect the magnitude and the transient distribution of the internal pressure.
The Klotz Group approaches the investigation of the effects of stacked and cased sources in three steps: In the first step, the primary fragment distribution is analytically predicted to yield the primary fragment impulse on the inside of the storage structure. The second step establishes the transient blast loading and gas pressure development in a numerical hydrocode simulation, including the venting process through coupled fluid-structure interaction modelling. The third step uses the results from the previous two steps to define the initial conditions for another, purely Lagrangian numerical model of the dynamic break-up process of the storage structure. The present contribution focuses on the first two steps.