UNCLASSIFIED
Distribution Statement A: Approved for public release. Distribution unlimited.
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International Explosive Safety Symposium & Exposition
San Diego, CA, August 6-9, 2018
(U) Metrics Analysis for the Improved Evaluation Methodology of the Hazard Severity of
Fragments Projected from Deflagrating Warheads
Daniel J. Pudlak, MS; US Army Armament Research, Development and Engineering Center;
Picatinny Arsenal, NJ, USA
Kevin T. Miers, MS; US Army Armament Research, Development and Engineering Center;
Picatinny Arsenal, NJ, USA
Brian E. Fuchs, Ph.D.; US Army Armament Research, Development and Engineering Center;
Picatinny Arsenal, NJ, USA
(U) Abstract
(U) While warhead developers have a fundamental understanding of the damage a detonating
munition inflicts from intended warhead fragmentation [2], there appears to be some inconclusive
evidence regarding the damage a fragment can inflict from a lower order, accidental deflagrating
munition. Both the Safety community and the Insensitive Munition (IM) community attempt to
characterize this phenomena, utilizing generic characterization methods such as mass vs. throw
distance, mass quantity density statistics, etc. However, it is not clear how much of a physical
science basis some of these methods have. A fragment’s geometry, along with its exterior /
terminal ballistics characteristics, should not be overlooked when evaluating its hazard potential.
(U) The U.S. Army conducted a hazardous fragment study to analyze the methods in which
fragments projected from munitions (e.g. warheads) are evaluated and characterized for their
projection energy and level of threat they pose to soldiers and their materiel. This study was
initiated due to the result of concerns raised by the community, questioning the validity of the
current metric (20J) used by the IM community to differentiate between a benign burning reaction
and a semi-violent deflagration. The purpose of the study was to determine if the current 20J
kinetic energy at 15m requirement is appropriate, if the previous 79J at 15m metric was more
appropriate, or perhaps if evidence proves an even more appropriate metric or criterion.
(U) This paper discusses the research conducted to investigate the origins of the current/previous
metrics used to categorize a fragment’s level of hazard, including blunt injury and skin
penetration tests performed as far back as the 1800’s. The equations used to develop the original
mass-distance curves that were used to evaluate fragment energy were recreated and analyzed by
the U.S. Army, are referenced in this paper, and discussed in a ‘sister’ paper, ‘Aeroballistics
Calculations for the Insensitive Munitions Hazardous Fragment Criterion, K. Miers, et. al.’ [1].
Several errors were discovered in the original ballistics equations of the existing energy-based
methodology, such as it improperly being based on launch energy, instead of impact energy. The
updated curves are discussed on this paper, and discussed in [1]. Furthermore, the U.S. Army
identified an advanced methodology to improve the evaluation of fragment hazard levels. This
paper discusses the newly proposed ‘energy density’ methodology that is currently under
evaluation for future use as a standard requirement, as well as the metrics under consideration by
the U.S. Army for final implementation.
