The Effect of Grit on Frictional Heating During Oblique Impacts with PBX 9501

Parker, Glenn R.; Heatwole, Eric; Holmes, Matthew; Gunderson, Jake Alfred; Novak, Alan M.; Dickson, Peter

doi:10.2172/1088887

Cited by 8 publications

(10 citation statements)

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“…Experiments shown initiation only when grits were used meaning that higher velocity and pressure are needed to ignite the explosive when sliding occurs on grit-free surfaces. This analysis was experimentally confirmed for PBX 9501 [10][11][12][13]. If an impact on a target made of glass does not show reactive event, the addition of free-grits on the surface of the target can result in light and explosion.…”

Section: Introductionmentioning

confidence: 76%

“…As a consequence of these finite element simulations, neither friction nor plastic shear can ignite our HMX-based explosive compositions. The influence of the abrasive paper on our experimental results and its interaction (friction) on the steel plate must to be reconsidered in the future as highlighted in previous researches [9][10][11][12][13].…”

Section: Finite Element Evaluation Of the Heatingmentioning

confidence: 99%

“…If an impact on a target made of glass does not show reactive event, the addition of free-grits on the surface of the target can result in light and explosion. Authors of [9][10][11][12][13] proposed the following interpretation: the sand grits having higher melting temperature than the PBX, their friction to the glass increases their temperature, then the grits acting as fixed "hot-spots" for the explosive part.…”

Section: Introductionmentioning

confidence: 99%

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Oblique Impacts and Friction of HMX and/or TATB‐based PBXs

Picart

Junqua-Moullet

2017

Propellants Explo Pyrotec

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Transportation, handling, vibrations can lead to dynamic loadings requiring the characterization of the safety of plastic‐bonded explosives (PBX). One of the addressed situations is the fall of explosive on a surface. Knowing that initiation can occur at a lower height during a vertical fall of a projectile on an inclined target than on a horizontal one, devices were developed to determine the critical thresholds. In this paper, data obtained on four HMX and/or TATB‐based PBXs using pendulum drop configurations are detailed. Two analytical models are compared to estimate the heat released by friction at the interface. The model proposed in this paper yields the better agreement with data, and with finite element numerical simulations of the oblique impact on a given PBX. Lastly, the mechanical dissipation at the interface is estimated using this model and the simulations. This paper confirms that PBX/target friction cannot be the heating mechanism leading to initiation during oblique impacts.

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Section: Introductionmentioning

confidence: 76%

Section: Finite Element Evaluation Of the Heatingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oblique Impacts and Friction of HMX and/or TATB‐based PBXs

Picart

Junqua-Moullet

2017

Propellants Explo Pyrotec

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“…This allowed the contact area to be measured as the impact occurred by the use of highspeed video cameras (see Fig.(6)). For a more detailed explanation of the experimental setup please see (Parker et al (2013)).…”

Section: Initial Assumptionsmentioning

confidence: 99%

“…Recent experiments indicate that frictionally heated grit can act as effective hot spots for the ignition of PBX 9501 (Parker et al (2013)). The most common mode for hot spot formation is when a piece of grit is dragged by the explosive across a high melting point surface, such as steel.…”

Section: Introductionmentioning

confidence: 99%

Probability Calculation of Grit-Grit Interaction on a Plastic Bonded Explosive During Glancing Impacts.

Heatwole¹,

Parker²,

Dickson³

et al. 2013

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Variation of Methods in Small‐Scale Safety and Thermal Testing of Improvised Explosives

Sandstrom

Brown

Preston

et al. 2014

Propellants Explo Pyrotec

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One of the first steps in establishing safe handling procedures for explosives is small‐scale safety and thermal (SSST) testing. To better understand the response of homemade or improvised explosives (HMEs) to SSST testing, 16 HME materials were compared to three standard military explosives in a proficiency‐type round robin study among five laboratories, two U.S. Department of Defense and three U.S. Department of Energy, sponsored by the Department of Homeland Security, Science & Technology Directorate, Explosives Division. The testing included impact, friction, electrostatic discharge (ESD) and thermal. The testing matrix was designed to address problems encountered with improvised materials: powder mixtures, liquid suspensions, partially wetted solids, immiscible liquids, and reactive materials. All testing materials and/or precursors came from the same batch distributed to each of the participants and were handled, pretreated, and mixed by standardized procedures. For this proficiency test, the participants had similar equipment, usually differing by vintage. This allowed for a direct comparison of the results from each participant to the average of the results from all the participants. Some general trends observed for each series of tests were: (1) Drop hammer – LLNL usually found the materials less sensitive than the average with materials that have high sensitivity to impact and LANL usually found the materials less sensitive than the average with materials that have high sensitivity to impact; (2) friction – LLNL found the materials less sensitive than the average; (3) and ESD – IHD usually found the materials less sensitive than the average. In this report, the proficiency test data from all the participants is compared and contrasted for impact, selected friction, and ESD testing. Other friction and thermal data will be addressed elsewhere as well as the statistical analysis of several repeated measurements on the proficiency test standards.

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The Effect of Grit on Frictional Heating During Oblique Impacts with PBX 9501

Cited by 8 publications

References 0 publications

Oblique Impacts and Friction of HMX and/or TATB‐based PBXs

Oblique Impacts and Friction of HMX and/or TATB‐based PBXs

Probability Calculation of Grit-Grit Interaction on a Plastic Bonded Explosive During Glancing Impacts.

Variation of Methods in Small‐Scale Safety and Thermal Testing of Improvised Explosives

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