skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

Abstract

In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

Authors:
 [1];  [2];  [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Materials Design, Inc., San Diego, CA (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1310267
Report Number(s):
SAND2016-7996J
Journal ID: ISSN 2469-9950; PRBMDO; 646689
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 5; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS

Citation Formats

Shan, Tzu -Ray, Wixom, Ryan R., and Thompson, Aidan P. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive. United States: N. p., 2016. Web. doi:10.1103/PhysRevB.94.054308.
Shan, Tzu -Ray, Wixom, Ryan R., & Thompson, Aidan P. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive. United States. doi:10.1103/PhysRevB.94.054308.
Shan, Tzu -Ray, Wixom, Ryan R., and Thompson, Aidan P. 2016. "Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive". United States. doi:10.1103/PhysRevB.94.054308. https://www.osti.gov/servlets/purl/1310267.
@article{osti_1310267,
title = {Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive},
author = {Shan, Tzu -Ray and Wixom, Ryan R. and Thompson, Aidan P.},
abstractNote = {In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.},
doi = {10.1103/PhysRevB.94.054308},
journal = {Physical Review B},
number = 5,
volume = 94,
place = {United States},
year = 2016,
month = 8
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 3works
Citation information provided by
Web of Science

Save / Share:
  • Cited by 3
  • In this paper, we report on the development of a diagnostic to provide constraints on the size of particles ejected from shocked metallic surfaces. The diagnostic is based on measurements of the intensity of laser light transmitted through a cloud of ejected particles as well as the angular distribution of scattered light, and the analysis of the resulting data is done using the Mie solution. Finally, we describe static experiments to test our experimental apparatus and present initial results of dynamic experiments on Sn targets. Improvements for future experiments are briefly discussed.
  • The common observation that the onset of a core MARFE (multifaceted asymmetric radiation from edge) is followed immediately by a H-L (high-to-low) confinement mode transition in DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] was investigated by comparing a theoretical prediction of the threshold nonradiative power across the separatrix needed to maintain H mode with an experimental determination of the nonradiative power flowing across the separatrix. It was found that in three shots with continuous gas fueling the increased neutral influx associated with the MARFE formation caused a sharp increase in the predicted threshold nonradiative power crossing the separatrix thatmore » was required for the plasma to remain in H mode to a value comparable to the experimental power crossing the separatrix.« less
  • We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamondmore » anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.« less
  • The shock response of two-dimensional model, high explosive crystals with various arrangements of circular voids is explored. We simulate a piston impact using molecular dynamics simulations with a Reactive Empirical Bond Order (REBO) model potential for a sub-micron, sub-ns exothermic reaction in a diatomic molecular solid. In square lattices of voids all of one size, reducing that size or increasing the porosity while holding the other parameter fixed causes the hotspots to consume the material more quickly and detonation to occur sooner and at lower piston velocities. The early time behavior is seen to follow a very simple ignition andmore » growth model. The hotspots are seen to collectively develop a broad pressure wave (a sonic, diffuse deflagration front) that, upon merging with the lead shock, transforms it into a detonation. The reaction yields produced by triangular lattices are not significantly different. With random void arrangements, the mean time to detonation is 15.5% larger than with the square lattice; the standard deviation of detonation delays is just 5.1%.« less