Atomistic Studies of Fundamental Properties and Processes in Energetic Materials: Relevance to Mesoscale Initiation Phenomena

• Autorzy: Sewell T. D.
• Języki publikacji: EN

Abstrakty

EN

Genuine, physics-based understanding of initiation phenomena in plasticbonded explosives (PBXs) requires knowledge of the physics and chemistry at mesoscopic scales that are far larger than can be simulated directly using atomistic detail, yet far smaller than is directly resolvable in practical engineering scale continuum simulations. Initiation is determined by localization phenomena that arise due to the heterogeneous character of most explosive formulations. Indeed, the "average" temperature behind a weak shock is not a useful measure for understanding initiation phenomena; rather, it is the tails of the distributions in temperature, stress, and strain rates, localized to small, spatially distributed volumes in the material (hot spots), that dictate the outcome of a given loading event. Important factors for predicting hot spot formation and subsequent extinction or growth/coalescence include particle size, concentration, morphology, and void content; physical and chemical interactions between grains and binder; thermophysical and mechanical properties of the constituents and interfaces between them; and, of course, the inherent chemical stability of the explosive component(s) in the formulation. We are in the process of computing many of the thermophysical and mechanical properties required for a complete specification of constituent models for use in mesoscale simulations, wherein grains and binder in representative volumes of a PBX are spatially resolved and then studied within a continuum hydrodynamic framework. In addition to calculating specific properties of interest, we have recently undertaken a series of large-scale molecular dynamics simulations of energetic crystals to understand dissipation phenomena in dynamically loaded single- or poly-crystalline samples; for instance, plastic deformation and stress/energy localization mechanisms, phase transitions, and so on. Recent and ongoing work in these areas will be discussed, along with their specific relevance to emerging mesoscale simulation capabilities.

Słowa kluczowe

EN

atomistic simulation; quantum chemistry; thermal and mechanical properties; localization; initiation

• Czasopismo: Central European Journal of Energetic Materials
• Rocznik: 2006
• Tom: Vol. 3, nr 1-2
• Strony: 19--38
• Opis fizyczny: Bibliogr. 48 poz.

Twórcy

autor

Sewell T. D.

• Theoretical Division, Explosives and Organic Materials Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA,

Bibliografia

• [1] Baer M. R., Modeling Heterogeneous Energetic Materials at the Mesoscale, Thermochim. Acta, 2002. 384, 351.
• [2] Sewell T. D., MenikofTR., Complete Equationof State for/?-HMXand Implications for Initiation, in: Proceedings of the 2003 APS Topical Conference on ShockCompression of Condensed Matter, Furnish M. D., Gupta Y. M., Forbes J. W.,ed.: AIR Melville, NY 2004, p. 157.
• [3] Armstrong R. W., Ammon H. L., Elban W. L., Tsai D. H., Investigation of Hot Spot Characteristics in Energetic Crystals, Thermochim. Ada, 2002, 384, 303.
• [4] Armstrong R. W, Elban W. L., Dislocations in Energetic Crystals, in.: Dislocations in Solids. Nabarro K R. N., Hirth J. P., ed.: North-Holland, New York 2004, Ch. 68.
• [5] Menikoff R.. Pore Collapse and Hot Spots in HMX," in: Proceedings of the 2003 APS Topical Conference on Shock Compression of Condensed Matter, Furnish M. D., Gupta Y. M., Forbes J. W., Eds., AIP, Melville, NY 2004, p. 393.
• [6] Menikoff R., Detonation Wave Profile inPBX-9501"(LA-UR 05-1633) to appear in the Proceedings of the 2005 APS Topical Meeting on Shock Compression of Condensed Matter, presently available online at: http://tl4web.lanl.gov/StaIf/rsin/Preprints/C Jprofile.pdf,
• [7] Hanson-Parr D. M.,ParrT. P., Thermal Properties Measurements of Solid Rocket Propellant Oxidizers and Binder Materials as aFunction of Temperature, J. Energ. Mater., 1999, 17, 1.
• [8] MenikofFR., Sewell T.D., Constituent Properties of HMX Needed for Mesoscale Simulations, Comb. Theory a. Modeling. 2002, 6, 103.
• [9] Menikoff R., Sewell T. D., Fitting Forms for Isothermal Data, High Press. Res., 2001,27, 121.
• [10] Sewell T. D., Monte Carlo Simulations of Crystalline TATB, in: Decomposition, Combustion, and Detonation Chemistry of Energetic Materials, Materials Research Society Symposium Proceedings, Brill T. B., Russell T. P., Tao W. C., Wardlc R. B., ed.: MRS, Pittsburgh 1996, 418, p. 67.
• [11] Sewell T. D.. Monte Carlo Calculations of the Hydrostatic Compression of Hexaliydro-L3r5-lrinilro-l,3J-triaxineand//-oc[a]iydro-1.3.5,7-tetranitro-l,3.5f7-tetrazocinc, J. AppL Phys., 1998, 83, 4142.
• [12J Sewell T. D., Bennett C. M., Monte Carlo Calculations of the Elastic Moduli and Pressure-Volume-Temperature Equation of State for Hexahydro-l-3-5-trinitro-1.3.5-triazine, ibid., 2000. 88. 88.
• [13] The HMX simulations resulting from the collaboration between T. D. Sewell at Los Alamos and the G. D. Smith group at the University of Utah are based on a flexible molecule, quantum chemistry -based force field: Smith G. D. and Bharadwaj R. K,, Quantum Chemistry Based Force Field for Simulations of HMX, J. Phys. Chem,, 1999, B 103. 3570,
• [14] Bedrov D.. Ayyagari C.. Smith G. D., Sewell T D., Menikoff R., Zaug J. M., Molecular Dynamics Simulations of HMX Crystal Polymorphs Using a Flexible Molecule Force Field, J. Comp.-Aided Mater, Design, 2002, 8. 77.
• [15] Sewell T. D., Menikoff R.. Bedrov D., Smith G. D., A Molecular Dynamics Simulation Study of Elastic Properties of HMX. J. Chem, Phys., 2003, 119. 7417.
• [16] Bedrov D., Smith G. D.. SeweJI T. D., Temperature-dependent Shear Viscosity Coefficient of octahydro-1.3,5.7-telranitro-l,3,5,7-tetrazocinc (HMX): A Molecular Dynamics Simulation Study, ibid., 2000.112, 7203.
• [17] BedrovD., Smith G. D.. Sewell T. D., Thermal Conductivity of Liquid Octahydro-1.3. 5.7-tetranitro-l,3,5,7-tetrazocine (HMX) from Molecular Dynamics Simulations, Chem. Phys. Lett., 2000, 324, 64.
• [18] Bedrov D., Smith G. D., Sewell T. D., Thermodynamics and Mechanical Properties of HMX from Atomistic Simulations, in: Energetic Materials Part 1. Decomposition, Crystal, and Molecular Properties, PolitxerP. and Murray J. S, ed.: Elsevier, Boston2003, Ch. 10, p. 279.
• [19] Smith G. D., Bcdrov D.. Byutner O., Borodin O.. Ayyagari C., Sewell T. D. A Quantum Chemistry-based Potential for a Poly(esteniretliane), J. Phys. Chem. A., 2003. 107. 7552.
• [20] Davande H., Borodin O.. Smith G. D., Sewell T. D., Quantum Chemistry-based Force Field for Simulations of Energetic Dinitro Compounds, J. Energ. Mater.,(submitted).
• [21] Verification: are we solving the equations right? Validation: are we solving the right equations?
• [22] BaerM. R.. Sewell T. D.. Linking Molecular Dynamics to Mcsoscale Simulation. in: Molecular Dynamics Simulations of Detonation Phenomena, Holian B., ed.: ITRI, Laurel, MD, 2003, Ch. 5, p. 79.
• [23] PBX-9501 is 95% by weight HMX 2.5%Estane™T and 2.5%BDNPF/A. A small amount of stabilizer is also present in the formulation, but we have no plans to develop a force field for this trace component.
• [24] Lewis J. P., Sewell T. D.. Evans R.B., Voth G. A., Electronic Structure Calculation of the Structures and Energies of the Three Pure Polymorphic Forms of Crystalline HMX../. Phys. Chern., 2000. B 104. 1009.
• [25] Gan C. K., Sewell T. D., Challacombe M., All Electron Density-functional Studies of Hydrostatic Compression of Pentaerythrilol Tetranitratc (PETN), Phys. Rev., 2004.569.035116.
• [26] Challacombe M., Schwegler E.. Tymczak C. J.. Gan C. K.. NemethK., Niklasson A. M. N.. H. Nymeyer, Henkleman G., Mondoscf vl.0ct7., A Program Suite for Massively Parallel, Linear Scaling SCF Theory and ah Initio Molecular Dynamics, 2001, http://www.tl2.lanl.gov/homfi/mchaUa, Los Alamos National Laboratory' (LA-CC 01-2), copyright University of California.
• [27] The 2003 Study Molecuiar Dynamics Simulations of Detonation Phenomena, chaired by B.L. Holian and funded by the International Technology Research Institute (ITRI), contains what is probably the most complete and up-to-date (through mid-2003) compendium of theoretical studies of energetic materials that lias been compiled. Contributing authors include Holian B. L. Baer M. R., Brenner D., Dlott D. D.: Redondo A.. Rice B. M.. Sewell T. D. and C.A. WIGHT.
• [28] Olingcr B., Roof B.. CADY H., The Linear and Volume Compression of β-HMX and RDX, in: Symposium International Sur le Comportement Des Milieux Denses Sous Hautes Pressions, CEA, Paris 1978. p. 3.
• [29] Yoo C.-S., CynnH., Equation of State, Phase Transition, Decomposition of β-HMX (octahydro-l,3,5,7-tetranitro-1.3,5,7-tetrazocine) at High Pressures, J. Chem. Phys,, 1999. 111. 10229.
• [30] HerrmannM..EngelW., EisenreichN.. Propellants, Explos., Pyrotech., 1992, 77, 190.
• [31] Herrmann M.: Engel W., Eisenreich N., Thermal Analysis of the Phases of HMX Using X-ray Diffraction. 2. Kristaltogr., 1993, 2047 121.
• [32] Saw C. K., Kinetics of HMX andPhase Transitions: Effects of Grain Size at Elevated Temperature, to appear in 12th' International Detonation Symposium, currently at http://w\vw.sainc.com/onr/detsymp/technicalProgram.htm
• [331 See Ref. [18]. Figure 9 (p. 305).
• [34] Day G. M.. Price S. L.. Leslie M.. Elastic Constant Calculations for Molecular Crystals, Crystal Growth and Design, 2001, 7, 13. Note especially entries in the tables where multiple experimental data are presented for the same substance.
• [35] SorescuD. C.. Rice B. M.. Thompson D. L., Theoretical Studies of the Hydrostatic Compression of RDX. HMX. HNIW, and PETN Crystals, J. Phys. Chem.B. 1999. 103,6783: and numerous references therein,
• [36] Haussuhl S.. Elastic and Thcrmoclastic Properties of Organic Crystals 2. Kristatlogr., 2001, 276, 339.
• [37] Dan Hooks (LANL), private communication to Tommy Sewell (March 2005).
• [38] Merrill Beckstead. private communication to Tommy Sewell.
• [39] Agrawal P. M.. Rice B. M., Thompson D. L., Molecular Dynamics Study of the Melting of Nitromethane, J. Chem. Phys., 2003. 119, 9617.
• [40] Gump J. C.. PEIRIS S. M.. Isothermal Equations of State of β-octahydro-1.3,5,7-tetranitro-1.3,5,7-tetrazocine. J, Appl Phys.. 2005, 97, 53513.
• [41] Sewell T. D. (in preparation).
• [42] For the present purpose, the differences between the linear compressions of OHnger et al. and Yoo & Cynn are probably negligible.
• [43] Plimpton S. J., Fast Parallel Algorithms for Short-Range Molecular Dynamics, J. Computational Phys., 1995, 777, 1, Plimpton S. I, Pollock R., Stevens M., Particle-Mesh Ewald and rRESPAfor Parallel Molecular Dynamics Simulations, in: Proceedings of the Eighth SIAhf Conference on Parallel Processing for Scientific Computing, Minneapolis, MN, March 1997.
• [44] Goddard III W.A. and co-workers have done some preliminary calculations of the specific heat Cv of β-HMX for temperatures up to 3000 K. These can presently be found in annual reports of the CalTech ASC/ASAP Level One Alliance: http://csdmi.caltech.edu/publications/annualreps.html; see also Ref. [8], p. 108.
• [45] See Fig. 1 of Ref. [8] and associated discussion.
• [46] Strachan A,, Van Duin A.C.T., Chakiaborty D., Dasgupta S., Goddard III W. A., Shock Waves in High-Energy Materials: The Initial Chemical Events in Nitramine RDX. Phys.Rev. Lett., 2003,91, 098301.
• [47] On the basis of many calculations performed recently by Alejandro Strachan (LANL) and Adri van Duin (CalTech).
• [48] ManaaM. R., FricdL. E., Mclius C. F, EIstnerM., FrauenlieimT, Decomposition of HMX at Extreme Conditions: A Molecular Dynamics Simulation, J. Phys. Chem. A. 2002. 106, 9024.