Thermodynamics of HMX Polymorphs and HMX/RDX Mixtures

Myint, Philip C.; Nichols, Albert L.

doi:10.1021/acs.iecr.6b03697

Cited by 31 publications

(27 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The HMX molecule is centrosymmetric and comprises an eight-membered chair-like ring of alternating carbon and nitrogen atoms, with each nitrogen atom attached to a nitro group [9]. Among the various solid phases of the crystal (α, β, γ, δ, ε) [10][11][12], the monoclinic β phase is stable in ambient conditions and has the highest density [13].…”

Section: Introductionmentioning

confidence: 99%

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

HMX (cyclotetramethylene tetranitramine) is an energetic material which releases substantial amounts of energy upon decomposition. The role of defects and deformation in causing reaction initiation was discussed in the literature but remains insufficiently understood. In this work, we identify, using computational methods, the slip systems which are potentially active in β-HMX and rank them in terms of their propensity for slip. To this end, we develop first a tentative ranking based on the degree of steric hindrance associated with slip. This is quantified using a geometric analog of the γ-surface. Further, we use atomistic models to compute the Peierls-Nabarro (PN) stress for the motion of dislocations in the slip systems with smallest degree of steric hindrance. A complex mechanical behavior is observed, including strong slip asymmetry, twinning and cleavage. The five systems with the lowest PN stress are ()[ ] 011 011 , ()[ ] 011 100 , ()[ ] 101 010 , ()[ ] 101 101 and ()[ ] 021 100. We conclude that the material has enough slip systems available for supporting a generalized state of plastic strain provided the twinning system ()[ ] 101 101 is taken into consideration and that the resolved shear stress is at least 260 MPa.

show abstract

Section: Introductionmentioning

confidence: 99%

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

show abstract

“…HMX crystallizes in the monoclinic β form at standard conditions 19 (see Figure 1) and can transition through one or two high temperature crystal polymorphs before melting at pressures below ≈0.15 GPa. 20 Above this pressure, β is expected to directly melt to liquid, but neither the pressure-dependent melt line, nor other properies of the liquid, are known for the GPa…”

Section: 1718mentioning

confidence: 99%

Sensitivity of Pore Collapse Heating to the Melting Temperature and Liquid-phase Shear Viscosity of HMX

Kroonblawd

Austin²

2020

Preprint

View full text Add to dashboard Cite

A multiscale modeling strategy is used to quantify factors governing the temperature rise in hot spots formed by pore collapse from supported and unsupported shock waves in the high explosive HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Two physical aspects are examined in detail, namely the melting temperature and liquid shear viscosity. All-atom molecular dynamics simulations of phase coexistence are used to predict the pressure-dependent melting temperature up to 5~GPa. Equilibrium simulations and the Green-Kubo formalism are used to obtain the temperature- and pressure-dependent liquid shear viscosity. Starting from a simplified continuum-based grain-scale model for HMX, we systematically increase the complexity of treatments for the solid-liquid phase transition and liquid shear viscosity in simulations of pore collapse. Using a realistic pressure-dependent melting temperature completely suppresses melting for supported shocks, which is otherwise predicted when treating it as a constant determined at atmospheric pressure. Alternatively, large melt pools form around pores during pressure release in unsupported shocks, even with a pressure-dependent melting temperature. Capturing the pressure dependence of the shear viscosity increases the peak temperature of melt pools by hundreds of Kelvin through viscous work. The complicated interplay of the solid-phase plastic work, solid-liquid phase transition, and liquid-phase viscous work identified here motivate taking a systematic approach to building increasingly complex grain-scale models and for guiding interpretation of predictions made using them.

show abstract

“…The heat of formations of species also need to be consistent with EOS. Both EOS and heat of formations are provided by the MAGPIE project [6][7][8][9] at Los Alamos National Laboratory, and summarized in Sec. II.2.…”

Section: Model Summarymentioning

confidence: 99%

“…Species EOS and heat of formation of all species has been provided by the MAGPIE project at Los Alamos National Laboratory (LANL) [6][7][8][9]. These models are utilized in the reacting flow research code BABBO capable of handling an arbitrary number of species and reactions.…”

mentioning

confidence: 99%

HMX detonation calculation using multi-reaction chain

Chang

Scannapieco

2020

View full text Add to dashboard Cite

Detonation of HMX has been simulated using a multi-reaction chain and species equationof-states. A reacting flow code capable of handling arbitrary number of reactions and species has been used. Computational results are compared to the results produced by a pressurebased single reaction model (AJEX) and a temperature-based single-reaction model. Results show that the multi-reaction approach is capable of producing detonation calculations comparable to the AJEX model calculations, demonstrating that the multi-reaction approach possesses the properties required for the detonation modeling, a prerequisite of deflagrationto-detonation transition modeling. I. INTRODUCTION HMX (High Melting Explosive, Her Majesty's Explosive, C 4 H 8 N 8 O 8) has been used in polymerbonded explosives (PBX) such as PBX-9404, PBX-9501, LX-10, and LX-20. Its detonation behavior of course has been extensively studied. Detonation calculations are routinely carried out with pressure-based reactive burn models such as Forest-Fire [1], AJEX [2], and SURF (Scaled Unified Reactive Front) [3]. They typically employ one reaction mechanism in which the reactant (solid unreacted HE) turns into the product mixture. Species composition of the product is not calculated. There also are single reaction models with temperature-based reaction rates in the Arrhenius form [4]. But these models have not been so widely used as the pressure-based models. The Jones-Wilkins-Lee (JWL) equation-of-state (EOS) has been widely used when these types of modeling approaches are employed. Use of the pressure-based detonation models, however, present difficulties in the modeling of high explosives (HE) in some situations. Burning characteristics can be significantly affected by the reaction history such as the evolution of temperature and species in the modeling of deflagration covering a wide range of the temperature. For consistent modeling, it is necessary to use a multi-reaction model with temperature-based reaction rates. Furthermore, accurate tracking of temperatures would require EOS with temperature-dependent specific heats. In short, in order to advance HE modeling, we need to have multi-reaction chains with temperature-based reaction rates and temperature-dependent specific heats. Note that a species can be a reactant in a reaction while a product in other reactions. Furthermore, when temperature history changes, species concentrations would also change. To account for these aspects, thermodynamic states of each species need to be evaluated with its own EOS, which can be combined to calculate the thermodynamic states of the mixture. In summary, an approach employing a multi-reaction chain, temperature-based reaction rates, and species EOS is necessary in advanced modeling of HE such as DDT (deflagration-to-detonation transition). However, this approach has not been used for detonation calculations, which is a prerequisite for DDT calculations. That is, detonation needs to be captured by this approach in order to perform DDT modeling using a single unified frame...

show abstract

Thermodynamics of HMX Polymorphs and HMX/RDX Mixtures

Cited by 31 publications

References 58 publications

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Peierls–Nabarro stresses of dislocations in monoclinic cyclotetramethylene tetranitramine (β-HMX)

Sensitivity of Pore Collapse Heating to the Melting Temperature and Liquid-phase Shear Viscosity of HMX

HMX detonation calculation using multi-reaction chain

Contact Info

Product

Resources

About