The Strength of Two HMX Based Plastic Bonded Explosives During One Dimensional Shock Loading

Millett, J. C. F.; Taylor, Peter C.; Roberts, A.; Appleby-Thomas, Gareth

doi:10.1007/s40870-017-0099-1

Cited by 16 publications

(4 citation statements)

References 53 publications

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“…Cyclotetramethylene tetranitramine (HMX) is an important secondary energetic material used in a variety of plastic bonded explosives [7,8]. 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].…”

Section: Introductionmentioning

confidence: 99%

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

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

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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.

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Section: Introductionmentioning

confidence: 99%

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

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

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“…A variety of plastic bonded explosives (PBX) use cyclotetramethylene tetranitramine (HMX) as the active constituent [7,8]. The centrosymmetric HMX molecule comprises an eight-atom chair-like ring of alternating carbon and nitrogen atoms, with each nitrogen atom attached to a nitro group [9].…”

Section: Introductionmentioning

confidence: 99%

Dislocation mobility and critical stresses at finite temperatures in molecular crystal cyclotetramethylene tetranitramine (β-HMX)

Khan

Pal

Picu

2018

Modelling Simul. Mater. Sci. Eng.

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Cyclotetramethylene tetranitramine (HMX) is an energetic material commonly found in plastic bonded explosives. Its crystallographic sensitivity to initiation and detonation has been linked to plastic slip in the various crystalline planes; shock directions which cannot accommodate substantial crystalline slip are expected to be more sensitive. In this work, we carry out constant stress-constant temperature molecular dynamics simulations of the motion of dislocations and characterize their behavior in the two most probable slip planes, (101) and (011), of this crystal. We evaluate critical thresholds for activating steady-state dislocation motion and the associated dislocation mobilities at various temperatures below 400 K. This information can be used to develop and calibrate larger scale models of plastic deformation in this material.

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“…The model is calibrated to strength measurements on high HMX content explosive formulations (90-95 %wt HMX) and single crystal HMX. This includes split Hopkinson pressure bar data in the ~10 3 s À 1 strain rate regime [36] and weak shock data in the ~10 6 s À 1 strain rate regime [37][38].…”

Section: Hmx Strengthmentioning

confidence: 99%

Simulating the Effects of Grain Surface Morphology on Hot Spots in HMX with Surrogate Model Development

Springer

Miller²,

Kroonblawd

et al. 2022

Propellants Explo Pyrotec

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There have been several numerical studies on the collapse of internal voids in energetic grains but fewer investigations have probed grain-grain interface effects. In this study, we examine the effects of grain surface morphology and binder conditions on hot spot mechanisms during shock loading using the multi-physics hydrocode, ALE3D, coupled with the thermochemical code, Cheetah. To improve the accuracy of our grain-scale simulations, the HMX material models have been updated from previous studies to incorporate new property predictions from molecular dynamics simulations. In our simulations of the interface between two neighboring energetic grains, the upstream grain surface is described by a single sinusoid with amplitude (0.5-2 μm) and wavelength (0.5-2 μm). The effects of grain surface coating, i. e., no binder, partially coated, and fully coated with binder, is also explored. A range of shock loading pressures (10-30 GPa) is considered. Bind-er coating reduces hot spots at grain-grain interfaces by limiting plastic deformation and heating of upstream grain surfaces as well as preventing transmission of localized deformation modes (e. g., jetting) to the downstream grain. More plastic work and heating is observed with new HMX material models versus the previous models because the strength does not thermally soften as much as a result of the higher melt temperature; this also reduces vortical flow and jetting mechanisms with the new HMX material models. A surrogate model based on neural networks is developed for the early stage reaction rate. Physics-based input features improve the performance of the neural networks over basic input features alone with a root mean squared error = 1.05 μs À 1 and R 2 = 0.98. Accurate and fast-running surrogate models can effectively serve as structure-property-sensitivity relationships.

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The Strength of Two HMX Based Plastic Bonded Explosives During One Dimensional Shock Loading

Cited by 16 publications

References 53 publications

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

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

Dislocation mobility and critical stresses at finite temperatures in molecular crystal cyclotetramethylene tetranitramine (β-HMX)

Simulating the Effects of Grain Surface Morphology on Hot Spots in HMX with Surrogate Model Development

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