Homogeneous dislocation nucleation in cyclotrimethylene trinitramine under shock loading

Cawkwell, Marc; Ramos, Kyle; Hooks, D. E.; Sewell, Thomas D.

doi:10.1063/1.3305630

Cited by 98 publications

(115 citation statements)

References 34 publications

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“…[13][14][15] More recently, NEMD simulations have been used to investigate atomic-scale plastic deformation processes in more complex crystal structures beyond these relatively simple fcc, hcp, and bcc lattices. For instance, the mechanical (i.e., nonreactive) shock response of the high-explosive crystals HMX 16 and RDX 17 have been reported. However, aside from the widespread interest in iron, 18 shock-induced phase transformations between two stable crystal polymorphs with more open and complex (and therefore more difficult to analyze) structures have not been widely studied.…”

Section: Introductionmentioning

confidence: 99%

Shock-induced phase transformations in gallium single crystals by atomistic methods

et al. 2013

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Utilizing a modified embedded atom method potential, we performed large-scale classical molecular dynamics simulations (with up to 50 million atoms) to investigate the response of Ga single crystals to shock compression along the three major orientations of the orthorhombic A11 ground state, i.e., [001], [010], and [100]. For weak shocks with particle velocity u p < 300 m/s, these defect-free single crystals respond elastically, but for stronger shocks, they undergo a structural phase transformation and then (for even stronger shocks) melt. For intermediate shock strengths (300 m/s < u p < 1.2 km/s) a split shock wave is formed, with an elastic precursor (uniaxial compression wave) leading the slower transformation wave. The transformed region consists of a mixed phase, with stripes of the product phase embedded into the uniaxially compressed parent phase, with the ratio of product to parent phase increasing with increasing shock strength, much like in martensitic phase transformations. Upon shock release from the free surface at the end of the sample, the transformation is reversed, leaving only some defects behind, which makes it difficult to experimentally investigate the structural transformation in shock-recovered samples. We investigated the structure produced by the shock and found it to be similar to the β phase of Ga which is obtained by supercooling from the liquid state. However, the product phase shows only half the period along [100] in the calculated diffraction pattern. Further investigation showed that this is due to a different stacking sequence in this direction, namely ABCD instead of AB for the β phase.

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Section: Introductionmentioning

confidence: 99%

Shock-induced phase transformations in gallium single crystals by atomistic methods

et al. 2013

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“…1a) has been widely studied both experimentally [38][39][40][41][42][43][44][45] and theoretically [35,[46][47][48][49][50][51][52]. There are four known polymorphs of RDX, denoted a [53], b [54], e [55], and c [56].…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of the Collapse of a Cylindrical Pore in the Energetic Material α-RDX

Eason

Sewell

2015

J. dynamic behavior mater.

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Molecular dynamics simulations were used to study the shock-induced collapse of cylindrical pores in oriented single crystals of the energetic material a-1,3,5-trinitroperhydro-1,3,5-triazine (a-RDX). The shock propagation direction was parallel to the [100] crystal direction and the cylinder axis of the initially 35.0 nm diameter pore was parallel to [010]. Features of the collapse were studied for Rankine-Hugoniot shock pressures P s = 9.71, 24.00, and 42.48 GPa. Pore collapse for the weak shock is dominated by visco-plastic deformation in which the pore pinches shut without jet formation and with little penetration of the upstream material into the downstream pore wall. For the strong shock the collapse is hydrodynamiclike and results in the formation of a jet that penetrates significantly into the downstream pore wall. Material flow during collapse was characterized by examining the spread and mixing of sets of initially contiguous molecules and evolution of local velocity fields. Local disorder during collapse was assessed using time autocorrelation functions for molecular rotation. Energy deposition and localization was studied using spatial maps of temperature and pressure calculated as functions of time.

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“…In α-HMX the deformation mechanism changes to one dominated by nanoscale shear bands as the shock strength increases (7.2 GPa ≤ P s < 23.2 GPa). Dislocation-mediated plasticity (homogeneously nucleated metastable stacking faults) has been predicted for weak shocks (1.3 GPa < P s < 2.0 GPa) on (111) 11 and (021) 12 planes in α-RDX; for that same material, nanoscale shear bands were predicted for shocks (P s ~ 10.0 GPa) propagating along [100] 13,14 and the polymorphic α-γ solid-solid phase transition was reported for shocks propagating along [001]. [14][15][16] These kinds of well-defined plastic deformation processes observed for PETN, α-HMX, and α-RDX are less pronounced in shocked crystalline nitromethane.…”

Section: For the [100] Shock Strength Considered P R-hmentioning

confidence: 99%

Investigation of Fundamental Processes and Crystal-Level Defect Structures in Metal-Loaded High-Explosive Materials under Dynamic Thermo-Mechanical Loads and their Relationships to Impact Survivability of Munitions (Thrust 4, Topic J)

Thompson¹,

Sewell²,

Bouma³

et al. 2014

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Homogeneous dislocation nucleation in cyclotrimethylene trinitramine under shock loading

Cited by 98 publications

References 34 publications

Shock-induced phase transformations in gallium single crystals by atomistic methods

Shock-induced phase transformations in gallium single crystals by atomistic methods

Molecular Dynamics Simulations of the Collapse of a Cylindrical Pore in the Energetic Material α-RDX

Investigation of Fundamental Processes and Crystal-Level Defect Structures in Metal-Loaded High-Explosive Materials under Dynamic Thermo-Mechanical Loads and their Relationships to Impact Survivability of Munitions (Thrust 4, Topic J)

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