Frontiers in the Constitutive Modeling of Anisotropic Shock Waves

Lukyanov, Alexander A.; Segletes, Steven B.

doi:10.1115/1.4006253

Cited by 2 publications

(4 citation statements)

References 52 publications

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“…III, were performed for spatially resolved regions containing contiguous molecular layers (e.g., ignoring minus signs, layers 1-2, 1-10, 61-80, etc.). Immediately behind the shock front the five two-layer-thick regions (again, ignoring minus signs) 1-2, 3-4, 5-6, 7-8, and 9-10 were used to define a ten-layer-thick one (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Throughout the analysis we considered only layers −1 to −220 behind the shock front and layers +1 to +20 ahead of the shock front.…”

Section: Of Ref 3 For An Illustration Of the Simulation Cellmentioning

confidence: 99%

“…[1][2][3][4] To make full use of shocks as an experimental technique for rapidly adding energy to solids or liquids, it is important that we come to understand the fundamental behavior of shocks in complicated anisotropic materials and at interfaces. [5][6][7][8] The large anisotropic strains and high strain rates imposed by shock wave passage through a crystal result in molecules containing relatively large amounts of energy that is, in general, non-thermally distributed immediately behind the shock front. Phonon and molecular modes that are close to mechanical resonances with the shock wave are preferentially excited, after which redistribution of the shock excitation energy to the remaining modes of the system occurs; this mechanism is widely accepted 9,10 and has come to be known as vibrational multi-phonon up-pumping.…”

Section: Introductionmentioning

confidence: 99%

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Post-shock relaxation in crystalline nitromethane

Rivera‐Rivera

Sewell

Thompson

2013

The Journal of Chemical Physics

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Molecular dynamics simulations of shocked (100)-oriented crystalline nitromethane were carried out to determine the rates of relaxation behind the shock wave. The forces were described by the fully flexible non-reactive Sorescu-Rice-Thompson force field [D. C. Sorescu, B. M. Rice, and D. L. Thompson, J. Phys. Chem. B 104, 8406 (2000)]. The time scales for local and overall thermal equilibration in the shocked crystal were determined. The molecular center-of-mass and atomic kinetic energy distributions rapidly reach substantially different local temperatures. Several picoseconds are required for the two distributions to converge, corresponding to establishment of thermal equilibrium in the shocked crystal. The decrease of the molecular center-of-mass temperature and the increase of the atomic temperature behind the shock front exhibit essentially exponential dependence on time. Analysis of covalent bond distance distributions ahead of, immediately behind, and well behind the shock front showed that the effective bond stretching potentials are essentially harmonic. Effective force constants for the C-N, C-H, and N-O bonds immediately behind the shock front are larger by factors of 1.6, 2.5, and 2.0, respectively, than in the unshocked crystal; and by factors of 1.2, 2.2, and 1.7, respectively, compared to material sufficiently far behind the shock front to be essentially at thermal equilibrium.

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Section: Of Ref 3 For An Illustration Of the Simulation Cellmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Post-shock relaxation in crystalline nitromethane

Rivera‐Rivera

Sewell

Thompson

2013

The Journal of Chemical Physics

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“…The EOS is of fundamental importance for describing the mechanical response to shock compressions [50,51]. As shown in figure 5, the EOS of aluminum at compressed states has been predicted at 0 K with the three potentials.…”

Section: Testing the Potentials Of Aluminummentioning

confidence: 97%

“…Equation of states is of fundamental importance for describing mechanical response to shock compressions [50,51]. As shown in Fig.…”

Section: B Testing the Potentials Of Aluminummentioning

confidence: 99%

A new embedded-atom method approach based on thepth moment approximation

Wang¹,

Zhu²,

Xiao

et al. 2016

J. Phys.: Condens. Matter

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Large scale atomistic simulations with suitable interatomic potentials are widely employed by scientists or engineers of different areas. The quick generation of high-quality interatomic potentials is urgently needed. This largely relies on the developments of potential construction methods and algorithms in this area. Quantities of interatomic potential models have been proposed and parameterized with various methods, such as the analytic method, the force-matching approach and multi-object optimization method, in order to make the potentials more transferable. Without apparently lowering the precision for describing the target system, potentials of fewer fitting parameters (FPs) are somewhat more physically reasonable. Thus, studying methods to reduce the FP number is helpful in understanding the underlying physics of simulated systems and improving the precision of potential models. In this work, we propose an embedded-atom method (EAM) potential model consisting of a new manybody term based on the pth moment approximation to the tight binding theory and the general transformation invariance of EAM potentials, and an energy modification term represented by pairwise interactions. The pairwise interactions are evaluated by an analytic-numerical scheme without the need to know their functional forms a priori. By constructing three potentials of aluminum and comparing them with a commonly used EAM potential model, several wonderful results are obtained. First, without losing the precision of potentials, our potential of aluminum has fewer potential parameters and a smaller cutoff distance when compared with some constantly-used potentials of aluminum. This is because several physical quantities, usually serving as target quantities to match in other potentials, seem to be uniquely dependent on quantities contained in our basic reference database within the new potential model. Second, a key empirical parameter in the embedding term of the commonly used EAM model is found to be related to the effective order of moments of local density of states. This may provide a way to improve the precision of EAM potentials further through more precise approximations to tight binding theory. In addition, some critical details about construction procedures are discussed.

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Frontiers in the Constitutive Modeling of Anisotropic Shock Waves

Cited by 2 publications

References 52 publications

Post-shock relaxation in crystalline nitromethane

Post-shock relaxation in crystalline nitromethane

A new embedded-atom method approach based on thepth moment approximation

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