Journal ArticleDOI
Plasticity Induced by Shock Waves in Nonequilibrium Molecular-Dynamics Simulations
Brad Lee Holian,Peter S. Lomdahl +1 more
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In this article, nonequilibrium molecular-dynamics simulations of shock waves in three-dimensional 10-million atom face-centered cubic crystals with cross-sectional dimensions of 100 by 100 unit cells were presented.Abstract:
Nonequilibrium molecular-dynamics simulations of shock waves in three-dimensional 10-million atom face-centered cubic crystals with cross-sectional dimensions of 100 by 100 unit cells show that the system slips along all of the available {111} slip planes, in different places along the nonplanar shock front. Comparison of these simulations with earlier ones on a smaller scale not only eliminates the possibility that the observed slippage is an artifact of transverse periodic boundary conditions, but also reveals the richness of the nanostructure left behind. By introducing a piston face that is no longer perfectly flat, mimicking a line or surface inhomogeneity in the unshocked material, it is shown that for weaker shock waves (below the perfect-crystal yield strength), stacking faults can be nucleated by preexisting extended defects.read more
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Book ChapterDOI
Accelerated Molecular Dynamics Simulations of Shock-Induced Chemistry: Application to Liquid Benzene
TL;DR: In this paper, replica-based accelerated molecular dynamics was used to simulate the chemical dynamics of liquid benzene with a semi-empirical reactive interatomic potential at timescales beyond those routinely accessible to traditional molecular dynamics simulations.
Journal ArticleDOI
Revisiting the Power Law Characteristics of the Plastic Shock Front under Shock Loading.
TL;DR: In this paper, a simple dislocation-based continuum model was developed, which reproduced the third power law and revealed very good agreement with recent experiments of multiple types of metals quantitatively.
Journal ArticleDOI
Molecular dynamic studies on materials under laser shocks
TL;DR: In this paper, embedded-atom simulations of shock-wave propagation through copper crystals of different orientation are used to understand the microscopic characteristics of shock propagation through solids and fluids, especially for the short spatial and temporal scales relevant to laser-driven shocks.
Journal ArticleDOI
Yield strength measurement of shock-loaded metal by flyer-impact perturbation method
Xiaojuan Ma,Zhan Shi +1 more
TL;DR: In this article, the authors measured material yield strength on the basis of correlation between the yield strength under shock compression and the damping of oscillatory perturbations in the shape of a shock front passing through the material.
Journal ArticleDOI
Convergence acceleration of molecular dynamics methods for shocked materials using velocity scaling
TL;DR: In this paper, a convergence acceleration method applicable to extended system molecular dynamics techniques for shock simulations of materials is presented, which uses velocity scaling to reduce the instantaneous value of the Rankine-Hugoniot conservation of energy constraint used in Extended System Molecular Dynamics methods to more rapidly drive the system towards a converged Hugoniot state.
References
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Journal ArticleDOI
Shock-wave structure via nonequilibrium molecular dynamics and Navier-Stokes continuum mechanics
TL;DR: In this article, a strong steady dense-fluid shock wave is simulated with 4800-atom nonequilibrium molecular dynamics, and the resulting density, stress, energy, and temperature profiles are compared with corresponding macroscopic profiles derived from Navier-Stokes continuum mechanics.
Journal ArticleDOI
Fracture simulations using large-scale molecular dynamics
Brad Lee Holian,Ramon Ravelo +1 more
TL;DR: It is found that the can suppress ductile behavior by including viscous damping in the equations of motion, thereby demonstrating a transition to brittle crack propagation as static, zero-strain-rate conditions are approached.
Journal ArticleDOI
Dislocation Dynamics and Dynamic Yielding
TL;DR: In this article, the dislocation dynamics of Gilman and Johnston were applied to the problem of elastic elastic flow in Armco iron at very high strain rates, and the initial density of dislocation lines, N0, was found to be 2.0×108 cm−2.
Journal ArticleDOI
Large-Scale Molecular Dynamics Simulations of Three-Dimensional Ductile Failure
TL;DR: In this paper, the authors performed massively parallel 3D molecular dynamics simulations with up to 35 million atoms to investigate ductile failure, obtaining mechanistic information at the atomistic level inaccessible to experiment.
Journal ArticleDOI
A mechanism for dislocation generation in shock-wave deformation
TL;DR: Hornbogen as discussed by the authors proposed a modification to Smith's (9) model, based on the fact that shockloaded iron (between 7 and II GPa) presents a substructure characterized by straight screw dislocations.