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
Citations
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Journal ArticleDOI
Fracture initiation mechanisms in α-alumina under hypervelocity impact
TL;DR: In this paper, the authors investigated the mechanisms of crack initiation and fracture in α-alumina under hypervelocity impact using large-scale molecular-dynamics simulations involving 540×106 atoms.
Unified Plasticity - An Engineering Approach
TL;DR: In this paper, the authors apply the term "constitutive equations" and "material modelling" to the analytical representation of the material response characteristics prior to total failure, which has received considerable attention over many years.
Journal ArticleDOI
Atomistic modelling of the plastic deformation of helium bubbles and voids in aluminium under shock compression
TL;DR: In this paper, the authors investigated the deformation of helium bubbles and voids in aluminium under shock compression by molecular dynamics simulations and found that dislocation nucleation at the leading side of a helium bubble is easier than that for a void.
Book ChapterDOI
Paradigms and Challenges in Shock Wave Research
TL;DR: Both experimental and computational results are used to show that shocks produce highly heterogeneous states of compression, which strongly influence observable material properties in the shocked state, and what kinds of measurements will be needed to resolve these issues.
Journal ArticleDOI
The void nucleation strengths of the Cu–Ni–Nb- based nanoscale metallic multilayers under high strain rate tensile loadings
TL;DR: In this article, the void always nucleates from within the Cu layers, where the partial dislocations intersect with each other or with existing stacking faults, and the void nucleation strength of the NMMs is closely related to the density of available sites.
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.