How to identify dislocations in molecular dynamics simulations?

Li, Duo; Wang, FengChao; Yang, Zhenyu; Zhao, Ya‐Pu

doi:10.1007/s11433-014-5617-8

Cited by 77 publications

(23 citation statements)

References 53 publications

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“…Actually, after fracking, the fracking pressure F, the viscosity µ and the velocity V of the fracking liquid, and the porosity n and surface energy γ of the rock could also influence the probabilities. Additionally, fracking processes are associated with the creation of extensive artificial fractures [25], so the probabilities of a nearest neighbor connection should be the results of the combined eects from existing (natural) fractures, potential cracks that can be connective under specific pressure, and newly created fractures. Thus equation (8) can be modified as…”

Section: Resultsmentioning

confidence: 99%

“…However, the number of configurations would increase extraordinarily. The number of configurations in a × × 5 5 5 formation is estimated to be × 3 10 7 ~ 2 25 . To resolve such contradiction, Reynolds and his colleagues [22] introduced a method that combines the RNG approach and Monte Carlo method, called the Monte Carlo renormalization group, to calculate critical parameters with a high degree of accuracy for site percolation by scaling with a large subsection.…”

Section: J Stat Mech (2016) 013205mentioning

confidence: 99%

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Microcrack connectivity in rocks: a real-space renormalization group approach for 3D anisotropic bond percolation

Zhao¹,

Chen²,

Yuan³

et al. 2016

J. Stat. Mech.

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Abstract. The onset of microcrack conductivity in anisotropic rocks, which is a concern in hydraulic fracturing, was treated as a three-dimensional (3D) bond percolation problem where the bonds in the three orthogonal directions are presented with dierent probabilities. A real-space renormalization group (RNG) approach was expanded to calculate the critical behavior in this percolation problem, which was demonstrated to have improved accuracy for estimating critical points. A 3D phase diagram for the anisotropic percolation problem was obtained to present the relation between rock permeability and crack density, which is suitable for the needs of engineering for its accuracy and visualization.

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Section: Resultsmentioning

confidence: 99%

Section: J Stat Mech (2016) 013205mentioning

confidence: 99%

Microcrack connectivity in rocks: a real-space renormalization group approach for 3D anisotropic bond percolation

Zhao¹,

Chen²,

Yuan³

et al. 2016

J. Stat. Mech.

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“…This method is a helpful measure of the local crystal structure around an atom, in which a characteristic signature is computed from the topology of bonds that connect the surrounding neighbor atoms. More details about the detection of crystal defects and specific dislocations are presented elsewhere [19].…”

Section: Atomistic Simulationmentioning

confidence: 99%

The roles of crystallographic orientation, high-angle grain boundary, and indenter diameter during nano-indentation

et al. 2015

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Molecular dynamics simulation of nano-indentation of single-crystal and bicrystal FCC aluminum is performed. The role of crystallographic orientation during nano-indentation of single-crystal aluminum is assessed. Then, the influence of the presence of a grain boundary is analyzed by adding high-angle symmetric tilt boundaries of 5<210>/(100) and 5<310>/(100) parallel to the surface on which the indentation is performed. Furthermore, in both cases, the size of the indenter is changed to investigate how the surface curvature of the indenter affects the nano-indentation process. The results suggest that in each crystallographic orientation, the presence of a grain boundary increases the required force for indentation, while the distance of a grain boundary from the indentation surface could affect the increase in the required force. Simulations prove that the grain boundary acts as a source of generation and emission of dislocations and restricts the penetration of the indenter by limiting the slip band formation and plastic deformation. The dislocation emission from the grain boundary restricts the penetration of the indenter and limits the formation of the octahedral slip systems of type {111}<110> and consequently increases the required force for indentation in bicrystals.

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“…The CS parameter at an atom is introduced to determine the local symmetry of lattice structures around the atom. Thus, it can be used to characterize if the atom possesses a structure of perfect lattice or a local defect at a surface (Li et al 2014). …”

Section: Two Dimensional Crack Propagationmentioning

confidence: 99%

Adjoint shape design sensitivity analysis of molecular dynamics for lattice structures using GLE impedance forces

Jang

Cho

2015

Int J Mech Mater Des

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We presented a shape design sensitivity analysis method for lattice structures using a generalized Langevin equation (GLE) to overcome the difficulty of discrete nature in atomic systems. Taking advantage of the GLE forces, the perturbed atomistic region is treated as the GLE impedance forces and the shape design problem of discrete atomic variations is converted into a non-shape problem with GLE impedance forces. We developed an adjoint variable method in order to improve the computational efficiency for molecular dynamics (MD) with many design variables. Due to the translational symmetry in lattice structure, the size of the time history kernel function that accounts for the boundary effects of reduced systems could be reduced to that of a single atoms DOFs. In numerical examples, the convergent characteristic of shape sensitivity according to the amount of shape variations is investigated in MD systems. Also, the results of the derived shape sensitivity turn out to be more accurate and efficient, compared with those of the finite difference ones.

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How to identify dislocations in molecular dynamics simulations?

Cited by 77 publications

References 53 publications

Microcrack connectivity in rocks: a real-space renormalization group approach for 3D anisotropic bond percolation

Microcrack connectivity in rocks: a real-space renormalization group approach for 3D anisotropic bond percolation

The roles of crystallographic orientation, high-angle grain boundary, and indenter diameter during nano-indentation

Adjoint shape design sensitivity analysis of molecular dynamics for lattice structures using GLE impedance forces

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