Molecular dynamics study of dislocation nucleation from a crack tip

Hess, Berk; Giessen, van der Erik; Thijsse, Barend J.

doi:10.1103/physrevb.71.054111

Cited by 20 publications

(13 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In both cases the highest stress are occurring around the crack tip and specifically behind the crack tip indicating that crack growth is about to occur. The (111) plane, being densely packed, would generate this brittle crack behavior as was observed in the simulation and which was also observed in MD simulations of fracture in FCC metals by Hess et al and Rafii‐Tabar et al .…”

Section: Test Casessupporting

confidence: 83%

Multiscale coupling using a finite element framework at finite temperature

Iacobellis

Behdinan

2012

Numerical Meth Engineering

View full text Add to dashboard Cite

SUMMARY This paper presents the formulation and application of a multiscale methodology that couples three domains using a finite element framework. The proposed method efficiently models atomistic systems by decomposing the system into continuum, bridging, and atomistic domains. The atomistic and bridging domains are solved using a combined finite element–molecular mechanics simulation where the system is discretized into atom/nodal centric elements based on the atomic scale finite element method. Coupling between the atomistic domain and continuum domain is performed through the bridging cells, which contain locally formulated atoms whose displacements are mapped to the nodes of the bridging cell elements. The method implements a temperature‐dependent potential for finite temperature simulations. Validation and demonstration of the methodology are provided through three case studies: displacement in a one‐dimensional chain, stress around nanoscale voids, and fracture. From these studies differences between multiscale and fully atomistic simulations were very small with the simulation time of the proposed methodology being approximately a tenth of the time of the fully atomistic model. Copyright © 2012 John Wiley & Sons, Ltd.

show abstract

Section: Test Casessupporting

confidence: 83%

Multiscale coupling using a finite element framework at finite temperature

Iacobellis

Behdinan

2012

Numerical Meth Engineering

View full text Add to dashboard Cite

show abstract

“…This dislocation nucleation behavior contrasts with that found by Li et al (2002) for spherical indentation of Al (using the same Ercolessi-Adams potential), where the dislocation is reported to be initiated from one {1 1 1} plane and then spread to adjacent {1 1 1} planes. On the other hand, it does share features seen by Hess et al (2005) in the nucleation of a dislocation from a crack tip.…”

Section: Structure Of the Nucleated Dislocationmentioning

confidence: 82%

“…Such dislocation structures contrast with the classical extended structures with a bend where glide occurs from one slip plane to another (cf. Hirth, 2000), but have also been observed during dislocation nucleation from a crack tip (Hess et al, 2005). It is also noted that the surface dislocations does not form surface steps, but 'swell out' instead as convex continuous smooth curvatures.…”

Section: Structure Of the Nucleated Dislocationmentioning

confidence: 95%

An analysis of dislocation nucleation near a free surface

Liu

Giessen

Needleman

2007

International Journal of Solids and Structures

Self Cite

View full text Add to dashboard Cite

Molecular dynamics analyses of defect-free aluminum single crystals subject to bending are carried out to investigate dislocation nucleation from free surfaces. A principal aim of the analyses is to provide background for the development of dislocation nucleation criteria for use in discrete dislocation plasticity calculations. The molecular dynamics simulations use an embedded atom potential for aluminum. Bending is imposed on a strip by specifying a linear variation of displacement rate on opposite edges. The overall bending response is determined and the character of the dislocations nucleated is identified. It is found that the stress magnitudes at the instant of dislocation nucleation are nearly an order of magnitude smaller than for homogeneous bulk dislocation nucleation. The characterization of dislocation nucleation in terms of various phenomenological nucleation criteria is explored, in particular: (i) a critical resolved shear stress; (ii) the onset of an elastic instability; and (iii) a critical stress-gradient criterion. It is found that dislocation nucleation is not well-represented by a critical value of the resolved shear stress but is reasonably well-represented by the critical stress-gradient criterion.

show abstract

“…As shown in Figure 1(a), cylindrical specimens of bcc W and diamond Si with several orientations are prepared. An atomically sharp crack is inserted into each specimen by applying the anisotropic displacement field calculated by the linear elastic fracture mechanics (LEFM) equation with a given initial stress intensity factor value [26,27]. Then, the specimen is divided into two regions.…”

Section: Resultsmentioning

confidence: 99%

Origin of unrealistic blunting during atomistic fracture simulations based on MEAM potentials

Lee

2014

Philosophical Magazine

View full text Add to dashboard Cite

Atomistic simulations based on interatomic potentials have frequently failed to correctly reproduce the brittle fracture of materials, showing an unrealistic blunting. We analyse the origin of the unrealistic blunting during atomistic simulations by modified embedded-atom method (MEAM) potentials for experimentally well-known brittle materials such as bcc tungsten and diamond silicon. The radial cut-off which has been thought to give no influence on MEAM calculations is found to have a decisive effect on the crack propagation behaviour. Extending both cut-off distance and truncation range can prevent the unrealistic blunting, reproducing many well-known fracture behaviour which have been difficult to reproduce. The result provides a guideline for future atomistic simulations that focus on various fracture-related phenomena including the failure of metallic-covalent bonding material systems using MEAM potentials.

show abstract

Molecular dynamics study of dislocation nucleation from a crack tip

Cited by 20 publications

References 20 publications

Multiscale coupling using a finite element framework at finite temperature

Multiscale coupling using a finite element framework at finite temperature

An analysis of dislocation nucleation near a free surface

Origin of unrealistic blunting during atomistic fracture simulations based on MEAM potentials

Contact Info

Product

Resources

About