Molecular dynamics investigation of dislocation pinning by a nanovoid in copper

“…The dynamics of edge dislocations in close-packed materials under dynamic loading has been studied earlier in the frames of classical molecular dynamics (CMD) by other researchers [1][2][3][4][5][6][7] as following. Typical scheme of the simulation model is presented in Fig.…”

Section: Traditional Methods Of Edge Dislocation Dynamics Simulationsmentioning

confidence: 99%

Atomistic modeling of the dislocation dynamics and evaluation of static yield stress

Karavaev

Dremov

Ionov

2015

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. Static strength characteristics of structural materials are of great importance for the analysis of the materials behaviour under mechanical loadings. Mechanical characteristics of structural materials such as elastic limit, strength limit, ultimate tensile strength, plasticity are, unlike elastic moduli, very sensitive to the presence of impurities and defects of crystal structure. Direct atomistic modeling of the static mechanical strength characteristics of real materials is an extremely difficult task since the typical time scales available for the direct modeling in the frames of classical molecular dynamics do not exceed a hundred of nanoseconds. This means that the direct atomistic modeling of the material deformation can be done for the regimes with rather high strain rates at which the yield stress and other mechanical strength characteristics are controlled by microscopic mechanisms different from those at low (quasi-static) strain rates. In essence, the plastic properties of structural materials are determined by the dynamics of the extended defects of crystal structure (edge and screw dislocations) and by interactions between them and with the other defects in the crystal. In the present work we propose a method that is capable to model the dynamics of edge dislocations in the fcc and hcp materials at dynamic deformations and to estimate the material static yield stress in the states of interest in the frames of the atomistic approach. The method is based on the numerical characterization of the stress relaxation processes in specially generated samples containing solitary edge dislocations.

show abstract

“…Fully atomistic methods have become an indispensible tool for providing direct physical insight into the mechanistic role of defects in materials [1][2][3][4][5][6]. Molecular statics simulations have been used extensively to study grain boundaries [7][8][9], dislocation cross-slip [10][11][12], crack tips [13,14], and dislocation/obstacle interactions [1-3, 5, 6, 15-33].…”

Section: Introductionmentioning

confidence: 99%

Analysis of spurious image forces in atomistic simulations of dislocations

Szajewski

2015

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

Abstract. Molecular Dynamics simulations of dislocation/obstacle interactions are enhancing our physical understanding of plasticity. However, despite increasing computational power, the interaction between simulation cell boundaries and the long ranged fields of dislocations make spurious image effects inevitable. Here, these image effects are examined in detail, providing a general map of the spurious image stress as a function of simulation cell size, aspect ratio, and bow-out for both nominally edge and screw dislocations. This is achieved using an approximate image solution of the resulting boundary value problem as well as an analytic model that captures most of the spurious image effects. A unique simulation cell shape is found to minimize spurious image effects for a fixed simulation volume (i.e. fixed total number of atoms) and specified initial dislocation line length. The results are used to estimate image stress effects in various literature studies involving dislocation bow-out. The image effects are non-negligible. Several case studies involving simulation cell dimensions are shown to converge due to a near-zero scaling of the image stress with respect to the simulation cell dimensions used. Finally, a direct comparison is made between a dislocation bow-out configuration under an applied load in a finite simulation cell and an image-free multiscale simulation of the same problem and the difference is shown to be consistent with our estimated image stresses. Overall, the results here provide guidance for both the development and interpretation of quantitative Molecular Dynamics studies involving curved dislocation structures.

show abstract

Molecular dynamics investigation of dislocation pinning by a nanovoid in copper

Cited by 78 publications

References 23 publications

Atomic-scale strengthening mechanism of dislocation-obstacle interaction in silicon carbide particle-reinforced copper matrix nanocomposites

Atomic-scale strengthening mechanism of dislocation-obstacle interaction in silicon carbide particle-reinforced copper matrix nanocomposites

Atomistic modeling of the dislocation dynamics and evaluation of static yield stress

Analysis of spurious image forces in atomistic simulations of dislocations

Contact Info

Product

Resources

About