Accelerated quasicontinuum: a practical perspective on hyper-QC with application to nanoindentation

Abstract

Hyper-QC is a multiscale method based on the quasicontinuum (QC) method in which time is accelerated using hyperdynamics through the addition of a suitable bias potential. This paper describes the practical details of implementing and carrying out hyper-QC simulations and introduces a novel mechanism-based bias potential for deformation processes in face-centred cubic (fcc) systems. The factors limiting the maximum achievable acceleration are discussed. The method is demonstrated for nanoindentation into a thin film of single crystal fcc nickel at near experimental loading rates. Speed up factors as high as 10,000 are achieved. The simulations reveal a thermally activated dislocation nucleation mechanism with a logarithmic dependence on temperature and indenter velocity in agreement with a theoretical model.

Keywords:

• Quasicontinuum
• hyperdynamics
• spatial multiscale
• temporal acceleration
• nanoindentation

Notes

No potential conflict of interest was reported by the authors.

1 Since all nodes must be co-located with atoms in the reference configuration, the atomic structure sets a lower limit on mesh refinement.

2 Atoms in the padding region whose positions are determined by interpolation are referred to as ‘dummy atoms’ in QC. Thus, in the present implementation dummy atoms are not allowed.

Additional information

Funding

WKK was supported in part by the National Science Foundation [award number 1463038]. EBT was supported in part by the National Science Foundation [award number 1462807].