Dynamics of virial stress in gold lattice after crack initiation

N Kumar and K Pochiraju, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, 226, 359-366 (2012).

DOI: 10.1177/0954406211429897

Virial stress measures in atomistic models obtained by appropriate spatial and temporal averaging are known to be representations of continuum stresses in bulk materials. Using molecular dynamics simulations, this effort shows that some local and dynamic features of the continuum stress exist in the dynamic response of the virial stress. The spatially averaged but temporally fluctuating behaviour of the hydrostatic component of the virial stress is observed in both time and frequency domains at a mean stress-free state for a nanostructure at a target temperature. An atomistic-scale model with one finite dimension and two infinite dimensions was utilized to represent a thin single crystal film. Numerical simulations were performed with force fields and lattice parameters corresponding to gold. The initial temperature, pressure, and volume states for the material were determined using two equilibrium procedures that produced convergent energy and stress states. The dynamics of the virial stresses in atomistic ensembles show several dynamic and local characteristics of the continuum stresses.

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