A material frame approach for evaluating continuum variables in atomistic simulations

Journal Article · Sat Mar 20 04:00:00 EDT 2010 · Journal of Computational Physics

DOI:https://doi.org/10.1016/j.jcp.2009.11.039· OSTI ID:21333941

Jones, Reese E ^[1]; Templeton, Jeremy A ^[2]

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1. Mechanics of Materials Department, Sandia National Laboratories, Livermore, CA 94551 (United States)
2. Thermal/Fluid Science and Engineering Department, Sandia National Laboratories, Livermore, CA 94551 (United States)

We present a material frame formulation analogous to the spatial frame formulation developed by Hardy, whereby expressions for continuum mechanical variables such as stress and heat flux are derived from atomic-scale quantities intrinsic to molecular simulation. This formulation is ideally suited for developing an atomistic-to-continuum correspondence for solid mechanics problems. We derive expressions for the first Piola-Kirchhoff (P-K) stress tensor and the material frame heat flux vector directly from the momentum and energy balances using localization functions in a reference configuration. The resulting P-K stress tensor, unlike the Cauchy expression, has no explicit kinetic contribution. The referential heat flux vector likewise lacks the kinetic contribution appearing in its spatial frame counterpart. Using a proof for a special case and molecular dynamics simulations, we show that our P-K stress expression nonetheless represents a full measure of stress that is consistent with both the system virial and the Cauchy stress expression developed by Hardy. We also present an expanded formulation to define continuum variables from micromorphic continuum theory, which is suitable for the analysis of materials represented by directional bonding at the atomic scale.

• OSTI ID: 21333941
• Journal Information: Journal of Computational Physics, Journal Name: Journal of Computational Physics Journal Issue: 6 Vol. 229; ISSN JCTPAH; ISSN 0021-9991
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ENERGY BALANCE
FUNCTIONS
HEAT FLUX
MOLECULAR DYNAMICS METHOD
SIMULATION
STRESSES
VECTORS