Zusammenfassung
In this paper, the validity and accuracy of three interatomic potentials,
commonly used to study carbon nanostructures in molecular dynamics, and the
continuum shell model of Ghaffari and Sauer 1 are investigated. The
mechanical behavior of single-layered graphene sheets (SLGSs) near zero Kelvin
is studied for this comparison. The validity of the molecular and continuum
models is assessed by direct comparison with density functional theory (DFT)
data available in the literature. The molecular simulations are carried out
employing the MM3, Tersoff and REBO+LJ potentials. The continuum formulation
uses an anisotropic hyperelastic material model in the framework of the
geometrically exact Kirchhoff-Love shell theory and isogeometric finite
elements. For the comparison, the nonlinear response of a square graphene sheet
under uniaxial stretching, biaxial stretching and pure bending is studied.
Results from the continuum model are in good agreement with those of DFT. The
results from the MM3 potential agree well with the DFT results up to the
instability point, whereas those from the REBO+LJ and Tersoff potentials agree
with the DFT results only within the range of small deformations. In contrast
to the other potentials, the Tersoff potential yields auxetic response in SLGSs
under uniaxial stretch. Additionally, the transverse vibration frequencies of a
pre-stretched graphene sheet and a carbon nanocone are obtained using the
continuum model and molecular simulations with the MM3 potential. The
variations of the frequencies obtained from these two approaches agree within
an accuracy of about 95%.
Nutzer