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Journal of Nanomaterials
Volume 2011 (2011), Article ID 380286, 6 pages
http://dx.doi.org/10.1155/2011/380286
Research Article

Size Dependence of the Nonlinear Elastic Softening of Nanoscale Graphene Monolayers under Plane-Strain Bulge Tests: A Molecular Dynamics Study

1Department of Mechanical Engineering, University of Wyoming, Laramie, WY 82071, USA
2Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA

Received 28 May 2010; Accepted 19 October 2010

Academic Editor: Sulin Zhang

Copyright © 2011 Sukky Jun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The pressure bulge test is an experimental technique to characterize the mechanical properties of microscale thin films. Here, we perform constant-temperature molecular dynamics simulations of the plane-strain cylindrical bulge test of nanosized monolayer graphene subjected to high gas pressure induced by hydrogen molecules. We observe a nonlinear elastic softening of the graphene with an increase in hydrogen pressure due to the stretching and weakening of the carbon-carbon bonds; we further observe that this softening behavior depends upon the size of the graphene monolayers. Our simulation results suggest that the traditional microscale bulge formulas, which assume constant elastic moduli, should be modified to incorporate the size dependence and elastic softening that occur in nanosized graphene bulge tests.