Atomistic simulation and continuum modeling of graphene nanoribbons under uniaxial tension

Modelling and Simulation in Materials Science and Engineering (Impact Factor: 1.49). 06/2011; 19(5):054006. DOI: 10.1088/0965-0393/19/5/054006

ABSTRACT Atomistic simulations are performed to study the nonlinear mechanical behavior of graphene nanoribbons under quasistatic uniaxial tension, emphasizing the effects of edge structures (armchair and zigzag, without and with hydrogen passivation) on elastic modulus and fracture strength. The numerical results are analyzed within a theoretical model of thermodynamics, which enables determination of the bulk strain energy density, the edge energy density and the hydrogen adsorption energy density as nonlinear functions of the applied strain based on static molecular mechanics simulations. These functions can be used to describe mechanical behavior of graphene nanoribbons from the initial linear elasticity to fracture. It is found that the initial Young's modulus of a graphene nanoribbon depends on the ribbon width and the edge chirality. Furthermore, it is found that the nominal strain to fracture is considerably lower for graphene nanoribbons with armchair edges than for ribbons with zigzag edges. Molecular dynamics simulations reveal two distinct fracture nucleation mechanisms: homogeneous nucleation for the zigzag-edged graphene nanoribbons and edge-controlled heterogeneous nucleation for the armchair-edged ribbons. The modeling and simulations in this study highlight the atomistic mechanisms for the nonlinear mechanical behavior of graphene nanoribbons with the edge effects, which is potentially important for developing integrated graphene-based devices.

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Available from: Rui Huang, Aug 28, 2015
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    • "MD simulations have also demonstrated that the mechanical response of graphene nanoribbons (GNRs) is nonlinear elastic and their size and chirality have significant influences on their mechanical properties [13]. It has been reported that 8 nm constitutes a critical width for GNRs beyond which the size effect largely disappears and their elastic properties converge to the values for bulk/infinite graphene [13] [14]. In addition, MD simulations have shown that while the Young's modulus of graphene remains fairly insensitive to the temperature up to 1200 K, the values of its failure strength and strain undergo a steady fall as temperature is increased from the absolute zero [15] [16]. "
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