Atomic geometry and energetics of carbon nanotube necking |
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Authors: | S Zhang T Zhu |
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Institution: | 1. Department of Mechanical Engineering , University Arkansas , Arkansas 72701, Fayetteville, USA szhang1@uark.edu;3. Woodruff School of Mechanical Engineering , Georgia Institute of Technology , Georgia 30332, Atlanta, USA |
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Abstract: | Molecular mechanics simulations were performed to probe the incipient plastic deformation in carbon nanotubes (CNTs), which involves nucleation of Stone–Wales (SW) defects and spiral glide of 5/7 dislocation dipoles that lead to quantized necking through a stepwise reduction in tube diameter. Quantification of the strain-dependent energetics of dislocation glide reveals that such dislocation motions are energetically favoured at high tensile strain. Pre-existing dislocations critically affect subsequent nucleation and separation of SW defects, as manifested by the competing deformation modes of symmetric versus asymmetric necking. The results provide a quantitative basis for the dislocation dynamics simulations of superplastically deformed CNTs. |
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Keywords: | La2O3 CeO2 DLC residual compressive stress |
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