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Paper   IPM / Nano-Sciences / 12340
School of Nano Science
  Title:   Fracture analysis of monolayer graphene sheets with double vacancy defects via MD simulation
1.  R. Ansari
2.  B. Motevalli
3.  Abbas Montazeri
4.  S. Ajori
  Status:   Published
  Journal: Solid State Commun.
  No.:  17
  Vol.:  151
  Year:  2011
  Pages:   6
  Publisher(s):   Elsevier Ltd.
  Supported by:  IPM
Carbon nanostructures such as carbon nanotubes (CNTs) and graphene sheets have attracted great attention due to their exceptionally high strength and elastic strain. These extraordinary mechanical properties, however, can be affected by the presence of defects in their structures. When a material contains multiple defects, it is expected that the stress concentration of them superposes if the separation distances of the defects are low, which causes a more reduction of the strength. On the other hand, it is believed that if the defects are far enough such that their affected areas are distinct, their behavior is similar to a material with single defect. In this article, molecular dynamics (MD) is used to explore the influence of separation distance of double vacancy defects on the mechanical properties of single-layered graphene sheets (SLGSs). To this end, critical stress and strain of SLGSs containing double vacancy with different distances are determined and the results are compared with those of perfect SLGSs and graphene sheets with single vacancy defect. The results reveal that the ultimate strength of the SLGS with double vacancy tends to the one with a single vacancy when the separation distance becomes further. In this regard, the threshold distance beyond which double defects behave like a single one is examined. Finally, Young?s modulus of perfect, single and double vacancy defected graphene sheets with different separation distances is determined. It is concluded that this property is slightly affected by the separation distance. Investigation of failure strain, ultimate strength, and Young?s modulus of SLGSs containing double vacancy defects. Exploring the effect of separation distance of defects on these mechanical properties. Extracting a fitting formula based on the obtained data. Suggestion of safe separation distance for which the effect of defects are not superposed.

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