Atomistic and continuum modelling of temperature-dependent fracture of graphene

Dewapriya, M.A.N.; Rajapakse, R. K. N. D.; Phani, A. Srikantha

doi:10.1007/s10704-014-9931-y

Cited by 105 publications

(60 citation statements)

References 34 publications

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“…Their fracture behaviour is very similar to that of pristine graphene, with the only difference being that the crack nucleates at the vacancy and propagates in two opposing directions. This is in good agreement with the work in [19,20,22]. In Figure 4(e), we show the fracture behaviour of a 12% randomly distributed vacancies for a ZZ graphene sheet during fracture and in a ZZ graphene sheet with uniformly distributed defects in Figure 4(f).…”

Section: Random and Uniformly Distributed Vacancy Defectssupporting

confidence: 89%

“…It is evident from these graphs that the fracture stress and strain decrease substantially with an increase in temperature for both ZZ and AC loading configurations. For ZZ-loaded graphene at 1100 K, the fracture stress decreases to 53.3 GPa (48% decrease from 0 K), while the fracture strain decreases to 0.053 (70% decrease from 0 K), while for AC graphene fracture stress and strain reduce by 39 and 58%, respectively, from 0 K. The same dependance of stress and strain on temperature has been observed using the AIREBO potential in [16,17,22,37,40,41]. For example, Zhang et al [41] obtained a 50% decrease in intrinsic strength when the sheet temperature is increased from 0 to 1200 K.…”

Section: Temperature Dependencesupporting

confidence: 67%

“…[13,[15][16][17] The introduction of Stone-Wales defects and single, double and larger vacancies was also studied resulting in a general reduction in fracture stress. [18][19][20] The fracture behaviour of pristine and defected graphene was also analysed in [14,15,[19][20][21][22] with the use of different computational and theoretical techniques. The fracture mode of graphene was generally found to be brittle, especially for pristine graphene.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical properties of pristine and nanoporous graphene

Anastasi

Ritos

Cassar

et al. 2016

Molecular Simulation

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We present molecular dynamics simulations of monolayer graphene under uniaxial tensile loading. The Morse, bending angle, torsion and Lennard-Jones potential functions are adopted within the mdFOAM library in the OpenFOAM software, to describe the molecular interactions in graphene. A well-validated graphene model using these set of potentials is not yet available. In this work, we investigate the accuracy of the mechanical properties of graphene when derived using these simpler potentials, compared to the more commonly used complex potentials such as the Tersoff-Brenner and AIREBO potentials. The computational speed up of our approach, which scales O(1.5N), where N is the number of carbon atoms, enabled us to vary a larger number of system parameters, including graphene sheet orientation, size, temperature and concentration of nanopores. The resultant effect on the elastic modulus, fracture stress and fracture strain is investigated. Our simulations show that graphene is anisotropic, and its mechanical properties are dependant on the sheet size. An increase in system temperature results in a significant reduction in the fracture stress and strain. Simulations of nanoporous graphene were created by distributing vacancy defects, both randomly and uniformly, across the lattice. We find that the fracture stress decreases substantially with increasing defect density. The elastic modulus was found to be constant up to around 5% vacancy defects, and decreases for higher defect densities. ARTICLE HISTORY

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Section: Random and Uniformly Distributed Vacancy Defectssupporting

confidence: 89%

Section: Temperature Dependencesupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

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Mechanical properties of pristine and nanoporous graphene

Anastasi

Ritos

Cassar

et al. 2016

Molecular Simulation

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“…So molecular dynamics simulation is an effective way to explore brittle fracture in atomic scale [24][25][26]. The main aim of this work is to investigate and compare fracture phenomenon of graphene, hBN and silicene with various length of cracks under uniaxial tension using molecular dynamics simulation.…”

Section: Introductionmentioning

confidence: 99%

Graphene and its elemental analogue: A molecular dynamics view of fracture phenomenon

Rakib

Mojumder

Das

et al. 2017

Physica B: Condensed Matter

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Abstract-Graphene and some graphene like two dimensional materials; hexagonal boron nitride (hBN) and silicene have unique mechanical properties which severely limit the suitability of conventional theories used for common brittle and ductile materials to predict the fracture response of these materials. This study revealed the fracture response of graphene, hBN and silicene nanosheets under different tiny crack lengths by molecular dynamics (MD) simulations using LAMMPS. The useful strength of these two dimensional materials are determined by their fracture toughness. Our study shows a comparative analysis of mechanical properties among the elemental analogues of graphene and suggested that hBN can be a good substitute for graphene in terms of mechanical properties. We have also found that the pre-cracked sheets fail in brittle manner and their failure is governed by the strength of the atomic bonds at the crack tip. The MD prediction of fracture toughness shows significant difference with the fracture toughness determined by Griffth's theory of brittle failure which restricts the applicability of Griffith's criterion for these materials in case of nano-cracks. Moreover, the strengths measured in armchair and zigzag directions of nanosheets of these materials implied that the bonds in armchair direction have the stronger capability to resist crack propagation compared to zigzag direction.

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“…13,14,17−27 A recent investigation suggested that the Griffith criterion is sound in cracks as short as 1 nm. 14 Because the authors used a tangential modulus (pertinent to the failure strain in a stress−strain curve) in the Griffith equation and also only considered cracks shorter than 3 nm, it is not clear whether the same equation can be applied to predict cracks with length of 3 nm to tens of nanometer. Hence, it remains unclear regarding the critical crack size when the Griffith criterion of brittle fracture breaks down.…”

mentioning

confidence: 99%

Griffith Criterion for Brittle Fracture in Graphene

et al. 2015

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There are prevailing concerns with the critical dimensions when conventional theories break down. Here we find that the Griffith criterion remains valid for cracks down to 10 nm but overestimates the strength of shorter cracks. We observe the preferred crack extension along the zigzag edge in graphene, and explain this phenomenon by local strength-based failure rather than energy-based Griffith criterion. These results provide a mechanistic basis for reliable applications of graphene in miniaturized devices and nanocomposites. KEYWORDS: Griffith criterion, graphene, fracture, edge energy, molecular dynamics M ost mechanical theories used in engineering practice are developed for relatively large structures. Their applicability in nanoscale systems is however uncertain. The continuum theories usually work well for the collective behavior of a large ensemble of basic building blocks like atoms or molecules but are not guaranteed to hold when they are applied to systems composed of a limited number of basic units. Indeed, deviation of certain properties in small systems from their bulk counterparts is foreseen by Feynman. 1 The ensuing question is whether or not there is a critical size for a theory, below which this theory fails to adequately capture the physical behavior of a miniaturized system. For engineering applications, knowing such critical size is of paramount significance for the design of small structures that are mechanically reliable. The Griffith criterion of brittle fracture is one of the most fundamental theories for characterizing the mechanical behavior of defective materials and has been widely used in engineering design. 2,3 In this work, we explore the physical limit of the Griffith criterion, that is, when it fails to predict the fracture strength of materials with small nanosized cracks. The challenge to address such question of size limit lies in the difficulty to bridge the studies of microscopic and macroscopic systems by either experiments or atomistic simulations. On one hand, while progress has been recently made in the nanomechanical testing of materials, 4−9 it is still difficult to conduct a series of controlled experiments by systematically reducing the sample size while retaining the consistent microstructural features. On the other hand, molecular dynamics (MD) simulations can effectively explore brittle fracture at the atomic scale, 10−14 but full atomistic simulations are yet too computationally expensive to simulate three-dimensional systems with feature size larger than 100 nm.To understand the applicability of the continuum mechanics theory to a discrete atomistic system, it is necessary to probe the mechanical behavior of sufficiently large samples with atomic resolution. To this end, graphene is an ideal model material to investigate the critical size when the Griffith criterion of brittle fracture breaks down. This is because the monolayer graphene is only one atom thick 15 such that the inplane dimensions can be taken to be adequately large (e.g., up to microme...

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Atomistic and continuum modelling of temperature-dependent fracture of graphene

Cited by 105 publications

References 34 publications

Mechanical properties of pristine and nanoporous graphene

Mechanical properties of pristine and nanoporous graphene

Graphene and its elemental analogue: A molecular dynamics view of fracture phenomenon

Griffith Criterion for Brittle Fracture in Graphene

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