Fracture Strength Of Graphene Research Articles

Fracture strength of Graphene at high temperatures: data driven investigations supported by MD and analytical approaches

Fracture strength of Graphene at high temperatures: data driven investigations supported by MD and analytical approaches

Effects of Stone-Wales and vacancy defects in fracture behavior of defective graphene

Graphene has much higher mechanical strength than other materials, but can be significantly influenced by the vacancy defect or Stone-Wales defect in the lattices. In this paper, we use molecular dynamics simulation to study the effects of vacancy and Stone-Wales defects in fracture behavior of the defective graphene. The results show that the fracture strength of graphene is more sensitive to the vacancy defects than that of Stone-Wales defect. When the defect is located in the center of graphene, the fracture strength of defect graphene is less than that of defect-free graphene. When the defect is far away from the center of graphene, the fracture strength of defect graphene will be enhanced, even greater than that of defect-free graphene. This study may help to understand the properties of graphene with defect, but also show the potential for graphene-based materials in engineering.

Effect of Defects on the Mechanical and Thermal Properties of Graphene.

In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that the Young’s modulus, fracture strength and fracture strain of graphene decreased with the increase of temperature, while the fracture strength of graphene along the zigzag direction was more sensitive to the strain rate than that along armchair direction by calculating the strain rate sensitive index. The mechanical properties were significantly reduced with the existence of defect, which was due to more cracks and local stress concentration points. Besides, the thermal conductivity of graphene followed a power law of λ~L0.28, and decreased monotonously with the increase of defect concentration. Compared with the pristine graphene, the thermal conductivity of defective graphene showed a low temperature-dependent behavior since the phonon scattering caused by defect dominated the thermal properties. In addition, the corresponding underlying mechanisms were analyzed by the stress distribution, fracture structure during the deformation and phonon vibration power spectrum.

Influence of hydrogen functionalization on the fracture strength of graphene and the interfacial properties of graphene–polymer nanocomposite

Using molecular dynamics and classical continuum concepts, we investigated the effects of hydrogen functionalization on the fracture strength of graphene and also on the interfacial properties of graphene–polymer nanocomposite. Moreover, we developed an atomistic model to assess the temperature and strain rate dependent fracture strength of functionalized graphene along various chiral directions. Results indicate that hydrogen functionalization at elevated temperatures highly degrade the fracture strength of graphene. The functionalization also deteriorates the interfacial strength of graphene–polymer nanocomposite. Near-crack-tip stress distribution depicted by continuum mechanics can be successfully used to investigate the impact of hydrogen passivation of dangling carbon bonds on the strength of graphene. We further derived a continuum-based model to characterize the non-bonded interaction of graphene–polymer nanocomposite. These results indicate that classical continuum concepts are accurate even at a scale of several nanometers. Our work provides a remarkable insight into the fracture strength of graphene and graphene–polymer nanocomposites, which are critical in designing experimental and instrumental applications.

Molecular Dynamics Simulation of Fracture Strength and Morphology of Defective Graphene

Different types of defects can be introduced into graphene during material synthesis, and significantly influence the properties of graphene. In this work, we investigated the effects of structural defects, edge functionalisation and reconstruction on the fracture strength and morphology of graphene by molecular dynamics simulations. The minimum energy path analysis was conducted to investigate the formation of Stone-Wales defects. We also employed out-of-plane perturbation and energy minimization principle to study the possible morphology of graphene nanoribbons with edge-termination. Our numerical results show that the fracture strength of graphene is dependent on defects and environmental temperature. However, pre-existing defects may be healed, resulting in strength recovery. Edge functionalization can induce compressive stress and ripples in the edge areas of graphene nanoribbons. On the other hand, edge reconstruction contributed to the tensile stress and curved shape in the graphene nanoribbons.

Molecular Dynamics Simulation of Fracture Strength and Morphology of Defective Graphene

Different types of defects can be introduced into graphene during material synthesis, and significantly influence the properties of graphene. In this work, we investigated the effects of structural defects, edge functionalisation and reconstruction on the fracture strength and morphology of graphene by molecular dynamics simulations. The minimum energy path analysis was conducted to investigate the formation of Stone-Wales defects. We also employed out-of-plane perturbation and energy minimization principle to study the possible morphology of graphene nanoribbons with edge-termination. Our numerical results show that the fracture strength of graphene is dependent on defects and environmental temperature. However, pre-existing defects may be healed, resulting in strength recovery. Edge functionalization can induce compressive stress and ripples in the edge areas of graphene nanoribbons. On the other hand, edge reconstruction contributed to the tensile stress and curved shape in the graphene nanoribbons.

Effect of Vacancy Defects on the Young's Modulus and Fracture Strength of Graphene: A Molecular Dynamics Study

AbstractThe Young's modulus of graphene with various rectangular and circular vacancy defects is investigated by molecular dynamics simulation. By comparing with the results calculated from an effective spring model, it is demonstrated that the Young's modulus of graphene is largely correlated to the size of vacancy defects perpendicular to the stretching direction. And a linear reduction of Young's modulus with the increasing concentration of mono‐atomic‐vacancy defects (i.e., the slope of −0.03) is also observed. The fracture behavior of graphene, including the fracture strength, crack initiation and propagation are then studied by the molecular dynamics simulation, the effective spring model, and the quantized fracture mechanics. The blunting effect of vacancy edges is demonstrated, and the characterized crack tip radius of 4.44 Å is observed.