Deformation Of Graphene Sheets Research Articles

Nonlinear Large Deformation of Graphene Sheets Using a Nonlocal-Based ANCF Method

A novel nonlinear model of single-layered graphene sheets (SLGSs) subject to large deformation is proposed using the absolute nodal coordinate formulation (ANCF) and the nonlocal elasticity theory. The geometrical definition of SLGSs is described by ANCF thin plate element while the strain energy is expressed by nonlocal theory. Then, the formulation of elastic force and the Jacobian of the elastic force is derived. We verify the proposed model by comparing the results with other published results and conduct corresponding numerical case study to clarify the influence of boundary conditions (BCs), nonlocal parameters, side length and aspect ratio. Large deformation problem of SLGSs with several BCs and different loading modes are simulated to study the mechanical nonlinearity of the SLGSs.

A Novel Graphene-Based Nanosensor for Detection of Ethanol Gas

This study is the first phase (a research model) of the construction of a multi-nanobiosensor to detect multiple gases simultaneously that will be published in a separate article. In this study, a nanobiosensor was fabricated for ethanol gas detection, and its electrochemical response to various concentrations of this gas was studied. In the first phase, in order to fabricate this nanobiosensor, the graphene oxide/polyaniline (GO/PANI) nanocomposite was synthesized. Chemical composition, morphology and the structure of the nanocomposites were studied by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The results show that the synthesis of graphene oxide (GO) is done correctly and the polyaniline (PANI) particles are well bonded on the surface of the GO sheets as physically and chemically. Owning to the formation of the correct GO/PANI nanocomposite, the analyses indicate that the formation of PANI polymer chains on the surface of GO have led to the deformation of graphene sheets, which are normally flattened and uniformed sheets into the form of non-flattened and non-uniformed sheets. In the second phase, the formed nanocomposite was placed on silver-coated electrodes, and then, by placing the nanoparticles of tin oxide, the nanobiosensors were sensitive toward the ethanol gas. Through the amperometric experiments, responsiveness and sensitivity and selectivity of the nanobiosensors to each of the ethanol, carbon dioxide, methane and ammonia gases were measured and the results showed that the sensitivity of nanobiosensor fabricated for detection of the ethanol gas is acceptable. The results of the electrochemical tests showed that the nanobiosensors also have responded slightly to ammonia and methane.

Compressive deformation mechanism of honeycomb-like graphene aerogels

Graphene aerogels (GAs) are a kind of advanced graphene assemblies, which are quite elastic and can easily restore their original form after compression. The macroscale compression behavior of the GAs is the result of microstructural evolution of the graphene sheets. In this paper, the microstructural compression response of honeycomb-like GAs is investigated via coarse-grained molecular dynamics (CGMD) method. Based on the coarse-grained (CG) model of a single-layer graphene, honeycomb-like structures can be built and arranged layer-by-layer to form the complete GA model. CGMD simulations presented in this work are carried out with a TersoffCG potential, which was developed specifically for single-layer graphene. The effects of layer number, size of the graphene sheets and the interlaminar overlap pattern on the compressive behavior of the GAs are studied. Moreover, the stress distribution in graphene networks of the GAs during the compression process is analyzed. Different microscale strain concentrations and stress localizations are discovered in the GAs with different network patterns. Furthermore, a negative Poisson's ratio of the models within a certain range of compressive strain is found, which is related to both the microstructural arrangement and the deformation of graphene sheet.

Wrinkling and thermal conductivity of one graphene sheet under shear

Tersoff-potential - based molecular dynamics method is used to simulate wrinkling deformation of one graphene sheet under shear, and the obtained deformation is compared with analytical solutions of macro-membrane. Furthermore, thermal conductivity of the wrinkled graphene at different temperatures is calculated. It is found that (1) the wrinkling deformation of graphene sheet under shear is close to the analytical solutions of macro-membrane under shear, which implies that the solutions of macro-membrane are applicable to predict the wrinkling deformation of graphene sheets under shear; (2) the more serious the wrinkling of the graphene under shear is, the stronger the phonon scattering is and, therefore, the lower the thermal conductivity of the wrinkled graphene is; (3) within the temperature range of 400–700 K, the thermal conductivity of graphene sheet decreases with increase in temperature.