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    Finite element modeling of single-walled carbon nanotubes with introducing a new wall thickness

    , Article Journal of Physics: Conference Series ; Volume 61, Issue 1 , 2007 , Pages 497-502 ; 17426588 (ISSN) Jalalahmadi, B ; Naghdabadi, R ; Sharif University of Technology
    Institute of Physics Publishing  2007
    A three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. By considering the covalent bonds as connecting elements between carbon atoms, a nanotube is simulated as a space frame-like structure. Here, the carbon atoms act as joints of the connecting elements. To create the FE models, nodes are placed at the locations of carbon atoms and the bonds between them are modeled using three-dimensional elastic beam elements. Using Morse atomic potential, the elastic moduli of beam elements are obtained via considering a linkage between molecular and continuum mechanics. Also, a new wall thickness (bond diameter) equal to 0.1296... 

    Finite element model of SWCNT under hydrostatic pressure

    , Article AIP Conference Proceedings, 10 April 2007 through 12 April 2007, Sharjah ; Volume 929 , 2007 , Pages 82-88 ; 0094243X (ISSN) ; 0735404399 (ISBN); 9780735404397 (ISBN) Sakhaee Pour, A ; Ahmadian, M. T ; Sharif University of Technology
    A finite element technique is used to mimic radial deformation of single-walled carbon nanotubes under hydrostatic pressure. The elastic deformation of nanotubes is modeled via elastic beams. Properties of the beam element are evaluated by considering characteristics of the covalent bonds between the carbon atoms in a hexagonal lattice. Applying the beam model in a three dimensional space, the elastic properties of the nanotube in the transverse direction are evaluated. The effects of diameter and wall thickness on the radial and circumferential elastic moduli of zigzag and armchair nanotubes are considered. Results are in good agreement with molecular structural mechanics data in the... 

    Transversal thermal transport in single-walled carbon nanotube bundles: Influence of axial stretching and intertube bonding

    , Article Journal of Chemical Physics ; Volume 139, Issue 18 , 2013 ; 00219606 (ISSN) Gharib Zahedi, M. R ; Tafazzoli, M ; Böhm, M. C ; Alaghemandi, M ; Sharif University of Technology
    Using reverse nonequilibrium molecular dynamics simulations the influence of intermolecular bridges on the thermal conductivity (λ) in carbon nanotube (CNT) bundles has been investigated. The chosen cross linkers (CH 2, O, CO) strengthen the transversal energy transport relative to the one in CNT bundles without bridges. The results showed that λ does not increase linearly with the linker density. The efficiency of the heat transport is determined by the number of linkers in the direction of the heat flux, the type of the linker, and their spatial ordering. The influence of a forced axial stress on the transversal λ has been also studied. The observed λ reduction with increasing axial... 

    An enhanced continuum modeling of the ideal strength and the angle of twist in tensile behavior of single-walled carbon nanotubes

    , Article Journal of Applied Physics ; Volume 114, Issue 5 , 2013 ; 00218979 (ISSN) Delfani, M. R ; Shodja, H. M ; Sharif University of Technology
    By utilizing the fourth-, sixth-, eighth-, and tenth-order elastic moduli tensors of graphene a highly nonlinear constitutive model for it is proposed. Subsequently, an accurate analytical formulation, describing the entire tensile behavior of single-walled carbon nanotubes (SWCNTs) from their initial unloaded states through their ideal strengths, is made possible. The angle of twist which is a critical parameter that varies with the tensile loading is also calculated within the current framework. The estimated value of the theoretical strength of SWCNTs with different chiralities and radii as well as that of graphene ranges from 0.39 to 0.44 TPa. Some peculiarities associated with chirality... 

    A new method for the analysis of transmission property in carbon nanotubes using Green's function

    , Article Applied Physics A: Materials Science and Processing ; Volume 102, Issue 1 , 2011 , Pages 231-238 ; 09478396 (ISSN) Fathi, D ; Forouzandeh, B ; Sarvari, R ; Sharif University of Technology
    A new method for the analysis of electron transmission property in single-walled carbon nanotubes (SWCNTs) using Green's function is presented in this paper for the first time. Using the proposed method, a new relation for the transmission function through a deformed SWCNT is obtained, which depends on the energy variations and the coupling matrices related to the mechanical deformations applied to the structure of CNT. The obtained new relation is explained by the presented results in the literature  

    Stability of C60-peapods under hydrostatic pressure

    , Article Acta Materialia ; Volume 55, Issue 16 , 2007 , Pages 5483-5488 ; 13596454 (ISSN) Najafi Sohi, A ; Naghdabadi, R ; Sharif University of Technology
    The stability of single-walled carbon nanopeapods under hydrostatic pressure is investigated using a continuum-based elastic shell model. The model incorporates nonbonded van der Waals interactions between the nested fullerenes and the host carbon nanotube. By deriving an explicit equation, it is shown that the critical hydrostatic pressure for the onset of structural instability of a completely packed C60@(10,10) nanopeapod is ∼1.11 GPa, while for the case of the pristine host (10,10) nanotube it is ∼1.84 GPa. Thus, it is concluded that the fullerene encapsulation weakens the host nanotube under hydrostatic pressure. In addition, it is quantitatively shown that any decrease in packing... 

    Bode stability analysis for single wall carbon nanotube interconnects used in 3D-VLSI circuits

    , Article World Academy of Science, Engineering and Technology ; Volume 77 , 2011 , Pages 568-571 ; 2010376X (ISSN) Nasiri, S. H ; Faez, R ; Davoodi, B ; Farrokhi, M ; Sharif University of Technology
    Bode stability analysis based on transmission line modeling (TLM) for single wall carbon nanotube (SWCNT) interconnects used in 3D-VLSI circuits is investigated for the first time. In this analysis, the dependence of the degree of relative stability for SWCNT interconnects on the geometry of each tube has been acquired. It is shown that, increasing the length and diameter of each tube, SWCNT interconnects become more stable  

    Nonlinear dynamic analysis of SWNTs conveying fluid using nonlocal continuum theory

    , Article Structural Engineering and Mechanics ; Volume 66, Issue 5 , 10 June , 2018 , Pages 621-629 ; 12254568 (ISSN) Hosseini Kordkheili, S. A ; Mousavi, T ; Bahai, H ; Sharif University of Technology
    Techno Press  2018
    By employing the nonlocal continuum field theory of Eringen and Von Karman nonlinear strains, this paper presents an analytical model for linear and nonlinear dynamics analysis of single-walled carbon nanotubes (SWNTs) conveying fluid with different boundary conditions. In the linear analysis the natural frequencies and critical flow velocities of SWNTs are computed. However, in the nonlinear analysis the effect of nonlocal parameter on nonlinear dynamics of cantilevered SWNTs conveying fluid is investigated by using bifurcation diagram, phase plane and Poincare map. Numerical results confirm existence of chaos as well as a period-doubling transition to chaos. Copyright © 2018 Techno-Press,... 

    Vibrational behavior of defective and repaired carbon nanotubes under thermal loading: A stochastic molecular mechanics study

    , Article Mechanics of Materials ; Volume 163 , 2021 ; 01676636 (ISSN) Payandehpeyman, J ; Moradi, K ; Zeraati, A. S ; Hosseinabadi, H. G ; Sharif University of Technology
    Elsevier B.V  2021
    Carbon nanotubes (CNTs) are promising candidates for high-resolution mass nanosensors owing to their unique vibrational behavior. The structural characteristic (e.g. defect type and density) and working temperature have a significant effect on the natural frequency of CNT-based sensors. Herein, a stochastic approach based on novel finite element and molecular mechanics simulations is implemented to model the effect of temperature and structural characteristics of single-wall CNTs including defects (vacancy defect with different densities) and chirality (zigzag and armchair) on their vibrational behavior. The results show that the vacancy defects exert a significant deterioration of the... 

    Development of an equation to predict radial modulus of elasticity for single-walled carbon nanotubes

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 222, Issue 6 , 2008 , Pages 1109-1115 ; 09544062 (ISSN) Sakhaee Pour, A ; Ahmadian, M. T ; Gerami, A ; Sharif University of Technology
    Finite element (FE) method is used to model radial deformation of single-walled carbon nanotube (SWCNT) under hydrostatic pressure. Elastic deformation of the nanostructure is simulated via elastic beams. Properties of the beam element are calculated by considering the stiffness of the covalent bonds between the carbon atoms in the hexagonal lattice. By applying the beam elements in a three-dimensional space, elastic properties of the SWCNT in transverse direction are obtained. In this regard, influences of diameter and tube wall thickness on the radial and circumferential elastic moduli of zigzag and armchair SWCNTs are considered. It is observed that there is a good agreement between the... 

    Simulation of Fluid Flow in Nonstraight Nanochannels

    , M.Sc. Thesis Sharif University of Technology Kargar, Sajad (Author) ; Mousavi, Ali (Supervisor)
    Understanding the flow of liquids and particularly water in nanochannels is important for scientific and technological applications, such as for filtration and drug delivery. In this study, we perform molecular dynamics simulations to investigate the transfer of single-file water molecules across straight or nonstraight single-walled carbon nanotubes (SWCNTs). In contrast with the macroscopic scenario, the nonstraight nanostructure can increase the water permeation. Remarkably, compared with the straight SWCNT, the nonstraight SWCNT with the minimal bending angle of 30° in the simulations can enhance the water transport up to 3.9 times. Also increasing length and diameter of carbon nanotubes... 

    Mechanics and morphology of single-walled carbon nanotubes: From graphene to the elastica

    , Article Philosophical Magazine ; Volume 93, Issue 17 , 2013 , Pages 2057-2088 ; 14786435 (ISSN) Delfani, M. R ; Shodja, H. M ; Ojaghnezhad, F ; Sharif University of Technology
    The elastica is referred to the shape of the curve into which the centreline of a flexible lamina is bent. Hence, single-walled carbon nanotubes (SWCNTs) are treated as the elastica obtained from bending of graphene. The corresponding large deformation accompanies both the material and geometrical non-linearities. The morphology of the free-standing SWCNTs such as the natural angle of twist, bond lengths, tube radius and wall thickness are determined. Moreover, it is shown that the induced self-equilibriated strain field has a remarkable impact on the mechanical behaviour of the nanotube. Utilization of an appropriate non-linear continuum constitutive relation for graphene leads to exact... 

    Simulation of biomanipulation using molecular dynamics

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 9, Issue PARTS A AND B , 2012 , Pages 137-143 ; 9780791845257 (ISBN) Pishkenari, H. N ; Mahboobi, S. H ; Mahjour, M. A ; Meghdari, A ; Sharif University of Technology
    In this paper, the simulation of biomolecules manipulation using molecular dynamics (MD) is studied. In order to investigate the manipulation behavior, we have used the ubiquitin as biomolecule, a single-walled carbon nanotube (SWCNT) as manipulation probe, a two-layer graphene sheet as substrate. Along this line, a series of simulations are conducted to study the effects of different conditions on the success of manipulation process. These conditions include tip diameter, vertical gap between the tip and substrate, initial orientation of protein, and the tip position with respect to the biomolecule  

    A new model for deformed carbon nanotubes using Green's function

    , Article Applied Physics A: Materials Science and Processing ; Volume 105, Issue 4 , 2011 , Pages 875-880 ; 09478396 (ISSN) Fathi, D ; Sarvari, R ; Sharif University of Technology
    A new method for modeling and analysis of deformed carbon nanotubes (CNTs) using Green's function, is presented in this paper, for the first time. Using the proposed method, a new circuit model is obtained for the deformation region of a deformed single-walled CNT (SWCNT), which the values of its elements depend on the type of deformation and also the deformation parameters such as the coupling matrices and the energy variations of deformation region. The comparison between the obtained results from the analysis of proposed model and the literature gives a good match which approves the accuracy and correctness of the proposed model  

    Application of elastically supported single-walled carbon nanotubes for sensing arbitrarily attached nano-objects

    , Article Current Applied Physics ; Volume 13, Issue 1 , 2013 , Pages 107-120 ; 15671739 (ISSN) Kiani, K ; Ghaffari, H ; Mehri, B ; Sharif University of Technology
    The potential application of SWCNTs as mass nanosensors is examined for a wide range of boundary conditions. The SWCNT is modeled via nonlocal Rayleigh, Timoshenko, and higher-order beam theories. The added nano-objects are considered as rigid solids, which are attached to the SWCNT. The mass weight and rotary inertial effects of such nanoparticles are appropriately incorporated into the nonlocal equations of motion of each model. The discrete governing equation pertinent to each model is obtained using an effective meshless technique. The key factor in design of a mass nanosensor is to determine the amount of frequency shift due to the added nanoparticles. Through an inclusive parametric... 

    Free vibrations of single-walled carbon nanotubes in the vicinity of a fully constrained graphene sheet

    , Article Computational Materials Science ; Volume 53, Issue 1 , 2012 , Pages 12-17 ; 09270256 (ISSN) Firouz Abadi, R. D ; Hosseinian, A. R ; Sharif University of Technology
    Carbon nanotubes (CNTs) have been recently taken into consideration as mechanical resonators of distinguished capabilities. This study aims at investigating the free vibration characteristics of a single-walled CNT in the vicinity of a fully constrained graphene sheet. Using a molecular structural mechanics model and considering nonlinear van-der-Waals interactions, the static deformation of the nanotube is obtained using an iterative procedure. Then, the governing equations of motion are linearized about the static equilibrium state and the natural frequencies are obtained. The molecular structural mechanics model is verified using established results in literature and then a survey is... 

    Differential quadrature method for nonlocal nonlinear vibration analysis of a boron nitride nanotube using sinusoidal shear deformation theory

    , Article Mechanics of Advanced Materials and Structures ; Volume 23, Issue 11 , 2016 , Pages 1278-1283 ; 15376494 (ISSN) Sadatshojaei, E ; Sadatshojaie, A ; Fakhar, M. H ; Sharif University of Technology
    Taylor and Francis Inc  2016
    This article presents a nonlocal sinusoidal shear deformation beam theory (SDBT) for the nonlinear vibration of single-walled boron nitride nanotubes (SWBNNTs). The surrounding elastic medium is simulated based on nonlinear Pasternak foundation. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion of the SWBNNTs are derived using Hamilton's principle. Differential quadrature method (DQM) for the nonlinear frequency is presented, and the obtained results are compared with those predicted by the nonlocal Timoshenko beam theory (TBT). The effects of nonlocal parameter, vibrational modes, length, and elastic medium on the nonlinear frequency of SWBNNTs... 

    Dynamic stability analysis of single walled carbon nanocone conveying fluid

    , Article Computational Materials Science ; Volume 113 , 2016 , Pages 123-132 ; 09270256 (ISSN) Rasouli Gandomani, M ; Noorian, M. A ; Haddadpour, H ; Fotouhi, M. M ; Sharif University of Technology
    Elsevier  2016
    This report aims the study of dynamic stability of single walled carbon nanocone for some axial length conditions and declination angles of 60°, 120°and 240°. For dynamic stability analysis of Single Walled Carbon Nanocone (SWCNC), the mode shapes and frequencies of the carbon nanocone are extracted using the molecular mechanics approach. The mechanical properties of SWCNC were obtained by the Molecular Mechanics (MM) method. The obtained parameters are used for extraction of the conical shell virtual model of nanocone with the same dimensions. The equations of coupled fluid-structural dynamics of SWCNC are derived using the modal expansion for the structural displacements of the conical... 

    A numerical study on the influence of interface recombination on performance of carbon nanotube/GaAs solar cells

    , Article Optical and Quantum Electronics ; Volume 48, Issue 8 , 2016 ; 03068919 (ISSN) Movla, H ; Ghaffari, S ; Rezaei, E ; Sharif University of Technology
    Springer New York LLC 
    Carbon nanotubes (CNT) have unique electronic properties and remarkable optical properties. Despite of on layer thickness of CNTs, it has able to absorb photons from visible to far infrared and terahertz. These unique properties lets to create heterojunction devices by semiconductor/CNTs or metal/CNTs junctions e.g. photodiodes, sensor and heterojunction solar cell. The CNTs can play the role of a heterojunction component for charge separation as a high conductive network for charge transport and as a transparent electrode for light illumination and charge collection. The main objective of the present article is to establish a relation between interface recombination and the characteristics... 

    Carbon nanotubes in microfluidic lab-on-a-chip technology: current trends and future perspectives

    , Article Microfluidics and Nanofluidics ; Volume 21, Issue 9 , 2017 ; 16134982 (ISSN) Ghasemi, A ; Amiri, H ; Zare, H ; Masroor, M ; Hasanzadeh, A ; Beyzavi, A ; Aref, A. R ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
    Advanced nanomaterials such as carbon nanotubes (CNTs) display unprecedented properties such as strength, electrical conductance, thermal stability, and intriguing optical properties. These properties of CNT allow construction of small microfluidic devices leading to miniaturization of analyses previously conducted on a laboratory bench. With dimensions of only millimeters to a few square centimeters, these devices are called lab-on-a-chip (LOC). A LOC device requires a multidisciplinary contribution from different fields and offers automation, portability, and high-throughput screening along with a significant reduction in reagent consumption. Today, CNT can play a vital role in many parts...