Ab initio calculations of the walls shear strength of carbon nanotubes (original) (raw)
Related papers
Nanomechanics of single and multiwalled carbon nanotubes
Physical Review B, 2004
Buckling behavior of single-walled and multiwalled carbon nanotubes is studied under axial compression in this work. Brenner's ''second generation'' empirical potential is used to describe the many-body short-range interatomic interactions for single-walled carbon nanotubes, while the Lennard Jones model for the van der Waals potential is added for multiwalled carbon nanotubes. Single-, two-, three-, and four-walled nanotubes are considered in the simulations in order to examine the effects of the number of layers on the structural properties of the multiwalled nanotubes. Results indicate that there exists an optimum diameter for singlewalled nanotubes at which the buckling load reaches its maximum value. The buckling load increases rapidly with the increase of the diameter up to the optimum diameter. A further increment beyond this diameter results in a slow decline in buckling load until a steady value is reached. The effects of layers on the buckling load of multiwalled nanotubes are also examined.
Experimental-Computational Study of Shear Interactions within Double-Walled Carbon Nanotube Bundles
Nano Letters, 2012
The mechanical behavior of carbon nanotube (CNT)-based fibers and nanocomposites depends intimately on the shear interactions between adjacent tubes. We have applied an experimental-computational approach to investigate the shear interactions between adjacent CNTs within individual double-walled nanotube (DWNT) bundles. The force required to pull out an inner bundle of DWNTs from an outer shell of DWNTs was measured using in situ scanning electron microscopy methods. The normalized force per CNT−CNT interaction (1.7 ± 1.0 nN) was found to be considerably higher than molecular mechanics (MM)-based predictions for bare CNTs (0.3 nN). This MM result is similar to the force that results from exposure of newly formed CNT surfaces, indicating that the observed pullout force arises from factors beyond what arise from potential energy effects associated with bare CNTs. Through further theoretical considerations we show that the experimentally measured pullout force may include small contributions from carbonyl functional groups terminating the free ends of the CNTs, corrugation of the CNT−CNT interactions, and polygonization of the nanotubes due to their mutual interactions. In addition, surface functional groups, such as hydroxyl groups, that may exist between the nanotubes are found to play an unimportant role. All of these potential energy effects account for less than half of the ∼1.7 nN force. However, partially pulled-out inner bundles are found not to pull back into the outer shell after the outer shell is broken, suggesting that dissipation is responsible for more than half of the pullout force. The sum of force contributions from potential energy and dissipation effects are found to agree with the experimental pullout force within the experimental error.
Double‐Wall Carbon Nanotubes: Classification and Barriers for Relative Motion of Walls
Fullerenes, Nanotubes and Carbon Nanostructures, 2005
The classification scheme for double-wall carbon nanotubes (DWCNT) based on their symmetry is proposed. According to the scheme each DWCNT ascribe to families of DWCNT with the same geometrical parameters. The barriers for wall relative rotation, sliding along nanotube axis and helical line of "thread" and threshold forces cause the wall relative motion are calculated for set of DWCNT.
On a thickness free expression for the shear modulus of carbon nanotubes
Journal of Applied Physics, 2016
The thickness of carbon nanotubes is an important issue for the characterization and design of these structures. In this article, thickness free expressions for the shear modulus of single-walled carbon nanotubes have been developed by finite element simulations on the minimum potential energy circle. As a part of this work, some equations have been obtained to define the relation between the thickness and the shear modulus, which are in good agreement with previous studies. Moreover, these expressions are in good agreement with both continuum and quantum mechanics and capable to support "Yakobson's paradox," that the scattering data for the elastic properties of carbon nanotubes are due to the not-well-defined thickness for these structures. Furthermore, these expressions can provide a tool for the prediction of the shear modulus of single-walled carbon nanotubes in regards to any thickness assumption when the experimental investigations are too difficult to realize.
Journal of Composite Materials, 2017
Carbon nanotubes have been proposed as an ideal reinforcement for the fabrication of nanocomposites. However, because of their chemical inertness, carbon nanotubes have to be functionalized in order to acquire superior properties. In the present paper, we examine the effect of functionalization of single-, double-, and triple-walled carbon nanotubes with ethylene-di-amine, analyzing their elastic properties. Condensed-phase optimized molecular potentials for atomistic simulations studies force field is used to model the interatomic interactions for armchair (5,5), (9,0), and (10,10) configuration carbon nanotubes. Molecular dynamics simulations for carbon nanotubes with various densities of the attached ethylene-di-amine molecules have been performed. This study quantitatively investigates the effect of amine functionalization (up to 12 numbers of ethylene-di-amine groups) on the Young's, bulk, and shear moduli and tensile strengths of different carbon nanotube structures.
Journal of Computational and Theoretical Nanoscience, 2012
This investigation deals with a new concept for the development of a multi-layered sandwich structure of functionally graded materials (FGM) by hand layup compressive moulding technique. The most common functionally graded materials are made of ceramic/metal non homogeneous structure, used for different applications and the composition for the development of functionally graded material is dependent on the properties requirement of the final product. After developing the sandwich structure mechanical properties were investigated and the analysis of characterisation of each layer with microstructural study of interface by scanning electron microscope (SEM) was done.