scholarly journals Development of Empirical Relations for the Transversely Isotropic Properties of Zigzag, Armchair and Chiral Single-Walled Carbon Nanotubes

2012 ◽  
Vol 21 (4) ◽  
pp. 096369351202100 ◽  
Author(s):  
S.K. Jalan ◽  
B. Nageswara Rao ◽  
S. Gopalakrishnan

Finite element analysis has been performed to evaluate transversely isotropic properties of the single walled carbon nanotubes (SWCNTs). Finite element models of SWCNTs are generated by specifying the C-C bond rigidities (which are arrived by equating the energies from molecular mechanics and continuum mechanics). The five independent transversely isotropic properties for different chiralities are evaluated using the stress fields of thick-walled cylinders and the elastic deformations of SWCNTs subjected to pure extension, internal pressure and pure torsion loads. The adequacy of the elastic properties is demonstrated through modelling of an equivalent overall orthotropic hollow thick-walled cylinder under different loading conditions. Empirical relations are provided for the five independent elastic constants useful for armchair, zigzag and chiral zigzag SWCNTs.

2013 ◽  
Vol 22 (6) ◽  
pp. 096369351302200
Author(s):  
S.K. Jalan ◽  
B. Nageswara Rao ◽  
S. Gopalakrishnan

Finite element analysis has been performed to study vibrational characteristics of cantilever single walled carbon nanotubes. Finite element models are generated by specifying the C-C bond rigidities, which are estimated by equating energies from molecular mechanics and continuum mechanics. Bending, torsion, and axial modes are identified based on effective mass for armchair, zigzag and chiral cantilever single walled carbon nanotubes, whose Young's modulus is evaluated from the bending frequency. Empirical relations are provided for frequencies of bending, torsion, and axial modes.


2011 ◽  
Vol 8 (1) ◽  
pp. 173-180
Author(s):  
Ratnakar Pandu ◽  
Chidanandappa Chidanandappa ◽  
N. C. S Reddy

In this present paper, an FE approach has been presented for the elastic bending and buckling behaviors of single-walled carbon nanotubes (SWCNTs). Finite element simulations are carried out to investigate the bending deformations and buckling behaviors of SWCNTs under various conditions. Both axial compression and bending loading conditions are considered. The computed results for SWCNTs agree well with atomistic simulations in the literature and the FE approach is confirmed successfully. In this paper, the steady state structural analysis has been performed to know the strength of the CNTs using shell93 element. For analysis of SWCNT has been considered as cantilever beam and loaded at the free end. SWCNTs with different lengths, different thicknesses under various materials and loadings have been studied. In static analysis, the defections and stress induced are estimated due to axial and bending loads. Under buckling analysis, the buckling factors and corresponding mode shapes are plotted. The displacement response is plotted and reported.


Author(s):  
Paola Jaramillo ◽  
Haym Benaroya

Carbon nanotubes are composed of C-C covalent bonds, which are the strongest bonds found in nature. Hence, carbon nanotubes are identified as the “ultimate fiber” due to their great strength in the direction of the nanotube axis and their ability to enhance the elastic properties of materials. The first indications of synthesizing carbon nanotubes date back to 1952. Russian scientists Radushkevich and Lukyanovich [1] were able to produce nanosized hollow carbon filaments. Nevertheless, it was until 1991 that multi-walled carbon nanotubes (MWCNTs) were discovered by Sumio lijima [2, 3] at NEC Corporation Lab, which was followed by his study and synthesis of single-walled carbon nanotubes (SWCNTs) in 1993. Since their discovery, there has been a constant pursuit to understand the properties and identify the optimal applications of these structures. The paper focuses on the importance of carbon nanotubes and their ability to enhance the mechanical properties of other materials due to their unique elastic properties. Additionally, carbon nanotubes can improve the capabilities and properties of other materials, like polymer composite. Currently, there is an ongoing process to accurately understand the fundamental characteristics of these structures, in particular, to develop the governing laws necessary to control, predict, and manipulate these properties. This will eventually have an impact on the bulk properties of materials where carbon nanotubes may be incorporated. The current research focuses on the ability to create simplified models that can accurately predict the response of carbon nanotube structures undergoing different types of loading conditions. In this way, the mechanical characteristics regarding single-walled carbon nanotubes (SWCNTs) through finite element modeling are computed. A simplified finite element model is created in ANSYS for different types of SWCNTs with varying input parameters. An input array for the elastic modulus and load is generated to control the physical effects of these parameters in the nanotube structure. The geometries of the nanotubes are altered through various thicknesses employed for the construction of the C–C bonds. The current work contributes to the generation of different model responses to monitor the stress distribution employing a wide range of parameter values. The ability to introduce variability in the parameters and boundary conditions without altering the capabilities and computational time in the model represents the main contribution of this work.


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