Advanced Materials: TechConnect Briefs 2015Advanced Materials TechConnect Briefs 2015

Carbon Nano Structures & Devices Chapter 3

Effect of length and radius of singlewall carbon nanotube on its mechanical properties

F.G. Alzubi, R. Cosby
Kuwait institute for scientific research, Kuwait

pp. 137 - 140

Keywords: CNT, Young's modulus, stress, strain, conductance, computational simulations

A first principles atomistic calculations and analysis of Young’s modulus for short arm chair carbon nanotubes with different lengths and radii is]]are reported. The atomic forces and total energies were computed for the carbon nanotubes using Density Functional Theory (DFT) encoded in a commercial software package. A maximum strain of 1% was applied through a speculative atomistic-level approach to investigate stress-strain relationships and to compute electronic structures. Over the variation of carbon nanotube length from 6.2 to 22.2 Å, Young’s modulus fluctuates for short carbon nanotubes, whereas it saturates around the value of 1.8 TPa for longer carbon nanotubes. When increasing the carbon nanotube’s radius from 2.7 Å to 4.1 Å, Young’s modulus value decreases. The consideration of Poisson ratio when calculating the values of Young’s modulus from total forces or total energies have shown a variation of up to 1 TPa in Young’s modulus values. We are also reporting the effect of stress on the conductance of short CNT length 6.2 Å. According to the results, the conductance of the CNT is decreased by ~4 μS when a strain of 0.65% was applied. This drop in the conductance for strained CNTs agrees with what is presented in the literature.