Stress calculations for carbon nanotubes

Atomic stresses were calculated for carbon nanotubes under stra n conditions. Graphitic tubules with radii ranging from approximately 2 to 11 Angstrom and two different tubule structures with varying atomic orientations were included in the calculations. Elongations and contractions were applied in the axial direction and atomic stress values were calculated fur infinitely long tubules. The calculations were carried out using Brenner's function which was developed for carbon species. Results indicate that the stress is tensile in the radial direction while it is compressive in the tangential direction. Variations in-stress values in the direction of the cylindrical axis were investigated as a function of applied strain. Furthermore, using thr: stress-strain curve (calculated based on atomic considerations), the values of Young's modulus and Poissons ratio for nanotubules were also estimated. (C) 1998 Elsevier Science S.A.