Defect-defect interaction in carbon nanotubes under mechanical loading

Topological defects are formed in carbon nanotubes (CNTs) during processing or subsequent deformation. The presence of defects is found to reduce the Young moduli of CNTs. When the number of defects is more than one, they may be either of the interacting or noninteracting type and this depends on whether the defects are within a specific interacting distance or not. A model for the reduction in Young's modulus for noninteracting defects has been proposed and validated. However, nonlinear effects dominate for interacting defects. Deviation from linearity can be explained in terms of a transition region followed by a steady-state region governed by interacting distance and the size of the defect. The interaction phenomenon is explained by invoking the concepts of local stresses and strain measures rather than the conventional energy quantities.