Load transfer mechanism in carbon nanotube ropes

We used molecular mechanics and molecular dynamics to study the nature of load transfer in a single walled carbon nanotube (SWCNT) bundle consisting of seven (10, 10) SWCNTs: one core tube surrounded by six tubes on the perimeter. The surface tension and the inter-tube corrugation are identified as the two factors that contribute to load transfer. The surface tension effectively acts over a "line" (roughly over the circumference of each tube). The inter-tube corrugation scales linearly with respect to the contact surface area, and increases non-linearly as the inter-tube distance decreases. Relaxation in the nanotube cross-section leads to better inter-tube load transfer as a slight "faceting" develops; the tubes appear to be partially polygonized, rather than perfect cylinders. Compared with parallel bundles, twisting can significantly enhance the load transfer between neighboring tubes; this has been computed as a function of twist angle for this nanotube bundle system. (C) 2003 Elsevier Ltd. All rights reserved.