Wednesday, 13 October 2004 - 9:00 AM

This presentation is part of : Nano Materials and Material Systems

Prediction of Plastic Yielding of Single-Walled Carbon Nanotubes

Liang Zhang and Jia Lu. University of Iowa, Department of Mechanical and Industrial Engineering, Center for Computer-Aided Design, Iowa City, IA 52242

Plastic yielding of carbon nanotube (CNT) induced by Stone-Wales (SW) transition is a mechanism for nanotube to release excessive strain energy. For an armchair nanotube under tension, SW transition occurs at about 10% of elongation, far below the reported failure (break) strain of ~40%. Therefore, to predict the strength of the nanotube, it is important to consider the SW transition and defect motion. The contribution of this work is to interpret the yielding process from the viewpoint of continuum mechanics. Yielding occurs only if the energy released via SW rotation (formation energy) surpasses the maximum energy along the possible kinematic pathway of SW formation (energy barrier). In this work, an Eshelby-type method is used to compute the formation energy and the energy barrier. An energy-equivalent continuum model is utilized in the analysis. The yielding strain and stress are estimated. It is shown that the plastic yielding of CNTs appears earlier in force controlled process than displacement controlled process. The influence of thermal effect is also considered.

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