Based upon the concept of molecular-level strain energy concentration, and a kinetic fracture model, the time-dependent fracture behavior of three types (zig-zag, armchair, chiral) of single-walled carbon nanotube with or without Stone-Wales defects were studied. It was found that the Stone-Wales defects had an effect upon the site of crack initiation, but the path of crack propagation was closely related to the chirality of the nanotube. Defect-free armchair and chiral tubes exhibited a higher static fatigue strength than did zig-zag nanotubes of similar size. All of the single-walled carbon nanotubes with Stone-Wales defects were predicted to have a shorter static fatigue life, compared with defect-free tubes. The geometrical form of the defects was found to influence the time-dependent behavior. The predictions of the present model agreed reasonably well with experimental stress-life data on single-walled carbon nanotube ropes in epoxy.

Time-Dependent Fracture Behavior of Single-Walled Carbon Nanotubes with and without Stone-Wales Defects. Y.Ren, T.Xiao, K.Liao: Physical Review B, 2006, 74[4], 045410