How long can single-walled carbon nanotube ropes last under static or dynamic fatigue?

We report a study on the static and dynamic fatigue behavior of unidirectional, aligned single-walled carbon nanotube (SWCNT) ropes. By bench marking against the behavior of graphite fiber, it is found that the static fatigue strength of SWCNT ropes is at least twice that of graphite fiber within 104 s and is similar to that of graphite fiber at longer times, while the dynamic fatigue strength is twice that of the graphite fiber to up to 107 cycles. Fatigue limit seems to exist for SWCNT ropes within the time scale of the investigation at 4-5 GPa. Based on experimental data and results of a molecular life prediction scheme, it is suggested that the fatigue behavior of SWCNT ropes may be controlled by preexisting defects.