Test Method;Bending Fatigue;Kevlar 49 Fiber;Cyclic Tension;Fracture Morphology
Abstract
In this paper, we report a bending fatigue testing apparatus which can test the bending fatigue resistance
of single Kevlar 49 fiber by setting the pretension and bending angle. The cyclic tension and the (number
of cyclic bending of fiber) were recorded by this apparatus. The cyclic tension curve showed that the
tension changes in periods during the bending fatigue process. The cyclic tension was theoretically
analyzed and found that the bending angle had significant effect on the cyclic tension. The cyclic
bending number N of Kevlar 49 fiber was plotted as a function of pretension S using S-N curves, which
shows that the bending angle and pretension have a significant effect on the fatigue lifetime of a fiber.
The bending fatigue morphologies of Kevlar 49 fiber explained the bending failure mechanism of the
Kevlar 49 fibers.
