抄録
An investigation has been carried out concerning the influence of stress waveform and wet environment on the fatigue fracture behavior of aramid single fiber. The aramid fiber used in this investigation was Kevlar 49 (du Pont). Tension-tension fatigue tests were conducted under sinusoidal, negative pulse and positive pulse waveforms for the fiber preconditioned in laboratory air and in wet air (RH 97%, 20℃). The fatigue strength of the fiber tested in wet air was lower than that in laboratory air, and the fatigue strength in air under negative pulse waveform was higher than those under other two waveforms. Fiber surface was examined with a high-resolution field emission type scanning electron microscope and an atomic force microscope, and the fatigue fracture mechanism of the fibers was discussed.
