Original paper(Vol.45 No.1 pp.72)

Effects of short fiber reinforcement and mean stress on tensile fatigue strength characteristics of polyethersulfone

Furue Harumi; Nonaka Katsunobu

Abstract:In order to characterize the fatigue strength of injection moulded advanced thermoplastics, such as Polyethersulfone (PES), short glass fiber reinforced PES and short carbon fiber reinforced PES, fatigue tests were conducted under tension-tension cyclic loading (stress ratio, R =0.1approx.0.7) at 23+-1 degree and 50+-5%RH. The effects of repeated stress amplitude, mean stress, characteristic of matrix and the kind of reinforced short fibers on the fatigue strength were investigated. The behavior of fatigue fracture in short fiber reinforced thermoplastics and matrix resin was also investigated on the basis of the fractographic examination of fatigue fracture surface.
The results are summarized as follows. (1) The influences of repeated stress amplitude and mean stress on the fatigue characteristic of PES series were revealed. (2) It was found that the effect of short fiber reinforcement on fatigue strength characteristic is high, and carbon fiber is more effective than glass fiber. (3) The short fiber reinforcement of those materials was also discussed on the basis of the fractographic examination.

Key Words:fatigue strength, stress amplitude, mean stress, injection moulded PES, short fiber reinforcement, glass fiber, carbon fiber