Original paper(Vol.46 No.10 pp.1197)

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

Furue Harumi; Nonaka Katsunobu; Hashimura Yasuhiko

Abstract:In order to characterize the fatigue strength of injection moulding advanced thermoplastic, such as Polyetheretherketon(PEEK), short glass fiber reinforced PEEK (GF/PEEK) and short carbon fiber reinforced PEEK(CF/PEEK), the fatigue tests were conducted under tension-tension cyclic loading (stress ratio, R = 0.1 - 0.7) at 23 +-1 degree, 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 on the basis of the fractographic examination of fatigue fracture surface.
The results are summarized as follows. (1) The influence of repeated stress amplitude and mean stress on the fatigue characteristic of PEEK series were revealed. (2) It was found that the effect of short fiber reinforcement on the fatigue strength characteristic is not high, the same as that on the static strength of PEEK series. (3) The short fiber reinforcement of those materials was also discussed on the basis of fractographic examination.

Key Words:fatigue strength, stress amplitude, mean stress, injection molded PEEK, short fiber reinforcement, glass fiber, carbon fiber