Abstract
The actual load on mechnical structures does not always have a constant stress amplitude. Therefore, it is very important for the prediction of fatigue life under complex load to investigate whether Miner's rule is valid or not. In this paper, rotating-bending fatigue tests for short carbon-fiber reiforced poly-ether-ether-ketone (CFRPEEK) under two-step loading were carried out to investigate the applicability of Miner's rule. In case of a short fiber reinforced composite like CFRPEEK, the fatigue process should be treated by dividing it into two stages, that is, the one where the fatigue damage concentrates on the edge of the short carbon fiber, and the other where the fatigue damage concentrates on near the fatigue crack's tip. From the result of the experiments, it was concluded that Miner's rule can be applied to the both stages in the short fiber reinforced composites as in the case of metals, and thus Miner's rule holds well under two step loading in CFRPEEK.
