Torsional Fatigue Strength of a Shrink Fitted Shaft

Abstract

Torsional fatigue strength of several types of shrink fitted shaft couplings is estimated based on the results of stress analysis, in which the changes of frictional coefficient and contact pressure during cyclic loading are taken into account. Then these estimated strengths are confirmed by torsional fatigue tests. The results are summarized as follows. The firictional coefficient in the slip region increases steadily with an increase of cycles and saturates for more than 10⁴ cycles. The saturated value of it is about 0.7. Torsional fatigue strength reduction factor of shrink fitted shaft is found to be K_f=1.28, which is far smaller than the rotational bending fatigue strength reduction factor (K_f=2∼3). Anti-fretting measures such as groove, taper are found to be not so effective for torsionalfatigue as for rotational bending fatigue.