Torsional fretting fatigue strength of a shrink-fitted shaft

The torsional fatigue strength of shrink-fitted shaft couplings was estimated by tests performed by varying the geometry of the shrink-fitted assembly, the load and the contact pressure. Press-fitting of the hub overhanging the shoulder was used to increase the contact pressure. The tests were performed using a grooved and a plain hub. These experiments showed that the fretting reduced with an increase in contact pressure because the slip amplitude decreased. The shaft was fractured slightly inside the end of the fit by fretting fatigue, but if the contact pressure is very high, the shaft is fractured at the fillet by normal fatigue. The fretting fatigue limit at a constant diameter ratio increases with an increase in the fillet radius, and reaches its maximum value at a certain radius using the grooved hub. As the diameter ratio becomes larger fatigue fracture occurs at the fillet.