On the Fatigue Strength of Press-Fitted Assemblies

Abstract

In press-fitting an axle into the hub of a wheel the part of the axle not yet in the hub must bear the total pressing force, while in the hub, the force is distributed along the fitting surface. As a result the amount of the axial contraction of the axle, due to pressing force, becomes different from that of the bore of the hub and, consequently, when the force is removed, large axial tensile stress will be induced on the surface of the axle near the portion just inside of the hub face. This stress will lower the fatigue strength of press-fitted assemblies. In this paper the effect of the stress stated above on the fatigue strength of press-fitted bars has been confirmed by calculating the said stress, as well as by measuring the fatigue strength of cracked bars with fillet or with a press-fitted part.