Effects of Contact Surface Roughness of Interference Shaft/Bush Joints on its Characteristics

For determining the characteristics of interference shaft/bush joints, we usually suppose perfect surface for contact profile and a constant value for friction coefficient. It is clear that imperfect surface of shafts and bushes with irregularities is inevitable, which creates non-uniform contact stress. Exact estimation of the friction coefficient in contact surface of the interference joints is dependent on precise modeling of real profile of the contact surfaces. Friction coefficient may not be determined exactly by assuming perfect profile, leading to uniform pressures on the contact surface. Here, a method has been proposed to construct a geometrical model of joint parts and surfaces with 1-A,A mu m resolution. Roughness measurements have been taken to consider the surface irregularities with amplitudes lower than 1 A,A mu m, which may cause stress singularities. Proposed method has been applied to correlate experimental extraction strength of some interference joints with numerical results list, finally resulting in estimation of the friction coefficient. In particular, the effects of the contact surface roughness on the friction as well as the evolution of wear upon decoupling were studied.