Influences of Morphology Parameters on the Contact Behavior of a Steel Interface

The surface roughness induced by geometric irregularities (asperities) has substantial influence on the contact stiffness, which further affects the working performance and service life of mechanical equipment. In this study, an elastic-plastic contact law between a sinusoidal asperity and a rigid smooth flat is first studied, which is then applied on a statistical model to simulate the contact behavior of a pair of 18CrMo4 steel surfaces to investigate the influences of morphology parameters on the contact stiffness. The analysis shows that smaller shape ratios xi and larger wavelengths lambda induce larger normal contact stiffness K-n for surfaces with identical roughness, wherein the roughness is defined by the mean value of asperity heights R-a and the standard deviation of asperity heights R-q. The normal contact stiffness increases as R-a decreases under the same loading conditions, while the normal contact stiffness increases as R-q decreases for surfaces with a fixed R-a. Besides, the normal pressure and normal contact, stiffness derived from the proposed contact model are validated. The results demonstrate the potential of the proposed model in contact design due to its ability of establishing the relations between the normal contact stiffness and surface morphology parameters