Investigation of metal contact mechanism by hard sphere indentation. Effect of surface lubrication and interference of deforming metal.

Abstract

It is important to examine the contact mechanism between metal surfaces for the accuracy improvement of guideway motion and for the pre-estimates of contact rigidity and damping capacity of mechanical systems. In the present study, the contact between a hard steel sphere and soft aluminium or duralumin surfaces are treated, and the effects of lubrication or the interference effect of soft metal deformation between protuberances are discussed. The effect of lubrication is significant in the mean contact pressure variation by the reduction of friction. The deformation by one sphere indenter is confirmed to be ruled by Meyer's law. When the soft metal is pressed by two sphere indenters, the deformation is similar to that of one indenter for a small press load. However, the load becomes sufficiently large, interference is initiated and the size of the indentation becomes small. The influence of this interference can be estimated by a simple equation of indenter size and material properties.