Computer simulation of topographical changes on gold contact surfaces caused by loading

The topographical changes in the asperities of a flat cobalt-hardened gold electroplated surface that occur as a result of being contacted by a sphere are simulated by computer superposition of a mathematically generated spherical surface and a Scanning Tunneling Microscope topograph of an actual flat sample surface. Both ideally smooth and rough spherical surfaces are considered. Two-dimensional maps of the location and size of contact areas and quantitative information on contact areas resulting from asperities that would have been deformed in actual contact events are presented. In addition, 3-dimensional plots and quantitative values of the location and volume of asperity material that would have been deformed in actual contact events are presented. Good agreement is found when the simulation results are compared with experimentally obtained contact results for the same sample surface region at the same indention depth. The simulation technique should prove useful in predicting changes in contact performance associated with changes in contact surface topography or contactor geometry. Computer simulation is much faster and easier than obtaining similar information by experimental techniques which are time consuming and require sophisticated sample contact and positioning hardware.