An Elastic-Plastic Finite Element Analysis of Interacting Asperity Contacts

A three-dimensional elastic-perfectly-plastic finite element model of asperity interaction has been developed. This model consists of two neighboring connecting hemispheres which contact a rigid and flat surface. For two asperities of the same radius and same height, as the approach of the rigid surface is increased, the contact area changes from isolated nearly circular contacts, to a wasp-waist area, and finally to a single nearly elliptical contact region. For asperities of different heights the results can be qualitatively similar to those for equal heights, but also exhibit a shielding effect. Graphs are given of the contact area boundary as a function of the approach, and also of force vs. interference, and contact area vs. interference for various values of asperity tip interferences, and for different asperity height differences.