Elastic Finite Element Analysis of Multi-Asperity Contacts

Abstract

The plane-strain contact problem of an elastic half-space indented by a nominally flat rigid surface having a finite number of regularly spaced cylindrical asperities is investigated using the finite element method to gain an understanding of the interactions in multi-asperity contacts. The significance of the number and spacing of asperities on the contact behavior at the center and edges of the interfacial region is examined. Subsurface stress fields of multi-asperity contacts are presented for various asperity distributions and indentation depths. Asperity interaction effects are quantified in terms of representative parameters, such as the maximum contact pressure, normal load, and maximum von Mises equivalent stress, normalized with similar quantities of the single-asperity contact problem. These nondimensional parameters are principally affected by the spacing and radius of asperities and secondarily by the indentation depth. Significant deviations from the single-asperity Hertzian solution may be encountered, especially in the neighborhood of asperity contacts, because of the unloading and superposition mechanisms which depend on the distance and radius of asperities and indentation depth. The finite element results are in fair qualitative agreement with the phenomenological behavior and analytical predictions.