A numerical slipline field for the sliding cylinder problem

Abstract

This paper presents a slipline field solution for a rigid cylindrical asperity sliding across an initially plane surface of a softer material. The numerical development of the model is described. The friction and strain pattern predictions of the model are tested against the results of experiments and finite element analysis. It is shown that the friction predictions of the model developed are in good agreement with the chord approximation model proposed by Challen and Oxley [J.M. Challen, P.L.B. Oxley, Slipline fields for explaining the mechanics of polishing and related processes, Int. J. Mech. Sci. 26 (6–8) (1983), 403–418]. Thus, it can predict well the friction coefficients measured from tests when a cylinder, whose trailing edge has been removed, slides across an aluminium alloy, as shown experimentally in Busquet and Torrance [M. Busquet, A.A. Torrance, Investigation of surface deformation and damage when hard cylindrical asperity slides over a soft smooth surface, Proc. 25th. Leeds-Lyon Symp. Tribol. (1998)]. However, this model is not suitable for predicting the friction coefficients when a full cylinder slides on aluminium. This has already been explained partly by the fact that the slipline field theory neglects elastic effects and also by the presence of detached particles trapped in the contact. The strain pattern calculated by the model presented here is much closer than the chord model of Challen and Oxley [J.M. Challen, P.L.B. Oxley, Slipline fields for explaining the mechanics of polishing and related processes, Int. J. Mech. Sci. 26 (6–8) (1983) 403–418] to visioplastic measurements of strain patterns produced by wedge-shaped asperities [Y. Yang, The prediction of the wear rates of ductile materials through their surface strains, PhD thesis, Trinity College, University of Dublin, September 1997], and this without strain-hardening. Furthermore, the morphology of the debris produced during wedge experiments has been explained to some extent by the model presented here without involving elastic effects.