Transient Friction Effects Due to Variable Normal Load in a Multi-Scale Asperity-Creep Friction Model

The study of multi-scale and fractal contact geometries holds many insights into the nature of surface contact. As a common feature of most fractal contact models, the presence of small-scale, plastically loaded asperities has emerged. The latter are, due to their loading close to the yield strength of the material, subject to creep deformation which is often held responsible for transient friction effect like dwell time- or velocity-dependent friction. In this paper, the transient behavior of friction under varying normal force will be studied in the framework of a multi-scale contact model with fractal input parameters. An advanced asperity creep model from previous research is used, yielding the time-dependent creep enlargement of the asperity contact area in response to arbitrary load transients.