Boundary and Mixed Friction in the Presence of Dynamic Normal Loads: Part II—Friction Transients

Abstract

The normal dynamic model of the sliding system developed in Part I of this paper is combined with a friction model, obtained separately from the same apparatus, to provide estimates of the friction under dynamic loading conditions. The two-dimensional friction model, developed from measurements at constant normal load and slowly varying sliding speeds, includes the normal approach of the sliding bodies as a key variable. From the combined model, estimates of friction under harmonic loading and of friction transients associated with short duration impacts are compared with measurements. The very good agreement between estimates and measurements indicates that, while a good friction model is required, the crucial and most variable aspect of the modeling of dynamic friction is the representation of the normal dynamics of the sliding system.