INVESTIGATION INTO THE INFLUENCE OF DYNAMIC FORCES ON THE TRIBOLOGICAL BEHAVIOR OF BODIES IN ROLLING/SLIDING CONTACT WITH PARTICULAR REGARD TO SURFACE CORRUGATIONS.

The influence of the action of a dynamic force on the tribological behavior of bodies in rolling/sliding contact without lubrication was examined both experimentally and theoretically. The tests showed that the coefficient of traction and the wear both decrease as the amplitude of the dynamic normal force increases. An attempt was made to explain this phenomenon with the aid of a torsional oscillation model. Using the same model, the mechanism of ripple formation on a plain carbon steel in the presence of slip was discussed. It was found that ripples originate from a formation of oxide stripes and that their further development, dependent on the stress conditions, is determined to varying degrees both by the plastic deformation and by the periodic wear conditioned by a motion similar to that of stick slip. If the dynamic influences on the rolling friction behavior are considered, it is understandable that the coefficient of traction measured on a railway locomotive will, because of the different dynamic conditions, deviate very considerably from that recorded on a rolling friction test rig in a quasistatic state. It has thus been demonstrated that the applicability of test rig results to a practical friction system can only then be assured when the influence of the dynamic system on the tribological behavior is taken into account.