2-DIMENSIONAL MODELS OF BOUNDARY AND MIXED FRICTION AT A LINE CONTACT

Two-dimensional dynamic friction models at a lubricated line contact, operating in boundary and mixed lubrication regimes, are developed. Th e friction coefficient is shown to be a function of the sliding veloci ty and the instantaneous separation of the sliding bodies, normal to t he sliding direction. The models are based an unsteady friction experi ments carried out under constant normal loads and under time-varying s liding velocities. The normal motions at the sliding contact were dete cted indirectly by contact resistance measurements. The contact resist ance is related to the theoretical central film thickness for smooth s urfaces. An advanced system identification technique (Minimum Model Er ror) is implemented to identify the most important terms in a number o f nonlinear friction models. Two friction models are then nondimension alized and parameterized. The validity and range of application of the models are then tested by comparing them with experiments and with se lected models proposed by other researchers.