A SURFACE-LAYER MODEL FOR THIN-FILM LUBRICATION

A theological model has been developed which can be applied to thin fi lm lubrication. It is known that great differences are seen between be havior in thin (molecular scale) films and in bulk (macroscopic) theol ogical measurements. There appear to be layers near the surface in whi ch viscosity is increased by many orders of magnitude. The model conta ins three material property parameters, i.e., the conventional viscosi ty, the thickness of the surface layer, and a surface layer viscosity. A modified Reynolds equation is developed. Behavior of correction fac tors to Reynolds' equation and to the shear stress are shown. Results are computed for a one-dimensional converging wedge contact. The effec t of increasing the layer thickness parameter is to increase the load and reduce the friction coefficient. Increasing the surface layer visc osity also tends to increase the load and reduce the friction coeffici ent.