The role of entrapped lubricant in asperity flattening under bulk plastic deformation.

The load bearing capacity of entrapped lubricant and resulting diminished asperity flattening are studied with a new specimen design that allows for both compression and biaxial bulk deformation of the subsurface material. Numerical simulations considering the experimental compressibility curve for the trapped oil support the analysis and show how incomplete filling of the valleys affect asperity flattening depending on the asperity flank angle. Finally, the new specimen design also allows quantifying the differences in friction when bulk deformation of the subsurface material is carried out with and without trapped oil in the valleys between asperities. [ABSTRACT FROM AUTHOR]