Microdisplacements Between Two Elastic Bodies Separated by a Thin Film of Polystyrene

Abstract

This paper describes and experimental investigation of the microdisplacements between two elastic bodies in contact under the action of a tangential force less than that of limiting friction. Experiments have been performed for the contact of 52100 steel ball with a 52100 steel flat separated by a thin film of polystyrene. Measurements of microdisplacements have been made under oscillating tangential forces of various frequencies (1 Hz to 1 KHz) and different film thicknesses (0.05 μm to 1.2 μm) were used to study the perturbations of the Mindlin’s theoretical two elastic body results. For very small tangential force (i.e., for displacements which are almost entirely elastic), the measured compliance of the present three body system is higher than the two body system studied by MINDLIN. The compliance increases noticeably with the film thickness. Furthermore, an approximate value of the elastic shear modulus of the pressurized film has been obtained. When the tangential force is greater than the elastic limits, it has been observed that the frictional energy loss per cycle in the contact area is related to the presence of the film and to its thickness.