Short duration sliding contacts between elastomers and smooth rigid substrates: exploratory studies with an instrumented pendulum skid tester

Measurements of dry and lubricated sliding for a wide range of elastomers (natural and synthetic) have been carried out using a specially modified British Pendulum Skid Tester. This instrument incorporates an optical position sensor, a high-precision electronic timer, and a computer interface. It monitors the swing of a pendulum at angular intervals of 0.14 degrees as it drives an elastomer slider across a horizontal surface at speeds of up to 3 m s(-1). Profiles of kinetic energy loss can be measured with 1.4 mm spatial resolution and path-averaged forces of sliding friction derived with a precision of better than 1%. Adhesive terms, largely associated with the transfer of elastomer films from slider to substrate, are responsible for between 78% and 98% of the kinetic energy lost to sliding friction on smooth surfaces. For some elastomers, oscillations in the friction force appear above a critical sliding velocity. These oscillations can be simulated numerically by a model of stick-slip friction in which the adhesive bond between elastomer and substrate interacts with the elastic properties of the bulk material. (C) 1999 Elsevier Science S.A. All rights reserved.