Measurement of Dynamic Friction: Apparatus and Early Results

A new apparatus for measuring dynamic friction is described. The apparatus comprises an oscillating platform on which a test mass is free to slide. The displacement of the test mass relative to the platform is measured with a Hall effect sensor, and the friction force is measured with an accelerometer. The apparatus is used to obtain the friction vs velocity curves for several interfaces between the contacting surfaces: polished metal against polished metal, lubricated polished surfaces, and teflon against teflon. For each surface interface several amplitudes and frequencies of motion are investigated. Results, generally consistent with earlier published results and with theory, demonstrate that the apparatus works. Recommendations for improvement of the apparatus are given.