Experimental Study of the Effects of Surface Roughness on Friction

Abstract

Experimental verification of lubrication theories for surface roughness effects is lacking. We have conducted an experimental study using riblet tapes to generate repeatable surfaces on the test samples. A computer-assisted pin-on-disk tribometer was developed to measure the friction of the test samples. To study the effects of roughness height and lay orientation on friction, machined samples and. samples with different riblet tapes mounted longitudinally and transversely were tested. Our results show that lower roughness height yields lower friction, and that transverse roughness has lower friction than longitudinal roughness. The surface roughness effects become increasingly significant as the film thickness decreases. These findings substantiate earlier theoretical studies. A flow visualization system for the tribometer was also developed to observe flow characteristics of different surface roughnesses.