LAUSR

Abstract The rubber friction coefficient, and the contact area during stationary sliding is calculated, for the contact of a polished rubber block and a concrete surface, when both surfaces are rough. The calculation is based on an extended version of Persson's contact mechanics theory. Compared to only the substrate being rough, when both of the surfaces are rough but their cross correlation is zero, the friction coefficient is larger. Introducing a positive correlation decreases the friction coefficient, while introducing a negative correlation increases the friction coefficient. To support these theoretical arguments, some experiments have been performed. We have produced roughness on the rubber surface, using abrasive paper, and measured the surface topographies for the concrete and the polished rubber surfaces. The auto spectral density functions for the both surfaces have been calculated, and the rubber viscoelastic modulus mastercurve has been obtained. We have measured the rubber friction at different sliding velocities, when the rubber surfaces are rough and smooth, and compared it to the theoretical results. It is seen that when the rubber surface is rough, the rubber friction coefficient is larger compared to the case the rubber surface is smooth. The theoretical results are in good agreement with experimental observation.