Average separation between a rough surface and a rubber block: Comparison between theories and experiments

We briefly review the most important contact mechanic theories regarding the average separation between an elastic solid with a nominal flat surface and a hard solid with a randomly rough surface, as a function of the squeezing pressure. We present experimental results for a silicon rubber (PDMS) block, squeezed against two different road surfaces. Finally we compare the theoretical predictions of the different theories with the experimental data.