Figure 2
From: Depth-dependent hysteresis in adhesive elastic contacts at large surface roughness
(a) Representative P–h curves measured in AFM contact experiments between a glass bead and a PDMS substrate6. The glass bead was of diameter ≈50 μm. The PDMS sample was cast on a silicon wafer having a RMS roughness ≈1.3 nm. As can be noted, the measured P–h curves for the loading and unloading phases of the experiment are different. The size of the hysteresis loop increases with the maximum indentation depth, |hmin|. The gray dashed curves are the fit of the loading and unloading branches of the measured P–h data to the JKR theory. (b) A plot showing the variation of total energy loss as function of the RMS roughness in the experiments. The RMS roughness refers to the surface roughness of the silicon wafer on which the PDMS substrates were cast. The indenting rate in the experiments corresponding to all data points shown in the plot was 1000 nm/s. See ref.6 for experimental details.
