Kinetics of adherence of a rigid flat-ended sphere in contact on a soft rubber-like material surface

Abstract

The equilibrium contact of flat-ended spheres applied against the flat and smooth surface of a soft elastomer sample (unfilled natural rubber) is examined as a function of the size of the flat. As previously shown by Maugis and Barquins, the elastic adherence force increases as the radius of the flat is enlarged. New results on the kinetics of adherence at imposed normal load are presented. They consist of a study of variations of the strain energy release rate G and of the associate dissipation function Φ=( G− w)/ w, where w is the Dupré energy of adhesion, as a function of the crack propagation speed V at the interface between the flat-ended sphere, with global radius R and flat radius a m, and the elastic solid. As expected, a master curve Φ( V) is found, confirming the variation of Φ as the 0.55 power function of V, as recently established by Barquins et al. in adherence and rolling of cylinders experiments and rebound of balls tests, with the same rubber-like material.