ADHESIVE CONTACT AND ROLLING OF A RIGID CYLINDER UNDER THE PULL OF GRAVITY ON THE UNDERSIDE OF A SMOOTH-SURFACED SHEET OF RUBBER

The mechanical approach of the rolling contact of a rigid cylinder und er the flat and smooth inclined surface of a natural rubber sample, if molecular attraction forces act, allows one to demonstrate, contrary to our first intuition, that the rolling of the cylinder occurs even i f its weight per unit axial length is much greater than the critical v alue for the static equilibrium under a horizontal surface, as previou sly studied. It is shown that the maximum value of the rolling force p er unit length is 50 times the static equilibrium force measured under a horizontal surface. The rolling force varies as an n power function of the rolling speed and the value n = 0.55 previously determined in recent rebound and rolling experiments with the same rubber-like mater ial is found again. Moreover, contact length measurements confirm theo retical predictions: the contact length varies as the n/3 = 0.183 powe r function of the rolling speed in a large range of velocities.