Anisotropic friction: assessment of force components and resulting trajectories

Abstract

We report on an experimental device that makes it possible to assess the frictional properties of the contact between a slider and a horizontal surface, and to study the resulting trajectories of the slider when pulled across the surface by means of a flexible link. First, we show experimentally that, when the frictional properties are anisotropic, the slider is subjected, in addition to the dissipative frictional force oriented along the trajectory, to a force, perpendicular to the trajectory, which thus does not contribute to energy dissipation. Therefore, the slider does not necessarily moves in the pulling direction. Second, we show that the trajectories of the slider, when in continuous motion, in absence of inertial effects, can be recovered by assuming that, at all time, the friction force compensates the pulling force. We point out that we prove experimentally that the normal component of the friction force is given as the derivative, with respect to the sliding direction, of the tangential component. This result is particularly interesting as the relation between the normal and the tangential components is compatible with “the maximum of energy release rate” criterion used in the theory of fracture.