Friction Force for Self-Excited Systems

Control and reduction of friction is one of the last frontier in the field of tribology. This paper presents a model for low friction made up of a self-excited oscillator sliding along a periodic potential. Many examples of such self-excited oscillators in electrical, mechanical and biological systems can be found in literature. As one of its most prominent features, stable limit cycles in phase space are established, emerging from a balance between energy gain and dissipation. The possible role of self-excitation on friction force is based on the idea that a limit cycle represents a no dissipation dynamics. If a self-excitated oscillator is pulled by a stage and it starts to slide, then, because the variation of position, the sliding process destroys the limit cycle setting up a stick-slip dynamics. Nevertheless, a reduction of energy could be observed if the self-excitation restoring the limit cycle is not completely destroyed by the sliding movement. It will be demonstrated that a selfexcitated sliding body tangential to a surface experiments changes of stick-slip dynamics and a low reduction of energy dissipation during the motion. PACS: 46.30.Pa; 05.70.Ln; 81.40.Pq