
26 Friction-Induced Vibration and Self-Organization
including the universality of the critical behavior, the reduction in the num-
ber of degrees of freedom, and the hierarchical structure of the system.
All the previously mentioned effects have relevance to frictional sliding,
which involves instabilities, vibrations, limiting cycles, self-organization,
reduction in the number of degrees of freedom, and even phase transitions
(between the stick and slip states). Thermodynamic quantities should be
introduced in order to account for the effect of ignored degrees of freedom.
Non-equilibrium thermodynamic analysis of instabilities, self-organiza