Some Considerations to the Energy Dissipation of Frictionally Stressed Lubricating Greases

The introduction of mechanical energy during a friction process stimulates the system to eliminate this disturbance and find ways for energy dissipation. There are two principal situations: the system is either near equilibrium or far from equilibrium. Near equilibrium, it can be expected that the disturbance will be damped after a certain time, and the system will settle in a stationary state at a level where it began. However, the situation could be entirely different when the system is far from equilibrium. After a phase of instability and crossing a critical parameter, there is a probability of a change in the order level. This means that a new structure will be formed. This paper describes some aspects of the criteria that lead a friction process inside the grease film to instability and examines the influence of different dependencies. In this publication, the dependencies are extended to verify the stability criterion. Finally, the rest phase of a thixotropic experiment is examined from the perspective of potential instability and, thus, the possibility of self-organizing processes occurring.