Self-organization and evolution in dynamic friction systems

The dynamic features of the friction process of the contacting pairs affect their durability and functional suitability. There-fore, the problems of their dynamics and vibrational activity always attract the attention of researchers in the field of tribology. It is known that self-organization processes take place during friction, such as the formation of selective transfer phenom-ena during friction, formation of equilibrium roughness. But known studies do not take into account changes in the dynamic properties of the system in the process of its functioning. The primary sources of self-organization are energetic in nature, but the relationship of these phenomena with the dynamic properties of the system has not been explained, and their modeling has not yet been performed. The paper presents the results of experimental and mathematical modeling of evolutionary changes of friction system due to the power of irreversible transformations of energy input to friction zone, which characterizes the goal of research. In order to achieve the goal, the paper deals with the mathematical modeling of the processes of self-organization in a dynamic friction system in combination with the analysis of the equilibrium of the system, its stability, and the manifolds formed in the vicinity of the equilibrium. It is shown that the proposed mathematical models are integro-differential functionally coupled equations that describe self-organization. Examples are given of dynamic restructuring of the friction system, including bifurcations of the attracting sets of its deformation displacements along the trajectory of the friction forces work. The paper briefly presents the results of the experimental study of the vibration characteristics of the contacting pairs during the development of their wear by the example of two systems: steel-brass and steel-glycerin-brass. It is shown that in the system of friction, new properties always establish naturally due to the work of forces. These properties are determined by the evolutionary change of the parameters of the dynamic coupling and the attractive sets of deformation displacements. The study and experiments show that measurement of parameters available for estimation of some coordinates in the dynamic friction system allows one to solve the problem of non-decoupled dynamic monitoring of the state of friction units and also opens new ways of improvement of friction units.