Internal synthesis of motion and the dynamic characteristics of external friction

On the example of a simple tribosystem in the form of a body sliding (rolling) over an inclined plane, it is demonstrated that the kinematic concept of external friction based on the Amonton-Coulomb law of modifications is not appropriate as a base for the study of the dynamics of external friction. The obtained dynamic friction characteristics in respect to the velocity and acceleration prove that the velocity of motion varies and that the dynamic equations are nonlinear both in respect to velocity and acceleration. The mechanism of dynamic feedback in tribosystems ensures both subordination to external effects and the capacity for effective synthesis of relevant motion types. The problem is analyzed of selecting adequate design types of motion elements of a tribosystem in relation to the frictional self-excited vibrations and the metrology of measuring the coefficients of sliding and rolling friction. In view of the high complexity of a priori modeling of external friction, it is concluded that methods of experimental tribodynamics should be developed.