Method for simultaneous estimation of rolling and spinning friction in a higher pair

Abstract

A spatial higher pair is characterized by a complex motion with the direct consequence: the occurrence in the contact point of a friction torsor having all possible components (sliding, spinning and rolling friction). There are cases, like thrust ball bearings, where the components of the friction torsor are interrelated, and actual separation of these is not possible. The present paper proposes an approach for simultaneous evaluation of the coefficient of rolling friction and of the coefficient of spinning friction using a cycloidal pendulum. As principle, the experimental device consists in a steel ball set on top of two cylindrical steel rods, parallel, mounted horizontally. When a vertical rod is attached to the ball, a cycloidal pendulum is obtained. The damping of oscillatory motion is due to the two friction torques: spinning and rolling. y relevant articles in literature searches, great care should be taken in constructing both. The motion of the pendulum is analyzed for two values of the gap between the horizontal rods. A system of two equations with the coefficients of rolling and spinning friction as unknowns is obtained. Based on the hypothesis that the dependencies for the torques versus the normal force are known, these two coefficients can be obtained.