The Particular Vibration Phenomena Due to Ball Bearings at the Major Critical Speed

Abstract

When single-row deep groove ball bearings with so-called small "angular clearance" are used in a shaft rotating with an angular velocity ω, there appear rotating anisotropies both of shaft stiffness and of unsymmetrical nonlinearity in the spring characteristics of the shaft. These anisotropies are induced by irregularities in rotating parts of the shaft system and also rotate with an angular velocity ω. These spring characteristics result in that, in the neighborhood of the major critical speed, an unstable region where unstable vibrations of frequency ω build up takes place or disappears, and furthermore resonance curves of forced vibrations caused by the unbalance of the rotor vary with the change of the angular position of the unbalance. In this paper, these particular phenomena of lateral vibrations of the rotating shaft are treated both analytically and experimentally.