Self-excited Vibration Caused by Internal Friction in Universal Joints and Its Stabilizing Method

Abstract

Stability of a rotor system induced by Coulomb friction in joints is investigated both theoretically and experimentally. The vibrating system consists of two shafts supported flexibly and connected by three universal joints including a cross-groove (CG) joint. The Coulomb friction in a CG joint, which is one of the most destabilizing joints among practically used ones, is treated. The friction is assumed to be a function of the relative angular velocity between the connected shafts. Three stabilizing effects are investigated: the initial intersecting angle in the CG joint, the asymmetry of the support stiffness and a dynamic damper (D/D). As a result, it is found that the initial intersecting angle has a remarkable stabilizing effect; D/D expands the stable region of the system with an initial intersecting angle; the asymmetry of the support stiffness also has a stabilizing effect on the system with an initial intersecting angle. These stabilizing effects are experimentally confirmed.