SELF-EXCITED VIBRATION CAUSED BY INTERNAL-FRICTION IN UNIVERSAL JOINTS AND ITS STABILIZING METHOD

Stability of a rotor system induced by Coulomb friction in joints is i nvestigated both theoretically and experimentally. The vibrating syste m consists of two shafts supported flexibly and connected by three uni versal joints including a cross-groove (CG) joint. The Coulomb frictio n in a CG joint, which is one of the most destabilizing joints among p ractically used ones, is treated. The friction is assumed to be a func tion of the relative angular velocity between the connected shafts. Th ree stabilizing effects are investigated: the initial intersecting ang le in the CG joint, the asymmetry of the support stiffness and a dynam ic damper (D/D). As a result it is found that the initial intersecting angle has a remarkable stabilizing effect; D/D expands the stable reg ion of the system with an initial intersecting angle; the asymmetry of the support stiffness also has a stabilizing effect on the system wit h an initial intersecting angle. These stabilizing effects are experim entally confirmed.