Text: A balance resonance during which the shaft dynamic mode shape assumes a simple single arc. Theoretically, below the translational balance resonance, the axis of rotation is the shaft geometric centerline - above the translational balance resonance, the axis of rotation is the shaft mass centerline (principal inertia axis) - and during the translational balance resonance region the axis of rotation translates (moves) from the shaft geometric centerline to the shaft mass centerline. Thus, a rotor corrects itself for its residual static mass imbalance distribution above this speed range. Again, theoretically, one nodal point will exist at each end of the rotor; however, depending on bearing stiffness, the nodes may be outside (outboard) of each end of the shaft.

See Also:

Source: 100