Balancing of Flexible Rotors Having Arbitrary Mass and Stiffness Distribution

A method for balancing a flexible rotor is developed which is based upon the dynamic response of the rotor in its normal modes as excited by the distributed mass unbalance. The balance corrections are determined by equating the modal components of the corrections to the modal components of the unbalance of the rotor. Methods of balancing individual modes as well as simultaneous balancing in any number of modes are presented. The suggested procedure requires calculation of the normal modes and critical speeds, and measurement of the dynamic amplitude at selected points along the rotor axis.