Study of ill-conditioned equations involved in a dynamic balancing process when influence coefficient method is used

Dynamic balancing technology provides the most important means for the elimination of unbalance faults of rotors while influence coefficient method (ICM) represents a major approach in dynamic balancing techniques. However, in practical operations the balancing efficiency may be lowered due to the influence of ill-conditioned equations. To cope with the problem of possible emergence of ill-conditioned equations, a single-span rotor model was established and by using rotor vibration mode theory the mechanism governing the appearance in the ICM of ill-conditioned equations analyzed. On this basis, an experimental study was conducted. The research results show that the ICM can be used for the dynamic balancing of flexible rotors. However, the rotors may be influenced by the ill-conditioned equations at a special rotating speed and a special counterweight plane while the selection of a rational balancing speed and balanced counterweight plane constitutes a main measure for avoiding the ill-conditioned equations.