Nonlinear normal modes and dynamic balancing for a nonlinear rotor system

The basis of rotor dynamic balancing procedures depends on the linearization hypothesis of the system. However, some dynamical characteristics of mechanical elements of rotor systems are nonlinear. To increase the balancing efficiency, an improved algorithm is proposed by applying the Nonlinear Normal Modes (NNMs) to the modal balancing procedure. To demonstrate the accuracy and effectiveness of the proposed method, a Jeffcott rotor with nonlinear restore force is balanced by both the NNMs method and the linear modal method for comparation. The simulations show that the balancing results by the NNMs method are significantly better than those by the linear modal method, regardless of levels of nonlinearity and eccentricity, by comparing the percentage reduction in vibration amplitude at critical frequencies, spectra of responses and resonance curves.