Characteristic analysis of looseness-rubbing coupling fault in dual-disk rotor system

For the looseness-rubbing coupling fault rotor-bearing system caused by pedestal looseness, the mechanical model and finite element model of dual-disk triad-supported looseness-rubbing coupling fault rotor-bearing system were established in this paper. The research of dynamics characteristics about the effect of rubbing stiffness and looseness stiffness on the system was done with equivalent stiffness model on the loose support, nonlinear finite element method, contact theory and the wavelet packet decomposition principle. It was demonstrated that alternating high and low peaks exist in the time domain while the trapezoidal shape appears in the orbit diagram of the signal. It was also found that the double frequency (2X) has a high energy distribution in the vibration signal. It could be used as fault frequency band of the looseness-rubbing coupling fault. These two characteristics (trapezoidal shape and double frequency) could serve as a basis in diagnosing looseness-rubbing coupling fault.