Rub-impact investigation on the lateral-torsional coupled vibration of a bolted joint rotor system with interface contact

Under speed-up conditions, the monotonically increasing load significantly affects the contact state of bolted joint interfaces, potentially exacerbating rubbing faults. Therefore, a numerical model is developed based on static simulations and the Iwan model. The proposed model's capability in capturing the interface contact state is confirmed through a comparison of static and dynamic responses. Subsequently, a coupled lateral-torsional vibration model for the bolted joint rotor system considering rubbing faults is developed by combining the lumped-mass method with the Stribeck model. Numerical results indicate that rubbing faults intensify interface contact variations, reducing the system’s equivalent stiffness. Moreover, during acceleration, the additional imbalance force induced by speed-up further exacerbates interface contact variations, resulting in more pronounced stiffness softening. Finally, experimental testing validates the effectiveness of the numerical simulation results. This study provides valuable theoretical guidance for rotor system structural design and fault diagnosis.