What happens when a rotor loses its magnetic support? This paper delves into the complex motion of an Active Magnetic Bearing (AMB) rotor when it transitions to backup bearings. Unlike linear rotor-bearing systems, this non-linear system can exhibit irregular, even chaotic, motion at certain speeds, with consequences for machinery durability. Through numerical simulations, the research reveals the existence of extra resonance frequencies beyond those predicted by linear models. In particular, these frequencies appear within a wide rotating speed range. When a power failure occurs in AMB machinery, the AMB rotor traverses these resonance frequencies, increasing the risk of full clearance whirl motion, which can lead to damage. Discussing methods to mitigate the non-linear response and circumvent full clearance motion, this study provides insights for preventing catastrophic failure in AMB systems. This research is crucial for ensuring the reliability and safety of high-precision rotating machinery, offering valuable data for optimizing AMB system design and control.
As a contribution to the Journal of Vibration and Acoustics, this paper aligns perfectly with the journal’s focus on understanding and mitigating vibration-related challenges in mechanical systems. The analysis of rotor motion in backup bearings contributes to the journal’s scope by addressing a critical aspect of machine dynamics and offering insights for improving system reliability.