Elastic rings are extensively utilized in aero-engine rotor systems owing to their compact size and ease of assembly, where they play a critical role in vibration suppression during engine operation. The dynamic behavior of elastic rings is governed by their structural parameters, with stiffness being a pivotal factor influencing the rotor system’s performance. This study employs finite element methods to investigate the effects of elastic ring structural parameters, particularly the geometric features of bosses and internal/external assembly clearances, on stiffness nonlinearity, with a focus on its mechanisms and contributing factors. The results reveal that stiffness nonlinearity emerges when the whirling radius exceeds a critical threshold. Specifically, increasing the boss width, reducing the boss height, or augmenting the number of bosses all attenuate stiffness nonlinearity under identical whirling radii. Furthermore, external clearances exhibit a stronger capability to suppress stiffness nonlinearity compared to internal clearances. Engineering insights suggest that maintaining a small clearance fit during assembly effectively mitigates stiffness nonlinearity, thereby enhancing the rotor’s dynamic performance. This study elucidates the stiffness nonlinearity behavior of elastic rings in practical applications and provides actionable guidance for their design and operational optimization in rotor systems.

The rotor is a crucial component in rotating machinery, where its stability directly impacts performance and safety. Imbalance-induced vibrations can cause severe component wear, resonance instability, and even catastrophic failures, especially in high-speed systems like aero-engines. While the squeeze film damper (SFD) is widely used for vibration suppression, the effects of imbalance (manifested as SFD eccentricity) on its dynamic performance are not well understood. Additionally, the combined impact of imbalance and acceleration on rotor–SFD system stability has not been systematically investigated. This study uses numerical simulations to explore the influence of SFD eccentricity, caused by imbalance, on its dynamic characteristics. Experimental tests are conducted to examine the effects of imbalance and acceleration on rotor–SFD dynamics. Results show that increasing imbalance raises SFD eccentricity, reducing the effective oil film bearing area. This results in a rapid increase in the oil film’s stiffness and slower growth in damping, enhancing nonlinearity and reducing stability. Under small imbalance conditions, increasing acceleration improves stability by facilitating critical speed crossing and reducing vibration amplitude. However, excessive imbalance renders acceleration control ineffective, exacerbating system instability. This study provides valuable insights into the interaction between imbalance, acceleration, and SFD performance, offering guidance for optimizing rotor–SFD system parameters and ensuring stable operation.