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.

To change the current situation of the seriously redundant design of the creep rupture life of low-cost short-life turbine rotor blades, this paper studies the creep rupture characteristics of the typical low-cost material K424 alloy of the integral casting turbine rotor at multiple high stress levels within the near-plastic and plastic ranges at 700°C. Based on the Larson-Miller equation, a creep rupture life equation is established, and a high-precision bivariate creep constitutive model within the high stress range is developed. Compared with the existing parameter methods, it shows obvious superiority, laying a foundation for the refined design of the creep rupture life of low-cost short-life turbine rotor blades.

Rotor-flexible casing rubbing can induce strong nonlinear dynamics in rotor systems. This study investigates the harmonic frequency characteristics of a rubbing rotor system with a flexible casing constraint. A nonlinear rub-impact model combined with a finite element-based rotor–casing coupling framework is developed to evaluate system responses under concentric and eccentric configurations. The harmonic components of rotor and casing vibrations are analyzed over a range of rotational speeds. Results show that, under concentric conditions, harmonic frequencies originate from rubbing-induced asynchronous motion. The harmonic sub-frequencies observed in the spectrum correspond to lobed rotor orbits formed during the transition from synchronous to asynchronous motion under continuous rubbing forces. Under eccentric rotor–casing alignment, the vibration spectrum becomes more complex and exhibits frequency clustering. The results provide insight into harmonic generation mechanisms and highlight the role of casing flexibility in rubbing-induced asynchronous motion.

To resolve the fatigue fracture occurring at the tip trailing edge of thin-walled single-crystal turbine rotor blades for a specific aero-engine, this paper derives the relationship between the single-crystal constitutive stiffness matrix and crystal orientation, and clarifies the influence mechanism of crystal orientation on blade-vibration characteristics. The influence rules and degrees of uncertain parameters on the vibration characteristics of thin-walled and thickened-profile blades are comparatively investigated. The results reveal that blade dynamic frequency is strongly affected by both blade profile thickness and crystal orientation, and blade profile optimization can effectively weaken the effects of crystal orientation and blade thickness on the dynamic frequency of critical modes. Based on the above results, the hazardous resonance overlooked in conventional engineering approaches is detected using uncertainty-based vibration analysis. The corresponding failure mechanism is illustrated, the resonant speed range is determined, and the risk of bending–torsion coupled flutter is detected. The outcomes provide valuable guidance for the frequency tuning design of turbine blades.

Spline couplings endure various external loads during operation, which induce complex variations in contact surfaces and significantly affect their stiffness behavior. This research focuses on a specific spline coupling to analyze its nonlinear stiffness characteristics and underlying mechanisms. Employing the finite element method, a simulation model is developed to investigate the nonlinear load-dependent stiffness changes under multiple contact surfaces. The study investigates the nonlinear stiffness characteristics of the spline coupling through sensitivity analysis of stiffness to contact surfaces and contact state changes, and reveals the patterns of contact state evolution. The analysis indicates that as external loads increase, the spline coupling stiffness decreases significantly. Variations in the contact states of each surface induce nonlinear stiffness variations, with centering surface B (the cylindrical centering surface on the right side of the spline coupling) exhibiting the most substantial influence on nonlinear stiffness changes. Furthermore, the effects of centering surface clearance, applied torque, and friction coefficients across contact surfaces on the spline coupling stiffness are examined. Stiffness increases as clearance decreases and torque increases, while friction coefficients exhibit a negligible impact on stiffness performance.