A comprehensive study on dynamic responses of the whole aero-engine system and design of variable stiffness brackets

The whole aero-engine usually consists of dual-rotor in the rotating parts and a stationary casing and accessory system. The study of the vibration characteristics and vibration reduction design of the aero-engine system has a critical impact on the performance of the aircraft. This paper delivers a comprehensive study of the dynamic response of the whole aero-engine system, which includes dual-rotor, casing, bracket, and accessories, taking into account the nonlinear bearings with Hertzian contact forces. To this end, the finite element (FEM) model of the entire aero-engine system is established. The sources of vibration and their transmission paths within the aero-engine were clearly identified via the analysis of amplitude-frequency curves, spectra and bifurcation diagrams. The optimal installation positions for the bracket and accessories were selected based on vibration energy analysis of the casing. A novel variable stiffness bracket, designed using the properties of shape memory alloys (SMA), was proposed for active vibration reduction of accessories. Experimental studies on stiffness regulation determined the overall stiffness of the bracket and its variation with temperature. Dynamic simulations confirmed that the bracket could effectively avoid the resonance frequencies of the accessories, resulting in a significant reduction in vibration amplitude. This research offers valuable engineering guidance for the design of aero-engine components and the vibration reduction and isolation of accessories.