Nonlinear dynamic analysis of the aero-engine incorporating the novel variable stiffness bracket

This study addresses the issue of excessive vibration in aero-engine systems and, based on the characteristics of smart materials, proposes a novel design method for variable stiffness brackets. First, the finite element method was used to create a dynamic model of a dual rotor bearing system, which was then tested on a dedicated dual rotor rig. Next, a comprehensive Finite Element Model (FEM) of the aero-engine, including the casing, was developed to conduct nonlinear dynamic analyses. These analyses served as the foundation for subsequent work, a novel self-adjusting variable-stiffness bracket was designed by leveraging the variable stiffness mechanism of Shape Memory Alloy (SMA) to achieve active vibration attenuation in the accessory. To experimentally validate the achievable stiffness modulation range and the underlying vibration-attenuation principle, a dedicated static-stiffness test platform and a vibration test rig for the variable-stiffness bracket were constructed. Experimental results reveal that the bracket exhibits a 22.56 % stiffness variation within the prescribed temperature envelope. Integrating finite-element predictions with experimental evidence, it was demonstrated that the proposed bracket effectively detuned the system from its resonant frequencies. Relative to conventional titanium-alloy brackets, the proposed variable-stiffness bracket yields a maximum amplitude reduction of 59.37 % in the accessory system.