Feasibility Analysis of the Rotor Elastic Support With Piezoelectric Damping

Abstract

The squirrel cage is a widely-used elastic support in aeroengine. The combination of the squirrel cage and damping structures, such as squeeze film dampers, can effectively suppress rotor vibration. The squeeze film damper, although providing significant damping, requires a specific auxiliary lubricant supply system, which occupies space and brings additional weight. Piezoelectric materials have the advantages of light weight, high energy density, and wide bandwidth. The electromechanical coupling effect ensures that they can be used as energy transducers, and the corresponding piezoelectric damping has attracted extensive attention. In this study, we propose an elastic support-piezoelectric damper system for rotors by integrating the piezoelectric damping to the squirrel cage. The purpose of this study is to demonstrate the feasibility of the piezoelectric squirrel cage to suppress the vibration of the low pressure rotor of aero-engine from both the aspects of vibration and strength. To do that, the finite element model of a dummy rotor with elastic support-piezoelectric damper system is established first. The polarization direction and the network topology are optimized to reduce the amount of circuit impedance under the premise of ensuring the modal electromechanical coupling factor. An in-house code to simulate the dynamic performance of the rotor with the elastic support-piezoelectric damper system is developed in ANSYS/MATLAB environment. To reduce the computational cost, the following acceleration techniques are adopted: 1) the specific modal synthesis method dedicated to piezoelectric structures is implemented to reduce the dimension of the governing equations; 2) the equivalent linearization method is carried out to transfer the synchronized switch damping (SSD) with nonlinear nature to a frequency-dependent impedance, thus the time-consuming nonlinear solver is avoided. The unbalance response of the rotor is analyzed numerically. The damping effects of two promising piezoelectric damping technologies, i.e. the resonant damping and the SSD, are compared and discussed. Results show that the SSD network can reduce the vibration level of the rotor significantly with good robustness; the number of the SSD control circuit is only the half of the number of squirrel cage bars; the failure strength margin is sufficient.