Abstract
Rolling bearing and squeeze film damper will introduce structural nonlinearity into the dynamic model of aeroengine. Rubbing will occur due to the clearance reduction design of the engine. The coupling of structural nonlinearity and fault nonlinearity will make the engine present rich vibration responses. This paper aims to analyze the nonlinear vibration behavior of the whole aeroengine including rolling bearing and squeeze film damper under rubbing fault. Firstly, the dynamic model of a turboshaft engine with nonlinear support and rubbing fault is established; The rolling bearing force, the oil film force and the rubbing force are introduced into a dual-rotor–casing model with six support points. Secondly, the linear part of the model is verified by the dynamic characteristics of the three-dimensional finite element model. Finally, the varying compliance vibration, the damping effect and the bifurcation mechanism are analyzed in detail in which the bearing clearance, speed ratio and rubbing stiffness are considered. Results show that the rubbing fault in the nonlinear support case will excite more significant varying compliance vibration in the low-speed region and expand the rotating speed range of the chaotic region in the high-speed region compared with that in the linear support case.
Highlights
The rotor-bearing-casing system is the core structure of a whole aeroengine including multinonlinearities
To reduce the vibration level during operation, the supporting structures are generally composed of rolling bearing and squeeze film damper (SFD)
The effectiveness of the nonlinear support is verified by the VC vibration frequency and the damping effect of the SFD
Summary
The rotor-bearing-casing system is the core structure of a whole aeroengine including multinonlinearities. As the clearance between blade and casing becomes smaller and smaller for higher efficiency, the rub impact of blade casing will be caused by the nonlinear supports, which will exhibit more complex nonlinearity [1]. These nonlinear factors will have a very distinct influence on the motion form and stability of the aeroengine. It’s necessary to investigate the nonlinear dynamic response of the rotor-bearing-casing system considering the multinonlinearities including nonlinear bearing force, nonlinear oil film force and nonlinear rubbing force
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