Analyse non-linéaire des paliers aérodynamiques à feuilles et applications à la dynamique des rotors

Abstract : The foil bearings are used for guiding and supporting small rotors with high rotational speeds. Their operating functioning does not require any oil or grease. These bearings have a compliant structure. The presence of friction in the compliant structure brings damping, which is necessary for the rotor-bearing system operating at high speeds.After a presentation of the technology, an overview of the existing models and the limitations of each of them is exposed. Subsequently, a nonlinear model of the compliant structure is introduced. In this model, foils are considered as elastic solids. The friction forces and the gaps between the foils are taken into account by using the Moreau-Signorini non-interference condition. Normal forces and friction forces are calculated by using the augmented Lagrange multiplier method and the penalty method. Then, the compliant structure is coupled to the fluid film, dealt with the Reynolds equation for mixed lubrication conditions.The study is then focused on the bearing as a whole : compliant structure, fluid film, rotor. The start-up torque, the lift-off speed as well as operating conditions at high speeds and important static loads are part of the steady regime analyses. The effect of machining errors is highlighted. For the dynamic regime, the study consists of the non-linear analysis of a Jeffcott rotor supported by foil bearings. The results show the stability limits of the rotor-bearing system and the influence of unbalance.
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Omar Benchekroun. Analyse non-linéaire des paliers aérodynamiques à feuilles et applications à la dynamique des rotors. Génie mécanique [physics.class-ph]. Université de Poitiers; LaMCoS - Laboratoire de Mécanique des Contacts et des Structures, UMR 5259 (Lyon, INSA), 2018. Français. ⟨NNT : 2018POIT2308⟩. ⟨tel-02179654⟩

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