ANGULAR MISALIGNMENT EFFECT ON HYDRODYNAMIC JOURNAL BEARINGS DYNAMICAL BEHAVIOUR 

Slim BOUAZIZ, Molka ATTIA HILI, Mohamed MAATAR, Tahar FAKHFAKH and Mohamed HADDAR

Unit of Dynamic Mechanical Systems (UDSM)
National Engineering School of Sfax (ENIS), BP.W. 3038 - TUNISIA
e-mail: mohamed.haddar@enis.rnu.tn
ABSTRACT
Major problems of rotating machinery are often caused by shaft misalignment. This defect generates some important overloads and vibrations, and can lead to a premature failure of the bearing, the shaft and the coupling. The objective of this work is to study the effect of the angular misalignment in the dynamic behaviour of a flexible shaft supported by two hydrodynamic journal bearings. Reynolds’ equation is obtained by considering the effect of mass transfer across the fluid film. This is solved numerically using the finite difference method. By integrating the oil pressure distribution, the hydrodynamic forces are calculated. The elasticity of the fluid film is modelled by stiffness and damping matrices. The effect of bearings geometry on the dynamic coefficients is presented. A theoretical model describing the angular misalignment defect is analysed in order to survey the vibratory response of the receptor shaft.

KEYWORDS
Reynolds’ equation, shaft misalignment, hydrodynamic journal bearings, dynamic behaviour.


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