LINEAR AND NONLINEAR MODELING OF CYLINDRICAL HYDRODYNAMIC BEARINGS
Jefferson Silva Barbosa1; Aldemir Aparecido Cavalini Júnior1; Vinícius Nunes Carvalho1; Valder Steffen Júnior1; André Beires1
1 Federal University of Uberlândia (UFU)
doi:10.20906/CPS/CILAMCE2015-0363
Resumo
This paper is dedicated to the analysis of the linear and nonlinear approaches frequently used to modeling cylindrical hydrodynamic bearings. Regarding the considered nonlinear model, hydrodynamic supporting forces are determined from the solution of the dimensionless Reynolds' equation for cylindrical and short journal bearings. In this case, the nonlinear hydrodynamic forces are applied directly on the rotating shaft. Similar results can be obtained from the linear model, in which stiffness and damping coefficients are determined imposing small perturbations around the equilibrium position of the rotating shaft (linearization process). The linear hydrodynamic forces are derived from the coefficients related with each bearing. A representative finite element model is used to obtain the dynamic responses of a rotating machine composed by a horizontal flexible shaft, three discs, and two cylindrical hydrodynamic bearings. Additionally, the displacement responses obtained from the linear and nonlinear short bearing theories are compared with the linear long bearing theory.
Palavras-chave: rotor dynamics; hydrodynamic journal bearing; linear and nonlinear modeling