Determinação de características de desempenho de mancais radiais elípticos utilizando o método de elementos finitos

Abstract

This work presents the determination of the performance characteristics of hydrodynamic oil lubricated journal bearings of fixed geometry, with elliptical profile using the finite element method. A finite element procedure based on the Galerkin weighted residual method is developed from the classical Reynolds Equation for incompressible fluids. Alinearized perturbation scheme is applied on the governing equation to render the zero-th and first-order lubrication equations, which permit to determine the bearing steady-state and dynamic performance characteristics of interest. The hydrodynamic pressure distribution on thefluid film is obtained by solving the zero-th order lubrication and is integrated over the fluid domain to render the bearing carrying-load capacity. The fluid film domain is modeled using four-node isoparametric finite elements. The fluid film reaction force and stiffness and dampingcoefficients are evaluated for elliptical journal bearings at several operating conditions. Performance characteristic curves, such as bearing load capacity and dynamic force coefficients, are obtained in relation to operating parameters and Sommerfeld number. The finite elementpredictions for elliptical journal bearing behavior show that non-cylindrical journal bearings present higher direct stiffness than that produced by cylindrical journal bearings, indicating that elliptical bearings are slightly more stable than cylindrical bearings.