Análise de rotores flexíveis apoiados em mancais radiais elípticos e cilíndricos utilizando o método de elementos finitos

Abstract

This work presents the development of a finite element procedure specially devised to predict the dynamic response of flexible rotors running on fluid film bearings. The proposed procedure can simulate many different types of rotor-bearing systems, with a flexible shaft, massive disks and rigid or fluid film circular or elliptical bearings. The shaft finite element model is based on Timoshenko Beam Theory, which includes shear effects, rotary inertia and gyroscopic moments.A finite element procedure for solution of the classical Reynolds equation for incompressible fluid films, in conjunction with a linearized perturbation procedure, is implemented to allow the computation of the dynamic force-coefficients of cylindrical and elliptical journal bearings. Thefinite element equations of motion for an unbalanced rotor supported on fluid film bearings are integrated by using the Newmark method, and the time-domain unbalance response is obtained. The results are validated by comparison with experimental data collected from a test rig as wellas from results obtained from the literature. Some algebraic expressions relating the bearing parameters and the unbalance response with thebearing geometric parameters (preload, Slenderness ratio, radial clearance) are presented. A range of operating conditions is identified, where these expressions are supposed to be close to the computational results obtained by the numerical procedure. The results presented in this work are valuable for rotating machine designers since it can properly predict its dynamic response under several operation conditions.