Exact Dynamic Reduction of Tilting-Pad Bearing Models for Stability Analyses

Abstract

A method is presented that enables full tilting-pad bearing models to be incorporated into transfer-matrix stability analyses of rotor systems. The method uses exact dynamic reduction to condense out pad rotational degrees of freedom at mass stations along the rotor at which tilting-pad bearings act. The continuity of the rotor model is preserved enabling the eigenvalues to be determined by satisfying the two end boundary conditions of the rotor. The result of the exact dynamic reduction is a set of new mass, damping, and stiffness matrices for the mass location in terms of the translational motion of the journal. The new mass, damping, and stiffness matrices result from a second order approximation of the exact relationship between pad rotations and journal translations. In addition, a frequency-dependent stiffness term is required to retain all of the dynamical information of the original system.

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Diego, California, October 19–21, 1992

Notes

Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Diego, California, October 19–21, 1992