Stability Considerations for a Gas-Lubricated Tilting-Pad Journal Bearing—Part 1: Analytical Methods

The multiplicity of parameters associated with a tilting-pad journal bearing demands that special consideration be given to the selection of an analytical method for stability prediction. The classical Frequency Response (small perturbation) method and the Nonlinear Orbit method (a direct numerical integration of all governing differential equations) are discussed and evaluated. A new approach for the determination of film response called the “Step-Jump” method is here extended to the tilting-pad bearing. Three means of utilizing the film response functions in the dynamical equations are outlined and compared. The relationship of the Frequency Response method to the Step-Jump method is explained and a comparison of the Step-Jump results with the Nonlinear Orbit approach is made. One of the techniques for applying the Step-Jump response functions, called the “Characteristic Equation” method, is shown to be most suitable for parametric studies of stability thresholds.