ABSTRACT
The linearised force coefficients method (LFCM) has traditionally been used to study the stability and compute the Campbell diagrams of rotor/foil-air bearing (FAB) systems, despite reported disagreement with low-amplitude dynamics of the nonlinear system. In this paper, a new approach for extracting the Campbell diagram from the Jacobian matrix of the nonlinear state-space model that simultaneously couples the rotor, air film and foil structure domains is used for the first time in a parametric study into the effect of variability in clearance shape and bump foil stiffness distribution in foil-air bearings. The results provide guidelines for improved foil-air bearing design that raises the onset of instability speed.
