Nonlinear dynamic analysis of worn gas foil bearings.

Highly nonlinear vibration is one of important factors influencing the failure of gas foil bearing-rotor systems. In this paper, an integrated nonlinear dynamic model is constructed to study the dynamic vibration of worn gas foil bearings. In the wear model, the deformation of foil is considered. The Iordanoff model is used to solve the stiffness of foil, and equivalent viscous damping is introduced to amend the friction factor at the interface between the foil and bearing bracket. The incompressible Reynolds equation is solved by using ADI method, and the Newmark-β method is applied to obtain the trajectory of axis center. In numerical examples, the effects of worn zone on the trajectory of axis center, the Poincare map and bifurcation diagram are discussed. The nonlinear vibration resulting from the worn zone is revealed. Comparison with existing results validates this model. [ABSTRACT FROM AUTHOR]