A fully coupled elastohydrodynamic model for static performance analysis of gas foil bearings

Abstract

Gas foil bearings are increasingly employed in advanced rotating machinery. Fast and accurate predictions of bearing performance are necessary and can greatly improve the design of gas foil bearings. This paper presents a novel fully coupled elastohydrodynamic model for the static performance analysis of gas foil bearings. The novelty is the presentation of a simultaneous solution of a coupled elastohydrodynamic model that considers the detailed configuration, complex contact/separation and friction behaviors of the foil structure. The coupled model is established within a standard finite element framework, so it is easy to implement. The top and bump foils are modeled in detail with 2D beam elements, and a general contact model that includes separation and friction behaviors is used to model the interactions of the top and bump foils. The simultaneous solution of the system equation using the Newton–Raphson method is presented. An analytical Jacobian matrix of the system equation is given to guarantee and improve the convergence performance. The validity of the proposed model was proved by comparisons with analytical and experimental results. The numerical examples show that the proposed model that allows the separation of the top and bump foils accords better with engineering facts. The implementation of the Gümbel condition is discussed by comparing the results calculated by different models.