The Effect of Rounding in Bump Foil Structure on the Dynamic Performance of Foil Journal Bearings

Abstract

The performance of air foil journal bearings is closely related to the stiffness of the bump foil. In this paper, the stiffness characteristics of bump foil having a rounding in the structure are investigated and compared with previous models. The dynamic coefficients of bearings and the stability threshold speed (STS) of a rotor supported by the bearings are numerically calculated using FEM and are compared to models with various rounding radius and friction coefficients. The results show that the presence of rounding indicates a significant effect on the total dynamic and the stability performance of foil bearings and there is an optimum rounding radius to maximize the structural stiffness and stability. The validity of the theoretical analysis was verified by the structural stiffness and stability experiments. The results are expected to be helpful to bearing designers, researchers, and academicians concerned.