Hysteresis Behaviors of a Bump-Type Foil Bearing Structure with Amended LuGre Friction Model

Abstract The gas foil bearing (GFB) has the prospect of application in the nuclear field because of its oil-free lubrication and high-speed as well as high-temperature performance. In this paper, the hysteresis behaviors of the bump foil structure of bump-type gas foil bearings are investigated. The bump foil is modeled by beam elements and reduced by Guyan reduction method. The amended LuGre friction model is adopted and all the state variables are solved simultaneously in the fully coupled scheme. It is found that, along with the decrease of the friction stiffness per normal force, the presliding behavior is enhanced and it is more and more difficult to distinguish the stick and slip states, which results a decrease of the energy dissipation of hysteresis curves. Besides, the differences of high-slope and low-slope hysteresis curves are caused by the changes of stick and slip states of partial contact nodes close to the free end of the bump foil. Finally, the simulation results considering the Stribeck effect indicate that the high-slope and low-slope parts of hysteresis curves are dominated by maximum static friction coefficient and kinetic friction coefficient, respectively. Moreover, the comparisons of simulation and experimental hysteresis curves prove that the presliding behavior and Stribeck effect are prevalent phenomena in bump foil structure and should be taken into account in the modeling of the GFB system.