On the non-linear stability of self-acting gas journal bearings

The non-linear stability of finite length self-acting gas journal bearings is studied by solving a time-dependent Reynolds equation using finite difference method. Two threshold values are discovered instead of one through which the self-acting gas journal bearings are changed from stable to unstable state. Keeping other parameters unchanged, when the mass of rotor exceeds the upper threshold value of mass, the system gets unstable; when the mass is less than the lower threshold value of mass, the system is stable; when the mass is between these two threshold values, the stability of bearings is determined by the amplitude of disturbance. Similar facts of two threshold values are also found when the stability parameter is chosen as external force or aspect ratio.