Nonlinear dynamical analysis of a micro self-acting gas journal bearing

The motion equations have been established for a micro gas bearing, and the non-linear gas film force of the finite journal bearing is calculated. The Reynold's equation of the gas film is solved by the finite difference method and the motion of the journal has been simulated with fourth-rank Runge-Kutta method. The linear stiffness and damping coefficients of the micro gas bearing are gotten and the linear threshold speed of the system has been derived. While, the non-linear gas film force is adopted to simulate the dynamical response of the micro rotor, which is perturbed slightly from the static equilibrium position. The orbit of the rotor center, frequency spectrum and phase trajectory of the system are used to analyze the non-linear characters of the rotor center in the horizontal and vertical directions at different operating conditions. It is shown that the dynamic behavior of the micro gas bearing system varies with the rotational speed in the case of the eccentricity is unchanged.