Abstract:The dynamic behaviors of a hydrodynamic tiltpad journal bearing under transient loads were investigated.A calculation method on nonlinear equations of motion for the rotorbearing system considering the journal inertia effects was proposed,which consisted of two steps,the one was solving the Reynolds equation by the finite element method,the other determining the transient journal center trajectories of the bearing with Euler scheme.The relationships between pad swing angle and eccentricity under different preload were analyzed,and the dynamic behaviors of the journal center trajectories,the pad forces and pad swing angles were studied under two kinds of dynamic loads,the step loads,and the sinusoidal impulse loads.The results show that under the transient loads,the center trajectories,the pad swing angle and journal force are all changed in large ranges with a certain degree of oscillation process.Because of the time limited of pulse load,when it attenuates the journal center trajectory still converges on the original equilibrium position,while the step load makes the journal center converge on a new equilibrium position.Tiltpad bearing has a better stability compared to the fixed pad bearing with the same condition.