LYAPUNOVS STABILITY OF NONLINEAR MISALIGNED JOURNAL BEARINGS

In this paper the stability of nonlinear misaligned rotor-bearing syst ems is investigated using the Lyapunov direct method. A finite element formulation is used to determine the journal bearing pressure distrib ution, Then the linear and nonlinear stiffness, damping, and hybrid (d epending on both displacement and velocity) coefficients are calculate d A general method of analysis based on Lyapunov's stability criteria is used to investigate the stability of nonlinear misaligned rotor bea ring systems. The equations of motion of the rigid rotor on the nonlin ear bearings are used to find a Lyapunov function using some of these coefficients, which depend on L/D ratio and the misalignment angles ps i(x), psi(y). The analytical conditions for the stability or instabili ty of some examined cases are given and some examples for the orbital stability are also demonstrated.