A STUDY ON STABILITY AND RESPONSE ANALYSIS OF A NONLINEAR ROTOR SYSTEM WITH MASS UNBALANCE AND SIDE LOAD

The stability of steady-state synchronous and nonsynchronous response of a nonlinear rotor system supported by squeeze-film dampers is inves tigated. The nonlinear differential equations that govern the motion o f rotor bearing systems are obtained by using the Generalized Polynomi al Expansion Method. The steady-state response of the system is obtain ed by using the hybrid numerical method, which combines the merits of the harmonic balance and collocation methods. The stability of system response is examined using the Floquet-Liapunov theory. Using the theo ry, the performance may be evaluated with the calculation of derivativ es of nonlinear hydrodynamic forces of the squeeze-film damper with re spect to displacement and velocity of the journal center. In some case s, these derivatives can be expressed in closed form and the predictio n of the dynamic characteristic of the nonlinear rotor system will be more effective. The stability results are compared to those using a di rect numerical integration method and both are in good agreement.