Numerical and experimental studies on nonlinear dynamic behaviors of a rotor-fluid film bearing system with squeeze film dampers

In this paper,, the nonlinear oil film forces of bearings and dampers with free boundary conditions are determined by the finite element method (FEM) and the complementary solution for variational inequalities. The mode synthesis technique is used to reduce the linear degrees of the high order finite element model. The periodic solution of the system and its stability are determined by the Poincare mapping method and the Floquet theory, respectively. The results of experiment show that squeeze film dampers (SFDs) can effectively prevent subsynchronous and nonsynchronous vibrations and some structural parameters have significant effects on the dynamic behaviors of the system. Comparing the numerical results with those of experiment, it is shown that the above theories and schemes are feasible and efficient in analyzing nonlinear behaviors of the high-order dynamic system with local nonlinearities.