Dynamic behaviours of the rotor non-linear system with fixed—tilting-pad journal bearings support

The variational constraint approach is used to calculate the non-linear oil force of fixed—tilting-pad journal bearings. The non-linear oil force of a single pad is calculated by the proposed method in its coordinate system and its Jacobi matrix is calculated simultaneously for compatibility. The oil force, damping, and stiffness coefficients of the bearing are obtained by the assembly method. The unbalanced responses of the symmetrical rigid rotor dynamic system supported by fixed—tilting-pad journal bearings are analysed by the Runge—Kutta method and a Poincaré map. The effects of the pivot ratio and the preload on the stability of the rotor are analysed. The numerical results reveal complex non-linear behaviours of the system, such as periodic, period-doubling, period-13, and quasi-periodic motion.