In this paper, a simplified nonlinear finite element for bump foil forming process of foil air bearings is developed. The bump foil is dealt with as flexible deformable body, the upper die and lower die are considered as the rigid body without deformation. The friction model between bump foil and dies with velocity-dependent friction forces is described by arctan function. The forming process of SS304 Stainless Steel bump foil under different loads is investigated with rigid-plastic finite element method. The simulation results are compared with theoretical values and experimental results. Therefore more feasible process parameters are obtained to fabricate the bump foils.

Vibration characteristics of a misaligned rotor with asymmetric shaft stiffness are studied. The system consists of two shafts connected by a flexible coupling with parallel misalignment, two rigid disks attached at the middle of each shaft and one of the shafts has asymmetric stiffness. The governing ordinary differential equations are derived using Lagrange dynamics and integrated through numerical methods. The effects of asymmetry, eccentricity and misalignment are studied through the peak-to-peak lateral vibration amplitude at different rotor speed. Simulation results show that the amplitude peaks at the natural frequency associated with unbalance and parallel misalignment, while half the natural frequency associated with the asymmetric shaft stiffness. This study may contribute to enrich understanding of the vibration of a rotor system under the cases of eccentricity, parallel misalignment and asymmetric shaft stiffness.

A general method is developed to deal with the compressibility of air film and to predict the linear dynamic stiffness and damping coefficients of air-lubricated bearings over the whole range of frequency. Numerical results reveal that both stiffness and damping coefficients are functions of not only the static parameters such as eccentricity and attitude angle, but also the frequency of disturbance. The coefficients are continuous and tend to certain values even when the frequency approaches zero or positive infinity. In general, the direct terms of the dynamic stiffness increase with the increase of the frequency, while the cross-coupling terms tend to an equal value when the frequency becomes infinite, and all the damping coefficients decrease in the higher frequency region and vanish when the frequency approaches positive infinity.

A general method is developed to deal with the compressibility of air film and to predict the linear dynamic stiffness and damping coefficients of air-lubricated bearings over the whole range of frequency. Numerical results reveal that both stiffness and damping coefficients are functions of not only the static parameters such as eccentricity and attitude angle, but also the frequency of disturbance. The coefficients are continuous and tend to certain values even when the frequency approaches zero or positive infinity. In general, the direct terms of the dynamic stiffness increase with the increase of the frequency, while the cross-coupling terms tend to an equal value when the frequency becomes infinite, and all the damping coefficients decrease in the higher frequency region and vanish when the frequency approaches positive infinity.

In order to investigate the cause of the typical bush rupture and wear damages in the journal bearing of the steam turbine generator set, the lubrication turbulence and thermo-hydrodynamic effects were studied. The generalized Reynolds equation, energy equation and heat conduction equations were solved with the finite difference method, and the pressure, temperature, thickness distribution of the oil film were obtained. Analysis results can be well explains the bearing bush burst in bearings maximum pressure place because of heavy load running. The bearing bush burst made friction intensified that caused oil temperature increasing and the viscosity reduce, which led to the rotor eccentricity increase, the minimum film thickness smaller and bearing static working point down, thus causing the wear damages until shutdown.