Our extensive research is based on a series of fundamental theories and systems. Find more information about our rotor bearing systems:

• Rotor-Bearing Dynamic System Simulation

• Reliability or Failure Concepts for Rotor-Bearing Design and System Optimization

• Theories of Bearings

• Probabilistic Robust Design

  Theory of Journal Bearing:

   The theoretical background of journal bearings including porous bearings, solid wall bearings with
  compressible as well as incompressible lubricants lies in References Wu [1] and [2].
  As the solid wall bearing can be considered as a special case of the porous bearing, the analysis of
  the porous bearing can be easily applied to the solid wall bearing. Furthermore, the case of compressible lubricant differentiate that of incompressible lubricant in the non-linearity of the governing Reynolds equation as variable lubricant density opposed to constant lubricant density for the incompressible case.
  Nevertheless, solution methodologies for both compressible and incompressible cases remain the same in terms of numerical formulations and solver selections. Here, illustration is presented only for the general case of the porous journal bearing with the compressible lubricant.

  Theory of Tilting-Pad Bearing:

  The governing equation, Reynolds equation, is similar to that for the journal bearing except that the
  expression for the lubricant film thickness contains additional terms contributed by the pad location,
  the pad extended angle, the pre-load parameter and the pad tilting angle. To facilitate the applications of
  the numerical techniques used in the previously illustrated journal bearing case, the pads are located in
  global coordinates. The tilt angle of each pad is allowed to vary until an equilibrium position is reached
  and the total carrying load matches the applied load. The steady state position of the shaft center is
  determined. Then, the numerical perturbation method is employed to calculate both stiffness and damping
  coefficients.

  Theory of Thrust Bearing:

  The governing equations for a thrust bearing is slightly different from that for a journal bearing as the bearing length is converted to the bearing pad radial distance. To include the capability of simulating pads with compliant surfaces, the film shapes are versatile to contain linear as well as nonlinear film thickness distributions. In the numerical computations, the finite-difference grids are selected to be variable extents so that the inherent edge boundary layer behavior can be realized to improve the numerical accuracy. Additionally, a inertial factor is included to enable the numerical solutions to correlate with the experimental results of high-speed  bearings e.g. foil thrust bearings.

  Theory of Rolling Element Bearing:

  The dynamic characteristics of rolling element bearings differ from that of fluid film bearings in the
  following aspects:
  (1) Due to direct contacts with races, restrained forces on rolling elements are in phase with deflections.
       Consequently, cross-coupling stiffnesses are insignificant.
  (2) Damping coefficients are small and negligible.
  To compute lateral/angular stiffnesses, the relationships between forces/moments and deflections/
  inclinations have to be established. Based on these relationships, the stiffnesses are calculated from the differentiations of forces/moments with respect to deflections/inclinations.
  As the motions of rolling elements are so complex that simplifications are usually made, i.e., treating
  the dynamic behaviors of rolling elements in quaisy stead state.

  For the current analysis package, the Reynolds equation is selected for all fluid film
  bearing formulations. The author however has developed three dimensional Navier-Stokes equation
  based analytical tools for both high speed journal and thrust bearing with thermoelasticity coupling to deal with air foil bearings. Those developments will be implemented in the future bearing analysis tools.