Rotordynamics and Air Lubrication

Aerodynamic foil bearings allow oil-free bearing of high-speed rotors and are designed for operation at high or low temperatures. The elastic foil structure in foil bearings ensures that thermal and mechanical deformations (e.g. expansion due to centrifugal forces) during operation and manufacturing inaccuracies can be compensated for, so that lubrication in the bearing is ensured without breakage despite higher eccentricity of the rotor. The effective structural damping mechanism in foils increases energy dissipation throughout the bearing, and with optimal design, self-excited vibration can be avoided over the entire speed range. The highly precise design and dimensioning of air bearings despite numerous advantages for different operating conditions is a challenging task due to complicated physics behind air as lubrication. SADAP is happy to support you with its expertise, software and hardware competences on the way to a successful design of new concepts or the application of oil-free bearing.

Air or Foil Bearings, That is the Question!

In applications where eccentric shaft operation poses no significant issue (e.g., in the automotive industry), foil bearings are recommended. Stability is ensured by the additional damping mechanism in the foil structure (due to friction effects), and the manufacturing of the bearing is simplified in terms of production tolerances. On the other hand, air bearings without a compliant foil structure are recommended for applications where there is little room for shaft movements (e.g., in medical technology or precision machining). These and other application-specific questions can be addressed with state-of-the-art expertise, significantly optimizing the performance and efficiency of the machine.

Click here for more information about our services in the field of rotor bearing systems.

Design with digital calculation tools

We design it for you …

SADAP supports customers on their way to successfully developing air and foil bearings for individual applications. By using high-precision digital design tools, air-lubricated bearings are developed for the machine (e.g. compressors in fuel cells) so that all requirements are met and have optimized properties against the effects that occur during operation. Particular attention is paid to the behavior of the rotor-bearing system under both static and dynamic operating conditions.

Is the development and utilization of air and foil bearings for individual machine concepts of interest to you? More information can be found by clicking here.

Experimental Studies

We measure it for you …

In addition to the design of air and foil bearings, SADAP offers experimental investigations as the next step in a cooperation with the TU Braunschweig. Here, the bearing designed in the first step (as a prototype) is tested and validated in and out of operation.

Experimental studies (out of operation):

The foil bearing consists primarily of compliant foil structures connected in series with the lubrication film to provide stiffness and damping. This additional viscoelastic property keeps the bearing more robust to harmonic and subharmonic shocks and protects the minimum lubrication film thickness from failure.

Based on this consideration, the dynamic properties of the foil structure as a function of the excitation frequency play an essential role. In this respect, SADAP offers a careful investigation of the dynamic behavior of the foil bearings with a focus on film structure and out of service. This type of investigation is called measurement of the mechanical impedance of the foil structure.

The bearing assumed for investigation is harmonically excited in two directions perpendicular to each other (up to 9000 Hz) and the deflection in the respective directions is measured. Post-processing of the measured data determines how the stiffness and damping coefficients of the foil structure react to different frequencies that may occur during operation.

Further information about our services in the form of experimental studies can be found here.

Training offers

We train your team …

Benefit from high-quality knowledge in the direction of optimizing your company’s performance.

  • Are you looking for a high-performance training partner?
  • Want to train your team at a specific location?
  • Or are you planning to have development staff on your team trained in specific areas of expertise?

We offer training services for industrial workers with unique knowledge potential in all areas covered by SADAP. These are mainly training services in the field of rotor dynamics calculation, bearing testing and evaluation of data from experimental investigations and simulation products.