ESA GNC Conference Papers Repository

The market demand for large reaction wheels with an angular momentum of 100 Nms and more to maneuver heavy satellites for telecommunications up to 7000 kg has risen sharply in recent years. At the same time the requirements of high vibration loads are increasing, especially during the launch or separation of the satellite from the rocket. The factor limiting the load capability of reaction wheels is the resulting forces on the ball bearings. FEM analysis shows that the first axial resonance of the flywheel mass has a predominant impact on the bearing load. In order to further use the well-proven TELDIX? bearing unit even with heavier reaction wheels, Rockwell Collins Deutschland GmbH (RCD) has developed a highly efficient damping system for structural resonances of flywheel masses to keep the launch loads compatible to the load capability of the TELDIX? bearing unit design. This damping concept is based on vibration absorbers. This paper provides an overview of the determination of the bearing loads and their limits, explains the influence of the structural resonances on the bearing loads and describes the major normal modes of a 100 Nms reaction wheel. Then the special evaluation method for non-linear FEM simulation is discussed in order to investigate the optimized damping behaviour. The focus of this article is on the resonance search results and the comparison with corresponding simulation results. This measurement is presented for the traditional damping system as well as for the improved and highly efficient damping system. Here, the principle of the damping system and the splitting of the resonance is explained. Finally, the mechanical verification is described.