Norbert Gstöttenbauer, Bernhard Manhartsgruber, Rudolf Scheidl,
"A Test Rig for an Adaptive Magneto-Rheological Fluid Bearing and an Analytical Model of its Load Carrying Capacity"
, in M Ivantysynova: Proceedings of the 4th FPNI-PhD Symposium, Sarasota 2006, Vol. 1, Seite(n) 129-141, 6-2006, ISBN: 1-4243-0499-7
A Test Rig for an Adaptive Magneto-Rheological Fluid Bearing and an Analytical Model of its Load Carrying Capacity
Sprache des Titels:
Proceedings of the 4th FPNI-PhD Symposium, Sarasota 2006
Magneto-rheological (MR) fluids are suspensions of micron-sized ferromagnetic particles in a non-magnetic carrier fluid. The essential characteristic behaviour is the rapid and reversible transition from the state of a Newtonian-like fluid to the behaviour of a stiff semi-solid by applying a magnetic field of about 0.1-0.4 Tesla. This feature, called the MR-effect, can be understood from the fact that the particles form chain-like structures aligned in field direction. The MR-fluid offers three modes of operation. Either the direct shear motion of two magnetic poles separated by the fluid generates shear forces, or the valve mode restricts the flow through passages. Due to its highly non-linear behaviour, the third mode of operation, the squeeze mode is up to now used for small amplitude vibration damping only.
A test rig for the exploration of the MR-fluid behaviour was designed for experimental purposes. Special emphasis was put on the dependence of the MR-fluid response with respect to parameter variations of the applied static magnetic field, the cyclic loading amplitude and frequency values. Thereby attained new perceptions gave reason to design an adaptive magneto-rheological fluid bearing in squeeze mode behaviour for industrial applications. A modification of the existing test rig was accomplished to prove the expected behaviour and benefits of this new concept. The substantial innovation is the rapid control of the radial load carrying capacity using current as control variable. Furthermore, high load carrying capacities at low rotational speed can be accomplished whereby rate dependence is negligible.
Particularly for the bearing in squeeze-mode the interrelationship of the radial force and the magnetic flux induction as well as the squeeze gap geometry is of great relevance. For design engineering preferably simple analytical approaches describing the load carrying capacity of such a bearing are of interest and will be discussed in this paper.