Damping of structural vibrations using an electromotive eddy current damper

Abstract

Structural vibrations are normally the cause for high cycle fatigue failure (HCF) in technical structures. For example, the blades of rotating bladed turbine disks are subjected to fluctuating gas forces during operation that cause blade vibrations. Therefore, one of the main tasks in the design of turbomachinery blading is the reduction of the vibration amplitudes of the blades and it is well known that the vibration amplitudes can be reduced significantly to a reasonable amount by means of friction damping devices such as underplatform dampers, tip shrouds and damping wires. If the temperature of the working fluid is not excessively high, the use of an electromotive eddy current damper can be a possible alternative to this well known classical friction damping devices. If a conducting material is moving in a stationary magnetic field, eddy currents are generated inside the conductor. These eddy currents cause an energy dissipation effect and damping forces are generated. This damping effect can be used to reduce the resonance amplitudes and therefore to decrease the risk of a HCF failure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)