Abstract
The present work proposes a non-contact hybrid exciter especially useful for harmonic excitation of lightly damped structures/rotors. In the proposed exciter an electromagnet is placed on a piezoelectric stack and the extension of the piezoelectric stack is made almost equal to the displacement of the structure using a simple tracking control. This largely eliminates stiffness coupling between the structure/rotor and the exciter and non-linearity in the excitation force due to the vibration of the structure/rotor. The stiffness and inertia of the piezoelectric stack is considered in the analysis. A SIMULINK model of the combined structure and the exciter is developed for a full time-domain simulation of the excitation system.
Highlights
Magnetic excitation of structure/rotor is attractive as excitation is possible without any physical contact [1,2]
A permanent magnet is attached to a standard electrodynamic exciter
The gap between the magnet and the structure changes as the electrodynamic exciter vibrates
Summary
Magnetic excitation of structure/rotor is attractive as excitation is possible without any physical contact [1,2]. The conventional magnetic actuator configuration can be used for the purpose of non-contact vibration excitation yet for a structure/rotor already in operation, it is much more convenient if the exciter is located at one side only. The present work analyses a hybrid magnetic exciter, which is one-sided, linear and free from mass and stiffness coupling and intended for harmonic excitation of a structure/rotor It is called a hybrid actuator since it combines a piezoelectric stack actuator and a magnetic actuator. Since the non-linear effects manifest more in lightly damped structures/rotors, the proposed exciter can be successfully used for such cases These hybrid exciters can apply forces from a very small value to a moderately high one and work within a frequency of several hundred Hertz. For very large excitation force and substantial inertia effect, proper tracking control of the hysteretic system may demand for a more sophisticated control strategy
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