Final work : Application of Piezoelectric actuators for controlled blade vibrations

Abstract

With the aim of modelling the structural dynamics of a system formed by a compressor blade excited by two piezoelectric actuators MFC, this thesis presents the development and methodology to build a FE model to study the harmonic excitation induced by an MFC actuator. This FE model is simplified to a flat plate of similar dimensions and it is also validated against experiments.

The starting point is a collection of experiments run in the past in a flat plate, they are used to develop a FE model which remarks the importance and the role of damping in this type of vibrations. The basic model highlights the possible relations between voltage, damping and vibration amplitude. Moreover, it is used to determine the most suitable actuator, which is the MFC. Lastly, a simple study about the optimum location is done.

From this know-how, a second FE model is developed based on the geometry of the compressor blade in order to develop the methodology that will be used for future test cases, for instance, the compressor blade. The compressor plate FE model shows again the importance of damping. The constraints from the compressor blade are applied to the compressor plate case, this means, that piezoelectric actuator is integrated in the surface so that interference with aerodynamics is minimised. Parametric studies about voltage and damping show the relation with vibration amplitude. The last study gives the optimal location of the piezo.

This model is validated against a collection of experiments, whose equipment is developed and chose to be run successfully. Their function is double, since this system is intender to be used for the future test in the compressor blade. The results from the experimental test validate the FE model and it estimates the vibration amplitudes with reasonable agreement, nevertheless it is dependent on damping. This points the need of a good ping test.

Finally, with all these conclusions a compressor blade FE model is developed and similar studies are run to determine the most suitable material and location to achieve the highest vibration amplitude possible.