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Active Vibration Control via Shunted Piezoelectric Materials


D. Niederberger

Australia, Seminar for the School of Electrical Engineering and Computer Science, University of Newcastle.

Smart materials have long been heralded as the dawn of a new era in the construction of automotive vehicles, airplanes and other structures that have to meet ever more demanding performance requirements. This talk will give an overview of such smart materials, which suppress vibration of structures in an effective and robust way. In the past, vibration of mechanical structures has been suppressed using passive damping materials, which are not very effective for low frequencies and add much additional weight to the structure. Therefore active vibration was introduced that can damp low frequencies effectively but needs a lot of electronic devices and much external energy. Another approach uses electrically shunted piezoelectric materials. The piezoelectrics convert mechanical vibration energy into electrical energy, which is thereafter dissipated by passive electronic shunt circuits. Among these shunt circuits, a resonant shunt consisting of an inductor and resistor (R-L shunt), achieves very good vibration suppression for one structure resonance. However, it suffers from the drawback that it is very sensitive to environmental variations, such as temperature and structural load. We will provide a new adaptation for R-L shunts that is very fast and simple to implement using analogue circuitry. Another drawback of R-L shunt circuit is their need of an external power supply, because a huge inductance L is needed, which can only be implemented using active operational amplifiers to form a virtual inductance. Recently, switching shunts and other nonlinear shunts were introduced. They are very simple and may be a good solution for smart materials, but they are not very well understood at present. Therefore, we will use a Hybrid System Approach to model this type of systems and apply Model Predictive Control to obtain an optimal switching law for the best vibration suppression of these shunts. The utilization of discrete actuator/sensor arrangements based on piezoelectric patches shows a number of limitations in terms of robustness to damage, actuation capability as well as major difficulties in integration into the structure. Much more interesting for real applications are therefore so called Active Fiber Composites (AFC). We will give a very short overview of these new active materials.


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