Adaptive acoustic metasurfaces for the noise shielding.

0481824 - ÚFP 2018 RIV GB eng C - Conference Paper (international conference)
Mokrý, P. - Václavík, J. - Nečásek, J. - Psota, Pavel - Steiger, Kateřina - Vápenka, David
Adaptive acoustic metasurfaces for the noise shielding.
Proceedings of the 24th International Congress on Sound and Vibration 2017. London: International Institute of Acoustics and Vibration, IIAV, 2017 - (Gibbs, B.), č. článku 129801. ISBN 978-1-906913-27-4. ISSN 2329-3675.
[International Congress on Sound and Vibration, ICSV 2017/24./. London (GB), 23.07.2017-27.07.2017]
R&D Projects: GA MŠMT(CZ) LO1206; GA ČR(CZ) GA16-11965S
Institutional support: RVO:61389021
Keywords : Acoustic metasurface * Negative elasticity * Noise shielding * Piezoelectric actuators
OECD category: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics
https://www.iiav.org/.../full_paper_598_20170404091125105.pdf

It is known that active acoustic metasurfaces (AAMSs), which consist of the curved glass shell with attached piezoelectric transducers, can provide efficient means for the noise shielding. The principle standing behind this effect is based on the electronic control of the acoustic impedance (AI) of the AAMS, which is achieved by connecting the piezoelectric transducers to the active shunt circuits. When the connected shunt circuit has a required value of the complex electrical impedance, it is possible to achieve extremely high negative values of the AI of the AAMS. This regime is often called the negative elasticity regime (NER) of the AAMS. In the NER, the incident sound wave can be completely reflected and the transmitted sound vanishes. Unfortunately, the working point of the electrical circuit is located near the edge of the stability region, when the AMMS operates in the NER. In this Paper, we demonstrate experimentally that it is possible to construct an adaptive AMMS, which is stable in varying operational conditions. The adaptive AMMS is achieved by introducing an additional feedback loop for the control of the required value of the AI. This is attained by introducing the system for the real-time estimation of the AI value and the accurate control of the complex electrical impedance of the shunt circuit by means of the iterative algorithm.
Permanent Link: http://hdl.handle.net/11104/0277818