Vibration and Wave Propagation Control of Plates with Periodic Arrays of Shunted Piezoelectric Patches

Periodic arrays of shunted, piezoelectric patches are employed to control waves propagating over the surface of plate structures, and corresponding vibrations. The shunted, piezoelectric patches act as sources of impedance mismatch, which gives rise to interference phenomena resulting from the interaction between incident, reflected and transmitted waves. Periodically distributed mismatch zones, i.e., the piezo patches, produce frequency dependent, wave-dynamic characteristics, which include the generation of band gaps, or stop bands in the frequency domain. The extent of induced band gaps depends on the mismatch in impedance generated by each patch. The total impedance mismatch, in turn, is determined by the added mass and stiffness of each patch as well as the shunting electrical impedance. Proper selection of the shunting electric-circuit thus provides control over the attenuation capabilities of the piezo-plate structure, as well as the ability to adapt to changing excitation conditions. Control of wave-propagation attenuation and vibration reduction for plates with periodic, shunted, piezoelectric patches is demonstrated numerically, employing finite-element models of the considered structures

Amortissement vibratoire multimodal de plaques par couplage à leurs réseaux piézoélectriques analogues

Le principe du shunt piézoélectrique résonant est étendu au contrôle d'une structure multimodale par multiplication du nombre de patchs piézoélectriques. Ceux-ci sont interconnectés via un réseau électrique ayant un comportement modal approximant celui de la structure à contrôler. Pour une plaque mince, l'application de la méthode des différences finies aux équations continues de Kirchhoff-Love permet d'obtenir un ensemble d'équations discrètes qui définissent un modèle différences finies d'une cellule élémentaire de plaque. À partir de ce modèle mécanique discret, l'analogie électromécanique mène à un réseau électrique analogue constituées d'inductances et de transformateurs. Quand le réseau bidimensionnel est connecté à un ensemble de patchs piézoélectriques, le système complet fait apparaître une coïncidence à la fois spatiale et fréquentielle entre les modes de résonance de plaque et ceux de l'analogue électrique. Le couplage piézoélectrique entre les deux sous-domaines génère un transfert énergétique surne large plage de fréquences. On obtient donc un réseau multi-résonant qui permet le contrôle simultané de plusieurs modes mécaniques. Expérimentalement, on observe des réductions d'amplitude vibratoire de plus de 20 décibels sur les 5 premiers modes d'une plaque. Ceci démontre le potentiel de la stratégie de contrôle passif en matière d'amortissement multimodal

Suppression of Friction-Induced Oscillations Through Use of High Frequency Dither Signals

Issued as final repor

Project 004A: Estimation of Noise Level Reduction

The specific goal of Project 4A was to better understand and improve the outdoor loudspeaker methods of estimating the noise level reduction (NLR) performance of buildings exposed to aircraft noise. Measurements and modeling were conducted on a test house located outdoors with a loudspeaker placed at an array of spatial positions to simulate angular coverage of aircraft flyover in both vertical and lateral directions. Results were used to evaluate and compare various NLR estimating approaches

Evaluation of criticality alarm system testing

Issued as final repor

Optimization in structural acoustics using FEM/BEM

Issued as Interim report, Reports [nos. 1-10], and Final report, Project E-25-W56Final report has author: S.P. Engelsta

Quarter-Cycle Switching Control for Switch-Shunted Dampers

Significant interest has been generated by the possibilities of active vibration contro

Hybrid passive-active modal networks for structural acoustic control

International audienceDistributions of piezoelectric patches bonded to structures provide a means to alter or control, through active or passive means, the dynamic response of the host structure. Numerous active control schemes for such composite structures have been explored. Alternatively, for certain structures, a passive electrical network may be implemented which presents an electrical analog of the modal response of the structure, effectively providing a multi-modal, distributed passive tuned mass modal damper capability. Numerous tuned-mass damper design concepts (“tunings”) may be applied to such a passive network. Further, the distributed network analog, when coupled with active control concepts, permits a hybrid distributed passive-active modal control capability. This paper explores this hybrid distributed network control concept applied to a clamped rectangular plate. A unit-cell discrete representation of the plate leads to an electrical analog comprised of passive inductors, transformers and resistors. Addition of synthetic (or controlled) impedances at a limited set of points within the network permits dynamic adjustment of the frequency response of the system