A two-dimensional array of piezoelectric transducer (PZT) shunted on negative capacitance circuit is designed and applied to achieve broadband vibration reduction of a flexible plate over tunable frequency bands. Each surface-bonded patch is connected to a single independent negative capacitance synthetic circuit. A finite element-based design methodology is used to predict and optimize the attenuation properties of the smart structure. The predictions are then experimentally validated by measuring the harmonic response of the plate and evaluating some derived quantity such as the loss factor and the kinetic energy ratio. The validated model is finally used to explore different configurations with the aim of defining some useful design criteria.
A recent technological revolution in the fields of integrated MEMS has finally rendered possible the mechanical
integration of active smart materials, electronics and power supply systems for the next generation of smart
composite structures. Using a bi-dimensional array of electromechanical transducers, composed by piezo-patches
connected to a synthetic negative capacitance, it is possible to modify the dynamics of the underlying structure.
In this study, we present an application of the Floquet-Bloch theorem for vibroacoustic power flow optimization,
by means of distributed shunted piezoelectric material. In the context of periodically distributed damped 2D
mechanical systems, this numerical approach allows one to compute the multi-modal waves dispersion curves into
the entire first Brillouin zone. This approach also permits optimization of the piezoelectric shunting electrical
impedance, which controls energy diffusion into the proposed semi-active distributed set of cells. Furthermore,
we present experimental evidence that proves the effectiveness of the proposed control method. The experiment
requires a rectangular metallic plate equipped with seventy-five piezo-patches, controlled independently by electronic
circuits. More specifically, the out-of-plane displacements and the averaged kinetic energy of the controlled
plate are compared in two different cases (open-circuit and controlled circuit). The resulting data clearly show
how this proposed technique is able to damp and selectively reflect the incident waves.