We present numerical and experimental investigations on the dynamics of a piezoelectric metamaterial waveguide with unit cell shunt impedance that can be varied in both space and time in a fully programmable manner. A piezoelectric bimorph with 30 separately bonded pairs of piezoelectric patches (i.e. 30 unit cells) is connected to a fully programmable gate array (FPGA)-based synthetic impedance system with 32 individually addressable shunt circuits. Spatial impedance profiles are programmed and stored in memory on the FPGA, allowing the system to switch between impedances at very high frequencies, resulting in nearly smooth time-modulation at low modulation frequencies. The switching rate between the stored impedances is determined by a digital trigger and external pulse train, allowing the modulation frequency to be smoothly varied. Four separate triggers enable different modulation frequencies to be set across the waveguide, such that multifrequency modulation schemes can also be explored. In this way, the developed experimental platform is capable of smooth, multi-directional spatiotemporal modulation of circuit parameters. Experimental results are presented for various inductive spatiotemporal modulation schemes, investigating the effect of modulation amplitude and directional behavior of the waveguide (e.g. for non-reciprocal propagation). Scanning laser Doppler vibrometer (SLDV) measurements provide full-field characterization of the waveguide. Numerical and experimental results demonstrate non-reciprocal behavior in the modulated waveguide.
We investigate a metamaterial beam with piezoelectric elements shunted to synthetic impedance circuits to demonstrate elastic wave trapping. We numerically and experimentally demonstrate the so-called rainbow trapping phenomenon, in which elastic waves of different wavelengths are trapped in different regions of the metamaterial beam. Guided by numerical simulations, experiments are performed on a beam with 30 piezoelectric elements with synthetic impedance circuits that have gradually varying inductance. Grading profiles are varied through the digital interface to understand its effect on the wave trapping behavior and conclusions are drawn.
We present the theoretical and experimental investigation of a piezoelectric metamaterial-based acoustic black hole leveraging programmable shunt circuits. A versatile experimental platform is developed comprising a piezoelectric bimorph beam with 30 unit cells, each with a pair of piezoelectric patches with individually programmable shunt impedance. By varying the impedance applied to each unit cell, the local dispersion properties of the beam can be precisely controlled. In this work, we explore a programmable implementation of an acoustic black hole, in which wave packets are slowed down and compressed in space using a smooth gradient in shunt impedance.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.