Tailoring the dispersion properties of guided waves in piezoelectric phononic crystals
Résumé
In the last decade, a noticeable effort has been realized, combining phononics with active materials, in order to provide versatile control of elastic waves within these structures. Among several possibilities, the use of piezoelectric materials constitutes an important source of inspiration for the design and realization of intelligent active devices based on their ability to combine electric circuits that offer ease in electric command of the dispersion properties of these structures. Here, we propose an active phononic crystal composed of a piezoelectric plate, structured periodically with millimeter-scaled metallic strips on its two surfaces. The metallic electrodes, used for the excitation of Lamb-like guided modes in the plate, ensure at the same time control of their dispersion by means of externally loaded electric circuits that enable non-destructive tunability in the frequency response of these structures. In previous studies, authors have established that an inductive shunt in association with the inherent capacitive nature of the piezoelectric material will operate as an equivalent electric resonant circuit that produces avoided crossings and, under certain conditions, opening up of hybridization gaps [1]. In this work, we explore, both theoretically and experimentally, the dispersion design possibilities offered by the use of connected active electric circuits, such as negative capacitances or inductances. [1] Smart Mater. Struct. 28 (2019) 115046