Evidence of a broadband gap in a phononic crystal strip.
We experimentally demonstrate a very large ultrasonic band gap in a one-dimensional phononic crystal. The structure consists of periodic tungsten pillars fixed to a tailored silicon strip with a layer of epoxy. Combining local resonances and Bragg scattering, the gap ranges from 450kHz to 1250kHz, which corresponds to a gap-to-midgap ratio of 94%, and the attenuation exceeds 35dB with only three periods. Numerical calculations with the Finite Element Method are performed to support the analysis and provide a better understanding of the behavior of the structure. In particular, the role of the thin layer of epoxy is studied and is shown to have a strong influence on the dispersion. This phononic structure with a very large band gap can be considered as a new tool to design acoustic devices with high performances.
Institut FEMTO-ST, UMR 6174, CNRS, ENSMM, Univ. Bourgogne Franche-Comté, 15B Avenue des Montboucons, 25030 Besançon Cedex, France. Electronic address: etienne.coffy@femto-st.fr.
Etienne
E
Coffy
Institut FEMTO-ST, UMR 6174, CNRS, ENSMM, Univ. Bourgogne Franche-Comté, 15B Avenue des Montboucons, 25030 Besançon Cedex, France.
Sébastien
S
Euphrasie
Institut FEMTO-ST, UMR 6174, CNRS, ENSMM, Univ. Bourgogne Franche-Comté, 15B Avenue des Montboucons, 25030 Besançon Cedex, France.
Mahmoud
M
Addouche
Institut FEMTO-ST, UMR 6174, CNRS, ENSMM, Univ. Bourgogne Franche-Comté, 15B Avenue des Montboucons, 25030 Besançon Cedex, France.
Pascal
P
Vairac
Institut FEMTO-ST, UMR 6174, CNRS, ENSMM, Univ. Bourgogne Franche-Comté, 15B Avenue des Montboucons, 25030 Besançon Cedex, France.
Abdelkrim
A
Khelif
Large band gap; Local resonances; Phononic strip