Isolation of flexural waves in a wide and low frequency range using a phononic beam with acoustic black hole configuration

Abstract

We propose a phononic beam to realize flexural wave bandgaps in wide and low frequency regimes. A unit cell of the phononic beam consists of two uniform parts and a tapered part with acoustic black hole configuration sandwiched between uniform parts. We identify the effects of geometrical parameters of the ABH-based phononic beam on band structures and determine those geometrical parameters to obtain a bandgap from 3.6 Hz to 237.9 Hz with a lattice constant of 1/33 wavelength. For experimental realization, the displacement transmission of the phononic beam is measured by impact hammer test, and the result shows that low transmission of –35 dB to–10 dB could be achieved in the wide bandgap.