Sonic stop-bands for periodic arrays of metallic rods: Honeycomb structure

Extensive band structures have been computed for periodic arrays (in the honeycomb structure) of rigid metallic rods in air. Multiple complete acoustic stop bands have been obtained within which sound and vibrations are forbidden. These gaps start opening up for a filling fraction f greater than or equal to 8% and tend to increase with the filling fraction, exhibiting a maximum at the close-packing. th tandem structure has also been proposed that allows an ultrawideband filter for environmental or industrial noise to be achieved in the desired frequency range. This work is motivated by the recent experimental observation of sound attenuation on the sculpture by Eusebio Sempere, exhibited at the Juan March Foundation in Madrid [21] and complements the corresponding theoretical work [22, 23]. (C) 1998 Academic Press.