Indexed on: 17 May '13Published on: 17 May '13Published in: Physics - Soft Condensed Matter
When waves are propagated through a medium with scatters and these elements are positioned periodically, as in the crystal structures, multiple scattering leads to a phenomenon known as banded structures. This means that waves can propagate in a certain frequency range, according to rules of dispersion, while in other frequency ranges the propagation is cancelled. The first are called allowed bands and the last deaf bands. This work part in order to verify the existence of forbidden bands in the zone of ultrasonic frequency to triangular structures formed by cylinders (hollow and solid) of different diameters (8 and 16mm.). The results indicate that the triangular structure has selective attenuation zones, obtaining results similar to those theoretically predicted for the two main directions of symmetry (0 and 30).