Ultrasonic beam propagation in periodic structures: verifying the existence of sonic crystals in triangular structures

TL;DR

This paper investigates ultrasonic wave propagation in periodic triangular structures to verify the existence of band gaps, demonstrating selective attenuation zones consistent with theoretical predictions for different symmetry directions.

Contribution

It provides experimental verification of forbidden ultrasonic frequency bands in triangular cylinder structures, confirming theoretical band gap predictions.

Findings

Triangular structures exhibit ultrasonic band gaps.

Selective attenuation zones are observed at specific frequencies.

Results align with theoretical models for symmetry directions.

Abstract

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).