Measurements and calculations of the sound attenuation by a phononic band gap structure suitable for an insulating partition application

Abstract

We report a strong attenuation of sound waves in a phononic band gap crystal of steel rods arranged in air. We investigate the attenuation level reached in the gaps for finite thickness samples. We show that a bypassing of sound waves by the sides of the sample are responsible for the observed saturation of the attenuation level in the gaps. Beyond this effect, we demonstrate the improvement of the acoustic insulation performance brought about by the periodicity of the crystal in comparison with the so-called mass law.

Design guidelines for flexural wave attenuation of slender beams with local resonators

“…But large resonators mean heavy add-on weight. Since attenuation in gaps of PCs is proportional to the number of periods it propagates through [15], the middle panel illustrates the potential attenuation property of the beam with different LRs considered here. From this panel one can conceive that a few large LRs will result in limited attenuation in wide frequency range while a large number of small LRs can result in large attenuation in limited frequency range.…”

“…In recent years, periodic composite materials known as phononic crystals (PCs) have received renewed attention [4][5][6][7][8][9][10][11][12][13][14][15][16] because PCs exhibit complete elastic band gaps within which sound and vibration are all forbidden. For finite PCs samples, wave propagation attenuation within the frequency ranges of gaps was found, which gives new idea for vibration isolation and noise control.…”

Classical vibrational modes in phononic lattices: theory and experiment

“…Hollow steel rods with square cross section (50 cm length, 3 cm side length, 3 mm wall thickness) were arranged on a square lattice (4.25 cm period), 40 rotated with respect to the lattice [198]. In the spectral range studied (0-15 kHz), sound attenuation up to 30 dB (2-6 kHz) was observed.…”

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

“…As with electronic and photonic crystals, the transmissive evolution of mechanical or elastic waves is revealed in the phononic crystal bandstructure, with many shared synthetic properties across the forms of energy. [7][8][9][10] Transmission stopgaps, 9 resonators, 11 and antiparallel group and phase velocity propagation 7 can all be attained through the appropriate crystal design. Metamaterials are most prominently known for their ability to produce synthetic properties including negative index and 'slow' propagation.…”