Low frequency bandgap characteristics of a 3D chiral acoustic metamaterial structure

Abstract

It has been proved that bandgaps in acoustic metamaterials can block elastic waves in certain frequencies, which offer an unprecedented solution to the low-frequency vibration control. However, there are still challenges of low bandgap frequencies and wide bandwidth. Meanwhile, chirality breaks the symmetry of the structures, which could also contribute to the formation of bandgaps in acoustic metamaterials. Based on research background mentioned above, this work proposes a type of novel 3D chiral acoustic metamaterial structures. The dispersion relations are investigated by using the Bloch's theorem. Then, the specimens are fabricated by 3D printing combined with glue processing. A series of tests is carried out to study their vibration characteristics. It is shown that the simulated results of the structures are in good agreement with experimental results, which verified the validity of the numerical models. The dispersion relations and corresponding frequency-response curves are plotted. After embedding fillers, the bandgaps of structures decrease about 62.4 % and total bandwidth decrease about 46.5 %. In addition, the regularity of bandgaps in structures with different parameters are analyzed and the structure optimized accordingly shows good vibration reduction performance in low-frequencies. This work can provide a new possibility for engineering application in the field of vibration and noise control.