Acoustic properties of honeycomb like sandwich acoustic metamaterials

Low frequency noise has strong penetrability and has always been an important part of environmental pollution. Limited by the law of mass, traditional lightweight porous materials are difficult to effectively control low-frequency noise. Based on the characteristics of honeycomb structure, Helmholtz resonator and acoustic metamaterials, a kind of honeycomb like sandwich acoustic metamaterials is proposed. This structure combines the lightweight characteristics of honeycomb sandwich structure and Helmholtz resonance characteristics. The finite element models of honeycomb and Helmholtz resonators element are established. The transmission loss (TL) characteristic shows that Helmholtz resonators element will be a TL peak in a narrow frequency band than honeycomb element. The effects of neck diameter, neck length and cavity volume of Helmholtz resonator on its TL are analyzed. The TL of single and multiple Helmholtz resonators are compared. Furthermore, The TL of honeycomb panel and honeycomb like sandwich acoustic metamaterials are analyzed. The results show that the different TL peaks can be introduced into honeycomb like sandwich acoustic metamaterials with different neck diameters. Each Helmholtz resonators element plays an active role in its own frequency band. The sound insulation performance of the honeycomb like sandwich acoustic metamaterials is tested by impedance tube experiment. Excellent sound insulation ability is confirmed. The reasonable design of honeycomb like sandwich acoustic metamaterials structural parameters can solve the problem of low-frequency noise of thin-layer lightweight structure.