Enhanced sound absorption of open-cell metallic foams using periodic structures with perforations in the lower frequency range

Here, a perforated periodic structure in the middle of open-cell metallic foams (OMF) was proposed to improve the sound absorption performance of OMF with higher porosity (92%~98%) in the lower frequency range. The effects of the perforation ratio, the hole diameter, the number of layers and positions of the perforated periodic structure on the sound absorption performance of OMF are further discussed investigated. The results show that the sound absorption frequency of the OMF with perforated periodic structure can be significantly reduced, but the sound absorption frequency band will be narrowed. Good sound absorption performance over a wider frequency range can be obtained in the OMF with two or three layers of perforated periodic structure. The porosity of the periodic structure is arranged from large to small, and the sound absorption effect is better. Combining OMF properties and thickness, controlling the specific position of the periodic structure in OMF can achieve better sound absorption in a specific sound absorption frequency band. The results and design method may works provide ideas for OMF with higher porosity in the middle and low frequency broadband noise reduction.