Directional Transmission Characteristics of Acoustic Waves Based on Artificial Periodic Structures

Abstract

Acoustic artificial periodic structures, also known as phononic crystal, have been widely used in special acoustic problems such as low-frequency vibration reduction and noise reduction due to their bandgap characteristics. Different from previous researches, which focus on the bandgap characteristics, we designed a locally resonant artificial periodic structure, which can not only use the bandgap characteristics to design a directional transmission channel of acoustic waves, but also use its bandpass characteristics to generate multidirectional transmission of acoustic waves. The vibration mechanism of two-dimensional, three-components phononic crystal lattice structures was given, and a variety of directional transmission models of acoustic waves were constructed based on the unit cell. The simulation results showed that acoustic directional transmission characteristics were produced by the locally periodic resonance structure, and the transmission direction depends on the design of the structure. By taking advantage of the superposition properties of acoustic waves, the incident acoustic wave in the horizontal direction can be converted into the outgoing acoustic wave in the vertical direction without changing the position of the model, and this capability greatly expands the application range of the artificial periodic structure. In addition, the transmission characteristics of the directional transmission effect have a strong correlation with the frequency; that is, limited by the wavelength, the acoustic pressure distribution mode at different frequencies will be different. At the resonant frequency of the structure, the transmission efficiency of the acoustic wave will be highest. Moreover, similar to the traditional artificial periodic structure, the acoustic model proposed in this paper also has bandgap characteristics. Using bandgap characteristics, we designed an acoustic directional transmission channel to achieve uniform directional transmission of acoustic waves. These results greatly enrich the application space of artificial acoustic structures and provide new ideas for acoustic communication, acoustic detection, and acoustic stealth.

Keywords

• Metamaterial
• local resonance
• artificial structures
• phononic crystals