Temperature-controlled tunable acoustic metamaterial with active band gap and negative bulk modulus

•The relative variation of the local resonant band gap is about 11%.•The relative variations of the negative material properties are about 11%.•The local resonant band gap is monotonic to the fluid temperature in [0 °C, 75 °C].•The negative material properties are monotonic to the fluid temperature in [0 °C, 75 °C].•The fluid temperature between 0 °C and 75 °C can be used to design tunable acoustic metamaterial.

The local resonant band gap and the negative bulk modulus of the acoustic metamaterial with Helmholtz resonators are strongly affected by the temperature of water. In this paper, the acoustic transmission line method (ATLM) is introduced to investigate the influences of the temperature of water on the local resonant band gap and the negative bulk modulus of the acoustic metamaterial. Results show that the relative variations of the local resonant band gap and the negative effective bulk modulus suffering from the change of the temperature of water are approximately equivalent and are up to about 11%. The reason is that the local resonant frequency is proportional to the sound speed of fluid which is strongly effects by the temperature of water. By achieving the unambiguous relationships between these unusual properties of the acoustic metamaterial and the temperature of water, we find that the temperature-controlled acoustic metamaterial with the active band gap and the active negative bulk modulus can be realized in theory. This idea opens a new avenue for the design of the tunable acoustic metamaterial that can modulate the acoustic wave propagation.