Sound transmission loss of metamaterial thin plates with periodic subwavelength arrays of shunted piezoelectric patches

• Metamaterial plate with subwavelength arrays of shunted piezoelectric patches.
• An effective medium method is developed to calculate the sound transmission loss.
• Much higher sound transmission loss in the mass-law region.
• Significantly increased sound transmission loss in the entire coincidence region.
• Bandwidth broadening by using negative capacitance shunting circuits.

This paper studies sound transmission loss (STL) of a metamaterial thin plate consisting of periodic subwavelength arrays of shunted piezoelectric patches bonded to the two surfaces of an unbounded homogeneous thin plate. An effective medium method is developed to calculate STL of such metamaterial thin plates. The effective medium method is validated by comparing with the results calculated from the finite element method. Numerical results show that the metamaterial plate with shunted piezoelectric patches (all of the shunting circuits are closed) can achieve much higher STL than the unshunted case (all of the shunting circuits are opened) within the mass-law region and coincidence region of sound transmission. The unique STL of the metamaterial plate can be well understood by explicit formulations derived based on the effective medium method. It is also shown that the bandwidth of increased STL of the metamaterial plate can be significantly broadened by utilizing negative capacitance shunting circuits.