Nonlinear effects in an acoustic metamaterial with simultaneous negative modulus and density

Nonlinear effects in an acoustic metamaterial with simultaneous negative modulus and density based on Helmholtz resonators and membranes periodically distributed along a pipe are studied theoretically. Analyses of the transmission coefficient and dispersion relation of the composite system are realized using the acoustic transmission line method and Bloch theory, respectively. Due to the nonlinearities of the Helmholtz resonators and membranes, the acoustic wave propagation properties vary with the different incident acoustic intensities, and the frequency band gaps of the transmission coefficient are amplitude dependent. The nonlinearities shift the double negative pass band into the adjacent modulus negative forbidden band and transform the metamaterial from an acoustic insulator into an acoustic conductor, leading to some new potential acoustic applications. Published by AIP Publishing.