Analysis of a Geometrical-Stiffening Membrane Acoustic Metamaterial with Individually Tunable Multi-Frequencies

To realize a structure which can be conveniently tuned to multiple and wideband frequency ranges, geometrical-stiffening membrane acoustic metamaterial (MAM) with individually tunable frequencies is presented. The MAM realized by stacked arrangement of two membrane-magnet elements, each has small piece steel attached in the centre. It adjusting position its compact magnet. normal incidence sound transmission loss investigated detail measurements an impedance tube. test sample results demonstrate that this easily achieve peaks shifted wide low-frequency range. A theoretical consideration analysed, analysis shows magnetic effect related distance leads nonlinear attractive force and, consequently, geometrical stiffening element, allows shifted. reasonable design make have good application prospect for noise insulation where there need adjust according spectrum source.