Low frequency sound absorption of adjustable membrane-type acoustic metamaterials

The membrane-type acoustic metamaterials with negative pressure cavity are designed to achieve near perfect sound absorption and sound absorption adjustment of low frequency spectrum line control. The soft membrane is replaced by PET membrane as the substrate to enhance tolerance. The membrane material has achieved strong geometric nonlinearity by the static negative pressure of the back cavity. The change in geometric stiffness caused by geometric nonlinearity is used to adjust structural sound absorption peak for low frequency spectrum line. The combined method of finite element and modal superposition is used to predict the sound absorption of membrane-type acoustic metamaterials. The experimental results agree well with the one from the analysis method. The advantages of this structure are that the location of the sound absorption peak can be adjusted. And a near perfect sound absorption can be achieved without damping adjustment. This structure has positive significance for low frequencies spectrum line noise control.