Abstract: This invention provides an acoustic metamaterial unit cell, consisting of a frame, a constraint stick placed in the frame and a piece of membrane covering at least one surface of the frame. This invention also provides an acoustic metamaterial plate comprised of the provided unit cells and a composite structure of acoustic materials. Additionally, the invention provides a method to design the operating frequency bands by modifying the structure and material properties of the frame, the constraint stick and the membrane in the proposed acoustic metamaterial. The proposed structure shows a priority in fabrication, stability and service life.

Abstract: The invention provides an acoustic material structure and an assembly method of the acoustic radiation structure. The acoustic material structure comprises acoustic units which can be attached onto surfaces of acoustic radiation structures. Each acoustic unit comprises a thin sheet, an air cavity between the thin sheet and the surface of the sound radiation structure, and openings penetrating through the acoustic unit with one end connected to the cavity. The openings can reduce the spring effect of the fluid medium in the cavity, so that the acoustic units attached onto the surface of the sound radiation structure can provide low-frequency sound insulation effects. The acoustic unit may also include support bodies, mass blocks, and constraint bodies. The working frequencies of the acoustic unit can be regulated by the support bodies, mass blocks and constraint bodies.

Abstract: This invention provides an acoustic metamaterial unit cell, consisting of a frame, a constraint stick placed in the frame and a piece of membrane covering at least one surface of the frame. This invention also provides an acoustic metamaterial plate comprised of the provided unit cells and a composite structure of acoustic materials. Additionally, the invention provides a method to design the operating frequency bands by modifying the structure and material properties of the frame, the constraint stick and the membrane in the proposed acoustic metamaterial. The proposed structure shows a priority in fabrication, stability and service life.