Basic structural units of acoustic metamaterials and their composite structures and assembly methods

Abstract

The invention relates to an acoustic meta-material basic structure unit, and the structure unit comprises a boundary constraint frame. The interior of the boundary constraint frame is provided with an in-frame constraint body. At least one of the upper and lower surfaces of the boundary constraint frame is covered with a film. The invention also provides an acoustic meta-material plate comprising the acoustic meta-material basic structure unit, and an acoustic composite structure comprising the acoustic meta-material plate. In addition, the invention also provides a method for achieving working frequency adjustment sound insulation band of an acoustic meta-material through the change of the structural size and material parameters of the boundary constraint frame of the acoustic meta-material, the in-frame constraint body and the film. The unit is simple in assembly technology, is long in service life, restrains the vibration mode of the film, and enables the performance and stability of a sound insulating material to be improved.

Description

technical field [0001] The invention relates to a basic structural unit of an acoustic metamaterial and a composite structure containing the same, which is suitable for making sound barriers and sound insulation covers with light and thin structures and good low-frequency sound insulation effects, and belongs to the field of materials. Background technique [0002] The emergence of acoustic metamaterials, especially local resonance acoustic metamaterials, breaks through the limitation of the mass theorem of uniform sound-insulating materials, and provides a powerful tool for people to use small-scale structures to effectively control the propagation of low-frequency sound waves (2000, Zhengyou Liu et al., Locally Resonant Sonic Materials, Science289, 1734; 2008, Z. Yang et al., Membrane-Type Acoustic Metamaterial with Negative Dynamic Mass, Physical Review Letters 101, 204301.). [0003] The three components of the basic structural unit of a typical local resonance acoustic ...

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Problems solved by technology

Since the pretension of the elastic diaphragm will slowly release the slack during long-term vibration, the effective working time of this type of material is relatively short

[0006] 3. After the three components of the basic structural unit form a total reflection phenomenon at a specific frequency, there will be a total transmission phenomenon immediately, causing the sound insulation effect in this frequency band to be far inferior to that of a uniform material

The acoustic metamaterial without counterweight mass disclosed in the patent (CN101908338B, US20140339014) is prone to multiple fully transparent frequency bands because it only relies on the vibration mode of the soft material / flexible diaphragm in the basic structural unit

[0007] 4. The frequency band of the total reflection peak is relatively narrow. In applications that require sound insulation in a wider frequency band, multiple total reflection peaks with different frequencies can only be used to isolate sound waves, and cannot effectively compensate for the sound insulation trough between the total reflection peaks. It is necessary to stack multiple layers of acoustic metamaterials, so the weight cost is extremely high, and it cannot be thin and light

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