Local resonance acoustic metamaterial cellular structure based on trampoline effect

Abstract

The invention discloses a local resonance acoustic metamaterial cellular structure based on a trampoline effect. The local resonance acoustic metamaterial cellular structure comprises a flat-plate-shaped base, a plurality of resonators arranged on the surface of one side of the base and a piezoelectric plate arranged at the center of the base. The plurality of resonators are arranged in an array, and the four resonators located in the center of the base are removed, so that a defect cavity is formed in the area, where the four resonators are removed, of the center of the base; and four fan-shaped through hole-shaped trampoline structures are arranged around the piezoelectric plate in the defect cavity area on the base. According to the local resonance acoustic metamaterial cellular structure based on the trampoline effect, high-density acoustic energy collection can be achieved based on the trampoline effect, and the problem that the power density of an existing acoustic metamaterial is not high enough is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial acoustic structures, and in particular relates to a local resonance acoustic metamaterial cellular structure based on a trampoline effect. Background Art

[0002] The rapid adoption of new energy vehicles and the expansion of renewable energy are further accelerating the green transition of the global energy mix. Noise pollution harms people's lives and health, and noise sources are ubiquitous. Common noise sources include machinery, traffic, and everyday life. Noise is a potential green energy source with considerable energy value. However, due to the low density of sound energy, the vast majority of sound energy is wasted during its propagation.

[0003] High-density acoustic energy harvesting technology can effectively address environmental noise issues and enable the collection of green energy. However, existing acoustic energy harvesting technologies, such as half-wavelength tube resonators, Helmholtz resonators, and acoustic metamaterial energy harvesters, have limited ability to increase acoustic energy density. To further increase acoustic energy density, acoustic metamaterial energy harvesters based on the trampoline effect have emerged in recent years.

[0004] Currently, there are methods to collect high-frequency elastic wave energy by localizing elastic wave energy through trampoline metamaterials, and to use double-defect acoustic metamaterials with trampoline effect and Helmholtz coupling to broaden bandwidth and improve energy collection efficiency. However, the power density is still not high enough. 1 Pa to 10 2 It is not applicable to high-intensity mechanical noise of the Pa level, especially high-speed train noise of up to 131dB (70.96Pa). Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and provide a local resonant acoustic metamaterial cellular structure based on the trampoline effect with higher power density and energy focusing and amplification functions.

[0006] As one aspect of the present invention, the present invention provides a local resonant acoustic metamaterial cellular structure based on the trampoline effect, which includes a flat base, a plurality of resonators arranged on a surface of one side of the base, and a piezoelectric piece arranged at the center of the base; the plurality of resonators are arranged in an array and the four resonators located at the center of the base are removed, so that the area in the center of the base where the four resonators are removed forms a defect cavity; four fan-shaped through-hole trampoline structures are arranged around the piezoelectric piece in the defect cavity area on the base.

[0007] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the material of the base includes an aluminum plate.

[0008] As a preferred solution of the local resonance acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the material of the resonator includes silicone rubber.

[0009] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the piezoelectric piece is in the shape of a circular piezoelectric patch.

[0010] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the base is in the shape of a square flat plate.

[0011] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the resonator is cylindrical and is arranged perpendicular to the base.

[0012] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the resonators are arranged in a 6×6 periodic array and the four central resonators are removed.

[0013] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention, the spacing between every two resonators is equal.

[0014] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention, the distance between every two trampoline structures is equal to the distance between every two resonators.

[0015] As a preferred solution of the local resonant acoustic metamaterial cellular structure based on the trampoline effect described in the present invention: the distance between the inner and outer diameters of the fan-shaped through hole is equal to the spacing between every two trampoline structures.

[0016] Beneficial effects of the present invention: The local resonant acoustic metamaterial cellular structure based on the trampoline effect provided by the present invention can achieve high-density sound energy collection based on the trampoline effect, solving the problem that the power density of existing acoustic metamaterials is not high enough. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, wherein:

[0018] Figure 1 Schematic diagram of the cellular structure of the local resonant acoustic metamaterial based on the trampoline effect.

[0019] Figure 2This is a comparison diagram of the output open-circuit voltage, stress distribution, and sound pressure distribution of the local resonant acoustic metamaterial (T-meta) based on the trampoline effect and the defect-type acoustic metamaterial (Meta) in the finite element software CO M SO LM ultiphysics simulation.

[0020] Figure 3 Figure 3 is an energy band structure diagram and a modal diagram of the local resonant acoustic metamaterial (b) and the defect-type acoustic metamaterial (a) based on the trampoline effect of the present invention in the simulation of the finite element software CO M SO LM ultiphysics.

[0021] Figure 4 This is the test experimental setup for the local resonant acoustic metamaterial cellular structure based on the trampoline effect. The inset is the transmission spectrum of the local resonant acoustic metamaterial cellular structure based on the trampoline effect. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0023] refer to Figure 1 The present invention provides a local resonant acoustic metamaterial cellular structure based on the trampoline effect, comprising a flat base 2, a plurality of resonators 1 arranged on one side surface of the base 2, and a piezoelectric piece 4 arranged at the center of the base 2; the plurality of resonators 1 are arranged in an array and the four resonators 1 located at the center of the base 2 are removed, so that a defect cavity is formed in the area in the center of the base 2 where the four resonators 1 are removed, thereby concentrating the acoustic resonance at the defect cavity in the center of the base 2; four fan-shaped through-hole trampoline structures 3 are arranged around the piezoelectric piece 4 in the defect cavity area on the base 2.

[0024] In the present invention, the resonator 1 generates acoustic resonance under the action of external sound waves, and concentrates the acoustic resonance in the defect cavity area at the center of the base 2. The fan-shaped through-hole structure of the trampoline structure 3 enhances the acoustic resonance movement at the defect cavity in the center of the base 2, thereby generating acoustic vibration energy. The generated acoustic vibration energy is then converted into electrical energy output through the piezoelectric sheet 4, forming a local resonant acoustic metamaterial cellular structure based on the trampoline effect.

[0025] As one embodiment of the present invention, the material of the base 2 is a square thin aluminum plate. As one preferred solution, the base 2 has a thickness of 0.4 mm and a side length of 60 mm.

[0026] In one embodiment of the present invention, the resonator 1 is made of silicone rubber. In a preferred embodiment, 36 resonators 1 are arranged in a 6×6 periodic array, with the four central resonators 1 removed. More specifically, each resonator 1 is cylindrical and positioned perpendicular to the base 2. Each resonator 1 has a radius of 3 mm and a height of 10 mm, with the spacing between every two resonators 1 being equal.

[0027] In one embodiment of the present invention, the four trampoline structures 3 have the same structure. In one preferred embodiment, the fan-shaped through-holes of the trampoline structures 3 have an outer diameter of 11 mm and an inner diameter of 7 mm, and the spacing between each two trampoline structures 3 is 4 mm. Preferably, the spacing between each two trampoline structures 3 (i.e., the shortest distance between the two trampoline structures 3) is equal to the spacing between each two resonators 1 (i.e., the shortest distance between each two resonators 1).

[0028] As one embodiment of the present invention, the piezoelectric patch 4 is a circular PZT-5H piezoelectric patch with a radius of 6 mm and a thickness of 0.2 mm, which is attached to the center of the defect cavity.

[0029] Experimental results:

[0030] The finite element software COMSOL Multiphysics is used to analyze the local resonance acoustic metamaterial (trampoline metamaterial) based on the trampoline effect of the present invention. Figure 2 This graph compares the output voltages of the present invention's locally resonant acoustic metamaterial based on the trampoline effect and a defect-based acoustic metamaterial (without a trampoline structure) in a simulation. The graph shows the output voltages generated by the defect-based and trampoline-based acoustic metamaterials, ranging from 2000 Hz to 2500 Hz. At the resonant frequency, the trampoline-based metamaterial generates a higher voltage than the defect-based acoustic metamaterial. The maximum open-circuit voltage of the trampoline-based metamaterial is 1.5 times that of the defect-based acoustic metamaterial. Figure 2 The stress distribution of the defect-type acoustic metamaterial in the upper right corner and the trampoline metamaterial in the upper left corner of the illustration show that under acoustic excitation at the resonant frequency, the stress is concentrated at the defect. The stress distribution of the defect-type acoustic metamaterial is concentrated at the edge of the piezoelectric patch, while the stress of the trampoline metamaterial is concentrated in the center of the piezoelectric patch. The trampoline metamaterial completes the function of energy focusing and amplification. The surface stress distribution of the trampoline metamaterial at the resonant frequency is more concentrated in the center of the piezoelectric patch than that of the defect-type acoustic metamaterial, which leads to an increase in the output voltage. When the incident sound pressure is 1Pa, the sound pressure fields of the defect-type acoustic metamaterial and the trampoline metamaterial at the resonant frequency are shown as follows: Figure 2 The right and left insets of the metamaterial subsystem are shown. After adding the trampoline structure at the defect in the metamaterial subsystem, the acoustic pressure is significantly more concentrated. This demonstrates that the trampoline effect has a positive impact on the stress distribution in the device, and the acoustic transmission is high enough to cause the piezoelectric patch to vibrate.

[0031] Figure 3 The figure below is a comparison of the band structure characteristics and defect mode of the trampoline metamaterial and defect-type acoustic metamaterial in the simulation. Figure 3 (b) Numerical simulations show that the band structure of the trampoline metamaterial supercell has a complete band gap from 1864 Hz to 2683 Hz. The flat band formed within the complete band gap is a defect band, with a frequency of 2374 Hz. Figure 3 The vibration mode of the defect-type acoustic metamaterial in a is Figure 3 The vibration modes of the trampoline metamaterial in Figure b are different. In the defect mode diagram, the energy of both the defect-based acoustic metamaterial and the trampoline metamaterial is concentrated at the defect location. Besides the defect location, the silicone rubber surrounding the defect in the defect-based acoustic metamaterial also experiences some relatively high energy. Due to the presence of the trampoline structure, the energy of the trampoline metamaterial is primarily concentrated at the central defect surrounded by the trampoline structure. Compared to the defect modes of the defect-based acoustic metamaterial, the trampoline effect results in a more concentrated energy concentration in the defect modes of the trampoline metamaterial.

[0032] In order to illustrate the method of constructing a trampoline acoustic metamaterial based on the invented cells and verify its energy concentration and amplification effects, the present invention specifically designed a sample of the trampoline acoustic metamaterial based on the cellular structure, and carried out vibration tests to test the vibration response characteristics under different incident sound pressure frequencies, verifying the effectiveness of the local resonance cell design method based on the trampoline effect.

[0033] The following is a detailed description of the experimental methods and results with reference to the illustrations.

[0034] Experimental setup such as Figure 4 In order to prevent the influence of environmental noise on the output signal, the entire experiment was carried out in an anechoic chamber.

[0035] The experiment involves three processes: sound signal generation, sound pressure acquisition, and signal processing. In the sound signal generation process, a sinusoidal signal is generated by an arbitrary function generator. The signal is then amplified by a power amplifier and fed to a speaker. Figure 4 Upper left device.

[0036] Sound pressure collection is achieved by converting sound energy into electrical energy using a local resonance acoustic metamaterial based on the trampoline effect. The speaker faces the local resonance acoustic metamaterial based on the trampoline effect, so the sound pressure is incident vertically. At the same time, the incident sound pressure is measured by a microphone placed parallel to the local resonance acoustic metamaterial based on the trampoline effect. The microphone is Figure 4 Lower left device.

[0037] For signal processing, a data acquisition device was used to record the sound pressure and voltage data. The device was connected to the local resonance acoustic metamaterial based on the trampoline effect and the microphone. A computer equipped with dynamic signal acquisition and analysis software finally received all the data from the data acquisition device. The data acquisition device is as follows: Figure 4 Shown on the right.

[0038] To ensure that the structure resonates, the incident sound pressure frequency ranged from 1500Hz to 3000Hz. To find the resonant frequency, the output voltage data per unit sound pressure was analyzed to eliminate the influence of sound pressure changes. To eliminate the influence of sound pressure stability, Figure 4 The upper right panel shows the transmission spectrum of the trampoline metamaterial's open-circuit voltage per unit acoustic pressure. The unit voltage reaches its maximum at a frequency of 2406 Hz. The maximum transmission spectrum of the trampoline metamaterial energy harvester (10 1.87 mV / Pa) is approximately 2.6 times the maximum voltage (39.71 mV / Pa) of the metamaterial-Helmholtz coupled energy harvester (MHCR). The maximum transmission spectrum of the defect-type acoustic metamaterial energy harvester (11.40 mV / Pa) is also significantly lower than that of the trampoline metamaterial energy harvester. Furthermore, the trampoline metamaterial energy harvester is sensitive to the most important frequency range (2000-2500 Hz) for mechanical noise, which produces relatively large transmission ratios.

[0039] According to the above experiments and simulations, the novel acoustic energy harvester based on the acoustic trampoline metamaterial of the present invention can effectively improve the energy density of acoustic energy harvesting. It can be seen from the defect mode, stress distribution and pressure distribution that the trampoline metamaterial exhibits a more concentrated acoustic energy focusing capability than the defect-type acoustic metamaterial. In the simulation, the maximum output voltage of the trampoline metamaterial is 1.5 times that of the defect-type acoustic metamaterial. Compared with the M HCR energy harvester (39.71mV / Pa) and the defect-type acoustic metamaterial energy harvester (11.40mV / Pa), the manufactured trampoline metamaterial acoustic energy harvester has a huge improvement in the transmission ratio of 101.87mV / Pa.

[0040] In summary, the present invention addresses the structural design and resonance enhancement issues of a sound pressure focusing module for a locally resonant acoustic metamaterial plate. This invention utilizes the unique periodic structure of the acoustic metamaterial to generate a localized resonance effect, and based on this, a trampoline structure is designed. This trampoline structure can further enhance vibrations at defects within the acoustic metamaterial and convert vibrational energy into electrical output via piezoelectric plates. Acoustic metamaterial structures designed using this cellular structure can absorb noise and convert it into usable energy.

[0041] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A localized resonant acoustic metamaterial cellular structure based on a trampoline effect, characterized by: The invention comprises a flat base (2), a plurality of resonators (1) arranged on a surface of one side of the base (2), and a piezoelectric plate (4) arranged at the center of the base (2); the plurality of resonators (1) are arranged in an array and four resonators (1) located at the center of the base (2) are removed, so that a defect cavity is formed in the area of ​​the center of the base (2) where the four resonators (1) are removed; Four fan-shaped through-hole trampoline structures (3) are arranged around the piezoelectric sheet (4) in the defect cavity area on the base (2).

2. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 1, characterized in that: The material of the base (2) includes an aluminum plate.

3. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 1 or 2, characterized in that: The material of the resonator (1) includes silicone rubber.

4. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 1 or 2, characterized in that: The piezoelectric piece (4) is in the shape of a circular piezoelectric patch.

5. The local resonance acoustic metamaterial cellular structure based on the trampoline effect according to claim 2, characterized in that: The base (2) is in the shape of a square flat plate.

6. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 1 or 2, characterized in that: The resonator (1) is cylindrical and is arranged perpendicular to the base (2).

7. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 6, characterized in that: The resonators (1) are arranged in a 6×6 periodic array with the central four resonators (1) removed.

8. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 1 or 2, characterized in that: The distance between every two resonators (1) is equal.

9. The localized resonant acoustic metamaterial cellular structure based on the trampoline effect according to claim 8, characterized in that: The distance between each two trampoline structures (3) is equal to the distance between each two resonators (1).

10. The local resonance acoustic metamaterial cellular structure based on the trampoline effect according to claim 9, characterized in that: The distance between the inner and outer diameters of the fan-shaped through hole is equal to the spacing between every two trampoline structures (3).

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