CN113140208A - Electromagnetic regulation and control film type active acoustic metamaterial - Google Patents

Electromagnetic regulation and control film type active acoustic metamaterial Download PDF

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Publication number
CN113140208A
CN113140208A CN202110316046.4A CN202110316046A CN113140208A CN 113140208 A CN113140208 A CN 113140208A CN 202110316046 A CN202110316046 A CN 202110316046A CN 113140208 A CN113140208 A CN 113140208A
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magnetic field
acoustic metamaterial
elastic film
double
film
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吴卫国
刘闯
毕佳楠
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Jiangsu University
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Jiangsu University
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials
    • G10K11/168—Plural layers of different materials, e.g. sandwiches
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
    • B32B25/20—Layered products comprising a layer of natural or synthetic rubber comprising silicone rubber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
    • B32B2307/102—Insulating

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Building Environments (AREA)

Abstract

The invention relates to the technical field of acoustic metamaterials with active control of low-frequency noise, in particular to an electromagnetically-controlled film type active acoustic metamaterial. The device consists of a double-layer elastic film with a controllable interlayer design, a weak magnetic property measuring block and a weak magnetic annular frame. Wherein the double-layer elastic film with the controllable interlayer design consists of ferromagnetic particles and an elastic film, and bolt holes which are uniformly distributed are reserved on the weak magnetic annular frame. The axial magnetic field generating device comprises an enameled copper wire, an aluminum annular tube, an insulating partition plate and the like. The axial magnetic field generating device is electrified to generate an axial uniform magnetic field, the tension of the double-layer elastic film with the controllable interlayer in the magnetic field is changed under the action of magnetic force, and finally the non-contact active control of the sound insulation characteristic of the acoustic metamaterial is realized.

Description

Electromagnetic regulation and control film type active acoustic metamaterial
Technical Field
The invention relates to the technical field of acoustic metamaterials with active control of low-frequency noise, in particular to an electromagnetically-controlled film type active acoustic metamaterial.
Background
The prosperity of science and technology and the development of industry + promote the progress of social productivity and bring pollution problems such as noise and the like. Noise, especially low frequency noise, not only affects people's daily life, but also destroys the normal operation of buildings and machinery. In noise treatment engineering, acoustic materials occupy the main position of noise treatment technology with the advantages of popularization, practicability, long acting and low price. Conventional acoustic materials are such as: due to the limitation of mass action law, the plate, the porous material and the composite sound absorption material generally need a complex structure to obtain a good sound insulation effect in a low frequency range, and have more limitations in application. Therefore, efficient treatment of low-frequency noise becomes one of the major and difficult points in the development of acoustic technology.
Since the twenty-first century, the development of new acoustic materials with a metamaterial as a core provides a new research idea for noise control. The acoustic metamaterial (acoustic metamaterial for short) is an artificial sub-wavelength composite material, and unique material characteristics can be realized by designing the geometric dimension and the shape structure of the material. In recent years, researchers have proposed a large number of acoustic metamaterials, which provide an advantageous structural model for low-frequency noise control. In 2016, Ficus microcarpa et al designed an acoustic metamaterial (patent application number is CN201611165543.4) with a silicon rubber film added into a Helmholtz cavity, and the natural frequency of the structure can be adjusted by changing the position of the film, so that semi-active control of the sound insulation performance of the acoustic metamaterial is realized. In 2018, anecdotal et al designed a magneto-rheological material-based magnetic solid coupling active acoustic metamaterial (patent application number is cn201811083083.x), and by applying a radial magnetic field on a magneto-rheological film, directional adjustment of the natural frequency of the acoustic metamaterial is realized in a low-frequency range.
The structure of the traditional acoustic material and the semi-active acoustic metamaterial is relatively fixed, and the inherent frequency is difficult to change; the preparation conditions of the magnetorheological material are complex, and once the magnetorheological material is prepared, the organization structure of the magnetorheological material is difficult to change and easy to settle, so that the magnetorheological material is difficult to adapt to a complex sound insulation environment.
The film type acoustic metamaterial has wide application prospect due to the light and high-efficiency low-frequency sound insulation performance. The sound insulation effect can be directionally controlled by changing the tension of the film, and the active control of sound insulation is realized.
Disclosure of Invention
The invention provides an electromagnetically regulated and controlled film type active acoustic metamaterial, which is characterized in that the magnetic field intensity is controlled by inputting currents with different magnitudes, the tension of an elastic film is further changed, and finally the directional regulation of the sound insulation peak value of the acoustic metamaterial is realized in a non-contact active control mode.
The technical scheme of the invention is as follows: the film type acoustic metamaterial comprises a film type acoustic metamaterial and an axial magnetic field generating device, wherein the film type acoustic metamaterial comprises a double-layer elastic film, a weak magnetic property measuring block and a weak magnetic annular frame, and the interlayer of the double-layer elastic film is controllably designed. Wherein the double-layer elastic film with the controllable interlayer design consists of ferromagnetic particles and an elastic film, and bolt holes which are uniformly distributed are reserved on the weak magnetic annular frame. The ferromagnetic particles have the characteristics of high magnetic permeability, high magnetic saturation rate and the like, the elastic film has the characteristics of light weight and high elasticity, and the weak magnetic quality gauge block is not influenced by the change of a magnetic field. The preparation process of the film type acoustic metamaterial comprises the following steps: an elastic film is horizontally placed on the experiment table, ferromagnetic particles are uniformly distributed on the elastic film according to a set thickness, the thickness of the elastic film can be controlled by a weak magnetic thickness plate, the ferromagnetic particles are uniformly leveled, and another elastic film is naturally placed on the upper surface of the ferromagnetic particles to prepare the double-layer elastic film with the controllable interlayer design. The method comprises the steps of applying prestress to a double-layer elastic film with a controllable interlayer by using a prestress loading device (the patent application number is CN201810840954.1), tensioning, respectively placing two weak-magnetic annular frames on the upper surface and the lower surface of the double-layer elastic film with the controllable interlayer, aligning reserved bolt holes of the two weak-magnetic annular frames, and screwing the weak-magnetic annular frames by using bolts. At the moment, the double-layer elastic film with the controllable interlayer design is fixedly clamped by the two weak magnetic annular frames. Cutting the double-layer elastic film with the controllable interlayer along the inner side of the prestress loading device by using an art designing knife, taking out the weak magnetic annular frame, cutting the weak magnetic annular frame for the second time along the edge of the weak magnetic annular frame by using the art designing knife, and removing burrs and cleaning the film. And (3) coating glue on the bottom surface of the weak magnetic property measuring block, and bonding the weak magnetic property measuring block to the center of a circle on one side of the double-layer elastic film with the controllable interlayer by using tweezers. And winding a layer of sound insulation adhesive tape on the outer side of the weak magnetic annular frame, and coating a layer of industrial vaseline to prevent sound leakage, thus finishing the preparation of the film type acoustic metamaterial. The axial magnetic field generating device comprises an enameled copper wire, a weak magnetic annular tube, insulating partition plates and the like, wherein the weak magnetic annular tube is processed into a cylinder shape, the enameled copper wire is tightly wound on the outer surface of the weak magnetic annular tube by a winding machine according to the number of turns required by the magnetic field intensity, wiring terminals at two ends are reserved to be connected with an external power supply, two insulating partition plates are respectively bonded on the outer surface of the weak magnetic annular tube by hot melt adhesives at two ends of the axial edge of the enameled copper wire, and the axial magnetic field generating device is prepared. And placing the film type acoustic metamaterial into the wound weak magnetic annular tube along the axial direction of the axial magnetic field generating device, wherein the film type acoustic metamaterial is close to one end of the N pole of the axial magnetic field generating device and is vertical to the axial direction of the weak magnetic annular tube during placement.
In the scheme, the ferromagnetic particles have the particle size of 1-50um and are carbonyl iron powder which is uniformly distributed with the elastic film.
Furthermore, the thickness of the ferromagnetic particles is 0.1-1.0mm, and the radius is 10-18 mm.
Furthermore, the thickness of the ferromagnetic particles is controlled by a weak magnetic thickness plate.
In the scheme, the radius of the elastic film is 10-18mm, and the thickness of the elastic film is 0.2-0.6 mm.
In the scheme, the radius of the weak magnetic property measuring block is 2-8mm, and the thickness of the weak magnetic property measuring block is 1-5 mm.
In the scheme, the radius of the weak magnetic annular frame is 10-18mm, and the thickness of the single piece is 1-4 mm.
In the scheme, the double-layer elastic film with the controllable interlayer is fixedly clamped by two weak magnetic annular frames and is screwed and fixed by bolts.
In the above scheme, the thin film type acoustic metamaterial member is disposed at one end of the axial magnetic field generating device close to the N pole.
Furthermore, the inner radius of the weak magnetic ring-shaped pipe is consistent with the outer radius of the weak magnetic ring-shaped frame in size, the length is 60mm,
further, the input current intensity range of the axial magnetic field generating device is 0-60A.
Furthermore, the N pole direction of the electrified axial magnetic field generating device is opposite to the incidence direction of the sound wave.
The invention has the advantages that:
1. the preparation is simple, the double-layer elastic film with the controllable interlayer design is clamped and fixed by the weak-magnetic annular frame, the preparation is convenient, the process is simple, and the batch production can be realized.
2. The prepared film type acoustic metamaterial has excellent controllability and adjustability in a magnetic field on the premise of ensuring good sound insulation performance.
3. The regulation and control method is simple, and when the noise frequency changes, the structure size of the film type acoustic metamaterial does not need to be changed, and a good sound insulation regulation and control effect can be achieved in a non-contact active control mode only by controlling the current.
4. The prepared film type acoustic metamaterial has uniform ferromagnetic particle distribution and stable property, can effectively avoid the problems of sedimentation and the like, and can be recycled.
Drawings
FIG. 1 is a schematic structural diagram of a thin film type acoustic metamaterial placed in an axial magnetic field generating device.
FIG. 2 is a schematic structural diagram of a thin film type acoustic metamaterial unit according to the present invention.
FIG. 3 is a schematic cross-sectional view of a thin film type acoustic metamaterial unit structure in accordance with the present invention.
FIG. 4 is a schematic diagram of the incident direction of sound waves and the direction of a magnetic field in the simulation process of the thin film type acoustic metamaterial.
FIG. 5 is a graph showing the variation of acoustic transmission loss when the thin film type acoustic metamaterial is subjected to different forces per unit area in the invention.
FIG. 6 is a graph showing the change of acoustic transmission loss when the structure is subjected to different forces per unit area when the thickness of carbonyl iron powder is 0.5mm, the thickness of a single-layer silicon rubber film is 0.2mm, and the thickness of a double-layer elastic film with a controllable interlayer design is 0.9 mm.
FIG. 7 is a graph showing the acoustic transmission loss variation of a structure under different forces per unit area when the thickness of carbonyl iron powder is 0.5mm, the thickness of a single-layer silicon rubber film is 0.3mm, and the thickness of a double-layer elastic film with a controllable interlayer design is 1.1 mm.
FIG. 8 is a graph showing the acoustic transmission loss variation of a structure under different forces per unit area when the thickness of carbonyl iron powder is 0.5mm, the thickness of a single-layer silicon rubber film is 0.4mm, and the thickness of a double-layer elastic film with a controllable interlayer design is 1.3 mm.
Fig. 9 is a comparison graph of sound insulation peak value movement amounts of the film type acoustic metamaterial when three interlayer controllable design double-layer elastic films with different thicknesses are selected, and when the same prestress is applied, the thicker the interlayer controllable design double-layer elastic film thickness is, the larger the sound insulation peak value movement amount is.
FIG. 10 is a graph showing the variation of the acoustic transmission loss of the structure of the present invention when the Young's modulus of the two-layer elastic film with controllable interlayer design is 1 MPa.
FIG. 11 is a graph showing the change of acoustic transmission loss of a structure with a Young's modulus of 3MPa in a two-layer elastic film with a controllable interlayer design according to the present invention.
FIG. 12 is a graph showing the change of the acoustic transmission loss of the structure when the Young's modulus of the two-layer elastic film with controllable interlayer design is 5 MPa.
Fig. 13 is a comparison graph of changes in sound insulation peak value movement amount of three interlayer-controllable double-layer elastic films with different young moduli, wherein when the thicknesses of the interlayer-controllable double-layer elastic films are the same, the young modulus is larger, and the sound insulation peak value movement amount is larger.
Description of reference numerals: 1-a weak magnetic property gauge block; 2-an elastic film; 3-a magnetically weak annular frame; 4-weak magnetic annular tube inner wall; 5-enameled copper wire; 6-direction of current flow; 7-current outflow direction; 8-ferromagnetic particles; 9-direction of incidence of the sound waves; 10-magnetic field direction.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings.
In the embodiment, the elastic film is a silicon rubber film, the ferromagnetic particles are carbonyl iron powder, the weak magnetic annular frame is an aluminum annular frame, the weak magnetic quality block is a lead quality block, and the weak magnetic annular tube is an aluminum annular tube.
Fig. 1 shows an electromagnetically controlled thin film type active acoustic metamaterial unit according to the present invention, which is implemented as follows,
the first step is as follows: horizontally placing a silicon rubber film on a test bed;
the second step is that: placing a thickness plate with a round hole on the silicon rubber film, adding carbonyl iron powder on the silicon rubber film along the round hole thickness plate, and stopping adding the carbonyl iron powder when the thickness of the carbonyl iron powder is consistent with the height of the round hole thickness plate;
the third step: and scraping redundant carbonyl iron powder along the round hole thickness plate by using a scraper, and ensuring that the thickness of the carbonyl iron powder is consistent with the height of the round hole thickness plate. Taking down the round hole thickness plate, and lightly paving the other layer of silicon rubber film on the upper surface of the carbonyl iron powder to prepare a double-layer elastic film with a controllable interlayer design;
the fourth step: putting the double-layer elastic film with the controllable interlayer design into a prestress loading device (with the patent application number of CN201810840954.1), applying prestress by the prestress loading device, and tensioning the double-layer elastic film with the controllable interlayer design;
the fifth step: clamping the upper side and the lower side of a double-layer elastic film with a controllable interlayer by using an aluminum annular frame, and screwing and fixing by using five bolts;
and a sixth step: cutting the double-layer elastic film with the controllable interlayer design along the edge of the inner side of the prestress loading device by using an art designer, and taking out the double-layer elastic film with the controllable interlayer design fixed by the aluminum annular frame;
the seventh step: bonding a lead mass block on one side of the double-layer elastic film with the interlayer controllable design by using glue;
eighth step: winding a layer of sound insulation adhesive tape on the outer side of the aluminum annular frame, and uniformly coating a layer of industrial vaseline to prevent sound leakage;
the ninth step: placing the prepared film type acoustic metamaterial structure in an axial magnetic field generating device, wherein the position of the prepared film type acoustic metamaterial structure is close to the position of 5cm on the N pole side of the axial magnetic field generating device;
the tenth step: and (3) introducing the direct-current power supply into the axial magnetic field generating device, adjusting the magnitude of the input current, and measuring an acoustic transmission loss curve chart of the film type acoustic metamaterial under different magnetic field strengths by the acoustic measuring system.
As shown in FIG. 2, the structure of the thin film type acoustic metamaterial is formed by an aluminum annular frame with an outer radius of 17mm and an inner radius of15mm, and the thickness of each single piece is 2 mm; the radius of the silicon rubber film is 15mm, and the single-layer thickness is 0.2 mm; the thickness of the carbonyl iron powder is 0.5 mm; the lead mass block has a radius of 4mm and a thickness of 4 mm. The material parameters of the thin film type acoustic metamaterial structure are as follows: aluminum [ density rho is 2700kg/m3(ii) a Elastic modulus E ═ 7E10 Pa; poisson ratio v is 0.33](ii) a Lead [ density rho 11680kg/m3(ii) a Elastic modulus E ═ 1.7E10 Pa; poisson ratio v is 0.42](ii) a Elastic film [ density rho 980kg/m3(ii) a Elastic modulus E ═ 3E6 Pa; poisson ratio v is 0.47]。
The sound insulation curve of the electromagnetically-controlled thin-film type active acoustic metamaterial is calculated by an 'acoustic-solid coupling and frequency domain' module in COMSOL Multiphysics5.5 finite element software, and FIG. 5 is a sound insulation curve change diagram of a structure of the thin-film type active acoustic metamaterial under different axial forces.
As shown in fig. 5, the input current of the axial magnetic field generator is sequentially changed, the force per unit area on the double-layer elastic film with the controllable interlayer is changed, the sound insulation peak frequency of the structure is obviously shifted, and the maximum shift amount is about 60Hz, so that the designed film type acoustic metamaterial can realize the non-contact active control of the sound insulation characteristic, and effectively broaden the controllable range of low-frequency sound insulation.
The electromagnetic control film type active acoustic metamaterial provided by the invention is used for achieving an ideal sound insulation effect, keeping the thickness of carbonyl iron powder unchanged and researching the influence of the thickness of a silicon rubber film on the change of sound insulation peak frequency. Keeping other parameters unchanged, respectively selecting the thickness of the double-layer elastic film with the controllable interlayer design as 0.9mm, 1.1mm and 1.3mm, and calculating the sound insulation effect of the film type acoustic metamaterial.
The prepared double-layer elastic film with the thickness of 0.9mm and the controllable interlayer is selected, and currents with different intensities are sequentially input to obtain the sound insulation curve change of the film type acoustic metamaterial under different magnetic field intensities, as shown in fig. 6.
The prepared double-layer elastic film with the controllable interlayer of 1.1mm is selected, and currents with different intensities are sequentially input to obtain the sound insulation curve change of the film type acoustic metamaterial under different magnetic field intensities, as shown in fig. 7.
The prepared double-layer elastic film with the controllable interlayer of 1.3mm is selected, and currents with different intensities are sequentially input to obtain the sound insulation curve change of the film type acoustic metamaterial under different magnetic field intensities, as shown in fig. 8.
As shown in fig. 9, the double-layer elastic films with controllable interlayer designs of different thicknesses are selected, and with the increase of the thickness of the double-layer elastic film with controllable interlayer design, the sound insulation peak value moves to high frequency overall, and the sound insulation peak value moving amount is gradually increased by applying the same force per unit area.
In order to achieve an ideal sound insulation effect, the influence of the double-layer elastic film with controllable interlayer design of different Young modulus on a sound insulation peak value is further researched. Keeping other parameters unchanged, respectively selecting a double-layer elastic film with a controllable interlayer design and Young modulus of 1MPa, 3MPa and 5MPa, and calculating the sound insulation effect of the film type acoustic metamaterial.
Selecting a double-layer elastic film with a controllable interlayer design and a Young modulus of 1MPa, and sequentially inputting currents with different intensities to obtain the sound insulation curve change of the film type acoustic metamaterial under different magnetic field strengths, as shown in FIG. 10.
Selecting a double-layer elastic film with a controllable interlayer design and a Young modulus of 3MPa, and sequentially inputting currents with different intensities to obtain the sound insulation curve change of the film type acoustic metamaterial under different magnetic field strengths, as shown in FIG. 11.
Selecting a double-layer elastic film with a controllable interlayer design and a Young modulus of 5MPa, and sequentially inputting currents with different intensities to obtain the sound insulation curve change of the film type acoustic metamaterial under different magnetic field strengths, as shown in FIG. 12.
As shown in fig. 13, as the young's modulus of the two-layer elastic film of the interlayer controlled design increases, the sound insulation peak frequency shifts to a high frequency as a whole, and the amount of shift of the sound insulation peak gradually increases when the same force per unit area is applied.
According to the characteristics of the electromagnetic control film type active acoustic metamaterial, the electromagnetic control film type active acoustic metamaterial can be applied to vibration reduction and noise reduction in the aspects of buildings, traffic, machinery and the like, and particularly has a good application prospect in the aspect of sound insulation regulation and control.
The above description is of a preferred embodiment and is not intended to be taken as an exhaustive description of the invention, and any obvious modifications or simple variations thereof based on the electromagnetically controlled membrane-type active acoustic metamaterial of the present invention are intended to be covered by the present invention.

Claims (7)

1. The electromagnetically regulated and controlled film-type active acoustic metamaterial is characterized by comprising a film-type acoustic metamaterial and an axial magnetic field generating device, wherein the film-type acoustic metamaterial is composed of a double-layer elastic film with a controllable interlayer, a weak magnetic property gauge block and a weak magnetic annular frame, the double-layer elastic film with the controllable interlayer is composed of ferromagnetic particles and an elastic film, the ferromagnetic particles are positioned between an upper layer of tensioned elastic film and a lower layer of tensioned elastic film and are uniformly distributed on the elastic film according to a set thickness; the weak magnetic annular frame for fixing is positioned on the upper surface and the lower surface of the double-layer elastic film containing ferromagnetic particles, and the weak magnetic quality gauge block is fixed at the circle center of one side of the double-layer elastic film with the controllable interlayer design; the film type acoustic metamaterial is placed into a weak magnetic annular pipe wound by the axial magnetic field generating device along the axial direction of the axial magnetic field generating device, current is introduced into the axial magnetic field generating device, the currents with different strengths are input to control the magnetic field strength, the tension of the double-layer elastic film with the controllable design of the interlayer is changed, and finally the directional regulation and control of the sound insulation peak value are realized.
2. The electromagnetically controlled thin film type active acoustic metamaterial as claimed in claim 1, wherein the axial magnetic field generating device is composed of an enameled copper wire, a weak magnetic ring tube and an insulating partition plate, the weak magnetic ring tube is processed into a cylindrical shape, the enameled copper wire is tightly wound on the outer surface of the weak magnetic ring tube according to the number of turns required by the magnetic field intensity, terminal blocks at two ends are left to be connected with an external power supply, and two insulating partition plates are respectively bonded on the outer surface of the weak magnetic ring tube by hot melt adhesives at two ends of the axial edge of the enameled copper wire to obtain the axial magnetic field generating device.
3. The electromagnetically tuned thin film active acoustic metamaterial according to claim 2, wherein the inner radius of the weakly magnetic toroidal tube is the same size as the outer radius of the weakly magnetic toroidal frame, and the length of the weakly magnetic toroidal tube is greater than 4 times the inner radius of the weakly magnetic toroidal tube.
4. The electromagnetically tuned thin film type active acoustic metamaterial according to claim 1, wherein said ferromagnetic particles have a particle size of 1-50um and are carbonyl iron powder; the thickness of the ferromagnetic particles is 0.1-1.0 mm.
5. The electromagnetically tuned thin film type active acoustic metamaterial according to claim 1, wherein the elastic thin film has a radius of 10-18mm and a thickness of 0.2-0.6 mm; the radius of the weak magnetic property measuring block is 2-8mm, and the thickness is 1-5 mm; the radius of the weak magnetic annular frame is 10-18mm, and the thickness of the single piece is 1-4 mm.
6. The electromagnetically tuned thin film type active acoustic metamaterial according to claim 1, wherein the thin film type acoustic metamaterial member is disposed at an end of the axial magnetic field generating device near the N-pole and perpendicular to an axial direction of the weakly magnetic toroidal tube.
7. The electromagnetically tuned thin film type active acoustic metamaterial according to claim 1, wherein the axial magnetic field generating means has an input current intensity ranging from 0 to 60A, and the N-pole direction of the energized axial magnetic field generating means is opposite to the incident direction of the acoustic wave.
CN202110316046.4A 2021-03-24 2021-03-24 Electromagnetic regulation and control film type active acoustic metamaterial Pending CN113140208A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117360026A (en) * 2023-12-07 2024-01-09 迈默智塔(无锡)科技有限公司 Composite material with sound insulation and electromagnetic prevention functions for building

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117360026A (en) * 2023-12-07 2024-01-09 迈默智塔(无锡)科技有限公司 Composite material with sound insulation and electromagnetic prevention functions for building

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