CN116129845A - Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism - Google Patents

Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism Download PDF

Info

Publication number
CN116129845A
CN116129845A CN202211622128.2A CN202211622128A CN116129845A CN 116129845 A CN116129845 A CN 116129845A CN 202211622128 A CN202211622128 A CN 202211622128A CN 116129845 A CN116129845 A CN 116129845A
Authority
CN
China
Prior art keywords
film
mode
metamaterial
magnetic
acoustic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202211622128.2A
Other languages
Chinese (zh)
Inventor
陈兴
刘兰华
伍向阳
张毅超
潘镜冲
谭辉
潘永琛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Academy of Railway Sciences Corp Ltd CARS
Energy Saving and Environmental Protection and Occupational Safety and Health Research of CARS
Original Assignee
China Academy of Railway Sciences Corp Ltd CARS
Energy Saving and Environmental Protection and Occupational Safety and Health Research of CARS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China Academy of Railway Sciences Corp Ltd CARS, Energy Saving and Environmental Protection and Occupational Safety and Health Research of CARS filed Critical China Academy of Railway Sciences Corp Ltd CARS
Priority to CN202211622128.2A priority Critical patent/CN116129845A/en
Publication of CN116129845A publication Critical patent/CN116129845A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

Abstract

The invention relates to a mode-switchable film type acoustic metamaterial structure based on a magnetic control mechanism, which relates to the technical field of noise control and comprises the following steps: (1) constructing a film metamaterial sound-vibration coupling model; (2) establishing a film metamaterial magnetic control force relationship; (3) designing a thin film type metamaterial structure; (4) calibrating magnetic force of the circular ring mass block; (5) The film type metamaterial is prepared, and mode switching based on a magnetic control mechanism is realized. The mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism has the characteristic of strong designability, and finally realizes non-contact and discontinuous regulation.

Description

Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism
Technical Field
The invention relates to an acoustic metamaterial with adjustable acoustic performance, in particular to a mode-switchable film-type acoustic metamaterial structure based on a magnetic control mechanism, and belongs to the technical field of noise control.
Background
Because natural materials have weak inherent dissipation in low frequency bands, the control of low frequency sound waves has always presented a great challenge. Although the traditional porous sound absorption material and impedance matching design can obtain better sound absorption effect in a middle-high frequency band, the traditional porous sound absorption material and impedance matching design still have inadaptability in the aspect of realizing small-size control of large wavelength.
As the acoustic performance of composite materials and structures has been studied intensively, it has been found that they have properties different from those of natural acoustic materials, and such structures are collectively referred to as acoustic artificial structures. The "acoustic metamaterial" refers to a structure which is formed by designing materials according to a specific combination mode to obtain acoustic properties which cannot be possessed by materials in nature, and is characterized in that the working wavelength is far greater than the geometric dimension of a cell of the material, and the material can be characterized by equivalent parameters. The elastic constant and density of the material in the nature are positive values, and the acoustic metamaterial enriches the selectable range of material parameters, such as negative equivalent material parameters, zero coefficient equivalent material parameters and the like. Therefore, the acoustic metamaterial structure design can improve the control capability of sound waves, and has good application prospect.
By utilizing a local resonance mechanism, the film type metamaterial can realize singular phenomena such as negative mass, negative modulus, double negative parameters, perfect sound absorption and the like in a low frequency band. However, due to the influence of the action mechanism, the passive metamaterial has a narrow working band, cannot adapt to the change of environment and requirements and has a single function. Therefore, researchers have proposed to design adjustable acoustic metamaterials using intelligent materials and controlling structural state changes. For example, it has been reported that thin film acoustic metamaterials based on piezoelectric materials can achieve continuous regulation of equivalent parameters within a certain range; elastic metamaterials have been reported that utilize structural buckling-induced structural geometry changes to achieve passband and forbidden band switching. However, the acoustic metamaterial adopting the electric control mode utilizes the force-electric coupling effect of the intelligent material, and has the advantages of high input voltage, limited regulation and control range and contact control. The existing regulation and control mechanism based on circuit feedback needs a more complex system, needs to apply a strong electromagnetic field, and mostly controls acoustic performance continuously.
Therefore, the mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism is provided, non-contact regulation and control are realized by utilizing a magnetic field, force change in the structure is induced, force symmetry in the structure is broken, an implicit asymmetric mode is excited, mutation of acoustic properties is realized, the problem that a strong electromagnetic field needs to be applied to the film type metamaterial based on the electromagnetic intelligent material parameter regulation and control mechanism is solved, the control mode is simple, and the design is convenient, so that the technical problem to be solved urgently in the technical field is solved.
Disclosure of Invention
The invention aims to provide a mode-switchable film type acoustic metamaterial structure based on a magnetic control mechanism, which utilizes a magnetic field to realize non-contact regulation and control, induces force change in the structure, breaks the force symmetry in the structure, excites an implicit asymmetric mode, realizes mutation of acoustic properties, solves the problem that a film type metamaterial based on an electromagnetic intelligent material parameter regulation mechanism needs to apply a strong electromagnetic field, and has simple control mode and convenient design.
The above object of the present invention is achieved by the following technical solutions:
a mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism, comprising: elastic film, paramagnetic metal circular ring sheet and circular ring mass block; the elastic film is fixed on the paramagnetic metal circular ring sheet, and the circular ring mass block is formed by compounding a ferromagnetic material and a paramagnetic material and is bonded and connected with the elastic film to form an axisymmetric structure.
Preferably, the annular mass has a uniform areal density.
Preferably, the ferromagnetic material is iron with a density of 7800kg/m 3 。
Preferably, the method comprises the steps of,the paramagnetic material is copper with the density of 8900kg/m 3 。
Preferably, the ferromagnetic material occupies 1/8-1/4 of the area of the annular mass block.
Preferably, the ferromagnetic material occupies 1/6 of the area of the annular mass.
Preferably, the flange device is further included, and the axisymmetric structure is fixed in the flange device.
Preferably, the axisymmetric structure is in threaded connection with the flange device.
The invention further aims to provide a preparation method of the mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism, wherein non-contact regulation and control are realized by utilizing a magnetic field, internal force change of the structure is induced, the internal force symmetry of the structure is broken, an implicit asymmetric mode is excited, mutation of acoustic properties is realized, the problem that a strong electromagnetic field needs to be applied to the film type metamaterial based on the electromagnetic intelligent material parameter regulation and control mechanism is solved, and the control mode is simple and convenient to design.
The above object of the present invention is achieved by the following technical solutions:
a preparation method of a mode-switchable film type acoustic metamaterial structure based on a magnetic control mechanism comprises the following steps:
(1) Construction of film-type metamaterial sound-vibration coupling model
Constructing a film type metamaterial sound-vibration coupling model to form a composite structure of an elastic film with a central bonding ring mass block, wherein the ring mass block is composed of ferromagnetic materials and paramagnetic materials and has uniform surface density;
(2) Establishing a magnetic control force relation of a film metamaterial
According to the film type metamaterial acoustic-vibration coupling model in the step (1), solving the influence of different magnetic forces on the internal force of the film structure, and calculating the modal frequency and the vibration mode of the film type metamaterial under the action of the different magnetic forces;
(3) Design film type metamaterial structure
According to the film type metamaterial acoustic-vibration coupling model in the step (1), establishing a relationship between film tension, geometric parameters and design parameters of a circular mass block and structural vibration characteristics, calculating the mode frequency and the vibration mode of the film type metamaterial in a concerned frequency band, designing a film type metamaterial structure according to the requirement of a target working frequency band, and determining magnetic force required to be applied for regulation and control according to the film type metamaterial magnetic control force relationship established in the step (2);
(4) Calibrating magnetic force of circular ring mass block
Determining a magnetic force action mode, and applying magnetic force to the circular ring mass block by adopting a permanent magnet or an electromagnet;
(5) The mode is switchable based on a magnetic control mechanism by preparing the film type metamaterial
And (3) fixing the film with uniform tension on the paramagnetic metal circular ring sheet according to the design parameters determined in the step (3), and bonding a circular ring mass block formed by compounding a ferromagnetic material and a paramagnetic material to the center of the film to form an axisymmetric structure.
Preferably, in the step (1), the area ratio of the ferromagnetic material to the annular mass is 1/6.
Preferably, in the step (1), a film metamaterial sound-vibration coupling model is constructed, and a kinetic equation is as follows:
Figure BDA0004002506660000031
wherein eta is the displacement of the elastic film by transverse vibration, sigma 0 Radial stress generated by initial tension of the elastic film, wherein ρ is the density of the elastic film, and f is the sound pressure load; the boundary between the circular ring mass block and the film follows the continuous conditions of displacement and speed, and the relation between sound pressure load and transmission coefficient is established by neglecting high-order scattered waves in consideration of the continuity of speeds at two sides of the film:
f＝2(1-T 0 )
wherein T is 0 Is the transmission coefficient in the case of plane wave incidence.
Preferably, in the step (1), the mode frequency and the mode shape regulation and control effect of the magnetic force on the film metamaterial are considered, and the magnetic control force relation of the film metamaterial is established, specifically:
taking magnetic force influence into consideration, establishing a kinetic equation of circular membrane vibration:
Figure BDA0004002506660000032
wherein sigma m Radial stress generated by initial tension of the elastic film is obtained through a numerical solution method, the distribution condition of the tension in the circular film is obtained, and the mode shape function and the frequency related to the magnetic force are obtained through calculation.
Preferably, in step (2), the following is specific: the natural frequency of the first-order mode is controlled through tension design and ring mass design, the natural frequency of the third-order mode is controlled through ring mass size design, and the magnetic force for realizing the target frequency is determined through calculating the dynamic equation of the vibration of the circular membrane after the magnetic field is applied.
Preferably, in the step (4), if a permanent magnet is adopted, the change condition of magnetic force along with the distance between the permanent magnet and the circular ring mass block needs to be calibrated, and the distance between the permanent magnet and the circular ring mass block in the step (3) is determined according to the requirement of magnetic field regulation and control frequency.
Preferably, in the step (4), the permanent magnet magnetic force loading module is a hollow cylindrical magnet formed by joining 14 small magnets (Nd-FeB).
Preferably, in the step (4), the hollow cylindrical magnet has an inner diameter of 52mm, an outer diameter of 80mm and a height of 100mm.
Preferably, in the step (4), if an electromagnet is adopted, the change condition of magnetic force along with the current intensity of the electromagnet needs to be calibrated, and the current intensity of the electromagnet in the step (3) is determined according to the requirement of magnetic field regulation and control frequency.
The beneficial effects are that:
compared with the prior art, the mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism is characterized in that firstly, a film type metamaterial acoustic vibration coupling model is built, a relation between key design parameters and structural vibration characteristics is built, the film type metamaterial structure design parameters are selected according to a target frequency band, then the magnetic force of a circular ring mass block is calibrated, the film type metamaterial magnetic control force relation is built, finally, the film type metamaterial is prepared, the magnetic control condition is determined, and the mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism is realized.
The mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism can realize non-contact and discontinuous regulation and control, realize mutation of acoustic performance of the structure, and provide a novel means for band gap regulation, equivalent parameter dispersion control and the like; moreover, the film type acoustic metamaterial based on the magnetic control mechanism is simple in regulation and control and high in designability, parameters such as film tension, geometric parameters, annular mass blocks and magnetic force can be designed according to application scenes and target frequency bands, and adaptability to different application scenes is improved.
The invention is further illustrated by the drawings and the detailed description which follow, but are not meant to limit the scope of the invention.
Drawings
FIG. 1 is a flow chart of a method for preparing a mode-switchable thin film acoustic metamaterial based on a magnetic control mechanism in embodiment 1 of the present invention;
fig. 2-1 is a schematic structural diagram of a film-type metamaterial acoustic-vibration coupling model in a mode-switchable film-type acoustic metamaterial structure based on a magnetic control mechanism in embodiment 1 of the present invention.
Fig. 2-2 are physical photographs of a film-type metamaterial acoustic-vibration coupling model in a mode-switchable film-type acoustic metamaterial structure based on a magnetic control mechanism in embodiment 1 of the present invention.
Fig. 3-1 is a schematic structural diagram of a hollow cylindrical magnet loading module formed by joining 14 small magnets (Nd-FeB) in a mode-switchable thin film acoustic metamaterial structure based on a magnetron mechanism according to embodiment 1 of the present invention.
FIG. 3-2 shows the radial tension distribution of the film before and after the application of the magnetic field in example 1 of the present invention.
Fig. 4 is a diagram of a magnetic control mechanism of a mode-switchable thin-film acoustic metamaterial structure based on the magnetic control mechanism.
FIG. 5-1 is an energy band diagram of a thin film acoustic metamaterial in example 1 of the present invention without a magnetic field applied.
Fig. 5-2 shows simulation results and test verification results of the transmittance of the thin film type acoustic metamaterial in example 1 of the present invention when no magnetic field is applied.
FIG. 6-1 is an energy band diagram of a thin film acoustic metamaterial after an external magnetic field is applied in example 1 of the present invention.
Fig. 6-2 shows simulation results and test verification results of the transmittance of the thin film type acoustic metamaterial after an external magnetic field is applied in example 1 of the present invention.
Fig. 7 is an assembly schematic diagram of a mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism in embodiment 1 of the present invention.
Detailed Description
Unless specifically stated, the components used in the invention are all commercially available components conventional in the art, and the connection mode is conventional in the art; the materials used are conventional in the art.
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and detailed description, but it will be understood by those skilled in the art that the examples described below are some, but not all, examples of the present invention, and are intended to be illustrative of the present invention only and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Example 1
Fig. 1 is a flowchart of a method for preparing a mode-switchable thin-film acoustic metamaterial based on a magnetic control mechanism according to embodiment 1 of the present invention;
the invention relates to a preparation method of a mode-switchable film type acoustic metamaterial based on a magnetic control mechanism, which comprises the following steps:
s1, constructing a film metamaterial sound-vibration coupling model;
s2, calculating the influence of different magnetic forces on the internal force of the film structure, obtaining the modal frequency and the vibration mode of the film metamaterial under the action of the different magnetic forces, and establishing the magnetic control force relation of the film metamaterial;
s3, designing a thin film metamaterial structure according to the relation between design parameters such as thin film tension, geometric parameters and annular mass blocks and structural vibration characteristics and determining magnetic force required to be applied for regulation and control based on the relation of magnetic control force of the thin film metamaterial;
s4, determining a magnetic force action mode, and calibrating the influence of magnetic force control parameters on the magnetic force of the circular mass block;
s5, preparing a film type acoustic metamaterial based on a magnetic control mechanism, and realizing a switchable sound propagation mode.
In particular embodiments:
in the S1, the film-type metamaterial acoustic-vibration coupling model is composed of an elastic film and a concentric ring mass block, as shown in fig. 2-1, and is a schematic structural diagram of the film-type metamaterial acoustic-vibration coupling model in the mode-switchable film-type acoustic metamaterial structure based on a magnetic control mechanism in embodiment 1 of the present invention; 2-2, a physical photograph of a film-type metamaterial acoustic-vibration coupling model in a film-type acoustic metamaterial structure based on a mode-switchable magnetic control mechanism in embodiment 1 of the present invention; the film type metamaterial sound-vibration coupling model is formed by bonding an elastic film and a concentric ring mass block to form a composite structure, wherein the concentric ring mass block is made of ferromagnetic materials and paramagnetic materials and has uniform surface density; because the rigidity of concentric ring mass block is far greater than the elastic film, can regard as the rigid body, concentric ring mass block is formed by copper and iron complex, through high matching design, ensure that the areal density is unanimous, still can regard as axisymmetric system on the physical model, the kinetic equation of circular film vibration can be expressed as:
Figure BDA0004002506660000061
wherein eta is the displacement of the elastic film by transverse vibration, sigma 0 The radial stress generated by the initial tension of the elastic film, ρ is the density of the elastic film, f is the sound pressure load, t is the ring mass width, and r is the radial coordinate; the boundary between the concentric ring mass block and the elastic film follows the continuous conditions of displacement and speed;
considering the continuity of speeds at two sides of the film, ignoring high-order scattered waves, and establishing the relationship between sound pressure load and transmission coefficient is as follows:
f＝2(1-T 0 )
wherein T is 0 Is the transmission coefficient in the case of plane wave incidence;
the transverse deflection of the film metamaterial is expressed by adopting a mode superposition method, and the selected vibration mode function is related to a target frequency band and expressed as follows:
Figure BDA0004002506660000071
wherein, N order modes are selected together, W n (R, θ) is the mode shape function of the nth order mode in the polar coordinate system, q n (t) is a mode coefficient corresponding to the nth order mode, considering a low frequency band below the cut-off frequency of the waveguide, ignoring the influence of the high order scattered wave, and obtaining a far field transmission coefficient as follows:
T 0 ＝ρ a c a ωη>
wherein T is 0 Is the transmission coefficient, ρ, of plane waves transmitted from the transmission of the thin film metamaterial to the far field a And c a The density and wave velocity of air, ω is the excitation circle frequency of the plane wave,<η>mean value of the elastic film transverse vibration displacement;
taking the continuity of speeds at two sides of the film into consideration, and solving and obtaining the mode coefficients of each order by utilizing the orthogonality of the film metamaterial modes:
Figure BDA0004002506660000072
wherein q n Is the mode coefficient corresponding to the nth order mode, W n (R, θ) is the mode shape function of the nth order mode in the polar coordinate system, ω n Is the excitation circle frequency of plane wave, T 0 The transmission coefficient of the plane wave transmitted from the thin film type metamaterial to the far field is represented by ρ, the density of the thin film type metamaterial and ω, the excitation circle frequency of the plane wave.
For an axisymmetric structure system, the axisymmetric structure system can be divided into an axisymmetric mode and an antisymmetric mode, under plane wave excitation, the integral of the antisymmetric mode shape on the surface of the structure is 0, and the corresponding mode coefficient is 0, which can be called as a recessive mode, so that the axisymmetric mode frequency and the mode shape function are main factors for determining the film metamaterial under the condition of no magnetic field;
in the step S2, a permanent magnet magnetic force loading module is selected to realize magnetic field application by using a permanent magnet, and is a hollow cylindrical magnet formed by joining 14 small magnets (Nd-FeB), as shown in fig. 3-1, and is a schematic structural diagram of the hollow cylindrical magnet loading module formed by joining 14 small magnets (Nd-FeB) in embodiment 1 of the present invention; for matching with the impedance tube, the inner diameter is designed to be 52mm, the outer diameter is 80mm, and the height is 100mm; the magnetic field can be provided within the range of 0-1T, and has a gradient magnetic field in the axial direction, and the loading of magnetic force is realized by changing the relative distance between the magnetic field and a test sample;
in order to illustrate the influence of magnetic force on the vibration mode of the film, the radial stress of the film in the non-magnetic and magnetic state is selected, as shown in fig. 3-2, which is the distribution of the radial tension of the film before and after the magnetic field is applied in embodiment 1 of the present invention; because the magnetic force only acts on the magnetic material part of the concentric circular ring mass block, the axial symmetry of the internal force of the circular film is changed due to the magnetic force, the structural vibration mode loses the axial symmetry and the antisymmetry, and after the magnetic field is applied, the dynamic equation of the circular film vibration can be expressed as follows:
Figure BDA0004002506660000081
wherein eta is the displacement of the elastic film by transverse vibration, sigma 0 Is radial stress generated by initial tension of the elastic film, ρ is the density of the elastic film, f is the sound pressure load, t is the ring mass width, r is the radial coordinate, and σ m Radial stress generated by the initial tension of the elastic film can be obtained by a numerical solution method;
the front third-order mode of the film metamaterial is shown in fig. 4, and the magnetic field causes local acting force to change the axisymmetry of the stress state of the structure, destroy the axisymmetric mode of the structure and realize the switching of the acoustic wave control mode; under the condition of no magnetic field, the mode shapes of the first order mode and the third order mode are axisymmetric modes, and the mode shape of the second order mode is antisymmetric mode; under the magnetic field condition, the symmetry of the model is broken, the front third-order mode shape no longer has axisymmetry or antisymmetry, and the model is a dominant mode under the action of plane waves;
the natural frequency of the first-order mode is controlled through tension design and ring mass design, the natural frequency of the third-order mode is controlled through ring mass size design, and the magnetic force for realizing the target frequency is determined through calculating the dynamic equation of the vibration of the circular membrane after the magnetic field is applied.
The thin film metamaterial and the structure have the characteristic of strong designability, the mode shape can be known that the first-order mode can be approximated to a spring mass system, an elastic thin film outside a circular ring mass block (concentric circular ring mass block) is analogous to a spring, and the circular ring mass block is analogous to a mass block, so that the natural frequency of the first-order mode can be controlled through tension design and circular ring mass design; the third-order mode is mainly based on the vibration of an elastic film outside the circular ring mass block and is similar to the vibration mode of an inner and outer diameter constraint ring film, so that the natural frequency of the third-order mode can be controlled through the mass size design of the circular ring mass block, the magnetic force for realizing the target frequency is determined through calculating the dynamic equation of the vibration of the circular film after a magnetic field is applied, and the relative position relation between the permanent magnet and the film metamaterial is determined through magnetic force calibration;
when designing the annular mass block, the requirement on external magnetic field strength can be reduced by increasing the proportion of the magnetic material, so that the power consumption is further reduced, and in the embodiment 1, the proportion of the ferromagnetic material to the area of the annular mass block is 1/6;
in the step S3, the first order natural frequency and the third order natural frequency are 170Hz and 1700Hz respectively under the condition of no magnetic field; after the magnetic field is applied, the natural frequency of the second order of 600Hz is displayed, and based on the relationship between the film type metamaterial acoustic-vibration coupling model and the magnetic control force, the structural parameters of the film type metamaterial are designed as follows:
TABLE 1 major design parameters for thin film metamaterials in example 1
Figure BDA0004002506660000082
Figure BDA0004002506660000091
In the step S4, a mode-switchable film type acoustic metamaterial structure based on a magnetic control mechanism is prepared according to structural design parameters, a film with pretension applied is fixed on a paramagnetic metal circular ring sheet, a circular ring mass block formed by compounding a ferromagnetic material and a paramagnetic material is bonded to the center of the film to form an axisymmetric structure, and the structure is fixed in a flange device, so that the testing, the assembling and the application are facilitated;
fig. 7 is an assembly schematic diagram of a mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism according to embodiment 1 of the present invention; mode-switchable thin-film acoustic metamaterial structures based on a magnetron mechanism, comprising: the flange device, the elastic film, the paramagnetic metal circular ring sheet (aluminum or other paramagnetic materials), the permanent magnet magnetic loading module and the circular ring mass block; the elastic film is fixed on the paramagnetic metal circular ring sheet, the circular ring mass block formed by compounding the ferromagnetic material and the paramagnetic material is bonded to the center of the film to form an axisymmetric structure, the axisymmetric structure is fixed in the flange device, and the distance between the permanent magnet magnetic loading module and the axisymmetric structure is determined according to a magnetic calibration result. The ferromagnetic material occupies 1/6 of the area of the circular mass block; the axisymmetric structure is fixed in the flange device; the axisymmetric structure is in threaded connection with the flange device.
The magnetic force loading module of the permanent magnet is a hollow cylindrical magnet formed by joining 14 small magnets (Nd-FeB), as shown in FIG. 3-1, and is a schematic structural diagram of the hollow cylindrical magnet loading module formed by joining 14 small magnets (Nd-FeB) in embodiment 1 of the invention; for matching with the impedance tube, the inner diameter is designed to be 52mm, the outer diameter is 80mm, and the height is 100mm; the magnetic field can be provided within the range of 0-1T, and has a gradient magnetic field in the axial direction, and the loading of magnetic force is realized by changing the relative distance between the magnetic field and the test sample.
According to the film type metamaterial acoustic-vibration coupling model, the energy band diagram is calculated by adopting the design parameters adopted in the table 1, and is shown in fig. 5-1, wherein the energy band diagram of the film type metamaterial is obtained when a magnetic field is not applied in the embodiment 1 of the invention; as shown in fig. 5-2, the simulation result and the test verification result of the transmittance coefficient of the thin film acoustic metamaterial in the case of no magnetic field applied in the embodiment 1 of the present invention are shown; the gray area represents that the wave vector is complex, and decays along the transmission direction of the sound wave, namely, a forbidden band appears; the band gap width of the thin film acoustic metamaterial is determined by the resonance frequency and the anti-resonance frequency by adopting a local resonance mechanism, so that the control of the acoustic wave transmission mode can be realized by regulating and controlling the local resonance characteristic of the structure; further, the transmission performance of the thin film type acoustic metamaterial designed in the embodiment 1 under the condition of no magnetic field is measured through a standing wave tube test method, and is compared with a design target to verify, so that the effectiveness of the thin film type acoustic metamaterial is proved;
according to the magnetic control force relation of the film type acoustic metamaterial, the magnetic control requirement in the table 1 is adopted, and an energy band diagram under the action of a magnetic field is calculated, and is shown in fig. 6-1, and the energy band diagram of the film type acoustic metamaterial after an external magnetic field is applied in the embodiment 1 of the invention; as shown in fig. 6-2, the simulation result and the test verification result of the transmittance coefficient of the thin film acoustic metamaterial after the external magnetic field is applied in the embodiment 1 of the present invention are shown; the local resonance characteristic of the film type acoustic metamaterial realizes regulation and control, and a new forbidden band appears near the second-order modal frequency, namely the transmission energy of sound waves can be controlled through a magnetic field, so that the effect of an acoustic switching device is realized; similarly, the transmission performance of the thin film type acoustic metamaterial designed in the embodiment 1 under the magnetic field is measured through a standing wave tube test method, and is compared with a design target for verification, so that the effectiveness of the mode-switchable thin film type metamaterial based on a magnetic control mechanism is verified.
Under the condition of plane wave incidence, when no magnetic field acts, the axial symmetry of the excitation and structure leads the structure vibration to be mainly dominated by an axial symmetry mode; after the magnetic field is applied, the local magnetic force breaks the axisymmetry of the internal force of the structure, excites more dominant modes, realizes a magnetic control mechanism, and based on the mode vibration type characteristic, the mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism has the characteristic of strong designability, and finally realizes non-contact and discontinuous regulation and control.
The film type acoustic metamaterial based on the magnetic control mechanism is simple in regulation and control and high in designability, parameters such as film tension, geometric parameters, annular mass blocks and magnetic force can be designed according to application scenes and target frequency bands, and adaptability to different application scenes is improved. The mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism can realize non-contact and discontinuous regulation and control, realize mutation of acoustic performance of the structure, and provide a new means for band gap regulation, equivalent parameter dispersion control and the like.
According to the method, for the thin film type metamaterial composed of the additional mass block and the thin film, firstly, an acoustic-vibration coupling model is built, then under the influence of magnetic force on the vibration performance of the thin film structure, the thin film type metamaterial structure is designed according to design targets, the magnetic force required to be applied for regulation and control is determined, then the magnetic force of the circular mass block is calibrated according to the magnetic force action mode, finally, the thin film type acoustic metamaterial based on a magnetic control mechanism is prepared, and the switchable acoustic propagation mode is realized.
The mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism can realize non-contact, discontinuous and rapid regulation and control, realize mutation of acoustic performance of the structure, and provide a new means for band gap regulation, equivalent parameter dispersion control and the like; moreover, the film type acoustic metamaterial based on the magnetic control mechanism is simple in regulation and control and strong in designability, and improves the adaptability to different application scenes.
The mode-switchable film type acoustic metamaterial structure based on the magnetic control mechanism realizes non-contact regulation and control by utilizing the magnetic field, induces force change in the structure, breaks the force symmetry in the structure, excites an implicit asymmetric mode, realizes mutation of acoustic properties, solves the problem that the film type metamaterial based on the electromagnetic intelligent material parameter regulation and control mechanism needs to apply a strong electromagnetic field, and has simple control mode and convenient design.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (10)

1. A mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism, comprising: elastic film, paramagnetic metal circular ring sheet and circular ring mass block; the elastic film is fixed on the paramagnetic metal circular ring sheet, and the circular ring mass block is formed by compounding a ferromagnetic material and a paramagnetic material and is bonded and connected with the elastic film to form an axisymmetric structure.
2. The mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism as claimed in claim 1, wherein the annular mass has a uniform areal density.
3. The mode-switchable film acoustic metamaterial structure based on a magnetron mechanism according to claim 2, wherein the ferromagnetic material occupies an area ratio of 1/8-1/4 of the annular mass.
4. The mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism as claimed in claim 3, wherein the ferromagnetic material occupies an area ratio of 1/6 of the annular mass.
5. The mode-switchable thin-film acoustic metamaterial structure based on a magnetron mechanism according to claim 1, further comprising a flange device, wherein the axisymmetric structure is screwed with the flange device.
6. A preparation method of a mode-switchable film type acoustic metamaterial structure based on a magnetic control mechanism comprises the following steps:
(1) Construction of film-type metamaterial sound-vibration coupling model
Constructing a film type metamaterial sound-vibration coupling model to form a composite structure of an elastic film with a central bonding ring mass block, wherein the ring mass block is composed of ferromagnetic materials and paramagnetic materials and has uniform surface density;
(2) Establishing a magnetic control force relation of a film metamaterial
According to the film type metamaterial acoustic-vibration coupling model in the step (1), solving the influence of different magnetic forces on the internal force of the film structure, and calculating the modal frequency and the vibration mode of the film type metamaterial under the action of the different magnetic forces;
(3) Design film type metamaterial structure
According to the film type metamaterial acoustic-vibration coupling model in the step (1), establishing a relationship between film tension, geometric parameters and design parameters of a circular mass block and structural vibration characteristics, calculating the mode frequency and the vibration mode of the film type metamaterial in a concerned frequency band, designing a film type metamaterial structure according to the requirement of a target working frequency band, and determining magnetic force required to be applied for regulation and control according to the film type metamaterial magnetic control force relationship established in the step (2);
(4) Calibrating magnetic force of circular ring mass block
Determining a magnetic force action mode, and applying magnetic force to the circular ring mass block by adopting a permanent magnet or an electromagnet;
(5) The mode is switchable based on a magnetic control mechanism by preparing the film type metamaterial
And (3) fixing the film with uniform tension on the paramagnetic metal circular ring sheet according to the design parameters determined in the step (3), and bonding a circular ring mass block formed by compounding a ferromagnetic material and a paramagnetic material to the center of the film to form an axisymmetric structure.
7. The method for preparing a mode-switchable thin-film acoustic metamaterial based on a magnetron mechanism as claimed in claim 6, wherein in the step (1), the area ratio of the ferromagnetic material to the annular mass block is 1/6.
8. The method for preparing a mode-switchable film acoustic metamaterial based on a magnetic control mechanism according to claim 7, wherein in the step (1), a film metamaterial acoustic-vibration coupling model is constructed, and a kinetic equation is as follows:
Figure FDA0004002506650000021
wherein eta is the displacement of the elastic film by transverse vibration, sigma 0 Radial stress generated by initial tension of the elastic film, wherein ρ is the density of the elastic film, and f is the sound pressure load; the boundary between the annular mass and the film follows the continuous conditions of displacement and speed, taking into considerationThe continuity of speeds at two sides of the film is achieved, high-order scattered waves are ignored, and the relation between sound pressure load and transmission coefficient is established as follows:
f＝2(1-T 0 )
wherein T is 0 Is the transmission coefficient in the case of plane wave incidence.
9. The method for preparing the mode-switchable film-type acoustic metamaterial based on the magnetic control mechanism, which is disclosed in claim 8, wherein in the step (1), the mode frequency and the mode shape regulation and control effects of magnetic force on the film-type metamaterial are considered, and the magnetic control force relationship of the film-type metamaterial is established, specifically:
taking magnetic force influence into consideration, establishing a kinetic equation of circular membrane vibration:
Figure FDA0004002506650000022
wherein sigma m Radial stress generated by initial tension of the elastic film is obtained through a numerical solution method, the distribution condition of the tension in the circular film is obtained, and the mode shape function and the frequency related to the magnetic force are obtained through calculation.
10. The method for preparing a mode-switchable thin-film acoustic metamaterial based on a magnetron mechanism as claimed in claim 9, wherein in the step (2), the method specifically comprises the following steps: controlling the natural frequency of a first-order mode through tension design and ring mass design, controlling the natural frequency of a third-order mode through ring mass size design, and determining the magnetic force for realizing the target frequency by calculating a dynamic equation of the vibration of the circular membrane after the magnetic field is applied;
in the step (4), if a permanent magnet is adopted, the change condition of magnetic force along with the distance between the permanent magnet and the circular ring mass block is required to be calibrated, and the distance between the permanent magnet and the circular ring mass block in the step (3) is determined according to the requirement of magnetic field regulation and control frequency; or alternatively
In the step (4), the permanent magnet is a permanent magnet magnetic force loading module and is a hollow cylindrical magnet formed by joining 14 small magnets (Nd-FeB);
in the step (4), the inner diameter of the hollow cylindrical magnet is 52mm, the outer diameter is 80mm, and the height is 100mm;
in the step (4), if an electromagnet is adopted, the change condition of magnetic force along with the current intensity of the electromagnet needs to be calibrated, and the current intensity of the electromagnet in the step (3) is determined according to the requirement of magnetic field regulation and control frequency.
CN202211622128.2A 2022-12-16 2022-12-16 Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism Pending CN116129845A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211622128.2A CN116129845A (en) 2022-12-16 2022-12-16 Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211622128.2A CN116129845A (en) 2022-12-16 2022-12-16 Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism

Publications (1)

Publication Number Publication Date
CN116129845A true CN116129845A (en) 2023-05-16

Family

ID=86307127

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202211622128.2A Pending CN116129845A (en) 2022-12-16 2022-12-16 Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism

Country Status (1)

Country Link
CN (1) CN116129845A (en)

Similar Documents

Publication Publication Date Title
Bok et al. Metasurface for water-to-air sound transmission
TW462201B (en) Acoustic device
Liu et al. A real-time controllable electromagnetic vibration isolator based on magnetorheological elastomer with quasi-zero stiffness characteristic
Wang et al. A compact and low-frequency acoustic energy harvester using layered acoustic metamaterials
CN104408227A (en) Loudspeaker distortion feature value simulation analysis method
CN104681021A (en) Magnetic-field-adjustable low-frequency sound insulation structure and sound insulation material
Su et al. Extraordinary sound isolation using an ultrasparse array of degenerate anisotropic scatterers
Mao Improvement on sound transmission loss through a double-plate structure by using electromagnetic shunt damper
CN116129845A (en) Mode-switchable film type acoustic metamaterial structure based on magnetic control mechanism
CN109119059B (en) Double-negative-acoustic metamaterial structure based on Helmholtz resonator coupling
RU2407929C1 (en) Hydraulic vibratory bearing
Li et al. Sound absorption of a shunt loudspeaker on a perforated plate
JP2016531320A (en) Non-reciprocal acoustic device based on linear or angular momentum bias
Wang et al. Plate-type metamaterials for extremely broadband low-frequency sound insulation
CN116834390A (en) Wide low-frequency sound absorption vibration reduction coating structure and design method
CN208637138U (en) Helmholtz resonator
Su et al. Customizable acoustic metamaterial barrier with intelligent sound insulation
CN104754439A (en) Low-frequency good-function receiver
Neri et al. A novel micromachined loudspeaker topology
RU2707587C1 (en) Sound generation method for testing structures and device for its implementation
Agashe et al. Development of compact electrodynamic zero-net mass-flux actuators
CN207219037U (en) A kind of blade of a sword iron, armature and receiver
Yan et al. Experiment-simulation study on noise reduction of cylinder shell with horn Helmholtz resonator
Dong et al. Simulation and experimental investigation of the resonance reduction of a tire cavity lined with porous materials
Peng et al. Helmholtz Resonator With Sonic Black Hole Neck.

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination