CN210110339U - Raised periodic structure plate with gradient refractive index - Google Patents
Raised periodic structure plate with gradient refractive index Download PDFInfo
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- CN210110339U CN210110339U CN201920558090.4U CN201920558090U CN210110339U CN 210110339 U CN210110339 U CN 210110339U CN 201920558090 U CN201920558090 U CN 201920558090U CN 210110339 U CN210110339 U CN 210110339U
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Abstract
The utility model relates to a convex periodic structure plate with gradient refractive index, which comprises a base plate (1) and m rows and n columns of scatterer vibrators arranged on the base plate (1) in a convex manner according to the periodicity; the base plate (1) and the scatterer vibrator jointly form an acoustic or elastic wave metamaterial with negative refraction characteristics; the same scatterer vibrator is formed by stacking an inner layer (2) of the vibrator and an outer layer (3) of the vibrator, wherein the inner layer and the outer layer are made of materials. The negative refraction can be realized for the incident elastic wave or sound wave with specific frequency, the gradual change of the refractive index is realized in the board along the wave propagation direction by gradually changing the geometric parameters of the vibrator, and the elastic wave or sound wave with specific frequency which enters the structure from any direction is gradually bent, so that the purpose of controlling the wave propagation direction is achieved, and no interference phenomenon exists between the elastic wave or sound wave and the incident wave. Has important value in the fields of waveguide, acoustic wave filter, etc.
Description
Technical Field
The present invention relates to a periodic structure, and more particularly to a raised periodic structure plate having a gradient refractive index.
Background
The periodic structure, also called a phononic crystal, refers to a periodic material or structure having a band gap of acoustic wave or elastic wave, and its internal elastic constant and density are periodically changed. In terms of material composition, the phononic crystal may be a solid/solid, solid/fluid or fluid/fluid system, or may be a single material system formed by periodically opening pores on a material substrate. The background material which is communicated with each other in the phononic crystal is a matrix, the material which is not communicated with each other is a scatterer, and both the matrix and the scatterer can be solid, liquid or gas. Phononic crystals can be classified into bragg scattering type phononic crystals and local resonance type phononic crystals according to the difference in band gap generation mechanism.
The metamaterial refers to an artificial microstructure material which can control the propagation of sound waves or elastic waves in the metamaterial through the design of microstructure functional elements and realize novel fluctuation characteristics. Structures that combine materials in a specific way via artificial design to achieve specific acoustic properties that do not exist in nature. The periodic structure plate with the gradient refractive index refers to a phonon crystal structure with the refractive index of elastic waves or acoustic waves changing in a gradient manner from crystal lattice to crystal lattice. The structure has the characteristic of changing the propagation direction of the elastic wave or the sound wave in a certain frequency range. The method of changing the refractive index of the elastic wave or acoustic wave includes changing the material of the matrix or the scatterer, changing the lattice length, changing the shape of the scatterer, changing the filling rate of the scatterer, and the like. Due to the large number of lattices in the structure, it is very complicated to design the structure by changing the shape of the material or the scattering body. Therefore, a simpler method for changing the geometrical size of the scatterer is adopted, specifically, the refractive index is gradually changed by gradually adjusting the thickness of the convex oscillator of each layer. By gradually changing the thickness of the oscillator layer, the elastic wave or the sound wave incident into the structure is gradually bent, so that the purpose of controlling the propagation direction of the wave is achieved, and no interference phenomenon exists between the elastic wave or the sound wave and the incident wave. The research has potential value in the fields of waveguide, acoustic wave filter and the like.
Disclosure of Invention
The technical problem is as follows: the utility model aims at providing a protruding type periodic structure board with gradient refracting index through the bellied oscillator of periodic arrangement to along arranging the thickness that the direction changes oscillator inlayer or skin gradually, change elastic wave or sound wave propagation direction gradually, thereby control the propagation direction of specific frequency wave.
The technical scheme is as follows: the utility model relates to a convex periodic structure plate with gradient refractive index, which comprises a base plate and m rows and n columns of scatterer vibrators arranged on the base plate in a convex manner according to the periodicity; the base plate (1) and the scatterer vibrator jointly form an acoustic or elastic wave metamaterial with negative refraction characteristics; the same scatterer vibrator is formed by stacking an inner layer of the vibrator and an outer layer of the vibrator.
The scatterer vibrator is a cylinder, a cuboid or a regular polygon; the smallest repeating unit constituting the periodic structure is called unit cell, and the arrangement shape among the unit cells can be square, triangle or other regular polygon.
The two layers of scatterer oscillators are the same in shape, radius or side length and unit cell arrangement mode and different in thickness.
The arrangement of the scatterer vibrators is completely the same in the row direction, the thickness of the inner layer of the scatterer vibrator is constant and the thickness of the outer layer of the vibrator is gradually changed in the column direction, or the thickness of the outer layer of the vibrator is constant and the thickness of the inner layer of the vibrator is gradually changed,
the thickness of the inner layer of the vibrator is changed gradually according to linear change or power exponent change.
The materials of the base plate and the outer layer of the vibrator are metal, concrete, ceramic or fiber reinforced composite materials; the material of the inner layer of the vibrator is rubber or epoxy resin.
And the base plate and the inner layer of the vibrator and the outer layer of the vibrator are connected in a sticking or welding mode.
Has the advantages that: compared with the prior art, the utility model has the advantages of it is following:
1) the periodic structure has the band gap characteristic, and can attenuate or shield the transmission of sound waves or elastic waves in a specific frequency range, so that the periodic structure plate can also achieve the aims of vibration reduction and noise reduction.
2) The traditional elastic wave or acoustic wave calibration element has large size and high manufacturing cost, and the size can be reduced and the manufacturing cost can be reduced by using the convex gradient periodic structure. Meanwhile, the manufacturing is convenient, and the standardized production is convenient.
3) The change of the material of the substrate or the scatterer by the traditional material is generally difficult to realize, and the gradient refractive index is easy to realize by gradually changing the thickness of the vibrator, so that the method is relatively simple and easy to implement. Has important value in the fields of waveguide, acoustic wave filter, etc.
Drawings
FIG. 1a is a structural diagram of a convex periodic plate with gradually changing thickness of the outer layer of the vibrator according to the present invention;
FIG. 1b is a structural diagram of a convex periodic plate with gradually changing thickness of the inner layer of the vibrator according to the present invention;
FIG. 2 is a diagram of a single cell of the raised periodic structure plate of the present invention;
FIG. 3 is a cross-sectional view of a single cell of a raised periodic structure plate according to the present invention;
FIG. 4 is a top view of the periodic structure plates arranged in regular triangles between the unit cells of the present invention;
FIG. 5a is a schematic diagram of the path of propagation of an acoustic or elastic wave incident on a periodic structure slab of graded index;
FIG. 5b is a schematic illustration of the path of propagation of an acoustic or elastic wave incident on a periodic structure slab with a gradient index;
the figure shows that: the vibrator comprises a base plate 1, a vibrator inner layer 2 and a vibrator outer layer 3.
Detailed Description
The forming method of the utility model is as follows:
the m rows and n columns of convex vibrators are arranged on the base plate according to a periodic arrangement, wherein the same vibrator is formed by stacking an inner layer of material and an outer layer of material. The vibrator can be a cylinder, a cuboid or a regular polygon. While the lattice shape of the periodic structure may be square, triangular or other regular polygonal shape. The two layers of scatterers of the same oscillator have the same shape, radius or side length and lattice mode, and only the possible thicknesses are different.
The arrangement of the inner and outer layer vibrators is the same in the row direction, and the thickness of the inner layer of the vibrator is constant and the thickness of the outer layer is gradually changed or the thickness of the outer layer is constant and the thickness of the inner layer is gradually changed in the column direction, and the arrangement can be changed according to linear change, power exponent change or other function combinations and the like.
The material of the base plate and the outer layer of the vibrator can be metal, concrete, ceramic or fiber reinforced composite material. The material of the inner layer of the vibrator can be rubber or epoxy resin. According to the materials of the base plate and each layer of the vibrator, the base plate and the inner layer of the vibrator as well as the inner layer and the outer layer of the vibrator can be connected in a sticking or welding mode.
The invention will be described in further detail by way of example with reference to the accompanying drawings:
the periodic structure, also called a phononic crystal, refers to a periodic material or structure having a band gap of acoustic wave or elastic wave, and its internal elastic constant and density are periodically changed. In terms of material composition, the phononic crystal may be a solid/solid, solid/fluid or fluid/fluid system, or may be a single material system formed by periodically opening pores on a material substrate. The background material which is communicated with each other in the phononic crystal is a matrix, the material which is not communicated with each other is a scatterer, and both the matrix and the scatterer can be solid, liquid or gas. Phononic crystals can be classified into bragg scattering type phononic crystals and local resonance type phononic crystals according to the difference in band gap generation mechanism. The distance from the center of a scatterer to the center of an adjacent scatterer is called the lattice constant.
Over the last decade, by analogy with electromagnetic metamaterials, many different types of acoustic metamaterials and elastic wave metamaterials have been designed. The metamaterial means that part of equivalent parameters are negative, such as negative equivalent mass density, negative equivalent bulk modulus, negative equivalent shear modulus, negative equivalent refractive index and the like. Thanks to these negative equivalent parameters, acoustic and elastic wave metamaterials have proven to achieve anomalous physical phenomena, as well as potential applications that break through the properties of natural materials. The metamaterial can be realized by combining topological optimization, and the limitation of manual and empirical design is broken through. One of the most prominent anomalous properties of metamaterials is negative refraction.
Example 1:
as shown in FIG. 1a, FIG. 2 and FIG. 3, the present embodiment is a convex periodic structure plate with constant thickness of the inner layer and gradually and linearly changing thickness of the outer layer of the vibrator, and adopts square lattice with lattice constant a1The m rows and n columns of cylindrical vibrators are arranged on the protrusions, the size of the vibrators in the same row is unchanged, and the thickness of the inner layer of each row of vibrators is t in the row direction0The thickness of the outer layer is from t1Change to t according to a certain function rule2Then change to t1. The base plate is made of concrete, the inner layer of the vibrator is made of silicon rubber, and the outer layer of the vibrator is made of steel.
Example 2:
as shown in FIG. 1b, FIG. 2 and FIG. 3, the present embodiment is a convex periodic structure plate with constant thickness of the outer layer and gradually and linearly changing thickness of the inner layer of the vibrator, and adopts square lattice with lattice constant set as a2The m rows and n columns of cylindrical vibrators are arranged on the protrusions, the size of the vibrators in the same row is unchanged, and the thickness of the outer layer of each row of vibrators is t in the column direction0The thickness of the inner layer is from t1Change to t according to a certain function rule2Then change to t1. The material of the base plate is concrete, and the vibratorThe inner layer is made of silicon rubber, and the outer layer is made of steel.
Example 3:
as shown in fig. 2, 3 and 4, the present embodiment is a convex periodic structure plate in which oscillators are arranged according to regular triangle lattices, the thickness of the inner layer of the oscillator is constant, the thickness of the outer layer is gradually changed linearly, regular triangle lattices are adopted, and the lattice constant is set as a3The m rows and n columns of cylindrical vibrators are arranged on the protrusions, the size of the vibrators in the same row is unchanged, and the thickness of the inner layer of each row of vibrators is t in the row direction0The thickness of the outer layer is from t1Change to t according to a certain function rule2Then change to t1. The base plate is made of concrete, the inner layer of the vibrator is made of silicon rubber, and the outer layer of the vibrator is made of steel.
As shown in fig. 5a and 5b, when an acoustic or elastic wave of a specific frequency is injected into a gradient periodic structure plate, negative refraction is generated on the plate, and then the propagation direction of the wave is bent inside the plate due to the gradient change of the refractive index and propagates along a predetermined path, which is similar to a waveguide in characteristics. The propagation path of the wave in the gradient periodic structure plate can be controlled by adjusting the incident angle and the frequency of the incident wave, and the adjustable waveguide can be obtained under the condition of not presetting defects.
The above description is only a preferred embodiment of the present invention, and it should be noted that: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present invention.
Claims (7)
1. A raised periodic structure plate with gradient refractive index is characterized in that the periodic structure plate comprises a base plate (1) and m rows and n columns of scatterer vibrators which are raised on the base plate (1) according to periodic arrangement; the base plate (1) and the scatterer vibrator jointly form an acoustic or elastic wave metamaterial with negative refraction characteristics; the same scatterer vibrator is formed by stacking an inner layer (2) of the vibrator and an outer layer (3) of the vibrator, wherein the inner layer and the outer layer are made of materials.
2. The convex periodic structure plate with a gradient refractive index according to claim 1, wherein the scatterer element is a cylinder, a rectangular parallelepiped or a regular polygonal body; the smallest repeating unit constituting the periodic structure is called unit cell, and the arrangement shape among the unit cells can be square, triangle or other regular polygon.
3. The convex periodic structure plate with a gradient refractive index according to claim 1, wherein the shape, radius or side length of the two scatterer oscillators, the arrangement mode of unit cells are the same, and the thicknesses are different, in the inner oscillator layer (2) and the outer oscillator layer (3) of the same scatterer oscillator.
4. The convex periodic structure plate with a gradient refractive index according to claim 1, wherein the arrangement of the scatterer elements is identical in the row direction, and the thickness of the inner layer (2) of the scatterer elements is constant while the thickness of the outer layer (3) of the elements is gradually changed or the thickness of the outer layer (3) of the elements is constant while the thickness of the inner layer (2) of the elements is gradually changed in the column direction.
5. The convex periodic structure plate with a gradient refractive index according to claim 1, wherein the thickness of the vibrator inner layer (2) is gradually changed in accordance with a linear change or a power exponent change.
6. The plate of claim 1, wherein the material of the base plate (1) and the vibrator outer layer (3) is metal, concrete, ceramic, or fiber-reinforced composite material; the material of the vibrator inner layer (2) is rubber or epoxy resin.
7. The raised periodic structure plate with the gradient refractive index as claimed in claim 1, wherein the substrate plate (1) and the vibrator inner layer (2) and the vibrator outer layer (3) are connected by means of adhesion or welding.
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| CN109961774A (en) * | 2019-04-23 | 2019-07-02 | 东南大学 | A kind of male-type periodic structure plate with graded index |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109961774A (en) * | 2019-04-23 | 2019-07-02 | 东南大学 | A kind of male-type periodic structure plate with graded index |
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