CN211525405U - Density-adjustable multilayer periodic structure - Google Patents
Density-adjustable multilayer periodic structure Download PDFInfo
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- CN211525405U CN211525405U CN201920959755.2U CN201920959755U CN211525405U CN 211525405 U CN211525405 U CN 211525405U CN 201920959755 U CN201920959755 U CN 201920959755U CN 211525405 U CN211525405 U CN 211525405U
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Abstract
The utility model relates to a density-adjustable multilayer periodic structure, which comprises a central film or plate base layer (1), an embedded block body (2) and an outer film or plate base layer (3); the central film or plate base layer (1) is located in the middle layer, the outer film or plate base layers (3) are arranged on two sides of the central film or plate base layer (1), and the embedded blocks (2) which are arranged in an integral periodic mode are uniformly arranged in the outer film or plate base layers (3), so that a multilayer periodic structure is stacked. The multi-layer periodic structure is fixed on a frame with higher rigidity to apply pretension, and the density of the periodic structure can be adjusted, so that the physical parameters of the periodic structure are changed, and the active control of the band gap of the periodic structure is realized. Can be applied to the field of vibration reduction and isolation. Compared with the traditional active and passive vibration isolation, the periodic structure has the advantages of light weight, wide vibration isolation frequency, high reliability and the like, and can actively control the band gap range.
Description
Technical Field
The invention relates to a periodic structure, in particular to a multilayer periodic structure with adjustable density.
Background
The periodic structure is also called a phononic crystal, and two main mechanisms for forming a forbidden band in the phononic crystal are a bragg scattering mechanism and a local resonance mechanism. Phononic crystals based on these two mechanisms are also called bragg scattering type phononic crystals and local resonance type phononic crystals, respectively. When an elastic wave propagates in a periodic structure, the elastic wave scatters at periodic interfaces. When the wavelength of the elastic wave is comparable to the size of the structure period, the forward traveling wave and the backward wave generate destructive interference, and the destructive interference can attenuate the wave form to a great extent, so that the elastic wave with certain frequency cannot be transmitted. This forbidden band mechanism is called bragg scattering type. The wavelength of the bragg scattering type forbidden band is comparable to the order of the structure size. Unlike bragg scattering type phononic crystals, locally resonant phononic crystals introduce locally resonant units in the matrix. The local resonance unit can be arranged inside the substrate or on the surface of the substrate; furthermore, the distribution of the local resonance cells is not strictly periodically restricted. When the frequency of the incident wave is close to the resonance frequency of the local resonance unit, the strong resonance mode of the resonance unit interacts with the eigenmode of the substrate, and the forbidden band is opened by mutual repulsion. For the local resonance type forbidden band, the corresponding wavelength can be far larger than the structure size, so that the limitation of the Bragg scattering type phononic crystal on the structure size in low-frequency application can be broken through.
The band gap characteristic of the periodic structure can realize vibration reduction and noise reduction. The purposes of vibration reduction and noise reduction can be achieved from three aspects of vibration source strength inhibition, vibration isolation and vibration elimination. By means of the design of the periodically improved vibration source of the phonon crystal, the vibration source with the band gap characteristic can be obtained. In the aspect of vibration isolation, the vibration isolator with the phononic crystal structure can be used for active vibration isolation or passive vibration isolation, so that the effective suppression and even isolation of vibration can be realized. The method adopts the physical mechanism of the local resonance type phononic crystal, and absorbs the kinetic energy of a vibration system by adding a periodic vibrator structure on a beam-slab structure. The vibration reduction and noise reduction have important significance for high-precision machining, a vibration-free machining environment can be provided for a high-precision machining system, and higher machining precision is guaranteed; and the instrument and equipment can be provided with a working environment without vibration, so that the working precision is improved, and the service life of the instrument and equipment is prolonged.
The performance of the previously designed periodic structure is fixed once it is fabricated. If the function is to be changed, such as changing the operating frequency or switching the operating state, the design and manufacture needs to be redesigned. Therefore, in order to dynamically control the performance of the periodic structure at any time, active tunable periodic structures have been studied. The adjustable periodic structure changes the properties of the periodic structure by applying an external field (such as electric, magnetic, acoustic, optical, thermal and mechanical fields) to dynamically adjust and control the performance of the periodic structure, such as changing or widening an operating frequency band and the like. The adjustable periodic structure is one of the most active research subjects in the field of phononic crystals and metamaterials at present due to the wonderful application prospect shown by the adjustable periodic structure, and the corresponding research result can play a leading role in the development of a plurality of engineering technologies.
Disclosure of Invention
The technical problem is as follows: the invention aims to provide a multilayer periodic structure with adjustable density. The multilayer periodic structure is formed by stacking the thin films or plate substrate layers with hard blocks arranged locally, uniformly and integrally in a periodic manner in the multilayer and clamping the thin films or plate substrate layers on two sides of the central substrate layer. The pre-stretching is applied by fixing the periodic structure on a frame with larger rigidity, so that the density of the periodic structure can be adjusted, the physical parameters of the periodic structure are changed, and the active control of the band gap of the periodic structure is realized. The vibration mode in the band gap frequency range can not pass through the periodic structure plate, so the vibration damping and isolating plate can be applied to the field of vibration damping and isolating.
The technical scheme is as follows: the invention relates to a density-adjustable multilayer periodic structure, which comprises a central film or plate substrate layer, an embedded block body and an outer film or plate substrate layer; the central film or plate substrate layer is positioned in the middle layer, the outer film or plate substrate layers are arranged on two sides of the central film or plate substrate layer, and embedded blocks which are integrally and periodically arranged are uniformly arranged in the outer film or plate substrate layers, so that a multilayer periodic structure is formed by stacking.
The embedded block is a solid geometry.
The solid geometry of the solid is a sphere, a cylinder or a cuboid.
The embedded blocks are locally and uniformly arranged on the outer thin film or the plate substrate in an integral periodic structure, and the locally and uniformly arranged shapes are circular, rectangular, triangular, star-shaped, circular and trapezoidal; and the smallest repeating unit composing the periodic structure is called unit cell, and the arrangement shape among the unit cells can be square, triangle or other polygons.
The embedded blocks have the same shape, material, size and arrangement form of the same layer; while the shape, material, size and arrangement of the embedded blocks of the different layers may be the same or different.
The thicknesses of the central film or plate base layer and the outer film or plate base layer are the same or different;
the embedded block is made of metal, concrete, ceramic or fiber reinforced composite materials, and the material of the central film or board matrix layer and the material of the outer film or board matrix layer are rubber or epoxy resin.
And a multilayer periodic structure is formed between the central film or plate base layer and the outer film or plate base layer and between the outer film or plate base layers in a sticking connection mode.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1) the periodic structure can be used for vibration reduction and noise reduction, and elastic waves or sound waves in a specific frequency range can be prevented from being transmitted by utilizing the band gap characteristic of the phononic crystal, so that the purposes of vibration reduction and noise reduction are achieved. The low-frequency Bragg scattering requires that the photonic crystal structure is large and the mass is heavy, and the local resonance forbidden band can break through the mass density law, so that the constraint of the low-frequency Bragg scattering forbidden band on the structure size can be broken through.
2) The traditional elastic wave or sound wave calibration element is large in size and high in manufacturing cost, and compared with the traditional sound insulation material, the multilayer periodic structure has the advantages of designable frequency, strong pertinence, small size, good effect and the like. Meanwhile, the manufacturing is convenient, and the standardized production is convenient.
3) The traditional periodic structure is based on a passive regulation design, cannot be changed after production and preparation are finished, cannot change the external environment to change the external environment, and is difficult to flexibly adapt to different working environments. The multilayer periodic structure can realize active regulation and control by applying pretension, change the density of the periodic structure, and actively change the working performance of the periodic structure in real time, so that the periodic structure can flexibly respond to the change of working environment, change the working state (working frequency) or switch the working mode.
Drawings
FIG. 1 is a general view of a density tunable multilayer periodic structure according to the present invention;
FIG. 2 is an exploded view of a density tunable multilayer periodic structure according to the present invention;
FIG. 3 is an exploded view of a unit cell of a periodic structure in which the upper and lower layers of embedded blocks are all small balls according to the present invention;
FIG. 4 is a single cell explosion diagram of a periodic structure in which the blocks embedded in the upper and lower layers are cuboids;
FIG. 5 is an exploded view of a unit cell with a periodic structure in which the upper layer of the embedded block is a pellet and the lower layer is a rectangular parallelepiped;
FIG. 6 is a top perspective view of a periodic structure of the present invention with cells arranged in regular triangles;
FIG. 7 is a schematic representation of the cell structure changes before and after the pre-stretch is applied in accordance with the present invention;
the figure shows that: a central film or plate substrate layer 1, an embedded bulk 2, and an outer film or plate substrate layer 3.
Detailed Description
The forming method of the invention is as follows:
m rows and n columns of local uniform hard small block masses are periodically or quasi-periodically arranged and embedded on the outer layer film or plate substrate; the hard small blocks can be spheres, cylinders, cuboids or multilateral bodies, the shapes of local uniform arrangement can be geometric shapes such as circles, rectangles, trapezoids and the like, the repeated unit with the minimum periodic structure is called a unit cell, and the arrangement mode among the unit cells can be squares, triangles or other polygons. The shape, material, size and arrangement form of the same layer are the same. The hard blocks in different layers can be the same or different in shape, material, size and arrangement mode; the material of the film or the plate substrate can be rubber or epoxy resin, and the material of the hard small block can be metal, concrete, ceramic or fiber reinforced composite material. The multilayer periodic structure film or the plate substrate is connected in a sticking mode, so that the multilayer periodic structure with adjustable density is formed.
The invention will be further described in detail by way of example with reference to the accompanying drawings in which:
example 1:
as shown in fig. 1, 2, 3 and 7, the present embodiment is a multilayer periodic structure with adjustable density. The hard small blocks are small spheres which are embedded on the upper and lower outer films or plate substrates, are locally and uniformly arranged according to a circle, are integrally arranged in m rows and n columns of circular areas, are arranged in a square way among the single cells, and have a lattice constant set as a1. And arranging a film or plate without a block body as a substrate on the middle layer, and connecting the multilayer film or plate substrates together in a sticking mode to form a multilayer periodic structure with adjustable density.
Example 2:
as shown in fig. 1 and 4, the present embodiment is a multilayer periodic structure with adjustable density. The hard small blocks are small cuboids embedded on the thin films or plate substrates on the upper and lower outer sides, are locally and uniformly arranged according to squares, are integrally arranged in square regions of m rows and n columns, are arranged among the single cells in a square manner, and have lattice constants set as a1. And arranging a film or plate without a block body as a substrate on the middle layer, and connecting the multilayer film or plate substrates together in a sticking mode to form a multilayer periodic structure with adjustable density.
Example 3:
as shown in fig. 1 and 5, the present embodiment is a multilayer periodic structure with adjustable density. The hard small blocks on the upper layer adopt small spheres which are locally arranged in a circle and are integrally arranged in m rows and n columns of the circle, the unit cells are arranged in a square, and the lattice constant is set as a1Embedded in the upper film or board substrate; the lower hard small blocks are small cuboids, the local parts of the small cuboids are arranged according to a square shape, square regions with m rows and n columns are integrally arranged, the unit cells are arranged in a square shape,the lattice constant is set to a2Embedded in the lower film or plate substrate. And arranging a film or plate without a block body as a substrate on the middle layer, and connecting the multilayer film or plate substrates together in a sticking mode to form a multilayer periodic structure with adjustable density.
Example 4:
as shown in fig. 1 and 6, the present embodiment is a multilayer periodic structure with adjustable density. The hard small blocks are small spheres which are embedded on the upper and lower outer side films or plate substrates, are locally and uniformly arranged according to a circle, are integrally arranged in m rows and n columns of circular areas, are arranged among the single cells by adopting a regular triangle, and have a lattice constant set as a1. And arranging a film or plate without a block body as a substrate on the middle layer, and connecting the multilayer film or plate substrates together in a sticking mode to form a multilayer periodic structure with adjustable density.
Example 5:
FIG. 7 is a schematic diagram showing the variation of the cell structure before and after applying a bi-directional pretension, where F1>F2. After pre-stretching, the circular areas originally embedded with the globules are stretched into elliptical areas. The density of the regions embedded in the spheres varies, and the band gap range of the periodic structure also varies correspondingly. Therefore, the band gap range of the multilayer periodic structure can be actively regulated through pre-stretching.
Once manufactured, conventional periodic structures typically have only a fixed operating frequency range. The density-adjustable multilayer periodic structure can adapt to different working requirements or flexibly cope with environmental changes. Compared with the traditional periodic structure, the density-adjustable multilayer periodic structure has the characteristics of high extensibility and reconfigurability and is easy to manufacture.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (6)
1. A multilayer periodic structure with adjustable density, characterized in that the periodic structure comprises a central film or plate substrate layer (1), an embedded block (2), an outer film or plate substrate layer (3); wherein, the central film or plate substrate layer (1) is positioned in the middle layer, the outer film or plate substrate layers (3) are arranged on the two surfaces of the central film or plate substrate layer (1), and the embedded blocks (2) which are integrally and periodically arranged are uniformly arranged on the surfaces of the outer film or plate substrate layers (3), so that a multilayer periodic structure is stacked;
the embedded blocks (2) are locally and uniformly arranged on the outer film or plate substrate layer (3) in an integral periodic structure, and the locally and uniformly arranged shape is circular, rectangular, triangular, star-shaped, circular or trapezoidal; and the smallest repeating unit composing the periodic structure is called unit cell, and the arrangement shape among the unit cells can be square, triangle or other polygons.
2. A multilayer periodic structure with adjustable density according to claim 1, characterized in that the embedded blocks (2) are of solid geometry.
3. A multilayer periodic structure with adjustable density according to claim 2, characterized in that the solid geometry is a sphere, a cylinder or a cuboid.
4. A multilayer periodic structure with adjustable density according to claim 1, characterized in that the embedded blocks (2) have the same shape, material, size and arrangement of the layers; the shape, material, size and arrangement of the embedded blocks (2) of different layers are the same or different.
5. A density tunable multilayer periodic structure according to claim 1, characterized in that the thickness of the central film or plate substrate layer (1), the outer film or plate substrate layer (3) is the same or different from layer to layer.
6. A multilayer periodic structure with adjustable density according to claim 1, characterized in that the multilayer periodic structure is formed by the adhesive connection between the central film or plate substrate layer (1) and the outer film or plate substrate layers (3) and between the outer film or plate substrate layers (3).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110332267A (en) * | 2019-06-25 | 2019-10-15 | 东南大学 | A kind of adjustable multilayered cylindrical shell of density |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110332267A (en) * | 2019-06-25 | 2019-10-15 | 东南大学 | A kind of adjustable multilayered cylindrical shell of density |
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