A bandgap-tunable vibration-damping metamaterial containing resonant units and its fabrication method

Abstract

This invention discloses a bandgap-tunable vibration-damping metamaterial containing resonant units, belonging to the field of vibration control technology. The invention consists of an array of cells with localized resonant characteristics arranged in a specific direction. Each cell is a negative Poisson's ratio combined with a spring oscillator structure, mainly composed of an outer negative Poisson's ratio structure frame, an S-shaped spring structure at the connection point, a cylindrical oscillator, and a ring. The cylindrical oscillator is embedded within the ring at the center of the negative Poisson's ratio combined with the spring oscillator structure and connected to the symmetrical centerline of the outer negative Poisson's ratio structure frame via the S-shaped spring. The internal S-shaped spring structure and the ring structure are rigidly connected. The ring structure and the cylindrical oscillator are fitted with an interference fit. The outer negative Poisson's ratio structure frame is made of low-density materials such as polyetheretherketone, polylactic acid, and aluminum alloy, while the cylindrical oscillator is made of high-density pure tungsten. This invention inhibits wave propagation along a predetermined direction within the bandgap range, achieving vibration reduction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vibration control, and relates to a vibration reduction metamaterial structure with a tunable band gap based on a local resonance mechanism. BACKGROUND

[0002] The local resonance acoustic metamaterial is a periodic composite material or structure with an elastic wave band gap characteristic. Specifically, the local resonance acoustic metamaterial is a periodic composite material or structure with an elastic wave band gap characteristic composed of two or more than two media, and has a distinctive feature that when an elastic wave propagates in the local resonance acoustic metamaterial, is affected by the internal periodic structure, a special dispersion relationship can be formed, and the frequency range between the dispersion curves is called a band gap. In the band gap frequency range, the propagation of the elastic wave will be inhibited.

[0003] The local resonance mechanism believes that under the excitation of a specific frequency of the elastic wave, the resonator unit produces resonance and interacts with the incident wave, so that the local resonance is formed around the resonator unit. The generation of the band gap is mainly attributed to the interaction between the structure of the resonator unit and the elastic wave. Therefore, for the acoustic metamaterials conforming to the local resonance mechanism, the band gap is closely related to the inherent vibration characteristics of the resonator unit, and has little to do with the periodicity of the resonator. The traditional local resonance acoustic metamaterial is mainly composed of multi-phase materials, and the intrinsic properties of the materials are greatly different, so that a better band gap vibration reduction effect can be achieved, and the low-frequency wide-band target can be achieved by a small-size structure, which opens up a new design idea for the design of the vibration reduction and noise reduction structure. SUMMARY

[0004] The main purpose of the application is to provide a resonant unit-containing band gap tunable vibration reduction metamaterial and a manufacturing method thereof. By embedding a pure tungsten oscillator in the structure to increase the mass of the resonant unit, a lower frequency band gap range can be obtained, and a low-density high-strength material is used as the matrix, so that the light weight and good bearing characteristics are combined. The resonant unit-containing band gap tunable vibration reduction metamaterial prohibits the wave propagation along a predetermined direction in the band gap range, thereby achieving a good vibration reduction effect.

[0005] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0006] The resonant unit-containing band gap tunable vibration reduction metamaterial disclosed by the application is arranged in an array in a certain specific direction by a cell with a local resonance characteristic, and the certain specific direction is defined as the X direction. The cell is a negative Poisson's ratio combined spring oscillator structure, mainly composed of an external negative Poisson's ratio structure outer frame, an S-shaped spring structure at the connection, a cylindrical oscillator and a circular ring. The cylindrical oscillator is embedded in the circular ring at the center of the negative Poisson's ratio combined spring oscillator structure, and is connected to the symmetric center line of the negative Poisson's ratio structure outer frame through the S-shaped spring.

[0007] The internal S-shaped spring structure and the ring structure are connected rigidly.

[0008] Preferably, the outer frame of the negative Poisson's ratio structure is made of polyether ether ketone (PEEK) material, and the cylindrical vibrator is made of pure tungsten.

[0009] The size of the cylindrical vibrator is adjusted to control the upper and lower limits of the band gap range, and the local resonance characteristics of the cylindrical vibrator are used to obtain a lower frequency band gap in a small-size structure.

[0010] The band gap range can be adjusted by selecting the material of the outer frame of the negative Poisson's ratio structure. The band gap range of the biodegradable biomass material polylactic acid (PLA) is lower than that of the PEEK material, thereby obtaining a lower band gap frequency range. The aluminum alloy AlSi10Mg material as a lower density metal material plays a role in bearing and damping, and is more conducive to engineering application.

[0011] The band gap range is adjusted by adjusting the material of the S-shaped spring structure and the effective number of turns.

[0012] Preferably, the unit cell is prepared by 3D printing.

[0013] Advantages:

[0014] 1. The band gap adjustable damping metamaterial containing a resonance unit disclosed in the application is arranged in an array in a certain specific direction by a unit cell having local resonance characteristics, and the certain specific direction is defined as the X direction. The unit cell is a negative Poisson's ratio combined spring vibrator structure, which includes an outer frame of a negative Poisson's ratio structure, an S-shaped spring structure at the connection, a cylindrical vibrator, and a ring. The cylindrical vibrator is embedded in the ring at the center position of the negative Poisson's ratio combined spring vibrator structure, and is connected to the center line of the negative Poisson's ratio structure outer frame through the S-shaped spring. The band gap adjustable damping metamaterial containing the resonance unit prohibits the wave propagation of vibration along the X direction within the band gap range, thereby achieving good damping effect.

[0015] 2. The band gap adjustable damping metamaterial containing a resonance unit disclosed in the application can obtain a lower frequency band gap range by embedding a pure tungsten vibrator in the structure to increase the mass of the resonance unit.

[0016] 3. The band gap adjustable damping metamaterial containing a resonance unit disclosed in the application can realize the upper and lower limits of the band gap range by adjusting the size of the cylindrical vibrator, and can adjust the band gap range by selecting the material of the outer frame of the negative Poisson's ratio structure. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0018] Figure 1 is a schematic diagram of a unit cell three-dimensional structure of the present application.

[0019] Figure 2 is a schematic diagram of a vibration damping metamaterial of the present application.

[0020] Figure 3 is a schematic diagram of a two-dimensional structure irreducible Brillouin zone of the present application.

[0021] Figure 4 is a band diagram of a vibration damping metamaterial structure of PEEK material in Example 1.

[0022] Figure 5 is a band diagram of a vibration damping metamaterial structure of PLA material in Example 2.

[0023] Figure 6 is a band diagram of a vibration damping metamaterial structure of AlSi10Mg material in Example 3.

[0024] Figure 7 is a first band distribution diagram of a vibration damping metamaterial structure in Example 4.

[0025] Wherein: 1 - negative Poisson's ratio structure outer frame, 2 - S-shaped spring structure, 3 - cylindrical vibrator, 4 - circular ring structure. DETAILED DESCRIPTION

[0026] Reference Figures 1 to 7 The embodiments of the present application are described.

[0027] Example 1:

[0028] As Figure 1 shown, the present embodiment discloses a resonant unit containing band gap adjustable vibration damping metamaterial, which is composed of two materials. The external negative Poisson's ratio structure outer frame 1 adopts PEEK material, and the internal cylindrical vibrator 3 adopts tungsten vibrator material, which is periodically arrayed along a certain direction. The unit cell is mainly composed of an external negative Poisson's ratio structure outer frame 1, a connecting S-shaped spring structure 2, a cylindrical vibrator 3, and a circular ring 4. The outer frame is a square ring structure with a size of 40 mm, the square inside is composed of a periodic negative Poisson's ratio structure outer frame 1 connected to a circular ring structure 4 through an S-shaped spring structure 2, and the two are rigidly connected. The circular ring structure 4 is embedded with a cylindrical vibrator 3 of pure tungsten material, and the circular ring structure 4 and the cylindrical vibrator 3 adopt an interference fit.

[0029] The structure cell size and material constant are defined below, and the energy band diagram thereof in the irreducible Brillouin zone X direction is calculated, and it is illustrated that the band gap can be generated to prohibit wave propagation. The outer negative Poisson's ratio structure outer frame 1 structure XY direction size is 40mm, the height Z direction is 20mm, the outer negative Poisson's ratio structure outer frame 1 thickness is 2.5mm, the circular ring 4 and the S-shaped spring structure 2 wall thickness is 0.5mm, the outer negative Poisson's ratio structure outer frame 1 material is PEEK, the density is 1.3g / cm 3 , the elastic modulus is 3.8GPa, the Poisson's ratio is 0.38, the PEEK material is a non-metallic material with a relatively high melting point (334℃), which can withstand high temperature and has a relatively light mass, the cylindrical vibrator 3 diameter is 15mm, the material uses pure tungsten, the density is 19.2g / cm 3 , the elastic modulus is 35.4GPa, the Poisson's ratio is 0.28, and the cell lattice constant is taken as 40mm. The single cell structure is arrayed along the X direction to form a periodic structure. The wave vector is scanned Figure 3 in the irreducible Brillouin zone, mainly considering the vibration propagation in the X direction, the first 12 order characteristic frequencies of the structure are calculated, and the obtained energy band structure is shown in Figure 4 , wherein the band gap is indicated by the gray shadow part, and the band gap range is 201Hz-329Hz, 4809Hz-5406Hz. In the band gap range, the wave propagation of vibration along the X direction is prohibited, thereby achieving good vibration reduction effect.

[0030] Embodiment 2:

[0031] As shown in Figure 1 , as shown in Figure 1 , the embodiment discloses a band gap adjustable vibration reduction metamaterial containing a resonance unit, and the negative Poisson's ratio structure outer frame 1 material is a biodegradable biomass material polylactic acid (PLA), the density is 1.18g / cm 3 , the elastic modulus is 2.38GPa, and the Poisson's ratio is 0.39. The band gap distribution is shown in Figure 5 . With the decrease of the density of the material, the band gap frequency range is 163Hz-276Hz, 4007Hz-4517Hz, and the band gap range is reduced compared with the PEEK material, thereby obtaining a lower band gap frequency band.

[0032] Embodiment 3:

[0033] As shown in Figure 1 , as shown in Figure 1 , the embodiment discloses a band gap adjustable vibration reduction metamaterial containing a resonance unit, and the negative Poisson's ratio structure outer frame 1 material is AlSi10Mg, the density is 2.7g / cm 3, the elastic modulus is 68.9GPa, and the Poisson's ratio is 0.33. The negative Poisson's ratio structure outer frame 1 is replaced by a metal aluminum alloy material, which is beneficial to bearing and more conducive to engineering application. As shown in Figure 6 As shown in FIG. 8, after being replaced by an aluminum alloy material, the first and second band gap frequency ranges are 831Hz-1038Hz, 14202Hz-15901Hz, and the band gap frequency increases with the increase of the density and elastic modulus of the frame matrix material.

[0034] Embodiment 4:

[0035] As shown in FIG. 8, as shown in FIG. 8, the first and second band gap frequency ranges are 831Hz-1038Hz, 14202Hz-15901Hz, and the band gap frequency increases with the increase of the density and elastic modulus of the frame matrix material. Figure 1 As shown in FIG. 8, as shown in FIG. 8, the first and second band gap frequency ranges are 831Hz-1038Hz, 14202Hz-15901Hz, and the band gap frequency increases with the increase of the density and elastic modulus of the frame matrix material. Figure 1 As shown in FIG. 8, as shown in FIG. 8, the first and second band gap frequency ranges are 831Hz-1038Hz, 14202Hz-15901Hz, and the band gap frequency increases with the increase of the density and elastic modulus of the frame matrix material. Figure 7 As shown in FIG. 8, as shown in FIG. 8, the first and second band gap frequency ranges are 831Hz-1038Hz, 14202Hz-15901Hz, and the band gap frequency increases with the increase of the density and elastic modulus of the frame matrix material.

[0036] In addition, the overall size, material composition and array number of the structure unit cell can be adjusted according to the size requirements of the engineering equipment to meet the size requirements of the equipment under actual working conditions.

[0037] The above specific description further describes the purpose, technical scheme and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A band gap tunable vibration damping metamaterial containing resonant cells, characterized in that: The cell with the local resonance characteristic is arranged in an array in a certain specific direction, and the certain specific direction is defined as an X direction; the cell is a negative Poisson's ratio combined spring oscillator structure, mainly composed of an external negative Poisson's ratio structure outer frame (1), an S-shaped spring structure (2) at a connection, a cylindrical oscillator (3) and a circular ring (4); the cylindrical oscillator (3) is embedded in the circular ring (4) at the center position of the negative Poisson's ratio combined spring oscillator structure, and is connected with the symmetric center line of the negative Poisson's ratio structure outer frame (1) through the S-shaped spring structure (2); The internal S-shaped spring structure (2) and the circular ring (4) are rigidly connected; the circular ring (4) and the cylindrical oscillator (3) adopt an interference fit.

2. The band gap tunable vibration damping metamaterial containing resonance units of claim 1, wherein: The negative Poisson's ratio structure outer frame (1) is a low-density material, and the low-density material includes polyether ether ketone (PEEK), polylactic acid PLA material and aluminum alloy AlSi10Mg; the cylindrical oscillator (3) adopts high-density material pure tungsten.

3. The band gap tunable vibration damping metamaterial containing resonance units of claim 1, wherein: The size of the cylindrical oscillator (3) is adjusted to realize up and down adjustment of the band gap range, and the local resonance characteristic of the cylindrical oscillator (3) is used to realize a small-size structure to obtain a lower frequency band gap.

4. The band gap tunable vibration damping metamaterial containing resonance units of claim 1, wherein: The material of the external negative Poisson's ratio structure outer frame (1) can be selected to adjust the band gap range.

5. The band gap tunable vibration damping metamaterial containing resonance units of claim 1, wherein: The cell is prepared by a 3D printing method.

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