Reinforced acoustic black hole plate with embedded local resonance structure

Abstract

The invention discloses a reinforced acoustic black hole plate with an embedded local resonance structure. The reinforced acoustic black hole plate comprises a main body, the local resonance structure and a damping layer, the local resonance structure is embedded in the main body, and the damping layer is adhered to the outer surface of the main body. By combining the energy gathering and dissipation effects of the acoustic black hole and the dynamic vibration absorption effect of the local resonance structure, the vibration control effect is improved, the effective action frequency of the black hole effect is reduced, and the acoustic black hole vibration damper has the characteristics of high efficiency, high damping, light weight and wide frequency. The band gap range can be regulated and controlled, broadband vibration suppression is achieved, the structure is simple, other assemblies such as piezoelectric patches and local resonators can be arranged on the outer surface of the plate structure more conveniently, and great potential is achieved in the broadband vibration reduction field.

Description

Technical Field

[0001] The invention belongs to the field of acoustic technology, and in particular relates to a reinforced acoustic black hole plate with an embedded local resonance structure. Background Art

[0002] Acoustic Black Hole, referred to as ABH, is the acoustic analogy of the concept of black hole in astrophysics in the field of mechanics. Its main implementation method is to gradually reduce the thickness of the thin plate structure to zero in the form of a power function, so as to concentrate the wave energy propagating in the structure to the position where the thickness approaches zero. This structural characteristic makes ABH have significant application value in vibration control, acoustic radiation suppression and energy collection. However, for a single ABH element, the broadband ABH effect of the system can only be achieved above a certain frequency when the incident wavelength is comparable to or smaller than the characteristic size of the ABH unit, which seriously hinders the application scope of ABH technology.

[0003] Therefore, the key issue for the practical application of ABH technology is to extend the ABH effect to the low-frequency region under a reasonable structural size. At present, this problem is mostly solved by embedding a double-blade acoustic black hole plate or using a phononic crystal structure.

[0004] For example, in the paper "Periodic plates with tunneled Acoustic-Black-Holes for directionalband gap generation" published in Mech.Syst.Signal, the acoustic black hole effect of the traditional embedded double-blade acoustic black hole plate can effectively realize the aggregation of bending waves only above a specific frequency threshold. This characteristic frequency is restricted by the characteristic size of the ABH. Under the condition of limited size, the control effect of the structure in the low-frequency range below this frequency is usually not ideal. In addition, in actual engineering, in order to ensure the strength and stiffness of the structure, the ABH size allowed for processing is generally small, which makes it difficult to achieve the ideal level of control effect in the low-frequency band. The actual thickness constraint in modern processing technology further limits this effect. It is difficult for the ABH structure to change the thickness to zero, but it will be truncated or a small amount of thickness will remain in the thin tip area. Once the ABH thickness change curve deviates from the ideal power function form, the bending wave will be reflected at the edge of the structure, thereby reducing its effective frequency range. This reflection effect significantly limits the control ability of the ABH in the low-frequency band, making it difficult to achieve a wider frequency coverage.

[0005] Traditional phononic crystal structures are based on Bragg scattering or local resonance mechanisms, such as the paper "Physics of band-gap formation and its evolution in the pillar-based phononic crystal structures" in J.Appl.Phys. Physics based on Bragg scattering requires a large number of units and a large lattice constant to ensure the Bragg-type band gap in the medium and high frequency range; such as the paper "Large band gaps in radial phononic crystal structure with round mass block" in EurPhys JAppl Phys. Although the phononic crystal structure based on the local resonance mechanism produces a resonant band gap at low frequencies, its bandwidth is relatively narrow. The previous acoustic black hole coupled local resonance structure could not achieve a lightweight structure, and the additional local resonator introduced a spring-oscillator, which increased the number of overall components, complicated processing, and was time-consuming. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a reinforced acoustic black hole plate with an embedded local resonance structure.

[0007] The present invention is achieved through the following technical solutions.

[0008] The present invention provides an acoustic black hole plate with an embedded local resonance structure, comprising a main body, a local resonance structure and a damping layer; the local resonance structure is embedded in the main body, and the damping layer is adhered to the outer surface of the main body.

[0009] Preferably, the main body includes a lower truncation platform, an upper truncation platform, a lower black hole part and an upper black hole part; the lower black hole part is respectively connected to both sides of the lower truncation platform, the upper black hole part is respectively connected to both sides of the upper truncation platform, and the lower black hole part and the upper black hole part are connected.

[0010] Preferably, the damping layer is adhered to the outer surfaces of the lower truncation platform and the upper truncation platform respectively.

[0011] Preferably, a groove is provided between the lower black hole portion and the upper black hole portion.

[0012] Preferably, the inner surface of the lower black hole portion is connected to the upper black hole portion by an exponential function curve from the end connected to the lower truncation platform;

[0013] The inner surface of the upper black hole portion is bent from one end connected to the upper truncation platform to the lower black hole portion in an exponential function curve.

[0014] Preferably, the expression of the exponential function is as follows:

[0015] h(x)=εx m ,(m≥2)

[0016] Among them, h(x) is the local thickness, ε is the constant coefficient, x is the position coordinate, and m is the control parameter.

[0017] Preferably, the local resonance structure comprises a local resonance unit and a single-leaf acoustic black hole plate; the single-leaf acoustic black hole plate is respectively connected to two sides of the local resonance unit.

[0018] Preferably, the local resonance unit comprises a mass unit and a functional material; the mass unit is arranged inside the functional material.

[0019] Preferably, a parallel plate is provided at one end of the single-leaf acoustic black hole plate, and the upper surface and the lower surface of the parallel plate are parallel;

[0020] One end of the single-leaf acoustic black hole plate is connected to the main body through a parallel plate, and the other end is embedded in the local resonance unit.

[0021] Preferably, the upper surface of the local resonance unit is parallel to the lower surface, the lower surface of the local resonance unit is connected to the lower truncation platform, and the upper surface of the local resonance unit is connected to the upper truncation platform;

[0022] The upper surface and the lower surface of the single-leaf acoustic black hole plate are respectively bent from one end connected to the main body in an exponential function curve and are stopped at the other end.

[0023] The beneficial effects of the present invention are:

[0024] The present invention improves the vibration control effect and reduces the effective action frequency of the black hole effect by combining the energy gathering and dissipation effect of the acoustic black hole and the dynamic vibration absorption effect of the local resonance structure, and has the characteristics of high efficiency, high damping, light weight and broadband. It can adjust the band gap range, broadband vibration suppression, simple structure, and can more conveniently arrange other components on the outer surface of the plate structure, such as piezoelectric sheets, local resonators, etc., and has great potential in the field of broadband vibration reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure provided by an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the main structure provided by an embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of a local resonance structure provided by an embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of the damping layer structure provided by an embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the connection structure of multiple embedded local resonance structure reinforced acoustic black hole plates provided by an embodiment of the present invention;

[0030] Figure 6 is a schematic diagram of a uniform plate structure provided by an embodiment of the present invention;

[0031] Figure 7 Schematic diagram of the structure of an embedded double-leaf acoustic black hole plate provided by an embodiment of the present invention;

[0032] Figure 8 It is one of the schematic diagrams of simulation experiment results provided by the embodiment of the present invention;

[0033] Fig. 9 This is the second schematic diagram of simulation experiment results provided by an embodiment of the present invention;

[0034] Fig.10 This is the third schematic diagram of simulation experiment results provided by the embodiment of the present invention.

[0035] In the figure, 1-main body, 2-local resonance structure, 3-damping layer, 4-lower truncated platform, 5-upper truncated platform, 6-lower black hole part, 7-upper black hole part, 8-single-leaf acoustic black hole plate, 9-local resonance unit, 10-mass unit, 11-groove, 12-functional material, 13-parallel plate. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0037] Embodiment 1:

[0038] like Figure 1 As shown, a reinforced acoustic black hole plate with an embedded local resonance structure includes: a main body 1, a local resonance structure 2 and a damping layer 3; the local resonance structure 2 is embedded in the main body 1, and the damping layer 3 is pasted on the outer surface of the main body 1.

[0039] The main body 1 is an acoustic black hole structure, which is internally coupled to a local resonance structure 2. The required frequency band range is adjusted by adjusting the structural parameters and material parameters of the local resonance structure 2; the action frequency of the acoustic black hole is reduced, and wide-band vibration suppression is achieved; and a lightweight design of the overall structure is achieved.

[0040] In this embodiment, a material with lower rigidity is used as the main body 1 and a material with higher rigidity is used as the local resonance structure 2, so that a wide-bandgap effect with a lower conduction frequency than the ABH can be obtained.

[0041] The function of the damping layer 3 is to effectively attenuate the vibration energy of the structure through an internal energy dissipation mechanism, that is, by converting the vibration energy into heat energy. The damping layer 3 is particularly important for optimizing the low-frequency control of the structure and reducing the peak value.

[0042] like Figure 2 As shown, the main body 1 includes a lower truncation platform 4, an upper truncation platform 5, a lower black hole portion 6 and an upper black hole portion 7; the lower black hole portion 6 is respectively connected to both sides of the lower truncation platform 4, the upper black hole portion 7 is respectively connected to both sides of the upper truncation platform 5, and the lower black hole portion 6 and the upper black hole portion 7 are connected.

[0043] The function of the lower black hole part 6 and the upper black hole part 7 is to utilize their unique thickness gradient characteristics to make the structure produce a concentration of wave energy within a specific frequency range, thereby effectively suppressing vibration. Specifically, the acoustic black hole part achieves local obstruction of sound wave propagation by gradually reducing the thickness, thereby focusing the wave energy. The function of the truncated platform is to ensure the mechanical properties and functions of the acoustic black hole structure. Under the existing processing conditions, the existence of the truncated platform can avoid structural instability caused by excessively weak areas.

[0044] The damping layer 3 is adhered to the outer surfaces of the lower truncation platform 4 and the upper truncation platform 5 respectively.

[0045] The damping layer 3 is pasted on the outer surface of the lower truncated platform 4 and the upper truncated platform 5 because this position is at the energy gathering point of the acoustic black hole structure, which can effectively absorb and dissipate vibration energy. In addition, this pasting position can also reduce interference with other parts of the structure and ensure the overall structural stability.

[0046] In this embodiment, the thickness of the damping layer 3 is uniform. Figure 4 shown.

[0047] A groove 11 is provided between the lower black hole portion 6 and the upper black hole portion 7 .

[0048] The groove 11 is used to connect the local resonance structure 2. Specifically, the groove 11 connects the local resonance unit 9 in the local resonance structure 2, and the connection stability is ensured by the mortise and tenon structure.

[0049] The inner surface of the lower black hole portion 6 is connected to the upper black hole portion 7 by an exponential function curve from one end connected to the lower truncation platform 4;

[0050] The inner surface of the upper black hole portion 7 is connected to the lower black hole portion 6 by an exponential function curve from one end connected to the upper truncation platform 5 .

[0051] The purpose of using the exponential function curve is to ensure the realization of the acoustic black hole effect while avoiding stress concentration caused by too rapid thickness change.

[0052] The expression of the exponential function is as follows:

[0053] h(x)=εx m ,(m≥2)

[0054] Among them, h(x) is the local thickness, ε is the constant coefficient, x is the position coordinate, and m is the control parameter.

[0055] Specifically, h(x) is the local thickness, which indicates the thickness of the structure at a certain position and varies with position; ε is a constant coefficient, which is usually used to define the scale factor of the power exponential function and control the rate at which the thickness changes with position; x represents the position coordinate, which indicates the spatial coordinate along the length or width of the structure, often at a point between the starting point and the end point of the structure; m is the control parameter, which defines the rate at which the thickness changes, and it determines the rate and type of change in the thickness of the structure with position.

[0056] The local resonance structure 2 includes a local resonance unit 9 and a single-leaf acoustic black hole plate 8 ; the single-leaf acoustic black hole plate 8 is connected to two sides of the local resonance unit 9 , respectively.

[0057] like Figure 3 As shown, the local resonance unit 9 includes a mass unit 10 and a functional material 12 ; the mass unit 10 is arranged inside the functional material 12 .

[0058] The functional material 12 wraps the mass unit 10 to form a local resonance unit 9, forming a typical spring-oscillator unit with significant low-frequency control bandgap characteristics, which can effectively suppress the propagation of bending waves in the structure within the bandgap range.

[0059] The main function of the functional material 12 is to improve the vibration control performance of the acoustic black hole structure. They can enhance the energy absorption capacity of the structure within a specific frequency range by optimizing the constitutive properties of the material, such as elastic modulus, density and other characteristics.

[0060] The role of the mass unit 10 is to change the vibration characteristics of the structure by adding mass. By embedding the mass unit in the functional material, the dynamic response of the system can be effectively adjusted to resonate within a specific frequency range, thereby enhancing the energy absorption and vibration suppression effects.

[0061] A parallel plate 13 is provided at one end of the single-leaf acoustic black hole plate 8, and the upper surface and the lower surface of the parallel plate 13 are parallel;

[0062] One end of the single-leaf acoustic black hole plate 8 is connected to the main body 1 through a parallel plate 13 , and the other end is embedded in the local resonance unit 9 .

[0063] The parallel plate 13 facilitates the connection of the single-leaf acoustic black hole plate 8 to the main body 1. The parallel plate 13 is inserted into the groove 11 to form a mortise and tenon structure to ensure the stable connection between the single-leaf acoustic black hole plate 8 and the main body. At the same time, the single-leaf acoustic black hole plate 8 is embedded in the local resonance unit 8 to ensure the stability of the overall structural connection.

[0064] The upper surface of the local resonance unit 9 is parallel to the lower surface, the lower surface of the local resonance unit 9 is connected to the lower truncation platform 4, and the upper surface of the local resonance unit 9 is connected to the upper truncation platform 5;

[0065] The upper surface and the lower surface of the single-leaf acoustic black hole plate 8 are respectively bent in an exponential function curve from one end connected to the main body 1 and are stopped at the other end.

[0066] The upper surface and the lower surface of the local resonance unit 9 are parallel, and the upper surface and the lower surface of the parallel plate 13 form a fitting surface.

[0067] There is a significant impedance mismatch between the local resonant structure 2 and the acoustic black hole wall to which it is attached. This impedance difference triggers Bragg scattering in the mid- and high-frequency bands.

[0068] The local resonance structure 2 plays an important role in enhancing the Bragg scattering. Through the synergistic effect of local resonance and Bragg scattering effect, a significant wide band gap is formed. Even a small and short local resonance unit 9 can expand the band gap to a higher frequency range of 4kHz and above by inducing the Bragg scattering effect.

[0069] The exponential function expression of the convergence curvature of the upper and lower surfaces of the single-leaf acoustic black hole plate 8 is the same as the exponential function expression of the convergence curvature of the inner surfaces of the lower black hole portion 6 and the upper black hole portion 7, which is as follows:

[0070] h(x)=εx m ,(m≥2)

[0071] Wherein, h(x) is the local thickness, ε is the constant coefficient, x is the position coordinate, and m is the control parameter. Similarly, the specific meaning of the symbols is the same as the exponential function expression of the convergent curvature of the inner surface of the lower black hole part 6 and the upper black hole part 7.

[0072] In this embodiment, the vibration analysis of the designed embedded local resonance structure reinforced acoustic black hole plate is carried out using finite element simulation software COMSOL, and compared with a uniform plate and an embedded double-blade acoustic black hole plate of the same size, material and boundary conditions. Figure 5 As shown, the uniform plate structure is Figure 6 As shown, the embedded double-leaf acoustic black hole plate structure is as follows Figure 7 shown.

[0073] The vibration response results of the three plate structures under the same boundary conditions obtained by COMSOL numerical calculation are shown in the figure below: Figures 8 to 10 As shown. Figure 8 In the paper, the comparison of transmission loss between the embedded local resonance structure reinforced acoustic black hole plate and the embedded double-blade acoustic black hole plate is shown. The results show that the embedded local resonance unit reinforced acoustic black hole plate effectively makes up for the lack of ideal vibration reduction effect of the embedded double-blade acoustic black hole plate in the low frequency band, and significantly enhances the vibration suppression effect in a wide frequency range; Fig. 9 In the paper, the transmission loss comparison between the embedded local resonance structure reinforced acoustic black hole plate and the uniform plate is presented. The analysis shows that after the thickness of the embedded double-blade acoustic black hole plate structure is tailored, the design can show excellent vibration suppression performance in a wide frequency range while maintaining the lightweight characteristics; Fig.10 In the paper, a comprehensive comparison of the three plate structures is conducted, which further verifies the advantages of the reinforced acoustic black hole plate with embedded local resonance structure in terms of vibration suppression effect and frequency range.

[0074] Embodiment 2:

[0075] This embodiment is improved on the basis of embodiment 1, and the specific differences are as follows:

[0076] In this embodiment, the local resonance structure is changed to an inertial amplification mechanism structure, thereby achieving enhanced low-frequency vibration reduction performance.

[0077] Similarly, other physical techniques can also enhance low-frequency vibration reduction performance.

[0078] In this embodiment, the acoustic black hole structure is improved through multi-objective optimization, data-driven methods, topology optimization and other approaches, so as to achieve the purpose of further optimizing low-frequency vibration reduction.

[0079] The present invention improves the vibration control effect and reduces the effective action frequency of the black hole effect by combining the energy gathering and dissipation effect of the acoustic black hole and the dynamic vibration absorption effect of the local resonance structure, and has the characteristics of high efficiency, high damping, light weight and broadband. It can adjust the band gap range, broadband vibration suppression, simple structure, and can more conveniently arrange other components on the outer surface of the plate structure, such as piezoelectric sheets, local resonators, etc., and has great potential in the field of broadband vibration reduction.

Claims

1. An acoustic black hole plate with a built-in local resonance structure, characterized in that: include: A main body (1), a local resonance structure (2) and a damping layer (3); the local resonance structure (2) is embedded in the main body (1), and the damping layer (3) is adhered to the outer surface of the main body (1).

2. The reinforced acoustic black hole plate according to claim 1, characterized in that: The main body (1) comprises a lower truncation platform (4), an upper truncation platform (5), a lower black hole portion (6) and an upper black hole portion (7); the lower black hole portion (6) is respectively connected to two sides of the lower truncation platform (4), the upper black hole portion (7) is respectively connected to two sides of the upper truncation platform (5), and the lower black hole portion (6) and the upper black hole portion (7) are connected.

3. The reinforced acoustic black hole plate according to claim 2, characterized in that: The damping layer (3) is respectively adhered to the outer surfaces of the lower truncation platform (4) and the upper truncation platform (5).

4. The reinforced acoustic black hole plate according to claim 2, characterized in that: A groove (11) is provided between the lower black hole portion (6) and the upper black hole portion (7).

5. The reinforced acoustic black hole plate according to claim 2, characterized in that: The inner surface of the lower black hole portion (6) is connected to the upper black hole portion (7) by bending in an exponential function curve from one end connected to the lower truncation platform (4); The inner surface of the upper black hole portion (7) is bent from one end connected to the upper truncation platform (5) to the lower black hole portion (6) in an exponential function curve.

6. The reinforced acoustic black hole plate according to claim 5, characterized in that: The expression of the exponential function is as follows: h(x)=εx m ,(m≥2) Among them, h(x) is the local thickness, ε is the constant coefficient, x is the position coordinate, and m is the control parameter.

7. The reinforced acoustic black hole plate according to claim 1, characterized in that: The local resonance structure (2) comprises a local resonance unit (9) and a single-leaf acoustic black hole plate (8); the single-leaf acoustic black hole plate (8) is respectively connected to two sides of the local resonance unit (9).

8. The reinforced acoustic black hole plate according to claim 7, characterized in that: The local resonance unit (9) comprises a mass unit (10) and a functional material (12); the mass unit (10) is arranged inside the functional material (12).

9. The reinforced acoustic black hole plate according to claim 7, characterized in that: A parallel plate (13) is provided at one end of the single-leaf acoustic black hole plate (8), and the upper surface and the lower surface of the parallel plate (13) are parallel; One end of the single-leaf acoustic black hole plate (8) is connected to the main body (1) via a parallel plate (13), and the other end is embedded in the local resonance unit (9).

10. The reinforced acoustic black hole plate according to claim 7, characterized in that: The upper surface of the local resonance unit (9) is parallel to the lower surface, the lower surface of the local resonance unit (9) is connected to the lower truncation platform (4), and the upper surface of the local resonance unit (9) is connected to the upper truncation platform (5); The upper surface and the lower surface of the single-leaf acoustic black hole plate (8) are respectively bent in an exponential function curve from one end connected to the main body (1) and are stopped at the other end.

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