An acoustic metamaterial pipe isolation device of a membrane cavity mass combination

Abstract

The application discloses a kind of acoustic metamaterial pipeline sound insulation devices of membrane cavity mass block combination, including multiple cavity-coupled acoustic metamaterial unit structures being assembled into one along pipeline inner wall, multiple cavity-coupled acoustic metamaterial unit structures are assembled into sound insulation device, and the outer edge structure of sound insulation device is matched with pipeline inner wall structure and closely adheres;Each of the cavity-coupled acoustic metamaterial unit structures is combined by cavity with certain thickness, film and multiple circular mass blocks;The top of the cavity is provided with round hole, and the film is fixed to the middle part of the cavity, so as to divide the cavity into upper cavity and lower cavity;The diameters of the multiple circular mass blocks are different, and the multiple circular mass blocks are symmetrically arranged on the film along the center line of the cavity and the film according to the position of center of circle.The application utilizes the resonance state coupling of different structures, so that the sound wave has greater energy loss when passing through the device, thereby achieving the effect of sound insulation.

Description

Technical Field

[0001] This invention relates to the field of low-frequency sound insulation technology, specifically to an acoustic metamaterial pipe sound insulation device composed of a membrane cavity mass block combination. Background Technology

[0002] Most existing industrial enterprises have complex piping systems. Mid-to-high frequency noise generated by these systems is relatively easy to control due to its higher frequency, shorter wavelength, and shorter transmission distance. However, low-frequency noise has a longer wavelength, a longer transmission distance, and is more harmful to human health; therefore, controlling pipeline noise is necessary. According to the mass law, materials used to block low-frequency noise are usually dense and heavy, which is disadvantageous for practical engineering applications. Acoustic metamaterials, however, can achieve sound insulation of low-frequency noise using lightweight, thin unit structures.

[0003] Acoustic metamaterials are artificially designed composite materials. By designing unit structures, some extraordinary physical properties can be obtained. Acoustic metamaterials based on the local resonance mechanism can exhibit negative equivalent properties, such as negative equivalent mass density and negative equivalent elastic modulus. These properties can be used to design acoustic metamaterial units with excellent noise reduction capabilities.

[0004] Thin-film acoustic metamaterials exhibit good sound insulation in the low-frequency range, but their sound insulation bandwidth is relatively narrow. Therefore, resonant coupling of the thin film, mass block, and cavity is utilized to expand their operating bandwidth. Besides the narrow sound insulation bandwidth, thin-film metamaterials also exhibit significant sound insulation peaks and valleys in the low-frequency range. This phenomenon is mainly due to changes in the modalities of the thin film itself. When the displacement direction of the film is opposite to the incident direction of the sound wave, sound insulation is favored, resulting in a sound insulation peak; when the displacement direction is the same as the incident direction of the sound wave, sound propagation is favored, resulting in a sound insulation valley. To improve these conditions, a cavity and mass block structure are used to couple resonantly with the thin film, enabling the composite structure to achieve good sound insulation bandwidth and performance in the low-frequency range. Simultaneously, the internal cavity does not affect the transport of the medium within the pipeline and can, to a certain extent, protect the thin film structure, ensuring the overall structure's service life. Summary of the Invention

[0005] To address the aforementioned technical problems, this technical solution provides an acoustic metamaterial pipe sound insulation device composed of membrane cavity mass blocks. By utilizing the rotational arrangement of composite acoustic metamaterial units, sound energy is converted into potential energy through a local resonance mechanism without affecting the flow of the medium inside the pipe, thus achieving the purpose of sound insulation; this effectively solves the above problems.

[0006] This invention is achieved through the following technical solution:

[0007] An acoustic metamaterial pipe sound insulation device composed of diaphragm cavity mass blocks includes multiple diaphragm cavity coupled acoustic metamaterial unit structures assembled along the inner wall of the pipe. The multiple diaphragm cavity coupled acoustic metamaterial unit structures are assembled into a sound insulation device, and the outer edge structure of the sound insulation device matches and fits tightly with the inner wall structure of the pipe. Each of the diaphragm cavity coupled acoustic metamaterial unit structures is composed of a cavity, a membrane, and multiple circular mass blocks. A circular hole is opened at the top of the cavity, and the membrane is fixed in the middle of the cavity, dividing the cavity into an upper cavity and a lower cavity. The multiple circular mass blocks have different diameters and are symmetrically arranged on the membrane along the center line of the cavity and the membrane according to their center positions.

[0008] Furthermore, the height H of the membrane cavity coupled acoustic metamaterial unit structure is 50mm, and the length is less than the radius of the pipe, so that the sound insulation device assembled from multiple membrane cavity coupled acoustic metamaterial unit structures has a through hole at its center.

[0009] Furthermore, in the aforementioned membrane cavity coupled acoustic metamaterial unit structure, the thickness of the sidewalls, bottom plate, and top plate forming the cavity is 1 mm.

[0010] Furthermore, the radius of the circular hole at the top of the cavity is 10 times the thickness of the sidewall, bottom plate, and top plate.

[0011] Furthermore, the sidewalls, bottom plate, and top plate of the cavity are made of ABS or photosensitive resin, the film is a silicone rubber film, and the circular mass block is made of aluminum.

[0012] Furthermore, the thickness t of the film m The thickness is 0.1 mm, and the distance between the thin film and the circular hole at the top of the cavity is 15 mm.

[0013] Furthermore, the height of the circular mass block is 10 times the thickness of the film, and four circular mass blocks are provided. The radii r1, r2, r3, and r4 of the four circular mass blocks are 5 times, 15 times, 25 times, and 40 times the thickness of the film, respectively.

[0014] The acoustic metamaterial pipe sound insulation device based on the combination of membrane cavity mass blocks proposed in this invention has the following advantages compared with the prior art:

[0015] (1) The sound insulation device of the present invention is based on the local resonance mechanism and uses metamaterial technology to design a membrane cavity coupled acoustic metamaterial unit structure. Through the resonant coupling of the membrane, mass block and cavity, when the sound wave passes through the sound insulation device on the inner wall of the circular pipe, the sound wave is incident into the unit structure, causing the air in the cavity, the membrane and the mass block to vibrate. The middle part of the membrane is displaced during the vibration, converting sound energy into potential energy. In the frequency range of 100Hz to 2000Hz, the average sound transmission loss is 25dB; low frequency noise reduction is achieved, thereby achieving the purpose of sound insulation.

[0016] (2) The sound insulation device in this invention has a through hole in the middle, which does not affect the transport of the medium inside the pipeline.

[0017] (3) The present invention takes into account the characteristics of a wide working bandwidth and a relatively stable sound insulation effect in the low frequency band. The external cavity is made by 3D printing rapid prototyping technology, the internal film is a silicone rubber film, and the mass block is made of aluminum, resulting in a low manufacturing cost.

[0018] (4) The unit structure in this invention is combined into a sound insulation device, which can be applied to circular pipeline facilities and is easy to widely use. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the sound insulation device of the present invention.

[0020] Figure 2 This is a top view of the sound insulation device of the present invention.

[0021] Figure 3 This is a top perspective view of the sound insulation device of the present invention.

[0022] Figure 4 This is a diagram showing the height H of the sound insulation device of the present invention.

[0023] Figure 5 This is a schematic diagram of a single membrane cavity coupled acoustic metamaterial unit structure in this invention.

[0024] Figure 6 This is a top view of the thin film in this invention.

[0025] Figure 7 This is a simulation diagram of the sound insulation device of the present invention.

[0026] Figure 8 This is a modal analysis diagram of the circular mass block with different radii in this invention.

[0027] Figure 8 (a) is the modal analysis diagram when the radius of the circular mass block is 0.5 mm and the characteristic frequency is 1207 Hz.

[0028] Figure 8(b) is the modal analysis diagram when the radius of the circular mass block is 1.5 mm and the characteristic frequency is 651 Hz.

[0029] Figure 8 (c) is the modal analysis diagram when the radius of the circular mass block is 2.5 mm and the characteristic frequency is 483 Hz.

[0030] Figure 8 (d) is the modal analysis diagram when the radius of the circular mass block is 4mm and the characteristic frequency is 395Hz.

[0031] Figure 9 This is a sound pressure diagram of the sound insulation device of the present invention at 1250Hz.

[0032] Figure 10 This is a diagram showing the displacement of the membrane in the sound insulation device of the present invention at 1250Hz.

[0033] Figure 11 This is a graph showing the sound transmission loss of the sound insulation device of the present invention.

[0034] The labels in the attached diagram are: 1-sound insulation device, 11-membrane cavity coupled acoustic metamaterial unit structure, 111-circular hole, 112-membrane, 113-circular mass block, 12-through hole. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. The described embodiments are merely some embodiments of the present invention, and not all embodiments. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention should fall within the protection scope of the present invention.

[0036] Example 1:

[0037] like Figure 1-7 As shown, an acoustic metamaterial pipe sound insulation device composed of membrane cavity mass blocks includes multiple membrane cavity coupled acoustic metamaterial unit structures 11 assembled as a single unit along the inner wall of a pipe. These multiple membrane cavity coupled acoustic metamaterial unit structures 11 are assembled along the inner wall of a circular pipe to form a ring-shaped sound insulation device 1. The outer edge structure of the sound insulation device 1 matches and tightly fits the inner wall structure of the pipe. The diameter of the sound insulation device 1 is the same as the inner diameter of the pipe; in this embodiment, the diameter of the sound insulation device 1 is 100 mm.

[0038] Each cavity-coupled acoustic metamaterial unit structure 11 is composed of a cavity, a thin film 112 and multiple circular mass blocks 113; the height H of the cavity-coupled acoustic metamaterial unit structure 11 is 50mm, and the length of each cavity-coupled acoustic metamaterial unit structure 11 is less than the radius of the pipe, so that the sound insulation device 1 assembled from multiple cavity-coupled acoustic metamaterial unit structures 11 has a through hole 12 at its center.

[0039] The film 112 is a silicone rubber film, fixed in the middle of the cavity, dividing the cavity into an upper cavity and a lower cavity; the thickness t of the film 112 is... m The thickness is 0.1 mm, and the distance between the thin film 112 and the circular hole at the top of the cavity is 15 mm.

[0040] The circular mass block 113 is made of aluminum. The multiple circular mass blocks 113 have different diameters and are symmetrically arranged on the film along the center line of the cavity and the film according to their center positions.

[0041] The height of the circular mass block 113 is 10 times the thickness of the film, that is, the height of the circular mass block 113 is 1mm; four circular mass blocks 113 are provided, and the radii r1, r2, r3, and r4 of the four circular mass blocks 113 are 5 times, 15 times, 25 times, and 40 times the thickness of the film 112, respectively; that is, the radii r1, r2, r3, and r4 of the four mass blocks M1, M2, M3, and M4 are 0.5mm, 1.5mm, 2.5mm, and 4mm, respectively.

[0042] By utilizing the local resonance mechanism, the membrane undergoes a certain displacement, converting acoustic energy into potential energy to achieve sound insulation. Modal analysis is performed on the structure composed of the membrane and mass blocks, using mass blocks of different radii to control the characteristic frequencies of the membrane, such as... Figure 8 As shown, Figure 8 (a) is a displacement diagram of the membrane when the mass block radius r1 = 0.5 mm and the characteristic frequency is 1207 Hz. Figure 8 (b) is a displacement diagram of the membrane when the mass block radius r2 = 1.5 mm and the characteristic frequency is 651 Hz. Figure 8 (c) is a displacement diagram of the membrane when the mass block radius r3 = 2.5 mm and the characteristic frequency is 483 Hz. Figure 8 (d) shows the displacement diagram of the membrane when the mass block radius r4 = 4 mm and the characteristic frequency is 395 Hz. Mass blocks of different radii are symmetrically placed on the thin film 112 according to the center position, resulting in a composite structure with a wide sound insulation bandwidth in the low frequency range, such as... Figure 5 and Figure 6 As shown.

[0043] To improve the peak and valley sound insulation issues of the thin-film-mass block structure in low-frequency sound insulation, the thin-film-mass block structure is combined with a cavity. The sidewalls, bottom plate, and top plate of the cavity are made of ABS or photosensitive resin. A circular hole is opened at the top of the cavity. The membrane cavity is coupled with an acoustic metamaterial unit structure. The thickness of the sidewalls, bottom plate, and top plate of the cavity is 1 mm. The radius of the circular hole at the top of the cavity is 10 times the thickness of the sidewalls, bottom plate, and top plate, and the radius of the circular hole at the top of the cavity is 10 mm.

[0044] In the described membrane-cavity coupled metamaterial unit structure, the displacement of the membrane converts acoustic energy into potential energy, achieving sound insulation. The combination of the membrane and mass blocks—four circular mass blocks of different radii symmetrically attached to the membrane at their centers—increases the sound insulation bandwidth. The combination with the cavity solves the problem of sound insulation peaks and valleys in the low-frequency range, making the sound insulation effect of the device more stable in the low-frequency range. Applying the design method of this scheme, sound insulation in the designed frequency band can be achieved, such as... Figure 7 As shown, the sound insulation device is placed in the middle of the pipeline. When the sound wave passes through the sound insulation device, due to the coupling of the membrane, mass block and cavity resonant state, the sound energy is converted into potential energy, causing the membrane to move, thereby achieving the purpose of sound insulation.

[0045] like Figure 9 As shown, at 1250Hz, the total sound pressure distribution is mostly confined to the incident end of the pipe, indicating that the sound insulation device has achieved its intended effect. Figure 10 As shown, at 1250Hz, the overall displacement direction of the membrane is still opposite to that of the incident sound wave, which verifies the correctness of the device design mechanism.

[0046] To verify the effectiveness of the sound insulation device of this invention, simulation software was used to simulate this implementation case. Three physical fields were used: pressure acoustics, frequency domain, solid mechanics, and membrane. For the solid mechanics field, a mass block was selected; for the membrane field, a thin film was selected; and for the pressure acoustics and frequency domain fields, the cavity portion of the unit structure was selected. The internal walls of the unit structure were set as hard boundaries, and the incident wave was set to 1 Pa. The coupling of the multi-physics fields was selected between the sound-structure boundary and the solid-thin structure connection. The set variables were used to calculate the sound transmission loss. The results are as follows: Figure 11 The sound transmission loss curve shown indicates that the designed device achieves a stable and good sound insulation effect from 100Hz to 2000Hz, and also shows that the designed sound insulation device has a good sound insulation bandwidth in the low frequency range.

[0047] The specific fabrication process of the acoustic metamaterial pipe sound insulation device composed of membrane cavity mass blocks is as follows:

[0048] (1) Based on the principle of local resonance, acoustic energy is converted into potential energy. Through the resonant coupling of the thin film, mass block and cavity, the unit structure has a stable and good sound insulation effect and sound insulation bandwidth in the low frequency band. The designed acoustic metamaterial unit is combined to obtain a sound insulation device for pipeline.

[0049] (2) The external cavity is modeled into upper and lower parts, and then processed separately using 3D printing technology.

[0050] (3) symmetrically attach the aluminum mass block to the film, place the film between the upper and lower cavities, and at the same time attach the cavity to the film.

[0051] (4) In order to verify the correctness of the sound insulation device function, the simulation results can be compared with the experimental results. When the experimental results are similar to the simulation results, that is, when there is a stable and good sound insulation effect in the range of 100Hz to 2000Hz, the preparation is complete.

Claims

1. An acoustic metamaterial pipe sound insulation device composed of a membrane cavity mass block assembly, characterized in that: The device includes multiple membrane cavity coupled acoustic metamaterial unit structures (11) assembled along the inner wall of the pipe. The multiple membrane cavity coupled acoustic metamaterial unit structures (11) are assembled into a sound insulation device (1). The outer edge structure of the sound insulation device (1) matches and fits tightly with the inner wall structure of the pipe. Each of the membrane cavity coupled acoustic metamaterial unit structures (11) is composed of a cavity, a membrane (112) and multiple circular mass blocks (113). A circular hole (111) is opened at the top of the cavity. The membrane (112) is fixed in the middle of the cavity, dividing the cavity into an upper cavity and a lower cavity. The multiple circular mass blocks (113) have different diameters and are symmetrically arranged on the membrane along the center line of the cavity and the membrane (112) according to their center positions.

2. The acoustic metamaterial pipe sound insulation device of the membrane cavity mass block combination according to claim 1, characterized in that: The height H of the membrane cavity coupled acoustic metamaterial unit structure (11) is 50mm; the radial length of the membrane cavity coupled acoustic metamaterial unit structure (11) is less than the radius of the pipe, so that the sound insulation device (1) assembled from multiple membrane cavity coupled acoustic metamaterial unit structures (11) has a through hole (12) at its center.

3. The acoustic metamaterial pipe sound insulation device of the membrane cavity mass block combination according to claim 1 or 2, characterized in that: The membrane cavity coupled acoustic metamaterial unit structure (11) has a cavity sidewall, bottom plate and top plate with a thickness of 1 mm.

4. The acoustic metamaterial pipe sound insulation device of the membrane cavity mass block combination according to claim 3, characterized in that: The radius of the circular hole (111) at the top of the cavity is 10 times the thickness of the side wall, bottom plate and top plate; when the thickness of the side wall, bottom plate and top plate is 1mm, the radius of the circular hole at the top of the cavity is 10mm.

5. The acoustic metamaterial pipe sound insulation device of the membrane cavity mass block combination according to claim 3, characterized in that: The sidewalls, bottom plate, and top plate of the cavity are made of ABS or photosensitive resin, the film (112) is a silicone rubber film, and the circular mass block (113) is made of aluminum.

6. The acoustic metamaterial pipe sound insulation device of the membrane cavity mass block combination according to claim 1, characterized in that: The thickness t of the thin film (112) m The thickness is 0.1 mm, and the distance between the thin film (112) and the circular hole (111) at the top of the cavity is 15 mm.

7. The acoustic metamaterial pipe sound insulation device of the membrane cavity mass block combination according to claim 5, characterized in that: The height of the circular mass block (113) is 10 times the thickness of the film (112). There are four circular mass blocks (113). The radii r1, r2, r3, and r4 of the four circular mass blocks (113) are 5 times, 15 times, 25 times, and 40 times the thickness of the film (112), respectively.

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