Design method of sound barrier with sound absorption superstructure and sound insulation superstructure composite structure

Abstract

The invention discloses a design method of a sound barrier with a sound absorption metamaterial and sound insulation metamaterial composite structure, which is characterized in that a porous sound absorption material, a metamaterial sound absorption unit and a metamaterial sound insulation unit are arranged in the sound barrier, and the metamaterial sound insulation unit adopts a thin plate local resonance structure. Through the cooperative coupling effect of the porous sound absorption material, the super-structure sound absorption unit and the super-structure sound insulation unit, the sound absorption function and the sound insulation function are combined. The technical bottleneck that the sound absorption and sound insulation performance of an existing sound barrier cannot be achieved at the same time is broken through, the composite super-structure sound barrier with the broadband sound absorption and efficient sound insulation capacity is constructed, and the sound absorption performance and the sound insulation performance of the sound barrier at low and medium frequencies can be remarkably improved at the same time; and the optimal sound absorption and insulation performance is achieved through the combined design and the synergistic coupling effect of the sound absorption superstructures, the porous sound absorption materials and the sound insulation superstructures.

Description

Technical Field

[0001] This invention relates to a design method for a sound barrier, and more particularly to a design method for a sound barrier with a composite structure of sound-absorbing and sound-insulating superstructures, belonging to the field of traffic and environmental noise control engineering technology. Background Technology

[0002] With the rapid development of transportation (high-speed rail, urban rail, highways) and industrial facilities, noise pollution has become an increasingly prominent problem. Sound barriers, as an effective means of blocking noise propagation paths, are widely used in noise-sensitive areas.

[0003] In traditional engineering applications, sound barriers often adopt a combination of "porous sound-absorbing materials + solid sound insulation panels". The basic structure is as follows: a perforated plate or open surface layer is set on the side facing the noise source, which is then filled with porous sound-absorbing materials such as rock wool, glass wool, and aluminum foam. The side facing away from the noise source is a solid panel such as a steel plate, aluminum plate, or reinforced concrete slab. Sound energy is dissipated through the porous layer on the front side, and sound waves are reflected and isolated through the mass and rigidity of the back panel.

[0004] In terms of sound absorption, traditional porous fiber materials such as rock wool, glass wool, and aluminum foam are mainly used to fill the barrier cavity. The sound absorption mechanism of these materials mainly stems from the viscous dissipation and thermal conduction effects generated after sound waves enter the pores. However, according to basic acoustic theory, the thickness of porous materials needs to reach one-quarter of the wavelength of the sound wave to produce a significant sound absorption effect. This results in traditional sound barriers having extremely low sound absorption efficiency for mid-to-low frequency noise with longer wavelengths (especially below 500Hz). Furthermore, increasing the material thickness leads to problems such as large volume, easy moisture absorption and deterioration, and reduced structural strength.

[0005] In terms of sound insulation, traditional sound barriers mainly rely on solid metal or concrete slabs at the back. According to the acoustic "mass law," sound insulation is directly proportional to the mass per unit area of ​​the material. To achieve ideal low-frequency sound insulation performance, the thickness and surface density of the barrier must be significantly increased, which not only increases the project cost but also places stringent requirements on the load-bearing capacity of the supporting foundation.

[0006] In recent years, the emergence of acoustic metamaterials has made it possible to break through the physical limits of traditional materials. With the development of metamaterial theory, researchers have proposed a variety of sound-absorbing metastructures based on mechanisms such as local resonance, spatial coiling, and metasurfaces. These structures can achieve strong absorption of low-frequency sound waves on ultrathin scales much smaller than the wavelength of sound waves, significantly breaking through the limitations of traditional porous materials in terms of low-frequency thickness.

[0007] Existing publicly available metastructure sound barriers or acoustic metastructure designs mostly focus on "sound-absorbing metastructures," that is, by setting up membrane resonant units, Helmholtz resonant units, coiled channel units, etc., to achieve high sound absorption coefficients or near-complete absorption within a specific frequency band, mainly addressing the problem of "not absorbing" low-frequency frequencies. However, most of these structures optimize their acoustic performance from the "absorption side," paying less attention to the sound wave transmission path and the overall sound insulation mechanism. The corresponding out-of-plane stiffness and equivalent areal density are often not systematically optimized, making it difficult to significantly improve the overall sound insulation of the sound barrier while ensuring high sound absorption performance.

[0008] In summary, while both sound-absorbing and sound-insulating metastructure technologies have made significant progress, their development paths are independent and lack integration. Sound-absorbing metastructures focus on "sound energy dissipation" but cannot effectively prevent transmission; sound-insulating metastructures focus on "blocking transmission" but at the cost of strong reflection. Currently, there is no composite sound barrier solution that integrates sound-absorbing and sound-insulating metastructures within the same sound barrier system, and it is still unable to effectively address the technical requirements of balancing efficient low- and mid-frequency noise reduction, lightweight structure, and engineering applicability in traffic noise control.

[0009] A search revealed no patent documents that are identical or similar to this application.

[0010] Therefore, how to provide a design method for a sound barrier with a composite structure of sound absorption and sound insulation superstructure, so that the designed sound barrier can overcome the technical bottleneck of the existing sound barrier's inability to achieve both sound absorption and sound insulation performance, and construct a composite superstructure sound barrier with both broadband sound absorption and high-efficiency sound insulation capabilities, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0011] The technical problem to be solved by this invention is to address the deficiencies in the existing technology by providing a design method for a sound barrier with a composite structure of sound-absorbing and sound-insulating metastructures. The sound barrier designed in this invention breaks through the technical bottleneck of existing sound barriers where sound absorption and sound insulation performance cannot be achieved simultaneously. It constructs a composite metastructure sound barrier that combines broadband sound absorption and high-efficiency sound insulation capabilities, which can significantly improve the sound absorption and sound insulation performance of the sound barrier in the mid and low frequencies. Through the combined design and synergistic coupling of sound-absorbing metastructures, porous sound-absorbing materials, and sound-insulating metastructures, optimal sound absorption and sound insulation performance is achieved.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a design method for a sound barrier with a composite structure of sound-absorbing metastructure and sound-insulating metastructure, wherein a porous sound-absorbing material, a metastructure sound-absorbing unit, and a metastructure sound-insulating unit are provided in the sound barrier, wherein the metastructure sound-insulating unit adopts a thin plate local resonance structure, and the porous sound-absorbing material, the metastructure sound-absorbing unit, and the metastructure sound-insulating unit are used to achieve the combined functions of sound absorption and sound insulation.

[0013] Preferably, the sound barrier includes a perforated panel facing the noise source and a base plate facing away from the noise source. A side plate is enclosed between the perforated panel and the base plate, forming an internal cavity. Multiple partitions are also provided between the perforated panel and the base plate and within the internal cavity, dividing the internal cavity into multiple independent sound-absorbing and sound-insulating unit chambers A. Multiple periodically distributed local resonant units are provided on the base plate, and each sound-absorbing and sound-insulating unit chamber A contains one or more local resonant units. The local resonant units are configured as mass blocks. Each sound-absorbing and sound-insulating unit chamber contains porous sound-absorbing material and an impedance modulation channel penetrating the porous sound-absorbing material. The impedance modulation channel is a rectangular channel. The local resonant unit is positioned inside the impedance modulation channel in each sound-absorbing and sound-insulating unit chamber A. The impedance modulation channel in each sound absorption and insulation unit chamber A is used to form a meta-structured sound absorption unit that works in conjunction with porous sound absorption material to absorb sound. The base plate and multiple local resonance units set on the base plate form a meta-structured sound insulation unit with a thin plate local resonance structure, thereby using the principle of thin plate local resonance to achieve sound insulation.

[0014] Preferably, the sound barrier includes a perforated panel facing the noise source and a base plate facing away from the noise source. A side plate is enclosed between the perforated panel and the base plate, forming an internal cavity. Multiple partitions are also provided between the perforated panel and the base plate and within the internal cavity, dividing the internal cavity into multiple independent sound-absorbing and sound-insulating unit chambers A. Multiple periodically distributed local resonant units are provided on the base plate, and each sound-absorbing and sound-insulating unit chamber A contains one or more local resonant units, which are configured as mass blocks. Each sound-absorbing and sound-insulating unit chamber A contains porous sound-absorbing material and an impedance modulation channel located at the top of the porous sound-absorbing material. The impedance modulation channel has a gradient V-shaped groove. An internal cavity is also formed at the bottom of the porous sound-absorbing material, isolating the internal cavity from the V-shaped groove. The local resonant unit is positioned within the internal cavity in each sound-absorbing and sound-insulating unit chamber A. The impedance modulation channel in each sound absorption and insulation unit chamber A is used to form a meta-structured sound absorption unit that works in conjunction with porous sound absorption material to absorb sound. The base plate and multiple local resonance units set on the base plate form a meta-structured sound insulation unit with a thin plate local resonance structure, thereby using the principle of thin plate local resonance to achieve sound insulation.

[0015] Preferably, the partition is configured as a flexible partition.

[0016] Preferably, the partition is configured as a flexible partition by using a soft material and having a straight shape, with the top and bottom of the straight plate connected to a perforated panel and a base plate, respectively.

[0017] Preferably, the partition is configured as a flexible partition by using a soft material and shaping it into an S-shape, with the top of the S-shaped partition and the bottom of the straight plate connected to the perforated panel and the bottom plate, respectively.

[0018] Preferably, the partition is configured as a flexible partition by using a rigid material and shaping it as a straight plate. The top of the straight plate is connected to a perforated panel, and the bottom of the straight plate is connected to a base plate via a rubber block.

[0019] Preferably, the sound barrier includes a perforated panel facing the noise source and a base plate facing away from the noise source. A side plate is enclosed between the perforated panel and the base plate, and the perforated panel, the base plate and the side plate enclose an internal cavity. A plurality of periodically distributed local resonant units are arranged on the base plate. The local resonant units are configured as acoustic black hole structures. A porous sound-absorbing material is also arranged in the internal cavity and on the side facing the noise source. The closed bottom end of the acoustic black hole structure is connected to the base plate, and the open top end of the acoustic black hole structure is inserted into the porous sound-absorbing material. The acoustic black hole structure is used to form a meta-absorbing unit that works in conjunction with porous sound-absorbing materials to absorb sound. The base plate and multiple acoustic black hole structures set on the base plate form a meta-insulation unit with a local resonance structure in a thin plate, thereby using the principle of local resonance in a thin plate to achieve sound insulation.

[0020] Preferably, the acoustic black hole structure includes a conical outer cylinder and multiple layers arranged sequentially inside the outer cylinder along its axial direction, with holes opened in the middle of each layer. A slit-type Helmholtz resonant cavity, consisting of a neck cavity and a belly cavity, is formed between the outer cylinders of two adjacent acoustic black hole structures. The slit-type Helmholtz resonant cavity is used to further absorb sound.

[0021] Preferably, a protruding ring is provided at the open top of the outer cylinder, and the bottom of the outer cylinder is rigidly connected to the base plate. The protruding ring at the open top of the outer cylinder is inserted into the porous sound-absorbing material.

[0022] The beneficial effects of this invention are as follows: This invention breaks through the technical bottleneck of existing sound barriers where "sound absorption" and "sound insulation" performance cannot be simultaneously achieved. It constructs a composite metastructure sound barrier that combines broadband sound absorption and high-efficiency sound insulation capabilities, which can significantly improve the sound absorption and sound insulation performance of the sound barrier in the mid-to-low frequency range. Through the combined design and synergistic coupling of the sound-absorbing metastructure, porous sound-absorbing material, and sound-insulating metastructure, optimal sound absorption and insulation performance is achieved. After the sound-absorbing metastructure and the sound-insulating metastructure are coupled, the frequency band is optimized with low or mid-to-low frequency as the core. The sound absorption bandwidth is broadened by the metastructure sound-absorbing unit, and the sound insulation bandwidth is broadened by the metastructure sound-insulating unit, achieving the effect of "strong performance in low frequencies and no dip in mid frequencies". A coupled design method is adopted, combining a porous material impedance modulation channel sound-absorbing metastructure with a thin-plate local resonance sound-insulating metastructure. The sound-absorbing side of this coupled design consists of a porous material impedance modulation channel (for sound energy absorption and reducing incident sound pressure), while the sound-insulating side consists of a thin-plate local resonance unit (for sound transmission blocking and suppressing structural vibration). This achieves a continuous and gradual change in acoustic impedance from air to the perforated plate, then to the porous material modulation channel, and finally to the thin-plate sound insulation layer, avoiding interface sound reflection caused by impedance abrupt changes and improving coupling efficiency. By setting the partition to have flexible functionality, the "damping vibration reduction + impedance adaptation + load decoupling" of the flexible interface solves the three key problems of vibration crosstalk, impedance abrupt changes, and resonant coupling failure under rigid connections. This retains the sound absorption advantages of the vertical partition in the sound-absorbing layer, such as cavity segmentation and impedance modulation, while avoiding the negative impacts of rigid partitions on the local resonance of the thin-plate (additional stiffness, vibration coupling, resonant frequency deviation, secondary noise, etc.), enhancing the low-frequency sound insulation performance of the thin-plate local resonance, and achieving a synergistic improvement in the performance and structural stability of the sound-absorbing and sound-insulating composite structure. A sound barrier with an acoustic black hole structure was designed, breaking the physical boundary between sound absorption and sound insulation. The acoustic black hole structure captures and consumes sound energy through the "slow sound effect" generated by its geometry inside, and acts as an additional mass block on the base plate outside, participating in the local resonance of the base plate to perform sound insulation. This design solves the two core indicators of sound absorption and sound insulation at the same time without adding extra space and components, and achieves a high degree of structural integration. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the vertical cross-sectional structure of the sound barrier in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the vertical cross-sectional structure of the sound barrier in Embodiment 2 of the present invention; Figure 3 This is a partial vertical cross-sectional view of the sound barrier in Embodiment 3 of the present invention; Figure 4This is a partial vertical cross-sectional view of the sound barrier in Embodiment 4 of the present invention; Figure 5 This is a partial vertical cross-sectional view of the sound barrier in Embodiment 5 of the present invention; Figure 6 This is a schematic diagram of the vertical cross-sectional structure of the sound barrier in Embodiment Six of the present invention; Figure 7 This is a schematic diagram of the vertical cross-sectional structure of the acoustic black hole in Embodiment Six of the present invention; Figure 8 This is a partial vertical cross-sectional view of the sound barrier in Embodiment Six of the present invention; Figure 9 This is a partial vertical cross-sectional view of the sound barrier in actual working condition according to Embodiment Six of the present invention; In the diagram: 1. Perforated panel; 2. Base plate; 3. Side plate; 4. Partition plate; 5. Local resonant unit; 6. Porous sound-absorbing material; 7. Impedance modulation channel; 8. Rubber block; 9. Internal cavity; 10. Acoustic black hole structure; 101. Outer cylinder; 102. Sheet plate; 103. Ring body; 11. Slit-type Helmholtz resonant cavity; 111. Neck cavity; 112. Abdominal cavity. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] This invention discloses a design method for a sound barrier with a composite structure of sound-absorbing and sound-insulating metastructures. The method involves incorporating porous sound-absorbing materials, metastructure sound-absorbing units, and metastructure sound-insulating units within the sound barrier. The metastructure sound-insulating units employ a thin-plate localized resonance structure. The sound absorption and sound insulation are achieved through the synergistic coupling effect of the porous sound-absorbing materials, metastructure sound-absorbing units, and metastructure sound-insulating units. This design overcomes the technical bottleneck of existing sound barriers where sound absorption and sound insulation performance cannot be simultaneously achieved. It constructs a composite metastructure sound barrier that combines broadband sound absorption with high-efficiency sound insulation capabilities, significantly improving both sound absorption and sound insulation performance in the mid-to-low frequency range. Through the combined design and synergistic coupling effect of the sound-absorbing metastructure, porous sound-absorbing materials, and sound-insulating metastructure, optimal sound absorption and insulation performance is achieved. After the sound-absorbing metastructure and the sound-insulating metastructure are coupled, the frequency band is optimized with low frequency or mid-low frequency as the core. The sound absorption bandwidth is widened by the metastructure sound-absorbing unit, and the sound insulation bandwidth is widened by the metastructure sound insulation unit, thus achieving the effect of "strong performance in low frequency and no depression in mid frequency".

[0026] The following describes six embodiments: Example 1: As Figure 1As shown, the sound barrier includes a perforated panel 1 facing the noise source and a base plate 2 facing away from the noise source. A side plate 3 is enclosed between the perforated panel 1 and the base plate 2, forming an internal cavity. Multiple partitions 4 are also provided between the perforated panel 1 and the base plate 2 and within the internal cavity, dividing the internal cavity into multiple independent sound-absorbing and sound-insulating unit chambers A. Multiple periodically distributed local resonant units 5 are provided on the base plate 2, and each sound-absorbing and sound-insulating unit chamber A contains one or more local resonant units 5. In this embodiment, the local resonant unit 5 is configured as a mass block. Each sound-absorbing and sound-insulating unit chamber A contains a porous sound-absorbing material 6 and an impedance modulation channel 7 penetrating the porous sound-absorbing material 6. The local resonant unit 5 is positioned inside the impedance modulation channel 7 in each sound-absorbing and sound-insulating unit chamber A. The impedance modulation channel 7 in each sound-absorbing and sound-insulating unit chamber A forms a meta-absorbing unit that works in conjunction with porous sound-absorbing material 6 for sound absorption. The base plate and multiple local resonance units 5 set on the base plate form a meta-insulating unit with a thin-plate local resonance structure, thus utilizing the principle of thin-plate local resonance for sound insulation. In this embodiment, the local resonance unit 5 in the meta-insulating unit is placed in the impedance modulation channel 7 that penetrates the porous sound-absorbing material 6. This allows the impedance modulation channel 7 to both work with the porous sound-absorbing material 6 for sound absorption and to provide vibration space for the local resonance unit 5. This ensures that the local resonance unit 5 can form a thin-plate local resonance with the base plate for sound insulation. Thus, by synergistically coupling the sound-absorbing meta-structure, the porous sound-absorbing material, and the sound-insulating meta-structure, optimal sound absorption and insulation performance is achieved. This embodiment employs a coupling design method of porous material impedance modulation channel sound-absorbing meta-structure + thin-plate local resonance sound-insulating meta-structure. The coupling design employs a porous material impedance modulation channel on the sound-absorbing side (for sound energy absorption and reducing incident sound pressure) and a thin-plate localized resonant unit on the sound-insulating side (for sound transmission blocking and suppressing structural vibration). This achieves a continuous and gradual change in acoustic impedance from air to perforated plate, porous material modulation channel, and thin-plate sound insulation layer, avoiding interface sound reflection caused by impedance abrupt changes and improving coupling efficiency. With "sound dissipation on the absorption side + sound insulation on the sound insulation side + interface synergistic matching" as its core, it specifically combines the broadband sound absorption characteristics of the porous impedance modulation channel (using flow resistance and tortuosity to control acoustic impedance and achieve sound energy dissipation) with the low-frequency strong sound insulation advantage of the thin-plate localized resonance (suppressing sound transmission through thin-plate-mass block resonance). Through gradual interface impedance change, complementary resonant frequency bands, and integrated structural constraints, it solves the problems of narrow-band limitations of single metastructures, sound reflection at the coupling interface, and vibration crosstalk, achieving a broadband (especially low-frequency) dual performance improvement in sound absorption and sound insulation under lightweight conditions.

[0027] By adjusting the viscous resonant frequency (sound absorption main frequency) of the porous material channel and resonant cavity and the bending resonant frequency (sound insulation main frequency) of the local resonance of the thin plate, the two are made to be non-overlapping and cover the target frequency band. At the same time, the transition zone of the two frequency bands is connected by fine-tuning the parameters to avoid the appearance of a sound absorption / sound insulation "recessed zone" after coupling; avoid the superposition of resonant frequencies to prevent the aggravation of interface vibration crosstalk and performance degradation.

[0028] By configuring the partition 4 as a flexible partition, the three key problems of vibration crosstalk, impedance abrupt change, and resonant coupling failure under rigid connection are solved through the "damping and vibration reduction + impedance matching + load decoupling" of the flexible interface. It retains the sound absorption advantages of the vertical partition of the sound-absorbing layer, such as cavity segmentation and impedance modulation, while avoiding the negative impact of rigid partitions on local resonance of thin plate (additional stiffness, vibration coupling, resonant frequency deviation, secondary noise, etc.). It enhances the low-frequency sound insulation performance of local resonance of thin plate, and realizes the synergistic improvement of the performance and structural stability of the sound-absorbing and sound-insulating composite structure. Its working mechanism revolves around three core dimensions: vibration transmission, acoustic impedance matching, and structural mechanical coupling. The benefits are reflected in the acoustic performance, structural performance, and engineering adaptability, forming a sound-absorbing and sound-insulating composite system that adapts to porous impedance modulation and local resonance of thin plate. This design offers several advantages: First, in existing technologies, rigid partitions are typically used. When these rigid partitions are connected to the back panel, they act as "stiffeners," significantly increasing the equivalent bending stiffness of the back panel according to thin-plate vibration theory. Flexible partitions solve this problem of additional stiffness, as their shear and bending stiffness are far lower than those of rigid partitions. Mechanically, this achieves dynamic decoupling between the sound-absorbing and sound-insulating layers. This means the local resonant units at the back panel can maintain their designed mass-spring system characteristics without the resonant frequency shifting to higher frequencies due to the partition's intervention, thus ensuring uncompromised low-frequency sound insulation performance. Second, rigid partitions create constraint boundaries, dividing the back panel into multiple small, rigid regions, severely limiting the vibration mode distribution of the panel. Flexible partitions, through their flexibility, allow the back panel greater freedom in the normal (vibration direction). This "weakly constrained" environment allows the displacement field of the local resonant unit to fully expand, thus maintaining the coherent sound attenuation effect of the metamaterial over a large area and significantly improving low-frequency sound insulation. Third, under acoustic pressure, the micro-vibrations of the flexible partition itself can form a multi-level coupling system with the vibration of the air column within the cavity and the local resonance of the backplate. This multi-degree-of-freedom coupling increases the path for sound energy dissipation, achieving both a wider sound absorption bandwidth and enhanced sound insulation depth without increasing thickness.

[0029] In this embodiment, the partition 4 is configured as a flexible partition by using a soft material such as silicone, polyurethane rubber, PVC, EPDM, or aluminum foil. It is a straight plate, with its top and bottom connected to the perforated panel 1 and bottom plate 2, respectively. The impedance modulation channel 7 is a rectangular channel.

[0030] The applicant also studied the additional bending stiffness requirements and matching relationship between the vertical partitions of the soft partition and the sound insulation back panel: When a flexible vertical partition is coupled to a thin-plate locally resonant sound insulation back panel, additional bending stiffness is introduced to the back panel through the viscoelastic constraint and distributed contact of the flexible interface. This stiffness is not necessarily better the greater it is; the core requirements are "weak constraint, high adaptability, and no resonance disturbance." It is necessary to improve the in-plane stiffness uniformity of the back panel and suppress excessive bending vibration in non-resonant areas through appropriate additional stiffness, while avoiding excessive additional stiffness that could lead to a shift in the local resonant frequency and distortion of the resonant modes, ultimately compromising low-frequency sound insulation performance. The design must revolve around the core requirement of local resonance in the sound insulation back panel, while also considering the integrity of the sound-absorbing layer channels and the overall mechanical stability of the composite structure. The additional bending stiffness must be a distributed weak stiffness, only increasing the basic bending stiffness of the back plate without changing the resonant mode type of the back plate's "thin plate + local mass block" (it remains a local micro-bending resonance at the mass block, not the overall bending resonance of the back plate). Simultaneously, the distributed additional stiffness must homogenize the overall bending stiffness of the back plate, eliminating weak points in the unpartitioned area, preventing amplification of local vibrations, and avoiding secondary radiation noise caused by excessive bending in non-resonance areas. The additional bending stiffness of the flexible partition 4 on the base plate 2 must be ≤50% of the base plate's inherent bending stiffness, and after the introduction of the additional bending stiffness, the design local resonant frequency shift of the base plate 2 should be ≤±10%, thereby preventing the resonant main frequency from deviating from the target noise reduction frequency band. The additional bending stiffness is determined by factors such as the flexible connection stiffness, arrangement, and contact form of the flexible partition, and can be precisely controlled through single parameter adjustment or multi-parameter coordinated adjustment. The arrangement of the flexible partitions must match the channel spacing and array form of the sound-absorbing layer to avoid damaging the sound-absorbing metastructure performance. The material and geometric parameters of the partition itself must ensure the softness of the partition to avoid excessive rigidity of the partition leading to failure of the flexible connection.

[0031] Example 2: The difference from Example 1 is as follows: Figure 2As shown, in this embodiment, the partition 4 is configured as a flexible partition by using a soft material and shaping it into an S-shape. The top of the S-shaped partition and the bottom of the straight plate are connected to the perforated panel 1 and the bottom plate 2, respectively. This design has several advantages: First, the S-shaped structure introduces curvature, converting axial tensile deformation into bending deformation. This geometric configuration greatly reduces the equivalent elastic modulus of the partition in the normal direction (vibration direction), making the S-shaped flexible partition, while providing physical separation, exert a constraint force on the back local resonance plate close to zero. Second, the S-shaped partition is similar to a "folding spring." When the back local resonance unit undergoes large-amplitude vibration, the S-shaped partition provides sufficient geometric margin, compensating for displacement through its own expansion and contraction. This ensures that the long-stroke vibration of the local resonance unit at extremely low frequencies is unrestricted, thereby maintaining stable low-frequency sound insulation performance. Third, the S-shaped partition increases the path length of sound waves propagating inside the partition material. In addition, the surface of the S-shaped partition increases the scattering of sound waves at the chamber boundary, which helps the sound energy to be further absorbed by the surrounding porous material.

[0032] Example 3: The difference from Example 1 is as follows: Figure 3 As shown, in this embodiment, the partition 4 is configured as a flexible partition. The partition 4 itself is made of a rigid material, such as metal or composite material, and is in the shape of a straight plate. The top of the straight plate is connected to the perforated panel 1, and the bottom of the straight plate is connected to the base plate 2 via a rubber block 8. A flexible buffer connection (such as the rubber block 8) is constructed between the rigid partition 4 and the sound insulation thin plate (such as the base plate 2). This interface does not damage the segmentation and sealing function of the sound absorption layer impedance modulation resonant cavity, nor does it affect the precise control of the vibration excitation, acoustic impedance transmission, and structural load distribution of the local resonance of the thin plate.

[0033] If rigid partitions are used for rigid connections, on the one hand, the additional stiffness of the sound insulation board will be significantly changed and greatly increased, affecting the normal realization of the local resonant sound insulation metastructure function; on the other hand, the vertical partitions of the sound-absorbing layer will become vibration conductors. After the incident sound energy excites the sound-absorbing layer, the solid vibration of the vertical partitions will be directly transmitted to the sound insulation thin plate, causing non-local resonant vibration of the thin plate (that is, in addition to the designed local resonance, in-plane bending vibration and overall vibration are generated), resulting in secondary radiation of noise from the thin plate and a significant reduction in sound insulation; in addition, the local resonant vibration of the thin plate will also be transmitted back to the sound-absorbing layer, destroying the sound propagation path of the sound absorption channel and reducing the sound absorption efficiency.

[0034] The low in-plane stiffness of the flexible interface can absorb vibration shocks, preventing the local vibration of the vertical diaphragm from directly exciting the large-area vibration of the thin plate. This ensures that the thin plate only experiences the designed local resonance (local micro-vibration of the thin plate-mass block), rather than overall vibration. There is a natural impedance abrupt change between the sound-absorbing vertical diaphragm and the sound-insulating thin plate. A rigid connection would lead to a significant increase in sound reflectivity at the interface (sound energy cannot be effectively transferred, the sound-absorbing layer's dissipation efficiency decreases, and the sound-insulating layer is insufficiently excited). Furthermore, the compressibility and deformability of the flexible material can transform the concentrated load of the vertical diaphragm on the thin plate into a uniform surface load, avoiding local stress concentration in the thin plate, ensuring uniform in-plane stiffness, and ensuring that the local resonant frequency matches the design value.

[0035] By replacing rubber blocks of different hardness, the additional stiffness of the partition 4 on the base plate 2 can be precisely adjusted. In this way, within the same set of rigid partition molds, only the parameters of the rubber blocks need to be adjusted to adapt to sound insulation metastructures with different frequency requirements, greatly improving the flexibility and versatility of this embodiment.

[0036] Example 4: The partition in this example is the same as in the previous examples, except that: Figure 4 As shown, the sound barrier includes a perforated panel 1 facing the noise source and a base plate 2 facing away from the noise source. A side plate 3 is enclosed between the perforated panel 1 and the base plate 2, forming an internal cavity. Multiple partitions 4 are also disposed between the perforated panel 1 and the base plate 2, within the internal cavity, dividing the internal cavity into multiple independent sound-absorbing and sound-insulating unit chambers A. Multiple periodically distributed local resonant units 5 are disposed on the base plate 2, with one or more local resonant units disposed in each sound-absorbing and sound-insulating unit chamber A. 5. In this embodiment, the local resonance unit 5 is configured as a mass block. Each sound-absorbing and sound-insulating unit chamber A contains a porous sound-absorbing material 6 and an impedance modulation channel 7 located at the top of the porous sound-absorbing material 6. The impedance modulation channel 7 has a gradient V-shaped groove. An internal cavity 9 is also formed at the bottom of the porous sound-absorbing material 6. The internal cavity 9 is isolated from the V-shaped groove. The local resonance unit 5 is positioned within the internal cavity 9 in each sound-absorbing and sound-insulating unit chamber A. This internal cavity 9 primarily provides sufficient space for the vibration of the local resonance unit 5. The impedance modulation channel 7 in each sound-absorbing and sound-insulating unit chamber A forms a meta-structured sound-absorbing unit that works in conjunction with the porous sound-absorbing material 6 to absorb sound. The base plate and the multiple local resonance units 5 on the base plate form a meta-structured sound-insulating unit with a thin-plate local resonance structure, thereby utilizing the principle of thin-plate local resonance for sound insulation.

[0037] In this embodiment, the impedance modulation channel 7 is designed as a gradient V-shaped groove. This design has several advantages: First, the gradient structure of the V-shaped groove allows the cross-sectional area of ​​the channel to change continuously with depth, thus achieving a smooth transition of acoustic impedance from air (low impedance) to porous sound-absorbing material (high impedance). This greatly reduces the reflectivity of sound waves at the interface, guiding more sound energy into the interior of the channel and the porous sound-absorbing material below, significantly improving sound absorption efficiency. Second, the inclined surface formed by the V-shaped groove forms an angle with the incident direction of the sound wave. When the sound wave enters the V-shaped groove, it will undergo multiple reflections between the two opposing inclined surfaces. Thus, compared to a flat surface, the propagation path of the sound wave within the V-shaped groove is significantly lengthened, increasing the number and area of ​​contact between the sound wave and the porous material. Each reflection converts some sound energy into heat energy; this "notch effect" gives the structure a strong ability to capture high-frequency and mid-frequency sound waves. Third, this gradient structure can cover a wider frequency range, enabling the sound barrier to exhibit more balanced broadband sound absorption characteristics when facing complex traffic noise (which includes both high and low frequencies).

[0038] Example 5: The difference from Example 4 is as follows: Figure 5 As shown, the impedance modulation channel 7 can also be designed as a rectangular groove.

[0039] Example 6: This example provides a sound barrier with a black hole structure, such as... Figure 6 As shown, the sound barrier includes a perforated panel 1 facing the noise source and a base plate 2 facing away from the noise source. A side plate 3 is enclosed between the perforated panel 1 and the base plate 2, forming an internal cavity. Multiple periodically distributed local resonant units are disposed on the base plate 2. In this embodiment, the local resonant units are configured as acoustic black hole structures 10. A porous sound-absorbing material 6 is also disposed within the internal cavity, located on the noise source side. The closed bottom end of the acoustic black hole structure 10 is rigidly connected to the base plate 2, such as by welding or bonding, and the open top end of the acoustic black hole structure 10 is inserted into the porous sound-absorbing material 6. The acoustic black hole structure 10 forms a meta-structured sound-absorbing unit that works in conjunction with the porous sound-absorbing material 6 to absorb sound. The base plate and the multiple acoustic black hole structures 10 disposed on the base plate form a meta-structured sound insulation unit with a thin-plate local resonance structure, thereby utilizing the principle of thin-plate local resonance for sound insulation. This embodiment breaks the physical boundary between sound absorption and sound insulation. Its acoustic black hole structure captures and consumes sound energy through the "slow sound effect" generated by its geometry inside, thus absorbing sound. On the outside, it acts as an additional mass block on the base plate, participating in the local resonance of the base plate to insulate sound. This design solves the two core indicators of sound absorption and sound insulation without adding extra space and components, thus achieving a high degree of structural integration.

[0040] like Figure 7 and Figure 8 As shown, the acoustic black hole structure 10 includes a conical outer cylinder 101 and multiple layers 102 arranged sequentially inside the outer cylinder 101 along the axial direction of the outer cylinder 101. Holes are opened in the middle of the multiple layers 102. By changing the size and distance of the openings in the multiple layers and reducing them in a power law, the propagation speed of sound waves at the end of the acoustic black hole structure approaches zero, thereby effectively gathering, absorbing and consuming sound wave energy.

[0041] Because the acoustic black hole structure 10 has a conical outer cylinder 101, a slit-type Helmholtz resonant cavity 11 is formed between the outer cylinders 101 of two adjacent acoustic black hole structures 10. This cavity consists of a narrow neck cavity 111 and a wide belly cavity 112. The slit-type Helmholtz resonant cavity is a typical variant of the Helmholtz resonant sound absorption structure. Its core is to use a slit as the resonant neck and the cavity as a closed cavity to achieve efficient absorption of sound energy in a specific frequency band by utilizing acoustic resonance and viscous heat loss. It is especially suitable for low-frequency / mid-low-frequency sound absorption needs. Furthermore, due to the planar arrangement characteristics of the slit, it is easier to integrate with metamaterials, sound insulation thin plates, etc. It is the mainstream low-frequency sound absorption unit in sound absorption and insulation composite metamaterials. Its sound absorption essence is the dual effect of "resonance coupling + energy dissipation": the incident sound wave excites the slit-cavity system to produce Helmholtz resonance, which converts the sound energy into the vibration energy of the structure at the resonance frequency. Then, through the viscous loss at the slit and the heat loss of the cavity wall, the vibration energy is converted into heat energy dissipation, and finally the sound energy is absorbed.

[0042] like Figure 7 As shown, a protruding ring 103 is provided at the open top of the outer cylinder 101. In actual operation, after the sound barrier is installed, its actual working state is as follows... Figure 9 The diagram shows a vertical installation. In this case, the axial direction of the outer cylinder 101 is horizontal, and the bottom of the outer cylinder 101 is welded to the base plate 2, which makes the outer cylinder 101 in a cantilever beam state. During resonance, since the local resonance sound insulation depends on the intense vibration of the unit at a specific frequency, the cantilever structure will generate a large bending moment and asymmetric mode instability in the resonance state, resulting in the following problems: the gravity droop or vibration offset of the cantilever end will cause the preset resonance frequency to shift; stress concentration at the root weld, which can easily lead to structural failure in the long term; and the relative motion between the outer cylinder and the porous material is not coordinated, affecting the sound energy conversion efficiency. Therefore, the protruding ring 103 set at the open top of the outer cylinder 101 is inserted into the porous sound-absorbing material 6. Through the flexible contact between the ring 103 and the porous material, the structural centering of the cylinder in the horizontal cantilever state is ensured, while the dynamic degree of freedom required for local resonance is preserved. After the ring 103 is inserted into the porous sound-absorbing material 6, the porous sound-absorbing material 6 reserves space to avoid vibration of the ring 103, which will not be described in detail here.

[0043] In summary, this invention overcomes the technical bottleneck of existing sound barriers where sound absorption and sound insulation performance cannot be simultaneously achieved. It constructs a composite metastructure sound barrier that combines broadband sound absorption with high-efficiency sound insulation, significantly improving both sound absorption and sound insulation performance in the mid-to-low frequency range. Through the combined design and synergistic coupling of the sound-absorbing metastructure, porous sound-absorbing materials, and sound-insulating metastructure, optimal sound absorption and insulation performance is achieved. After coupling the sound-absorbing and sound-insulating metastructures, the frequency band is optimized with low or mid-to-low frequencies as the core. The sound absorption bandwidth is broadened by the metastructure sound-absorbing unit, and the sound insulation bandwidth is broadened by the metastructure sound-insulating unit, achieving the effect of "strong performance in low frequencies and no dip in mid-frequency range." A coupled design method is adopted, combining a porous material impedance modulation channel sound-absorbing metastructure with a thin-plate local resonance sound-insulating metastructure. The sound-absorbing side of this coupled design consists of a porous material impedance modulation channel (for sound energy absorption and reducing incident sound pressure), while the sound-insulating side consists of a thin-plate local resonance unit (for sound transmission blocking and suppressing structural vibration). This achieves a continuous and gradual change in acoustic impedance from air to the perforated plate, then to the porous material modulation channel, and finally to the thin-plate sound insulation layer, avoiding interface sound reflection caused by impedance abrupt changes and improving coupling efficiency. By setting the partition to have flexible functionality, the "damping vibration reduction + impedance adaptation + load decoupling" of the flexible interface solves the three key problems of vibration crosstalk, impedance abrupt changes, and resonant coupling failure under rigid connections. This retains the sound absorption advantages of the vertical partition in the sound-absorbing layer, such as cavity segmentation and impedance modulation, while avoiding the negative impacts of rigid partitions on the local resonance of the thin-plate (additional stiffness, vibration coupling, resonant frequency deviation, secondary noise, etc.), enhancing the low-frequency sound insulation performance of the thin-plate local resonance, and achieving a synergistic improvement in the performance and structural stability of the sound-absorbing and sound-insulating composite structure. A sound barrier with an acoustic black hole structure was designed, breaking the physical boundary between sound absorption and sound insulation. The acoustic black hole structure captures and consumes sound energy through the "slow sound effect" generated by its geometry inside, and acts as an additional mass block on the base plate outside, participating in the local resonance of the base plate to perform sound insulation. This design solves the two core indicators of sound absorption and sound insulation at the same time without adding extra space and components, and achieves a high degree of structural integration.

[0044] In the embodiments, "multiple" refers to "two or more". The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the invention, which is defined by the claims.

Claims

1. A design method for a sound barrier with a composite structure of sound-absorbing and sound-insulating metastructures, characterized in that: The sound barrier is composed of porous sound-absorbing material, meta-structured sound-absorbing unit, and meta-structured sound-insulating unit. The meta-structured sound-insulating unit adopts a thin-plate local resonance structure. By utilizing the synergistic coupling effect of the porous sound-absorbing material, meta-structured sound-absorbing unit, and meta-structured sound-insulating unit, the functions of sound absorption and sound insulation are combined.

2. The design method according to claim 1, characterized in that: The sound barrier includes a perforated panel facing the noise source and a base plate facing away from the noise source. A side plate is enclosed between the perforated panel and the base plate, forming an internal cavity. Multiple partitions are also provided between the perforated panel and the base plate and within the internal cavity, dividing the internal cavity into multiple independent sound-absorbing and sound-insulating unit chambers A. Multiple periodically distributed local resonant units are provided on the base plate. Each sound-absorbing and sound-insulating unit chamber A contains one or more local resonant units, which are configured as mass blocks. Each sound-absorbing and sound-insulating unit chamber contains porous sound-absorbing material and an impedance modulation channel penetrating the porous sound-absorbing material. The impedance modulation channel is rectangular. The local resonant unit is positioned inside the impedance modulation channel in each sound-absorbing and sound-insulating unit chamber A. The impedance modulation channel in each sound absorption and insulation unit chamber A is used to form a meta-structured sound absorption unit that works in conjunction with porous sound absorption material to absorb sound. The base plate and multiple local resonance units set on the base plate form a meta-structured sound insulation unit with a thin plate local resonance structure, thereby using the principle of thin plate local resonance to achieve sound insulation.

3. The design method according to claim 1, characterized in that: The sound barrier includes a perforated panel facing the noise source and a base plate facing away from the noise source. A side plate is enclosed between the perforated panel and the base plate, forming an internal cavity. Multiple partitions are also provided between the perforated panel and the base plate and within the internal cavity, dividing the internal cavity into multiple independent sound-absorbing and sound-insulating unit chambers A. Multiple periodically distributed local resonant units are provided on the base plate, and each sound-absorbing and sound-insulating unit chamber A contains one or more local resonant units, which are configured as mass blocks. Each sound-absorbing and sound-insulating unit chamber A contains porous sound-absorbing material and an impedance modulation channel located at the top of the porous sound-absorbing material. The impedance modulation channel has a gradient V-shaped groove. An internal cavity is also formed at the bottom of the porous sound-absorbing material, which is isolated from the V-shaped groove. The local resonant unit is positioned within the internal cavity of each sound-absorbing and sound-insulating unit chamber A. The impedance modulation channel in each sound absorption and insulation unit chamber A is used to form a meta-structured sound absorption unit that works in conjunction with porous sound absorption material to absorb sound. The base plate and multiple local resonance units set on the base plate form a meta-structured sound insulation unit with a thin plate local resonance structure, thereby using the principle of thin plate local resonance to achieve sound insulation.

4. The design method according to claim 2 or 3, characterized in that: The partition is configured as a flexible partition.

5. The design method according to claim 4, characterized in that: The partition is configured as a flexible partition by using a soft material and having a straight plate shape. The top and bottom of the straight plate are connected to a perforated panel and a base plate, respectively.

6. The design method according to claim 4, characterized in that: The partition is configured as a flexible partition by using a soft material and shaping it into an S-shape. The top of the S-shaped partition and the bottom of the straight plate are connected to the perforated panel and the bottom plate, respectively.

7. The design method according to claim 4, characterized in that: The partition is configured as a flexible partition by using a rigid material and shaping it into a straight plate. The top of the straight plate is connected to a perforated panel, and the bottom of the straight plate is connected to a base plate via a rubber block.

8. The design method according to claim 1, characterized in that: The sound barrier includes a perforated panel facing the noise source and a base plate facing away from the noise source. A side plate is enclosed between the perforated panel and the base plate, forming an internal cavity. Multiple periodically distributed local resonant units are arranged on the base plate. The local resonant units are configured as acoustic black hole structures. Porous sound-absorbing material is also arranged in the internal cavity and on the side facing the noise source. The closed bottom end of the acoustic black hole structure is connected to the base plate, and the open top end of the acoustic black hole structure is inserted into the porous sound-absorbing material. The acoustic black hole structure is used to form a meta-absorbing unit that works in conjunction with porous sound-absorbing materials to absorb sound. The base plate and multiple acoustic black hole structures set on the base plate form a meta-insulation unit with a local resonance structure in a thin plate, thereby using the principle of local resonance in a thin plate to achieve sound insulation.

9. The design method according to claim 8, characterized in that: The acoustic black hole structure includes a conical outer cylinder and multiple layers arranged sequentially inside the outer cylinder along its axial direction, with holes in the middle of each layer. A slit-type Helmholtz resonant cavity, consisting of a neck cavity and a belly cavity, is formed between the outer cylinders of two adjacent acoustic black hole structures. The slit-type Helmholtz resonant cavity is used to further absorb sound.

10. The design method according to claim 8, characterized in that: A protruding ring is provided at the open top of the outer cylinder, and the bottom of the outer cylinder is rigidly connected to the base plate. The protruding ring at the open top of the outer cylinder is inserted into the porous sound-absorbing material.

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