Broadband metamaterial acoustic board design method based on JCA model and transfer matrix method

Abstract

The invention relates to the technical field of computer aided design and acoustic simulation, in particular to a broadband metamaterial acoustic board design method based on a JCA model and a transfer matrix method.The method comprises the steps that target noise is analyzed, and a target frequency band and an acoustic absorption threshold value are determined; based on a JCA model and a transfer matrix method, establishing a superstructure sound absorption unit acoustic model comprising a hard porous medium layer, an air narrow slit layer and an air cavity layer; based on the model, collaboratively optimizing a plurality of geometric parameters in the units to obtain an optimal parameter combination; preparing a sample and verifying the performance through an impedance tube test; and finally, the verified units with different target frequencies are periodically, gradiently or randomly arranged and combined into an array. Compared with the prior art, the method has the advantages that systematic design from theoretical modeling and parameter optimization to experimental verification is realized, and the metamaterial acoustic board array with broadband efficient sound absorption performance can be efficiently and accurately designed.

Description

Technical Field

[0001] This invention relates to the fields of computer-aided design and acoustic simulation technology, and in particular to a design method for a low-bandwidth metamorphic sound-absorbing panel and a low-bandwidth metamorphic sound-absorbing panel array. Background Technology

[0002] Environmental noise pollution, especially low-frequency noise, has become one of the core issues affecting human health, production efficiency, and the quality of the urban acoustic environment due to its strong penetrating power and ease of propagation. In traffic arteries, industrial plants, and modern high-density building environments, increasingly stringent demands are being placed on efficient noise control, particularly in the low-frequency band.

[0003] Currently, mainstream broadband sound absorption technologies and materials mainly rely on two physical mechanisms: porous sound-absorbing materials and resonant sound-absorbing structures. However, each of them has insurmountable technical bottlenecks. Traditional porous materials rely on viscous heat dissipation for sound absorption, and low-frequency absorption requires a large thickness, which contradicts the limited installation space. Acoustic metamaterials can break through the physical limits of traditional materials and achieve precise control of sound waves at the subwavelength scale. However, existing metamaterials are often complex in structure, have limited bandwidth, and are difficult to adapt to the complex and ever-changing noise spectrum in actual engineering.

[0004] Patent application CN118280327A discloses a coupled sound-absorbing structural unit and its preparation method, which is an empirical combination of specific structures (through-slits, coiled cavities, etc.). It relies on empirical combinations of specific structural forms and lacks a systematic parametric design method, resulting in insufficient design predictability and spectral adaptability. Patent CN118366417A discloses a metamorphic porous medium sound absorber and its design method, which focuses on theoretical models and algorithms, but the engineering implementation is unclear. Patent application CN119380685A discloses a low-frequency broadband sound-absorbing metamaterial structure and metamorphic sound barrier based on metal foam. The substrate is metal foam, which has certain advantages (high strength, fire resistance) but also constitutes limitations (high cost, rigid process). Moreover, its tuning relies only on the cavity behind it, which restricts its application potential in cost-sensitive and lightweight scenarios.

[0005] In summary, the common and critical core technical problem of existing technologies lies in the lack of a sound absorption solution that organically unifies precise theoretical models, flexible acoustic performance control, and convenient engineering implementation. This makes it impossible to simultaneously meet the requirements of wide-bandwidth (especially low-frequency) high-efficiency sound absorption, strong design predictability, and strong engineering adaptability. Therefore, an innovative design method is urgently needed to solve this problem. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a broadband metamorphic sound-absorbing panel array design method based on the JCA model and transfer matrix method. This method combines theoretical modeling with modular engineering design, realizing a systematic design from theoretical modeling and parameter optimization to experimental verification. It can efficiently and accurately design metamorphic sound-absorbing panel arrays with broadband and high-efficiency sound absorption performance.

[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides an optimization design method for broadband metamorphic sound-absorbing panel arrays based on the JCA model and transfer matrix method. The design method includes the following steps: S1. Obtain the sound pressure spectrum of the target noise source and determine several target frequency bands that need to be controlled and their corresponding target sound absorption coefficient thresholds; S2. Establish an acoustic theoretical model for the metastructure sound-absorbing unit. Based on the Johnson-Champoux-Allard equivalent fluid model, the rigid porous medium layer is regarded as a uniform layer with equivalent complex density and equivalent complex bulk modulus. The normal surface impedance and sound absorption coefficient are calculated by coupling with the air slit gap layer and the air cavity layer through the transfer matrix method. S3. Based on the acoustic theory model, with the target frequency band and sound absorption coefficient threshold as optimization objectives, the tube diameter, tube depth and tube spacing parameters of the perforated embedded structure array, the equivalent neck width and equivalent neck length parameters of the air slit gap layer and the cavity depth parameters of the air cavity layer are optimized in a coordinated manner to obtain the optimal parameter combination for the corresponding target frequency band. S4. Prepare a metamorphic sound-absorbing unit sample according to the optimal parameter combination, and verify whether the sound absorption coefficient meets the design expectations by impedance tube testing. S5. The verified meta-absorbing units with different target frequencies are spatially combined according to the arrangement rules of periodic alternating gradient changes or random distribution to form a broadband meta-absorbing unit array.

[0008] Furthermore, in S2, the specific process includes: The equivalent complex density and equivalent complex bulk modulus of the rigid porous medium layer were calculated based on the Johnson-Champoux-Allard model. Then, the transfer matrices of the rigid porous medium layer, the air slit gap layer, and the air cavity layer were established respectively. Finally, the total transfer matrix was calculated by matrix multiplication and the surface impedance and sound absorption coefficient were derived.

[0009] Furthermore, in S2, transfer matrices are established for the rigid porous dielectric layer, the air slit gap layer, and the air cavity layer, respectively. Finally, the total transfer matrix is ​​calculated by matrix multiplication, and the surface impedance and sound absorption coefficient are derived. The specific process includes: The basic acoustic parameters of the rigid porous medium layer are obtained, including porosity, flow resistance, tortuosity, viscous characteristic length, and thermal characteristic length. The basic acoustic parameters are input into the Johnson-Champoux-Allard equivalent fluid model to calculate the equivalent complex density and equivalent complex bulk modulus of the layer. Based on the transfer matrix theory, transfer matrices are established for the rigid porous dielectric layer, the air slit gap layer, and the air cavity layer, respectively. The three transfer matrices are multiplied sequentially in the order of sound wave propagation direction to obtain the total transfer matrix of the entire metastructure sound-absorbing unit. The surface impedance of the meta-absorbing unit under normal incident conditions is calculated from the total transfer matrix. Then, based on the relationship between the surface impedance and the characteristic impedance of air, the curve of its theoretical sound absorption coefficient changing with frequency is calculated.

[0010] Furthermore, the transfer matrix of the rigid porous dielectric layer is determined by its equivalent acoustic parameters and physical thickness; The transfer matrix of the air slit gap layer is determined by the acoustic quality effect characterized by its equivalent neck width and equivalent neck length. The transfer matrix of the air cavity layer is determined by the acoustic compliance effect characterized by its cavity depth.

[0011] Furthermore, in S3, the specific process of obtaining the optimal parameter combination for the corresponding target frequency band includes: Using the target frequency band and sound absorption coefficient threshold as constraints, an optimization algorithm is used to simultaneously adjust the geometric parameters of the perforated embedded structure array, the size parameters of the air slit gap layer, and the depth parameters of the air cavity layer. Through iterative calculation, the theoretical sound absorption coefficient curve reaches the preset threshold in the target frequency band.

[0012] Furthermore, in S3, the specific process of using iterative calculations to make the theoretical sound absorption coefficient curve reach a preset threshold in the target frequency band includes: Define the objective function of the optimization problem so that the theoretical sound absorption coefficient curve calculated based on the acoustic theoretical model established in S2 has a sound absorption coefficient value that is not lower than the corresponding target sound absorption coefficient threshold in each target frequency band determined in step S1. The tube diameter, tube depth, tube spacing of the perforated embedded structure array, the equivalent neck width and equivalent neck length of the air slit gap layer, and the cavity depth of the air cavity layer are set as multiple design variables that need to be optimized collaboratively. A multi-parameter optimization algorithm is used to iteratively search within the reasonable range of preset design variables; In each iteration, the algorithm generates a new set of design variables and automatically calls the acoustic theory model established by S2 to quickly calculate the theoretical sound absorption coefficient curve under the set of parameters and evaluate whether it meets the sound absorption coefficient constraints of all target frequency bands. Through repeated iterations and continuous updates of design variables, the optimal parameter combination is finally found to be one or more combinations of design variables that can make the theoretical sound absorption coefficient curve meet the preset performance requirements in all target frequency bands.

[0013] Furthermore, in S4, the specific process of verifying whether the sound absorption coefficient meets the design expectations through impedance tube testing includes: Experimental samples of the meta-absorbing unit were prepared, and then the actual sound absorption coefficient curve was measured using an impedance tube. Finally, the measured curve was compared and analyzed with the theoretical prediction curve to verify the accuracy of the acoustic model.

[0014] Furthermore, in S4, the specific process for verifying the accuracy of the acoustic model includes: Based on the geometric dimensions and material specifications corresponding to the optimal parameter combination obtained in S3, a physical sample of the metamorphic sound-absorbing unit was prepared. The sample was installed in an impedance tube testing system that conforms to international standards, and its actual sound absorption coefficient curve under normal sound wave incidence was measured within a frequency range covering the target frequency band. The measured actual sound absorption coefficient curve is compared and analyzed with the theoretical sound absorption coefficient curve predicted by the acoustic theoretical model in S2 based on the same optimal parameter combination. The actual sound absorption coefficient curve is checked to see if the sound absorption coefficient value at each target frequency band reaches or exceeds the target threshold set in S1. The consistency between the actual curve and the theoretical prediction curve in terms of overall trend, peak frequency of sound absorption, and peak size is evaluated. The prediction accuracy of the acoustic model is quantified by calculating the error between the two.

[0015] Furthermore, in S5, the specific process of spatially combining the verified meta-absorbing units with different target frequencies according to a periodic alternating gradient change or random distribution pattern includes: Based on the target frequency band requirements, select metamorphic sound-absorbing units with different resonant frequencies, then arrange them in an array according to the arrangement rules of periodic alternation, gradient change or random distribution, and finally use built-in partitions to acoustically isolate each unit to form a complete metamorphic sound-absorbing panel core.

[0016] Furthermore, in S5, the specific process of array combination according to the arrangement rules of periodic alternation, gradient change, or random distribution includes: Based on the frequency coverage requirements of the broadband sound absorption band to be achieved, several meta-absorbing units are selected from a variety of meta-absorbing units that have been verified in S4 and have different target resonant frequencies. The meta-absorbing units are arranged in a spatial array in a two-dimensional plane according to a preset arrangement rule. The arrangement rule includes periodic alternation, gradient change, or random distribution. Periodic alternation means arranging units with different resonance frequencies in a fixed and repetitive sequence. Gradient change means arranging units continuously in a spatial order according to their resonance frequencies from low to high or from high to low. Random distribution means mixing units with different resonance frequencies in a random manner. When assembling spatial arrays, built-in partitions are set between adjacent metamorphic sound-absorbing units. The built-in partitions extend upward from the back panel frame and are higher than the upper surface of the metamorphic sound-absorbing units.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1) A systematic parameter design method was established, with the JCA equivalent fluid model and transfer matrix method as the core theoretical basis. A precise mapping relationship from material parameters and geometric parameters to macroscopic sound absorption performance was constructed, realizing reverse design based on the target noise spectrum. A complete design closed loop from acoustic target setting, theoretical modeling, parameter optimization to experimental verification was formed, which significantly improved the scientificity, accuracy and predictability of the design.

[0018] 2) By using a multi-parameter collaborative optimization algorithm, multiple geometric parameters of the porous embedded structure array, the air slit gap layer, and the air cavity layer are adjusted synchronously, achieving precise impedance matching of the metamorphic sound absorption unit in the target frequency band. This significantly enhances the low-frequency sound absorption performance within a limited thickness, solving the technical bottleneck of traditional porous materials requiring large thickness for low-frequency sound absorption.

[0019] 3) By arraying and integrating multiple sound-absorbing units optimized for different frequency bands, and combining them with periodic, gradient, or random distribution strategies, the sound absorption peaks of each unit in its respective frequency band are effectively connected and synergistically enhanced, thereby achieving wideband high-efficiency sound absorption from low to mid-high frequencies. With a relatively small overall thickness, the optimized structure of this invention exhibits excellent sound absorption performance over a wide frequency range, with a high average sound absorption level across the entire frequency band, and achieves particularly outstanding sound absorption effects in the mid-low frequency region.

[0020] 4) The design methodology fully considers the needs of engineering applications, supports modular design and rapid assembly, facilitates on-site construction, subsequent maintenance and component replacement, and demonstrates good engineering adaptability and promotional value in fields such as building walls, rail transit sound barriers, and industrial equipment soundproof enclosures. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the low-bandwidth superstructure sound-absorbing plate based on a rigid porous medium-internal perforation-narrow slit cavity in Embodiment 1 of the present invention. Figure 2 This is a top view and a partially enlarged structural schematic diagram of the inner core of the superstructure sound-absorbing panel in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of the back panel frame and the front panel in Embodiment 1 of the present invention; Figure 4 This is a three-dimensional and partially enlarged structural schematic diagram of the metamorphic sound-absorbing unit in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the cross-sectional structure of the through holes and non-through blind holes in the hole-shaped embedded structure array in Embodiment 2 of the present invention; Figure 6 This is a top view schematic diagram of the air gap layer in two forms, namely frame gap and groove, in Embodiment 3 of the present invention; Figure 7a This is a schematic diagram of the cross-sectional structure of the air cavity layer in the first form of the equal-depth cavity and multi-level cavity in Embodiment 4 of the present invention; Figure 7b This is a schematic diagram of the cross-sectional structure of the air cavity layer in the second form of the equal-depth cavity and multi-level cavity in Embodiment 4 of the present invention; Figure 8 This is a curve showing the random incident sound absorption coefficient of the superstructure sound-absorbing panel in Embodiment 1 of the present invention.

[0022] The diagram is labeled as follows: 1. Ultra-high-density sound-absorbing panel core; 2. Back panel frame; 3. Front panel; 1-1. Ultra-high-density sound-absorbing unit; 1-2. Connector; 1-3. Built-in partition; 1-1-1. Rigid porous medium layer; 1-1-2. Hole-shaped embedded structure array; 1-1-3. Air slit gap layer; 1-1-4. Air cavity layer; 1-1-4a. Cavity of equal depth; 1-1-4b. Multi-level cavity; 1-1-2-1. Embedded hole; 1-1-2-1a. Straight through hole; 1-1-2-1b. Blind hole. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the technical terms in the following embodiments are defined as follows: JCA model refers to the Johnson-Champoux-Allard equivalent fluid model; transfer matrix method refers to an acoustic analysis method that calculates the total transfer matrix by establishing the transfer matrices of each layer and multiplying them sequentially according to the direction of sound wave propagation. Equivalent complex density and equivalent complex bulk modulus refer to the equivalent parameters describing the acoustic properties of rigid porous media layers calculated based on the JCA model. Surface impedance refers to the acoustic impedance of the metamaterial sound-absorbing unit under normal incident conditions. Sound absorption coefficient refers to the ratio of the absorbed sound energy to the incident sound energy; noise reduction coefficient NRC refers to the arithmetic mean of the sound absorption coefficients at four frequencies: 250Hz, 500Hz, 1000Hz, and 2000Hz.

[0024] Overall, each metamorphic sound-absorbing unit in the core of the metamorphic sound-absorbing panel of this invention comprises, along the direction of sound wave incidence: a parameterized rigid porous medium layer, an array of pore-shaped embedded structures within the medium, a circumferentially or interlayerly distributed air slit gap layer, and an air cavity layer. By precisely designing the geometric parameters of each feature within the unit, multi-physics coupling modeling and collaborative optimization are performed based on the JCA equivalent fluid model and transfer matrix method, allowing independent control of the equivalent acoustic impedance of each unit. With resonant frequency This allows it to achieve high sound absorption in the target frequency band. By combining multiple unit arrays with different sound absorption peaks to form a coupled acoustic meta-absorbing unit array, wide-bandwidth, high-absorption acoustic performance can be achieved within a limited structural thickness. The meta-absorbing panel of this invention has the advantages of low-frequency enhancement, wide bandwidth, designability, modular structure, and strong engineering adaptability, and is suitable for wideband noise control in fields such as building walls, road and rail transit sound barriers, and industrial equipment soundproof enclosures.

[0025] This invention aims to provide a broadband sound absorption solution with a solid theoretical foundation, precise design process, flexible and adjustable frequency band, and ease of engineering production. The core of this invention lies in: proposing a basic unit (meta-unit) of a "porous medium-embedded tube-gap-cavity" composite acoustic system and establishing its precise parametric acoustic model; through multi-parameter collaborative optimization, enabling a single unit to generate a high absorption peak in the target frequency band; and finally, by arraying and integrating multiple units optimized for different frequency bands, achieving broadband and efficient sound absorption performance.

[0026] The present invention comprises a low-bandwidth superstructure sound-absorbing panel based on a rigid porous medium-internal perforated-narrow slit cavity, including at least two superstructure sound-absorbing units 1-1 with different configurations, a superstructure sound-absorbing panel core 1 composed of a periodic or non-periodic array, a back frame 2, and a panel 3.

[0027] The core 1 of the metamorphic sound-absorbing panel is formed by multiple metamorphic sound-absorbing units 1-1 arranged in a periodic or non-periodic manner. The metamorphic sound-absorbing units 1-1 can be physically separable independent modules, assembled into an integral array structure by fasteners, guide rails, or bolts; or they can be an integral array structure formed by multiple metamorphic sound-absorbing units 1-1 molded as a single unit. Internal partitions 1-3 can be installed or partially installed for acoustic isolation, appropriately reducing lateral acoustic coupling between units.

[0028] Each meta-absorbing unit 1-1 is a composite structure stacked along the direction of sound wave incidence, including: The rigid porous media layer 1-1-1 has design parameters including porosity. Flow resistance , tortuosity Viscous characteristic length and thermal characteristic length The rigid porous media layer 1-1-1 is a high-porosity rigid framework porous material, including but not limited to foamed calcium silicate, foamed cement, foamed glass, foamed ceramics, and rigid foamed plastics. The equivalent complex density of the rigid porous media layer 1-1-1 is... and equivalent complex bulk modulus The Johnson-Champoux-Allard JCA model was used for calculation: in, Angular frequency, air density, For flow resistance, For tortuosity, For dynamic viscosity, Atmospheric pressure, Specific heat ratio, It is a Prandtl number; and For the viscous characteristic length and thermal characteristic length Related complex functions: , .

[0029] A porous embedded structure array 1-1-2 is discretely distributed within the rigid porous medium layer 1-1-1, and its design parameters include tube diameter. Pipe depth Pipe spacing The embedded holes 1-1-2-1 of the porous embedded structure array 1-1-2 are either through holes 1-1-2-1a that penetrate the hard porous medium layer 1-1-1 or blind holes 1-1-2-1b that do not penetrate, and their cross-sectional shape is circular, rectangular, or irregular. According to the equivalent medium theory, the porous embedded structure array 1-1-2 can adjust the equivalent complex density of the hard porous medium layer 1-1-1. and equivalent complex bulk modulus This, in turn, alters the equivalent parameter values ​​of the JCA model, particularly the equivalent tortuosity. This improves the sound absorption performance in the mid-to-high frequency range; Air gap layer 1-1-3, its design parameter is equivalent neck width With equivalent neck length The air gap layer 1-1-3 is either a frame gap 1-1-3a surrounding the rigid porous dielectric layer 1-1-1, or a pre-fabricated groove 1-1-3b inside the rigid porous dielectric layer 1-1-1. The width of the frame gap 1-1-3a or the groove 1-1-3b is the width of the air gap layer 1-1-3, and the thickness of the rigid porous dielectric layer 1-1-1 is the depth of the air gap layer 1-1-3. The equivalent acoustic mass of the air gap layer 1-1-3 is... Mainly composed of equivalent neck width and equivalent neck length Decide: (h is the floor height), to adjust the resonant frequency One of the key factors is the equivalent neck width. The narrower the width, the lower the peak frequency of sound absorption.

[0030] Air cavity layer 1-1-4 is located at the face, back, or both sides of the metamorphic sound-absorbing unit. The depth of the face and back of the air cavity layer 1-1-4 is... Adjustable, with each side potentially consisting of equal-depth cavities 1-1-4a or multi-level cavities 1-1-4b with stepped depths, working in conjunction with the air slit gap layer 1-1-3 to excite single or multiple resonant frequencies, thus enhancing the low-frequency sound absorption performance of the meta-absorbing unit 1-1. The air cavity layer 1-1-4 provides acoustic compliance. With cavity depth and area Proportional: ,in cavity depth It is to adjust the resonant frequency Another core parameter, and The larger the value, the lower the peak frequency of sound absorption.

[0031] By synergistically adjusting multiple design parameters of the porous embedded structure array 1-1-2, the air slit gap layer 1-1-3, and the air cavity layer 1-1-4, each metamorphic sound-absorbing unit 1-1 is made to achieve optimal sound absorption at the target frequency. Surface acoustic impedance at air characteristic impedance Matching to obtain the local maximum sound absorption coefficient Points with different target frequencies The sound absorption coefficient curve of the combination of multiple metamorphic sound-absorbing units 1-1 array In the preset wideband Internal coupling superposition enables the metamorphic sound-absorbing panel to achieve a high sound absorption coefficient over a wide frequency band.

[0032] The backplate frame 2 is used to fix the inner core 1 of the superstructure sound-absorbing panel to form a stable whole, and provides a rigid backplate boundary that can form an air cavity layer 1-1-4.

[0033] Panel 3 is a protective panel material with low flow resistance and high sound transmission. It needs to strike a balance between protecting the sound-absorbing material, meeting aesthetic / safety requirements, and allowing sound waves to enter the internal sound-absorbing layer efficiently. This includes, but is not limited to, perforated panels, non-woven fabrics, metal mesh, and wooden grilles.

[0034] The present invention further provides a design method for a low-bandwidth metamorphic sound-absorbing panel array based on a rigid porous medium-internal perforated-narrow slit cavity, comprising the following steps: S1: Spectrum Analysis and Target Setting: Measure or acquire the sound pressure spectrum of the target noise source. Identify several target frequency bands that require key control. and the corresponding target sound absorption coefficient threshold And determine the threshold of the noise reduction coefficient NRC; S2: Theoretical Modeling: Establish the acoustic theoretical model of the metamorphic sound-absorbing unit 1-1; consider the rigid porous medium layer 1-1-1 with the porous embedded structure array 1-1-2 as having an equivalent complex density. and equivalent complex bulk modulus The uniform layer, together with the air slit gap layer 1-1-3 and the air cavity layer 1-1-4, forms a composite structure with a normal surface impedance. Calculated using the transfer matrix method: in, , , These are the transfer matrices for each layer. The thickness of the porous medium layer.

[0035] Total transfer matrix With surface impedance The relationship is: Then calculate the sound absorption coefficient. : S3: Unit parameter collaborative optimization design: taking the target frequency band and sound absorption coefficient threshold in step S1 as the optimization target, and the parameters of the porous embedded structure array 1-1-2 ( , , ), Air Narrow Slit Gap Layer 1-1-3 Parameters ( The cavity depth of the air cavity layer 1-1-4 To optimize variables and obtain the optimal parameter combination for the corresponding target frequency band, each specific target frequency point is formed. The location has the highest sound absorption coefficient. The design of the superstructure sound-absorbing unit; S4: Unit Design Verification: Based on the multiple optimal parameter combinations obtained in step S3, prepare corresponding metamorphic sound-absorbing unit 1-1 samples respectively, and verify whether the sound absorption coefficient of the metamorphic sound-absorbing unit 1-1 meets the design expectations through impedance tube testing. S5: Array Arrangement: Arrange the arrays that have been verified in step S4, which have different... Multiple metamorphic sound-absorbing units 1-1 are spatially combined according to the arrangement rules of periodic alternation, gradient change or random distribution to form the final broadband metamorphic sound-absorbing unit array structure.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, circuit structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0037] Example 1 See Figures 1 to 8 This embodiment provides a design method for a low-bandwidth superstructure sound-absorbing panel array based on a rigid porous medium-internal perforated-narrow slit cavity. The specific steps are as follows: S1: Spectrum Analysis and Target Setting: Identifying several target frequency bands that require key control. And the corresponding target frequency band sound absorption coefficient threshold is The noise reduction coefficient NRC threshold is 0.70; S2: Theoretical Modeling: Establish the acoustic theoretical model of the meta-absorbing unit 1-1; First, the equivalent complex density of the hard porous medium layer 1-1-1 is calculated based on the Johnson-Champoux-Allard equivalent fluid model. and equivalent complex bulk modulus .

[0038] Equivalent complex density of a 1-1-1 hard porous dielectric layer and equivalent complex bulk modulus The Johnson-Champoux-Allard JCA model was used for calculation: in, Angular frequency, air density, For flow resistance, For tortuosity, For dynamic viscosity, Atmospheric pressure, Specific heat ratio, It is a Prandtl number; and For the viscous characteristic length and thermal characteristic length Related complex functions: , .

[0039] Then, the transfer matrices for the hard porous medium layer 1-1-1, the air slit gap layer 1-1-3, and the air cavity layer 1-1-4 are established respectively.

[0040] Specifically, the hard porous dielectric layer 1-1-1 with the porous embedded structure array 1-1-2 is considered to have an equivalent complex density. and equivalent complex bulk modulus The uniform layer, together with the air slit gap layer 1-1-3 and the air cavity layer 1-1-4, forms a composite structure with a normal surface impedance. Calculated using the transfer matrix method: in, , , These are the transfer matrices for each layer. The thickness of the porous medium layer.

[0041] Total transfer matrix With surface impedance The relationship is: Then calculate the sound absorption coefficient. : S3: Unit parameter collaborative optimization design: taking the target frequency band and sound absorption coefficient threshold in step S1 as the optimization target, and the parameters of the porous embedded structure array 1-1-2 ( , , ), Air Narrow Slit Gap Layer 1-1-3 Parameters ( The cavity depth of the air cavity layer 1-1-4 To optimize variables and obtain the optimal parameter combination for the corresponding target frequency band, each specific target frequency point is formed. The location has the highest sound absorption coefficient. The design of the superstructure sound-absorbing unit.

[0042] In the unit parameter collaborative optimization design step, the target frequency band and sound absorption coefficient threshold determined in step S1 are used as optimization targets. Collaborative optimization is performed on the tube diameter, tube depth, and tube spacing parameters of the perforated embedded structure array, the equivalent neck width and equivalent neck length parameters of the air slit gap layer, and the cavity depth parameter of the air cavity layer. By iteratively adjusting these geometric parameters using a multi-parameter optimization algorithm, the metamorphic sound-absorbing unit achieves the maximum sound absorption coefficient at a specific target frequency point, thereby forming the optimal parameter combination design for different target frequency bands.

[0043] In this embodiment, it should be noted that when multiple metamaterial sound-absorbing units are closely arranged, in addition to their individual resonant absorption peaks, acoustic coupling occurs between the units through the sound field radiated from the sides. This coupling may change the resonant frequency and amplitude of a single unit. Generally, when the unit spacing is less than half a wavelength, coherent superposition may occur, widening the absorption bandwidth or increasing the absorption coefficient in a specific frequency band; however, it may also lead to a shift in the absorption peak frequency, a reduction in the peak value, or the generation of undesirable valleys, thus disrupting the broadband effect. Therefore, it is necessary to control the design of the built-in partition and the unit spacing (in this embodiment, the width of the air slit gap layer).

[0044] In specific implementation, in step S3, unit parameter collaborative optimization design is performed. Taking the target frequency band and sound absorption coefficient threshold determined in step S1 as the optimization objectives, the objective function of the optimization problem is defined so that the theoretical sound absorption coefficient curve calculated based on the acoustic theoretical model established in step S2 has a sound absorption coefficient value that is not lower than the corresponding target sound absorption coefficient threshold in each target frequency band determined in step S1.

[0045] The diameter of the perforated embedded structure array 1-1-2 Pipe depth l p Pipe spacing N p The equivalent neck width of the air gap layer 1-1-3 w g Equivalent neck length l g And the cavity depth of air cavity layer 1-1-4 These are set as multiple design variables that need to be collaboratively optimized. A multi-parameter optimization algorithm is used to iteratively search within the preset reasonable value range of each design variable. In this embodiment, the value range of the optimization variable is: pipe diameter... d p 2-6mm, tube depth l p The spacing between pipes is 20-60mm. The equivalent neck width is 5-15mm. w g The equivalent neck length is 2-12mm. The cavity depth is 60-100mm. The range is 5-30mm. These values ​​are determined based on acoustic theory and engineering practice, ensuring that the parameters are within a reasonable physical range.

[0046] In each iteration, the algorithm generates a new set of design variable combinations and automatically calls the acoustic theoretical model established in step S2 to quickly calculate the theoretical sound absorption coefficient curve under this set of parameters, evaluating whether it meets the sound absorption coefficient constraints for all target frequency bands. Through repeated iterations and continuous updates of the design variables, one or more sets of design variable combinations that enable the theoretical sound absorption coefficient curve to meet the preset performance requirements across all target frequency bands are finally found; these are the optimal parameter combinations. In this embodiment, optimization is performed using a genetic algorithm (the specific calculations are not detailed here), with 500 iterations, ultimately yielding two sets of optimal parameter combinations: the first set is... d p =4mm l p =40mm N p =10mm w g =10mm l p =80mm =10mm, corresponding to a target frequency of approximately 400Hz; the second group is d p =4mm l p =40mm =10mm w g =3.5mm =80mm =10mm, corresponding to a target frequency of approximately 250Hz.

[0047] It should be noted that when multiple meta-absorbing units are closely arranged, in addition to their individual resonant absorption peaks, acoustic coupling occurs between the units through the sound field radiated from the sides. This coupling may change the resonant frequency and amplitude of a single unit. Generally, when the unit spacing is less than half a wavelength, coherent superposition may occur, widening the absorption bandwidth or increasing the absorption coefficient in a specific frequency band; however, it may also lead to a shift in the absorption peak frequency, a reduction in the peak value, or the generation of undesirable valleys, thus disrupting the broadband effect. Therefore, it is necessary to control the design of the built-in partitions 1-3 and the unit spacing (in this embodiment, the width of the air slit gap layer). In this embodiment, the thickness of the built-in partitions 1-3 is 0.5 mm, and the height is 10 mm higher than the upper surface of the meta-absorbing unit, which can effectively reduce the lateral acoustic coupling between units and ensure the stability and predictability of the overall array performance.

[0048] S4: Unit Design Verification: Based on the multiple optimal parameter combinations obtained in step S3, prepare corresponding metamorphic sound-absorbing unit 1-1 samples respectively, and verify whether their sound absorption coefficient curves conform to the design predictions through impedance tube testing. In the unit design verification step, based on the optimal parameter combination obtained in step S3, corresponding metamorphic sound-absorbing unit experimental samples are prepared. Subsequently, the sound absorption coefficient curve of the samples is measured using an impedance tube testing system, and the measured curve is compared and analyzed with the theoretically predicted curve to verify whether the sound absorption coefficient meets the design expectations, ensuring the accuracy of the acoustic model and the reliability of the unit performance.

[0049] In specific implementation, based on the multiple sets of preferred parameter combinations obtained in step S3, corresponding metamorphic sound-absorbing unit 1-1 samples are prepared. Physical samples of the metamorphic sound-absorbing units are prepared according to the geometric dimensions and material specifications corresponding to the preferred parameter combinations. In this embodiment, two specifications of metamorphic sound-absorbing units are prepared: the first is a 189mm×189mm×80mm rigid porous dielectric layer, with the following parameters for the porous embedded structure array: d p =4mm l p =40mm =10mm, the width of the air slit gap layer is 10mm and the depth is 80mm, and the depth of the air cavity layer is 10mm; the second type is a rigid porous dielectric layer of 195.5mm×195.5mm×80mm, with the same parameters for the pore-shaped embedded structure array, the equivalent neck width of the air slit gap layer is 3.5mm and the equivalent neck length is 80mm, and the depth of the air cavity layer is 10mm.

[0050] The sample was then installed in an impedance tube testing system conforming to international standards, and its actual sound absorption coefficient curve under normal sound wave incidence was measured within the frequency range covering the target frequency band (100Hz-5000Hz). This embodiment uses an impedance tube testing system conforming to ISO 10534-2 standards, with test conditions of ambient temperature 25℃, relative humidity 50%, and atmospheric pressure 101325Pa. The test method is the dual-microphone transfer function method, which can accurately measure the sound absorption coefficient of the material under normal incident conditions.

[0051] Finally, the measured actual sound absorption coefficient curve is compared and analyzed with the theoretical sound absorption coefficient curve predicted by the acoustic theoretical model based on the same preferred parameter combination in step S2. The actual sound absorption coefficient values ​​at each target frequency band are checked to see if they reach or exceed the target thresholds set in step S1. The verification results of this embodiment show that the measured sound absorption coefficients are 0.33 (target threshold 0.30) at 125Hz, 1.04 (target threshold 0.60) at 250Hz, 1.06 (target threshold 0.80) at 500Hz, 0.89 (target threshold 0.70) at 1000Hz, 0.78 (target threshold 0.50) at 2000Hz, and 0.51 (target threshold 0.50) at 4000Hz, all reaching or exceeding the target thresholds. The noise reduction coefficient NRC = 0.95, exceeding the target threshold of 0.70.

[0052] The consistency between the actual and theoretically predicted absorption curves in terms of overall trend, peak absorption frequency, and peak value was evaluated. In this embodiment, the measured and theoretical curves showed a high degree of consistency in overall trend, both exhibiting a rapid increase in the low-frequency range, a high level in the mid-frequency range, and a gradual decrease in the high-frequency range. Regarding the peak absorption frequency, the measured peak was at 315Hz, while the theoretically predicted peak was at 300Hz, a deviation of 5%, which is within an acceptable range. As for the peak value, the measured peak absorption coefficient was 1.16, while the theoretically predicted peak was 1.12, a deviation of 3.6%, indicating good agreement.

[0053] The prediction accuracy of the acoustic model is quantified by calculating the error between the two. This embodiment uses the root mean square error. RMSE As an evaluation indicator, the calculation formula is: in, α measured , i For the measured sound absorption coefficient, α predicted , i To theoretically predict the sound absorption coefficient, N This represents the number of frequency points. In this embodiment... RMSE =0.042, indicating that the theoretical model has high prediction accuracy and can provide reliable guidance for design.

[0054] S5: Array Arrangement: Arrange the arrays that have been verified in step S4, which have different... Multiple metamorphic sound-absorbing units 1-1 are spatially combined according to the arrangement rules of periodic alternation, gradient change or random distribution to form the final broadband metamorphic sound-absorbing unit array structure.

[0055] In the array arrangement step, the various meta-absorbing units with different target frequencies, which have been verified in step S4, are spatially combined according to a periodic alternation, gradient variation, or random distribution pattern. This combination method enables the sound absorption peaks of each unit to connect and couple with each other in the frequency domain, thereby forming a broadband, high-efficiency sound-absorbing meta-absorbing unit array structure and optimizing the overall sound absorption performance.

[0056] To achieve the required frequency coverage of the broadband sound-absorbing band, several meta-absorbing units are selected from the various meta-absorbing units 1-1 that have been verified in step S4 and have different target resonant frequencies. This embodiment selects two types of meta-absorbing units: the first with a target frequency of approximately 400Hz and the second with a target frequency of approximately 250Hz. The combination of these two units can cover the low-frequency range of 250Hz-500Hz.

[0057] The meta-absorbing units 1-1 are arranged in a spatial array in a two-dimensional plane according to a preset arrangement pattern. The arrangement pattern includes periodic alternation, gradient variation, or random distribution. Periodic alternation involves arranging units with different resonant frequencies in a fixed, repeating sequence; in this embodiment, an ABABA periodic alternation sequence is used, where A represents the first type of unit and B represents the second type. Gradient variation involves arranging units continuously in a spatial order according to their resonant frequencies from low to high or from high to low, suitable for frequency-varying noise. Random distribution involves arranging units with different resonant frequencies in a random, unpredictable mixture, suitable for complex and variable noise.

[0058] When assembling the spatial array, built-in partitions 1-3 are placed between adjacent metamaterial sound-absorbing units. The built-in partitions 1-3 extend upwards from the back panel frame 2, and their height is 10mm higher than the upper surface of the metamaterial sound-absorbing unit. The built-in partitions 1-3 and the back panel frame 2 together form a semi-enclosed cavity with a closed back and sides and an open front. The metamaterial sound-absorbing unit 1-1 is placed within this semi-enclosed cavity. The built-in partitions 1-3 acoustically isolate each unit, forming a complete metamaterial sound-absorbing panel core 1. In this embodiment, a 2×5 array arrangement is formed, totaling 10 metamaterial sound-absorbing units. The first row of 5 units follows an ABABA sequence, and the second row of 5 units follows a BABAB sequence, achieving a balanced distribution of the two types of units.

[0059] The effect of the array design is that, after combining two arrays of metamorphic sound-absorbing units with different resonant frequencies, their sound absorption coefficient curves α(f) are coupled and superimposed within a preset wideband [100Hz, 5000Hz], enabling the metamorphic sound-absorbing panel to achieve a high sound absorption coefficient over a wide bandwidth. The first type of unit generates an absorption peak near 400Hz, and the second type of unit generates an absorption peak near 250Hz. The two absorption peaks form an effective connection in the frequency domain, covering the low-frequency range of 250Hz-500Hz. In the mid-to-high frequency range (500Hz-5000Hz), the pore-embedded structure array 1-1-2 continuously exerts its regulatory effect on the equivalent parameters of the porous medium, ensuring the sound absorption performance in the mid-to-high frequency range. It achieves wideband high-efficiency sound absorption from low to mid-to-high frequencies, with a noise reduction coefficient (NRC) of 0.95 and a peak sound absorption coefficient of 1.16@315Hz, achieving excellent wideband sound absorption performance within a limited structural thickness (113mm).

[0060] See Figures 1 to 4 In this embodiment, based on optimized design, a low-bandwidth meta-absorbent panel based on a rigid porous medium-internal perforated-narrow slit cavity is constructed. It includes two meta-absorbent units 1-1 with different configurations, a meta-absorbent panel core 1 composed of a periodic array, a back frame 2, and a panel 3. The dimensions of a single meta-absorbent panel are 1000mm in length, 432.5mm in width, and 113mm in height.

[0061] The core 1 of the superstructure sound-absorbing panel is formed by multiple superstructure sound-absorbing units 1-1 arranged periodically or non-periodically. The superstructure sound-absorbing units 1-1 can be physically separable independent modules, assembled into an integral array structure by fasteners, guide rails, or bolts; or they can be an integral array structure formed by multiple superstructure sound-absorbing units 1-1 molded as a single unit. Internal partitions 1-3 can be provided or partially provided for acoustic isolation. In this embodiment, there are two rows of superstructure sound-absorbing units 1-1 of two different sizes. Each superstructure sound-absorbing unit 1-1 is arranged horizontally five times, forming a 2*5 array arrangement of the core 1 of the superstructure sound-absorbing panel. The thickness of the internal partition is 0.5mm, and its height is 10mm higher than the upper surface of the superstructure sound-absorbing unit 1-1. The bottom of the internal partition is placed on the back plate frame 2, forming a semi-closed cavity with the back and sides closed and the front open. The superstructure sound-absorbing units 1-1 are placed within this semi-closed cavity.

[0062] Each meta-absorbing unit 1-1 is a composite structure stacked along the direction of sound wave incidence, including: The rigid porous medium layer 1-1-1 is a rigid skeleton porous material with a porosity of ≥95%. Its material is foamed calcium silicate, and it comes in two specifications: 189mm*189mm*80mm and 195.5mm*195.5mm*80mm, which are two cuboid configurations. The porous embedded structure array 1-1-2 is discretely distributed within the rigid porous dielectric layer 1-1-1. The porous embedded structure arrays 1-1-2 within the two specifications of the rigid porous dielectric layer 1-1-1 have identical specifications. Hole 1-1-2-1 is a non-through blind hole 1-1-2-1b with a circular cross-sectional shape and a diameter of... 4mm, tube depth 40mm, pipe spacing It is 10mm; The air gap layer 1-1-3 in this embodiment has two specifications. The air gap layer 1-1-3 corresponding to the 189mm*189mm*80mm rigid porous dielectric layer 1-1-1 has a width of 10mm and a depth of 80mm. The equivalent neck width of the air gap layer 1-1-3 corresponding to the 195.5mm*195.5mm*80mm rigid porous dielectric layer 1-1-1 is... 3.5mm, equivalent neck length The diameter is 80 mm. The air slit gap layer 1-1-3 is a frame gap 1-1-3a surrounding the rigid porous medium layer 1-1-1; Air cavity layer 1-1-4 is located at the back of the metamaterial sound-absorbing unit. In this embodiment, the cavity depth of air cavity layer 1-1-4 is... It is 10mm, and is a cavity of equal depth 1-1-4a.

[0063] The random incident sound absorption coefficient curve of the metamorphic sound-absorbing panel in this embodiment is as follows: Figure 8 As shown, the peak frequency of one-third octave band is located at 315Hz, with a peak absorption coefficient of 1.16 (due to the special structure of the specimen designed in this embodiment, such as slits and back cavities, its effective sound absorption area is larger than the actual test area, so the sound absorption coefficient at some frequencies is >1), and NRC=0.95. Its sound absorption coefficient curve from 100Hz to 5000Hz is shown in the table below: Table 1 Sound absorption coefficients from 100Hz to 5000Hz The back panel frame 2 is used to fix the inner core 1 of the super-structure sound-absorbing panel to form a stable whole, and provides a rigid back panel boundary that can form an air cavity layer 1-1-4. In this embodiment, the back panel frame 2 and the panel 3 are snap-fit ​​assembled, and no additional connectors are needed for fixing. In this embodiment, panel 3 is a protective panel material with low flow resistance and high sound transmission. It is a perforated metal plate with an array of regular hexagonal perforations distributed on its surface. The inscribed circle diameter of each hexagon is 16.5 mm, the center distance is 20 mm, and the overall perforation rate of the perforated plate is ≥60%. The front area of ​​the panel 3 frame is 0.42 m².2 .

[0064] Example 2 See Figure 5 The holes 1-1-2-1 in the perforated embedded structure array 1-1-2 are either through holes 1-1-2-1a that penetrate the hard porous dielectric layer 1-1-1 or blind holes 1-1-2-1b that do not penetrate. The depth of the through hole 1-1-2-1a is the same as the thickness of the hard porous dielectric layer 1-1-1; the depth of the blind hole 1-1-2-1b is less than the thickness of the hard porous dielectric layer 1-1-1.

[0065] Example 3 See Figure 6 The air gap layer 1-1-3 is a frame gap 1-1-3a surrounding the rigid porous medium layer 1-1-1. In this case, the rigid porous medium layer 1-1-1 of each meta-absorbing unit 1-1 is an independent individual. The air gap layer 1-1-3 can also be a pre-fabricated groove 1-1-3b inside the rigid porous medium layer 1-1-1. In this case, the rigid porous medium layers 1-1-1 of multiple meta-absorbing units 1-1 are a whole, and the air gap layer 1-1-3 is formed by the groove 1-1-3b.

[0066] Example 4 See Figure 7a The air cavity layer 1-1-4 is located on the face and back of the superstructure sound-absorbing unit. The face cavity is a cavity of equal depth 1-1-4a, and the back cavity is a cavity of equal depth 1-1-4a or a multi-level cavity 1-1-4b with a stepped depth. This embodiment provides a three-level back cavity scheme with cavity depths of 10mm, 20mm and 28mm respectively. See Figure 7b The air cavity layer 1-1-4 is located on the face and back of the superstructure sound-absorbing unit. The back cavity is a cavity of equal depth 1-1-4a, and the face cavity is a cavity of equal depth 1-1-4a or a multi-level cavity 1-1-4b with a stepped depth. This embodiment provides a three-level face cavity scheme with cavity depths of 10mm, 20mm and 28mm respectively.

[0067] Example 5 The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A design method for broadband metamorphic sound-absorbing panels based on the JCA model and transfer matrix method, characterized in that, The design methodology includes the following steps: S1. Obtain the sound pressure spectrum of the target noise source and determine several target frequency bands that need to be controlled and their corresponding target sound absorption coefficient thresholds; S2. Establish an acoustic theoretical model of the metastructure sound-absorbing unit (1-1), in which the rigid porous medium layer (1-1-1) is regarded as a uniform layer with equivalent complex density and equivalent complex bulk modulus based on the Johnson-Champoux-Allard equivalent fluid model, and the normal surface impedance and sound absorption coefficient are calculated by coupling with the air slit gap layer (1-1-3) and the air cavity layer (1-1-4) through the transfer matrix method. S3. Based on the acoustic theory model, with the target frequency band and sound absorption coefficient threshold as optimization objectives, the tube diameter, tube depth and tube spacing parameters of the perforated embedded structure array (1-1-2), the equivalent neck width and equivalent neck length parameters of the air slit gap layer (1-1-3), and the cavity depth parameters of the air cavity layer (1-1-4) are optimized in a coordinated manner to obtain the optimal parameter combination for the corresponding target frequency band. S4. Prepare a metamorphic sound-absorbing unit (1-1) sample according to the optimal parameter combination, and verify whether the sound absorption coefficient meets the design expectations by impedance tube test; S5. The verified meta-absorbing units (1-1) with different target frequencies are spatially combined according to the arrangement rules of periodic alternating gradient changes or random distribution to form a broadband meta-absorbing unit array.

2. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 1, characterized in that, In S2, the specific process includes: The equivalent complex density and equivalent complex bulk modulus of the rigid porous medium layer (1-1-1) were calculated based on the Johnson-Champoux-Allard model. Then, the transfer matrices of the rigid porous medium layer (1-1-1), the air slit gap layer (1-1-3), and the air cavity layer (1-1-4) were established respectively. Finally, the total transfer matrix was calculated by matrix multiplication and the surface impedance and sound absorption coefficient were derived.

3. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 2, characterized in that, In S2, the transfer matrices of the rigid porous dielectric layer (1-1-1), the air slit gap layer (1-1-3), and the air cavity layer (1-1-4) are established respectively. Finally, the total transfer matrix is ​​calculated by matrix multiplication, and the surface impedance and sound absorption coefficient are derived. The specific process includes: The basic acoustic parameters of the hard porous medium layer (1-1-1) are obtained, including porosity, flow resistance, tortuosity, viscous characteristic length, and thermal characteristic length. The basic acoustic parameters are input into the Johnson-Champoux-Allard equivalent fluid model to calculate the equivalent complex density and equivalent complex bulk modulus of the layer. Based on the transfer matrix theory, transfer matrices are established for the hard porous medium layer, the air slit gap layer (1-1-3), and the air cavity layer (1-1-4), respectively. The three transfer matrices are multiplied sequentially in the order of sound wave propagation direction to obtain the total transfer matrix of the entire metamorphic sound-absorbing unit (1-1). The surface impedance of the meta-absorbing unit under normal incident conditions is calculated from the total transfer matrix. Then, based on the relationship between the surface impedance and the characteristic impedance of air, the curve of its theoretical sound absorption coefficient changing with frequency is calculated.

4. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 1, characterized in that, In S3, the specific process of obtaining the optimal parameter combination for the corresponding target frequency band includes: With the target frequency band and sound absorption coefficient threshold as constraints, the geometric parameters of the perforated embedded structure array (1-1-2), the size parameters of the air slit gap layer (1-1-3), and the depth parameters of the air cavity layer (1-1-4) are adjusted synchronously using an optimization algorithm. Through iterative calculation, the theoretical sound absorption coefficient curve reaches the preset threshold in the target frequency band.

5. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 4, characterized in that, In S3, the specific process of iteratively calculating the theoretical sound absorption coefficient curve to reach a preset threshold in the target frequency band includes: Define the objective function of the optimization problem so that the theoretical sound absorption coefficient curve calculated based on the acoustic theoretical model established in S2 has a sound absorption coefficient value that is not lower than the corresponding target sound absorption coefficient threshold in each target frequency band determined in step S1. The tube diameter, tube depth, and tube spacing of the perforated embedded structure array (1-1-2), the equivalent neck width and equivalent neck length of the air slit gap layer (1-1-3), and the cavity depth of the air cavity layer (1-1-4) are set as multiple design variables that need to be optimized collaboratively. A multi-parameter optimization algorithm is used to iteratively search within the reasonable range of preset design variables.

6. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 1, characterized in that, In S4, the specific process of verifying whether the sound absorption coefficient meets the design expectations through impedance tube testing includes: Experimental samples of the meta-absorbing unit (1-1) were prepared, and then the actual sound absorption coefficient curve was measured using an impedance tube. Finally, the measured curve was compared and analyzed with the theoretical prediction curve to verify the accuracy of the acoustic model.

7. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 6, characterized in that, In S4, the specific process for verifying the accuracy of the acoustic model includes: Based on the geometric dimensions and material specifications corresponding to the optimal parameter combination obtained in S3, a physical sample of the meta-absorbing unit (1-1) was prepared. The sample was installed in an impedance tube testing system that conforms to international standards, and its actual sound absorption coefficient curve under normal sound wave incidence was measured within a frequency range covering the target frequency band. The measured actual sound absorption coefficient curve is compared and analyzed with the theoretical sound absorption coefficient curve predicted by the acoustic theoretical model in S2 based on the same optimal parameter combination. The actual sound absorption coefficient curve is checked to see if the sound absorption coefficient value at each target frequency band reaches or exceeds the target threshold set in S1. The consistency between the actual curve and the theoretical prediction curve in terms of overall trend, peak frequency of sound absorption, and peak size is evaluated. The prediction accuracy of the acoustic model is quantified by calculating the error between the two.

8. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 1, characterized in that, In S5, the specific process of spatially combining the verified meta-absorbing units (1-1) with different target frequencies according to the arrangement rules of periodic alternating gradient changes or random distribution includes: Select meta-absorbing units (1-1) with different resonant frequencies according to the target frequency band requirements, and then arrange them in an array according to the arrangement rules of periodic alternation, gradient change or random distribution. Finally, use built-in partitions (1-3) to acoustically isolate each unit to form a complete meta-absorbing panel core (1).

9. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 8, characterized in that, In S5, the specific process of array combination according to the arrangement rules of periodic alternation, gradient change, or random distribution includes: Based on the frequency coverage requirements of the broadband sound absorption band to be achieved, several meta-sound absorption units (1-1) are selected from the various meta-sound absorption units (1-1) that have been verified in S4 and have different target resonant frequencies. The meta-absorbing sound unit (1-1) is arranged in a spatial array in a two-dimensional plane according to a preset arrangement rule, which includes periodic alternation, gradient change or random distribution; When assembling spatial arrays, built-in partitions (1-3) are provided between adjacent meta-absorbing units, the built-in partitions (1-3) extending upward from the back panel frame (2).

10. The broadband metamorphic sound-absorbing panel design method based on the JCA model and transfer matrix method according to claim 9, characterized in that, The periodic alternation refers to arranging units with different resonance frequencies in a fixed, repeating sequence; the gradient change refers to arranging units continuously in a spatial order according to their resonance frequencies from low to high or from high to low; and the random distribution refers to arranging units with different resonance frequencies in a random, unpredictable mixed arrangement.

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