Gear acoustic metamaterial structure for broadband noise reduction
By designing a gear-based acoustic metamaterial structure, the problem of existing acoustic metamaterials being unable to cope with broadband noise in low-frequency noise scenarios was solved. This achieved low-frequency broadband noise reduction and efficient optimization design, significantly improving the bandgap width and resulting in significant attenuation of sound waves within the bandgap frequency band.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WUXI UNIV
- Filing Date
- 2025-07-24
- Publication Date
- 2026-06-26
Smart Images
Figure CN224417289U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of noise control technology, and more specifically, to a gear acoustic metamaterial structure for broadband noise reduction. Background Technology
[0002] Noise pollution is ubiquitous in daily work and life, constantly troubling people. It not only harms physical health but also damages mental health. As people's demands for quality of life increase, noise problems are becoming increasingly prominent, becoming an important issue that urgently needs to be addressed.
[0003] In recent years, acoustic artificial structures have attracted much attention in the field of sound absorption and insulation. Due to their characteristics such as "negative equivalent elastic modulus" and "negative equivalent mass," people can obtain unique properties completely different from their constituent materials by designing appropriate configurations. Compared with traditional materials, acoustic artificial structures, with their subwavelength structural design, can flexibly adjust the physical properties of materials and effectively control sound waves, providing a new solution for low-frequency sound absorption and insulation.
[0004] Currently, researchers have made significant progress in this field, and remarkable achievements have been made in the engineering research of various acoustic metamaterials and the improvement of noise reduction devices. For example, patent document with publication number "CN221427365U" provides an acoustic constraint device based on a labyrinth acoustic metamaterial, including a base plate with a guide rail embedded in it. A slider is slidably connected to the inner side of the guide rail. A first motor is provided on both sides of the surface of the base plate, and the output end of the first motor is connected to a lead screw. A second motor is fixedly provided on the top of the slider. A rotating platform is provided above the slider, and a first labyrinth acoustic metamaterial component is provided above the rotating platform. A rotating rod is connected to one side of the rotating platform, and the end of the rotating rod is connected to a second labyrinth acoustic metamaterial component. Although the existing acoustic constraint device based on a labyrinth acoustic metamaterial has a significant sound constraint effect, better adjustability, and greater flexibility, its acoustic metamaterial still faces many challenges in terms of performance, function, and optimized design, especially in low-frequency noise scenarios, where it is difficult to provide a sufficiently wide effective sound absorption / insulation band to cope with broadband noise environments. Furthermore, the modular design, optimization, and application of acoustic metamaterials are also limited by structural configuration, making it difficult to achieve efficient design. Utility Model Content
[0005] To overcome the shortcomings of existing acoustic metamaterials in the above-mentioned technologies, such as difficulty in adapting to broadband noise environments and low optimization design efficiency, this utility model provides a gear acoustic metamaterial structure for broadband noise reduction. It designs a low-frequency broadband and highly efficient noise-reducing acoustic metamaterial and achieves its efficient design and optimization through modular design.
[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:
[0007] An acoustic metamaterial structure for broadband noise reduction of gears includes: a base plate, and acoustic metamaterial units disposed on the base plate;
[0008] The acoustic metamaterial unit includes several layers of resonant cavities; the resonant cavities are cylindrical cavities with different cross-sectional radii and coaxially arranged; the outer wall of each layer of the resonant cavity is provided with a vertical through opening; the inner wall of the outermost resonant cavity and the outer walls of the other resonant cavities are respectively provided with gear structures.
[0009] Preferably, the number of acoustic metamaterial units is multiple, and they are arranged in a periodic repeating pattern.
[0010] Preferably, the height and arrangement density of the acoustic metamaterial units are independently adjustable; the ratio of the inner and outer radii, the opening angle, the gear radius, and the number of gear teeth of each layer of the resonant cavity are also independently adjustable.
[0011] Preferably, both the base plate and the acoustic metamaterial unit are made of thermoplastic polymer materials.
[0012] Preferably, the thermoplastic polymer material is any one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, and acrylic plastics.
[0013] Preferably, the acoustic metamaterial unit has three layers of resonant cavity.
[0014] Preferably, the gear acoustic metamaterial structure is prepared by three-dimensional printing.
[0015] Compared with the prior art, the beneficial effects of this utility model's technical solution are:
[0016] This utility model provides a gear acoustic metamaterial structure for broadband noise reduction, wherein the gear acoustic metamaterial structure includes: a base plate, and acoustic metamaterial units disposed on the base plate; the acoustic metamaterial units include several layers of resonant cavities, which are cylindrical cavities with different cross-sectional radii and coaxially arranged; the outer wall of each layer of resonant cavity is provided with a vertical through opening; the inner wall of the outermost resonant cavity and the outer walls of other resonant cavities are respectively provided with gear structures;
[0017] This invention introduces a multi-layered gear-shaped resonant cavity into acoustic metamaterials for the first time. By enhancing sound wave reflection and energy dissipation through the tooth-like structure, it breaks through the performance limitations of traditional Helmholtz resonators. In addition, based on the stretchable combination characteristics of acoustic metamaterial units, this invention can obtain a highly tunable acoustic metamaterial array, thereby meeting the needs of broadband noise reduction in multiple scenarios. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the gear acoustic metamaterial structure provided in Example 1.
[0019] Figure 2 This is a top view of the gear acoustic metamaterial structure provided in Example 1.
[0020] Figure 3 This is a schematic diagram of the acoustic metamaterial units arranged in a periodic array as provided in Example 1.
[0021] Figure 4 This is a flowchart illustrating the preparation method of a gear acoustic metamaterial structure for broadband noise reduction provided in Example 2.
[0022] Figure 5 This is the flowchart of the genetic algorithm iteration provided in Example 2.
[0023] Figure 6 The graph shows the iterative evolution curve and velocity curve of GAM provided in Example 2.
[0024] Figure 7 The acoustic metamaterial configurations and dispersion curves at different stages provided in Example 2 are shown.
[0025] Figure 8 This is a schematic diagram of the time-domain transient simulation model provided in Example 2.
[0026] Figure 9 This is a comparison of transient simulations inside and outside the bandgap provided in Example 2.
[0027] Figure 10 This is a schematic diagram of the pressure acoustic frequency domain simulation model settings, simulation model, and sound transmission loss curve provided in Example 2.
[0028] Figure 11 The diagram shows the sound pressure cloud map and sound power streamline of modes 1 to 4 provided in Example 2.
[0029] Figure 12 This is a schematic diagram of the ideal experimental model for the GAM test provided in Example 3.
[0030] Figure 13 This is a schematic diagram of the on-site setup for the GAM test provided in Example 3.
[0031] Figure 14 This is a comparison chart of the measured STL and simulated STL results within 1 / 3 octave band provided in Example 3. Detailed Implementation
[0032] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this application.
[0033] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions.
[0034] It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.
[0035] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.
[0036] Example 1
[0037] This embodiment provides a gear acoustic metamaterial structure for broadband noise reduction, including: a base plate 1, and acoustic metamaterial units 2 disposed on the base plate 1;
[0038] The acoustic metamaterial unit 2 includes several layers of resonant cavities 21; the resonant cavities 21 are cylindrical cavities with different cross-sectional radii and coaxially arranged; the outer wall of each layer of resonant cavity 21 is provided with a vertically penetrating opening 22; the inner wall of the outermost resonant cavity 21 and the outer walls of other resonant cavities 21 are respectively provided with gear structures 23;
[0039] The number of acoustic metamaterial units 2 is multiple, and they are arranged in a periodic repeating pattern;
[0040] The height and arrangement density of the acoustic metamaterial unit 2 are independently adjustable; the ratio of the inner and outer radii, the opening angle, the gear radius, and the number of gear teeth of each layer of the resonant cavity 21 are independently adjustable.
[0041] Both the base plate 1 and the acoustic metamaterial unit 2 are made of thermoplastic polymer materials;
[0042] The thermoplastic polymer material is specifically any one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, and acrylic plastics;
[0043] In the acoustic metamaterial unit 2, the resonant cavity 21 has three layers.
[0044] The gear acoustic metamaterial structure was prepared by 3D printing.
[0045] In the specific implementation process, such as Figure 1As shown, this embodiment proposes a basic configuration of a gear acoustic metamaterial (GAM) (where the dashed lines around the base plate 1 represent periodic boundaries); to increase the broadband resonance of the phonon crystal, this embodiment introduces a different number of resonant cavities 21 in a single scatterer tube. The resonant cavity 21 is similar to a Helmholtz resonator, and each resonant cavity 21 corresponds to an opening 22; considering the thickness of the partition and actual processing issues, this embodiment combines three layers of resonant cavities 21 into a unit; at the same time, the cavity wall uses a gear structure 23 to further increase the reflection and dissipation of sound wave energy within the cavity;
[0046] like Figure 2 As shown, in this embodiment, the two-dimensional cross-section of the acoustic metamaterial unit 2 is stretched to form a three-layer concentric cylindrical structure, which is connected by a base plate 1; wherein, the side length of the base plate 1 is a, and the two-dimensional cross-section of the acoustic metamaterial unit 2 is the core design area; the gear acoustic metamaterial cross-section is mainly affected by the cross-sectional radius R of the three-layer ring. i Inner and outer radius ratio m i , opening angle θ i Number of gear teeth N i Control, where i represents the i-th layer of the annulus;
[0047] like Figure 3 As shown, Figure 3 It is an array of periodically arranged acoustic metamaterial units. In practical applications, the gear acoustic metamaterials can be reasonably stretched in height and arranged according to requirements, thereby giving full play to the advantages of modular design.
[0048] This embodiment introduces a multi-layered gear-shaped resonant cavity into an acoustic metamaterial. The tooth-like structure enhances sound wave reflection and energy dissipation, thereby breaking through the performance limitations of traditional Helmholtz resonators. At the same time, based on the stretchable combination characteristics of the acoustic metamaterial units, this embodiment can obtain a highly tunable acoustic metamaterial array, thereby meeting the needs of broadband noise reduction in multiple scenarios.
[0049] Example 2
[0050] like Figure 4 As shown, this embodiment provides a method for preparing a gear acoustic metamaterial structure for broadband noise reduction, used to prepare the gear acoustic metamaterial structure described in Example 1, including the following steps:
[0051] S1: Initialize the core parameters of each resonant cavity in the acoustic metamaterial unit, wherein the core parameters include at least: inner-outer radius ratio, opening angle, gear radius, and number of gear teeth;
[0052] S2: The core parameters are iteratively optimized based on a genetic algorithm to obtain the optimal core parameters; wherein, the optimization objective is to maximize the first-order phonon bandgap width;
[0053] S3: Prepare acoustic metamaterial units according to the optimal core parameters and assemble them with the base plate to complete the preparation;
[0054] S4: Based on the pressure acoustic transient module in COMSOL MUTIPHYSICS software, time-domain simulation of acoustic propagation at different frequencies is performed to verify the bandgap characteristics of gear acoustic metamaterial structure;
[0055] In step S2, the objective function of the genetic algorithm during the optimization process is expressed as:
[0056]
[0057] in, H This represents the width of the first-order phonon bandgap; and It is divided into the first and second characteristic frequency sequences obtained by solving;
[0058] Step S2 includes:
[0059] S2.1: Population initialization: The core parameters of each resonant cavity in the acoustic metamaterial unit after initialization are used as the genome to be optimized to generate an initial population, and the initial population is randomly genetically processed.
[0060] S2.2: Fitness Calculation: Based on the set objective function, calculate the fitness value of each individual, and find the optimal core parameters of the current population by searching for the best fitness value;
[0061] S2.3: Termination Criterion: Determine whether the preset number of iterations has been reached. If it is, proceed to step S2.5; otherwise, proceed to step S2.4.
[0062] S2.4: Optimization algorithm: Select the next generation parent based on the fitness value and selection operator, generate a new population through crossover and mutation operations, and repeat steps S2.2~S2.3;
[0063] S2.5: Save and output the optimal core parameters obtained from the last population iteration;
[0064] In step S3, acoustic metamaterial units are prepared using 3D printing technology based on the optimal core parameters.
[0065] In the specific implementation process, 12 parameters including gear radius, radius ratio, 3 opening angles and 3 layers of teeth were first collected as the gear acoustic metamaterial genome to be optimized; the initialized parent genome contained a population of 50 individuals;
[0066] Next, a coupled module under the COMSOL with MATLAB interface is constructed. A genetic algorithm program is written in MATLAB to control COMSOL MUTIPHYSICS 6.0 to calculate the objective function. The calculated width of the first-order bandgap is used as the objective function.
[0067]
[0068] in, H This represents the width of the first-order phonon bandgap; and It is divided into the first and second characteristic frequency sequences obtained by solving;
[0069] After natural selection of the objective function, dominant genes are retained. Then, gene crossover and mutation are performed on these dominant genes, with a crossover factor of 0.2 and a mutation factor of 0.1. Iteration stops after 40 iterations. The specific optimization process of the genetic algorithm for gear acoustic metamaterials is as follows: Figure 5 As shown;
[0070] During the optimization process, the gene evolution curves of the structures were extracted during the co-simulation process, and the results are as follows: Figure 6 As shown, it can be seen that the band gap width increases continuously with the increase of the number of evolutions. When the number of iterations reaches 30, the band gap width of the structure gradually becomes stable, and the evolution rate of the structure gradually approaches 0. This phenomenon proves that the evolution of the structure has basically reached the optimal. In this embodiment, the gene parameters corresponding to the evolution result of the 40th iteration are selected as the optimal gene parameters, that is, the optimal acoustic metamaterial configuration.
[0071] Next, acoustic metamaterial units were prepared using 3D printing technology based on the optimal core parameters and assembled with the base plate to complete the preparation.
[0072] To verify the validity of the calculation results in this embodiment, Figure 7 The dispersion curves of the acoustic metamaterial configurations in the 1st, 5th, 15th and 40th evolution processes were extracted respectively; the dispersion structures of the four structures in the first Brillouin zone all showed bandgap characteristics;
[0073] Table 1 shows the specific results of the start frequency and cutoff frequency of the first-order bandgap for the four structures A, B, C, and D;
[0074] Table 1. First-order bandgap information for the four structures (unit: Hz)
[0075]
[0076] As shown in Table 1, as the structure evolves, the configuration of the structure continues to evolve, and the width of the first bandgap continues to widen. Among them, the optimized GAM has a bandgap range of 916Hz in the range of 1262Hz to 2178Hz; the optimized structure D has a bandgap width that is 3.55 times that of structure A, which is 658Hz wider.
[0077] In addition, this embodiment also uses the pressure acoustic transient module in COMSOL MUTIPHYSICS software to perform time-domain simulation of acoustic propagation at different frequencies to verify the bandgap characteristics of the gear acoustic metamaterial structure.
[0078] Specifically, the simulation model settings for the GAM array and acoustic simulation domain established in this embodiment are as follows: Figure 8 As shown in the figure; four air propagation domains are set on the four sides of the GAM array in the model; the ports of the four air domains are all set to plane wave radiation conditions, where the red ports represent plane wave radiation boundaries with incident pressure fields; the incident pressure field F in The settings are as follows:
[0079]
[0080] in, It is the amplitude of the incident pressure; The incident pressure frequency; t For time;
[0081] In this simulation, 600Hz and 1600Hz are selected as input frequencies. 600Hz is outside the bandgap frequency band, while 1600Hz is within the bandgap frequency band of 1262Hz~2178Hz. Figure 9 The sound pressure field distributions at different times (0s, 0.001s, 0.003s, and 0.006s) were extracted. When t1=0s, incident sound waves were input. When t2=0.001s, the incident sound waves began to enter the GAM array. When t3=0.003s, the incident sound waves had fully diffused within the GAM array. Specifically, the 600Hz incident sound wave easily passed through the GAM array and diffused in all directions; this process exhibited passband characteristics. However, the 1600Hz incident sound wave converged within the GAM array, and its propagation in all directions was blocked; this process exhibited bandgap characteristics. Similar to the acoustic propagation pattern at t2, when t3=0.006s, the 600Hz incident sound wave exhibited passband characteristics, while the 1600Hz incident sound wave exhibited bandgap characteristics. These analysis results verify the suppression effect of the GAM bandgap on sound waves.
[0082] To further quantify and analyze the acoustic attenuation characteristics of GAM in the passband and bandgap ranges, this embodiment also establishes as follows: Figure 10 The pressure acoustic frequency domain analysis model shown in (a) is a 3×3 GAM array, as shown in Figure (a). Figure 10 As shown in (b); this setup is to be consistent with the acoustic experimental environment of a 100×100mm impedance tube; the simulation model has perfectly matched layers at both ends to prevent sound wave reflection; the GAM sample is located in the middle of the impedance tube, with the left port of the tube being the incident end and the right port being the receiving end;
[0083] The acoustic transmission loss (STL) of the GAM sample is calculated using the following formula:
[0084]
[0085] in, The total acoustic power of the sound scattering surface. Represents the total acoustic power at the incident surface. STL The unit is dB;
[0086] Figure 10 (c) shows the STL calculation results, which can be seen that the sound wave transmission attenuation is significant within the bandgap range, with an average sound insulation of over 20dB; the maximum peak value can reach 50dB; this result also effectively verifies the strong sound attenuation capability within the bandgap frequency band.
[0087] To further explore the noise reduction mechanism, this embodiment also... Figure 10 Four modes (mode1, mode2, mode3 and mode4) were selected for simulation analysis in (c); Figure 11 To extract the sound pressure contour map and sound power streamline, from Figure 11 As can be seen from (a) and (d), the sound pressure level in the incident region and the sound pressure level in the receiving region are relatively close in modes 1 and 4; the sound power flow can pass through the GAM relatively easily, thus exhibiting passband characteristics; from Figure 11 As can be seen from (b) and (c), the sound pressure level in the sound incident region is significantly higher than that in the sound receiving region under both mode 2 and mode 3; the sound power flow in this mode exhibits reflection or sound swirl phenomena in the sound incident region; sound energy is difficult to propagate through GAM, thus exhibiting bandgap characteristics.
[0088] This embodiment proposes a design scheme based on genetic algorithm for gear metamaterials. The genetic algorithm realizes dynamic expansion and optimization of bandgap width. The optimized structure has a bandgap width increased by 3.55 times (up to 916Hz), which breaks through the design bottleneck of traditional manual trial and error. This embodiment can obtain a highly adjustable acoustic metamaterial array, thereby meeting the needs of broadband noise reduction in multiple scenarios.
[0089] Example 3
[0090] This embodiment provides an acoustic experiment to verify the effectiveness of the gear acoustic metamaterial structure described in Embodiment 1.
[0091] In the specific implementation process, this embodiment uses the four-sensor rectangular impedance tube method to determine the acoustic transmission loss (STL) of the GAM sample.
[0092] Ideal experimental design such as Figure 12 As shown, the ideal experimental system consists of a custom impedance tube, a broadband sound source, four microphone sensors, a data acquisition unit, and an experimental sample structure. The broadband sound source is located on the left side of the impedance tube, the experimental sample is located in the middle of the impedance tube, and the right end is covered with porous sound-absorbing material to form a low-reflection boundary to suppress sound wave reflection.
[0093] The on-site setup plan for the experiment is as follows: Figure 13 As shown, the custom-designed impedance tube has an effective test area of 100 mm × 100 mm and provides hard acoustic field boundary conditions. The GAM sample is obtained by 3D printing of the thermoplastic polymer Acrylonitrile Butadiene Styrene (ABS) and is fixed between the impedance tubes. Four sets of high-sensitivity ICP-type acoustic microphone sensors are configured before and after the GAM sample. The four acoustic microphone sensors are respectively installed on the incident section and the receiving end of the impedance tube, and their distances from the sample are as follows. , , and The microphone signal is input to a multi-channel data acquisition unit via a data cable. The computer system analyzes and processes the data, and the sound transmission loss is calculated using the following formula. :
[0094]
[0095] Where j is the imaginary part sign and k is the sound wave number;
[0096] Figure 14 The measured STL and simulated STL results within 1 / 3 octave band were compared. It can be seen that although the accuracy of the experimental data is lower than that of the simulated data, the development patterns of the measured STL and simulated STL curves are basically consistent. In addition, the peak frequency bands of both are relatively obvious, and there is a high sound insulation in the bandgap frequency range. It is worth noting that due to interference factors such as nonlinear damping and thermal viscosity of the material, the peak value will decrease and the valley value will increase. Therefore, there is a certain numerical difference in the peak values between the two.
[0097] The experimental results showed that the sound insulation effect can reach 29.6dB in the bandgap frequency band. In addition, there is also good sound insulation in other frequency ranges, such as more than 14.1dB in the frequency band after 2000Hz.
[0098] Overall, the experimental results effectively verified the simulation results and demonstrated the high sound insulation performance of the gear acoustic metamaterial structure within a certain bandgap range.
[0099] The same or similar labels correspond to the same or similar parts;
[0100] The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this application.
[0101] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.
Claims
1. A gear acoustic metamaterial structure for broadband noise reduction, characterized in that, include: The base plate (1) and the acoustic metamaterial unit (2) disposed on the base plate (1); The acoustic metamaterial unit (2) includes several layers of resonant cavities (21); the resonant cavities (21) are cylindrical cavities with different cross-sectional radii and coaxially arranged; the outer wall of each layer of resonant cavity (21) is provided with a vertical through opening (22); the inner wall of the outermost resonant cavity (21) and the outer walls of other resonant cavities (21) are provided with gear structures (23).
2. The gear acoustic metamaterial structure for broadband noise reduction according to claim 1, characterized in that, The number of acoustic metamaterial units (2) is multiple and they are arranged in a periodic repeating pattern.
3. The gear acoustic metamaterial structure for broadband noise reduction according to claim 2, characterized in that, The height and arrangement density of the acoustic metamaterial unit (2) are independently adjustable; the ratio of the inner and outer radii, the opening angle, the gear radius and the number of gear teeth of each layer of the resonant cavity (21) are independently adjustable.
4. The gear acoustic metamaterial structure for broadband noise reduction according to claim 1, characterized in that, The base plate (1) and the acoustic metamaterial unit (2) are both made of thermoplastic polymer materials.
5. The gear acoustic metamaterial structure for broadband noise reduction according to claim 4, characterized in that, The thermoplastic polymer material is specifically any one of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, and acrylic plastics.
6. A gear acoustic metamaterial structure for broadband noise reduction according to any one of claims 1 to 5, characterized in that, In the acoustic metamaterial unit (2), the resonant cavity (21) has three layers.
7. The gear acoustic metamaterial structure for broadband noise reduction according to claim 1, characterized in that, The gear acoustic metamaterial structure was prepared by 3D printing.