Acoustic metamaterial structure with pre-tension thin film and design method

Abstract

The invention relates to the technical field of vibration noise control, and discloses an acoustic metamaterial structure with a pre-tension thin film and a design method, low-frequency vibration noise is controlled through local resonance of an accessory mass block and the pre-tension thin film in each unit of a honeycomb structure, and the acoustic metamaterial structure is simple in structural form and easy to form and process in batches; the used materials are conventional materials, so that the cost is low and the environment is protected; the overall structure is light, the thickness is small, and the practical engineering application requirement can be met; according to the acoustic metamaterial structure, the broadband and high sound insulation and vibration reduction performance are achieved, and the limitation of the sound insulation quality law is broken through.

Description

Technical Field

[0001] This invention relates to the field of vibration and noise control technology, and discloses an acoustic metamaterial structure with a pre-tensioned membrane and its design method. Background Technology

[0002] Low-frequency vibration and noise has always been a bottleneck problem in industries such as aviation, aerospace, shipbuilding, weaponry and rail transportation. Traditional materials and structures have relatively high technical levels in engineering applications, but due to the inherent limitations of their physical properties and mechanisms, they are often ineffective in low-frequency vibration reduction and noise reduction. The weight and volume costs in engineering applications are also high, which contradicts the current demand for lightweighting. Summary of the Invention

[0003] The purpose of this invention is to provide an acoustic metamaterial structure and design method with a pre-tensioned membrane, which can achieve low-frequency vibration noise control, and has a simple structure that is easy to mass-produce.

[0004] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: An acoustic metamaterial structure with a pre-stressed membrane, comprising: A honeycomb structure, wherein two honeycomb structures are stacked together and a pretensioning film is sandwiched between the two honeycomb structures. An additional mass block is attached to the surface of the pretensioning film and the additional mass block is located in the honeycomb hole of the honeycomb structure. An upper cover plate and a lower cover plate are used to cover the end faces of the honeycomb structure, respectively.

[0005] Furthermore, the upper cover plate may be provided with sound-absorbing holes.

[0006] Furthermore, the honeycomb structure is one of aluminum honeycomb, paper honeycomb, and resin honeycomb.

[0007] Furthermore, the additional mass block may be a metal block.

[0008] A method for designing an acoustic metamaterial structure with a pre-tensioned membrane, comprising: The sound insulation performance optimization objectives and design constraints of the acoustic metamaterial structure to be designed are determined; the sound insulation performance optimization objectives include the target sound insulation amount, the target sound insulation frequency band, and the target sound absorption coefficient; the design constraints include the installation space limitations, weight limitations, and fabrication process limitations of the acoustic metamaterial structure to be designed. The acoustic metamaterial structure design parameters corresponding to the constraints are used as optimization variables; a mapping relationship between optimization variables and optimization objectives is constructed, and the sensitivity of the influence of different optimization variables on the optimization objectives is analyzed. The value range of the optimization variables is determined according to the design constraints; for optimization variables with low sensitivity, the number of values ​​of the optimization variables is reduced, and for optimization variables with high sensitivity, the number of values ​​of the optimization variables needs to be increased. Within the value range of the optimization variables, an initial sample group is generated, and each sample group consists of a set of the optimization variables. By establishing the mapping relationship between optimization variables and optimization design objectives, the acoustic metamaterial structure model to be designed is analyzed under the target sound insulation frequency band, and the sound insulation frequency band analysis value, sound insulation value and sound absorption coefficient analysis value of the acoustic metamaterial structure to be designed corresponding to the initial sample group are obtained. An optimization algorithm is used to perform a global search by changing the optimization variables. The deviation between the sound insulation frequency band analysis value corresponding to each sample group and the target sound insulation frequency band is determined. The optimal sample group with the smallest deviation is retained. If there are multiple optimal sample groups, the optimal structural scheme that meets the optimization objective and constraints needs to be selected based on actual requirements.

[0009] Furthermore, the optimization variables include the thickness of the honeycomb panel, the mechanical parameters of the honeycomb panel material, the honeycomb side length, the honeycomb thickness, the honeycomb height, the mechanical parameters of the thin film material, the thin film thickness, the thin film pre-tension, the size of the additional mass block, the bonding position of the additional mass block, and the weight of the additional mass block.

[0010] Compared with the prior art, the beneficial effects of this invention are: The acoustic metamaterial structure of this invention achieves low-frequency vibration noise control through the local resonance of the accessory mass blocks and the pre-tensioned membrane in each unit of the honeycomb structure. Moreover, the structure is simple and easy to mass-produce. All materials used are conventional, low-cost and environmentally friendly. The overall structure is lightweight and thin, which helps to meet the requirements of practical engineering applications. The acoustic metamaterial structure of this invention achieves broadband and high sound insulation and vibration reduction performance, breaking the limitations of the sound insulation quality law. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the first state of the acoustic metamaterial structure with a pre-tensioned membrane in the embodiment. Figure 2 This is a schematic diagram of the second state of the acoustic metamaterial structure with a pre-tensioned membrane in the embodiment. Figure 3 This is a flowchart illustrating the design method of an acoustic metamaterial structure with a pre-tensioned membrane in the embodiments. Among them, 1-upper cover plate, 2-honeycomb structure, 3-additional mass block, 4-pretension membrane, 5-lower cover plate. Detailed Implementation

[0012] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0013] Example See Figure 1 and Figure 2 An acoustic metamaterial structure with a pre-stressed membrane, comprising: A honeycomb structure 2 is provided, consisting of two stacked honeycomb structures. The honeycomb structure 2 can be one of aluminum honeycomb, paper honeycomb, or resin honeycomb, and serves as the main load-bearing substrate of the acoustic metamaterial structure. The honeycomb cells of the two honeycomb structures 2 are aligned. A pre-tensioning membrane 4 is sandwiched between the two honeycomb structures 2, and the honeycomb structure 2 and the pre-tensioning membrane 4 are bonded together with an adhesive. An additional mass block 3 is attached to the surface of the pre-tensioning membrane 4, and the additional mass block 3 is located in the honeycomb cells of the honeycomb structure 2. The pre-tensioning membrane 4 can be made of materials such as polyimide, polyethylene, polyethylene terephthalate, nylon, or silicone rubber, and the pre-tensioning of the membrane is pre-formed using a stretching device to ultimately form the pre-tensioning membrane 4. The additional mass block 3 is attached to the surface of the pre-tensioning membrane 4; the additional mass block 3 serves as a low-frequency sound dissipation oscillator structure and can be made of metal blocks such as aluminum alloy or stainless steel.

[0014] The upper cover plate 1 and the lower cover plate 5 are used to cover the end faces of the honeycomb structure 2. The upper cover plate 1 and the lower cover plate 5 can be metal covers or composite material covers. The composite material can be carbon fiber composite material or resin-based glass fiber composite material. Sound-absorbing holes can be opened on the upper cover plate 1 as needed to improve the sound absorption performance of the acoustic metamaterial structure in a preset frequency band. It should be noted that in order to achieve the sound absorption effect of the acoustic metamaterial structure at different frequencies, the perforation rate and perforation diameter of the sound-absorbing holes on the upper cover plate 1 can be adjusted.

[0015] In the acoustic metamaterial structure of this invention, due to the significant density difference between the added mass block 3 and the pre-tensioned membrane 4, the entire acoustic metamaterial exhibits two intrinsic vibration modes: the first intrinsic mode is caused by the local resonance of the spring-mass system composed of the added mass block 3 and the pre-tensioned membrane 4, and the second intrinsic mode is caused by the self-resonance of the membrane between the added mass block 3 and the boundary. The two intrinsic modes are independent of each other. When the frequency of the incident noise wave is greater than the frequency of the first intrinsic mode, the spring-mass system composed of the added mass block 3 and the pre-tensioned membrane 4 vibrates out of phase, which can significantly improve the sound insulation performance of the entire structure. Moreover, since the spring-mass oscillator composed of the added mass block 3 and the pre-tensioned membrane 4 can effectively dissipate low-frequency vibration energy under resonance, the acoustic metamaterial structure of this invention can achieve good control of vibration noise.

[0016] This invention relates to an acoustic metamaterial structure with a pre-tensioned membrane. By adding a pre-tensioned membrane and a mass block to a traditional honeycomb structure, it can effectively suppress low-frequency vibration noise with a small amount of added weight.

[0017] The acoustic metamaterial structure of this invention achieves low-frequency vibration noise control through the local resonance of the attached mass blocks in the two units of the honeycomb structure and the pre-tensioned membrane 4. Moreover, the structure is simple and easy to mass-produce. All materials used are conventional materials, which are inexpensive and environmentally friendly. The overall structure is lightweight and thin, which helps to meet the requirements of practical engineering applications. The acoustic metamaterial structure of this invention achieves broadband and high sound insulation and vibration reduction performance, breaking the limitations of the sound insulation quality law.

[0018] Based on the same inventive concept, see [link to inventive concept] Figure 3 This embodiment provides a design method for an acoustic metamaterial structure with a pre-tensioned membrane, used to design the aforementioned acoustic metamaterial structure with a pre-tensioned membrane, including: Step 1: Determine the sound insulation performance optimization target and design constraints of the acoustic metamaterial structure to be designed; the sound insulation performance optimization target includes the target sound insulation amount, the target sound insulation frequency band, and the target sound absorption coefficient; the design constraints include the installation space limit, weight limit, and fabrication process limit of the acoustic metamaterial structure to be designed.

[0019] Step Two: The acoustic metamaterial structure design parameters corresponding to the constraints are used as optimization variables. A mapping relationship between the optimization variables and the optimization objective is constructed, and the sensitivity of different optimization variables to the optimization objective is analyzed. The value range of the optimization variables is determined according to the design constraints. For optimization variables with low sensitivity, the number of values ​​for the optimization variables is reduced; for optimization variables with high sensitivity, the number of values ​​for the optimization variables needs to be increased. Within the value range of the optimization variables, an initial sample group is generated, and each sample group consists of a set of the optimization variables. The optimization variables include honeycomb panel thickness, honeycomb panel material parameters, honeycomb side length, honeycomb thickness, honeycomb height, thin film material parameters, thin film thickness, thin film pre-tension, size of the additional mass block 3, bonding position of the additional mass block 3, and weight of the additional mass block 3. The mechanical parameters of the honeycomb panel material and the thin film material include density, Poisson's ratio, elastic modulus, etc. In this embodiment, honeycomb panel density and thin film density are used. Those skilled in the art can select the mechanical parameters of the honeycomb panel material and the thin film material as needed.

[0020] It should be noted that for the same optimization variable, sensitivity analysis is performed using multiple values ​​within its range. If the sensitivities of the multiple values ​​differ little and the trend is gradual, the optimization variable is considered to have low sensitivity. Conversely, if the sensitivities of the multiple values ​​differ significantly and the trend is abrupt, the optimization variable is considered to have high sensitivity.

[0021] Step 3: By establishing the mapping relationship between the optimization variables and the optimization design objectives, the acoustic metamaterial structure model to be designed is analyzed under the target sound insulation frequency band to obtain the sound insulation frequency band analysis value, sound insulation value, and sound absorption coefficient analysis value of the acoustic metamaterial structure to be designed corresponding to the initial sample group.

[0022] Step 4: Using an optimization algorithm, change the optimization variables to perform a global search, determine the deviation between the sound insulation frequency band analysis value corresponding to each sample group and the target sound insulation frequency band, and retain the optimal sample group with the smallest deviation. If there are multiple optimal sample groups, it is necessary to select the optimal structural scheme that meets the optimization objectives and constraints based on actual needs.

[0023] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An acoustic metamaterial structure with a pre-tensioned membrane, characterized in that, include: A honeycomb structure (2) is provided, two honeycomb structures (2) are stacked, and a pretensioning film (4) is sandwiched between the two honeycomb structures (2). An additional mass block (3) is attached to the surface of the pretensioning film (4), and the additional mass block (3) is located in the honeycomb holes of the honeycomb structure (2). The upper cover plate (1) and the lower cover plate (5) are used to cover the end face of the honeycomb structure (2), respectively.

2. The acoustic metamaterial structure with a pre-tensioned membrane according to claim 1, characterized in that, The upper cover plate (1) is provided with sound-absorbing holes.

3. The acoustic metamaterial structure with a pre-tensioned membrane according to claim 1, characterized in that, The honeycomb structure (2) is one of aluminum honeycomb, paper honeycomb, and resin honeycomb.

4. The acoustic metamaterial structure with a pre-tensioned membrane according to claim 1, characterized in that, The additional mass block (3) is a metal block.

5. The acoustic metamaterial structure with a pre-tensioned membrane according to claim 1, characterized in that, The honeycomb holes of the two honeycomb structures (2) are aligned.

6. A method for designing an acoustic metamaterial structure with a pre-tensioned membrane, used to design an acoustic metamaterial structure with a pre-tensioned membrane as described in any one of claims 1-5, characterized in that, include: Determine the sound insulation performance optimization objectives and design constraints for the acoustic metamaterial structure to be designed; The sound insulation performance optimization targets include target sound insulation amount, target sound insulation frequency band, and target sound absorption coefficient; The design constraints include the installation space limitations and weight limitations of the acoustic metamaterial structure to be designed. The acoustic metamaterial structure design parameters corresponding to the constraints are used as optimization variables; Construct a mapping relationship between optimization variables and optimization objectives, and analyze the sensitivity of the influence of different optimization variables on the optimization objectives. Determine the value range of the optimization variables according to the design constraints. For optimization variables with low sensitivity, reduce the number of values ​​of the optimization variables. For optimization variables with high sensitivity, increase the number of values ​​of the optimization variables. Within the value range of the optimization variables, generate an initial sample group, and each sample group consists of a set of optimization variables. By establishing the mapping relationship between optimization variables and optimization design objectives, the acoustic metamaterial structure model to be designed is analyzed under the target sound insulation frequency band, and the sound insulation frequency band analysis value, sound insulation value and sound absorption coefficient analysis value of the acoustic metamaterial structure to be designed corresponding to the initial sample group are obtained. An optimization algorithm is used to perform a global search by changing the optimization variables. The deviation between the sound insulation frequency band analysis value corresponding to each sample group and the target sound insulation frequency band is determined. The optimal sample group with the smallest deviation is retained. If there are multiple optimal sample groups, the optimal structural scheme that meets the optimization objectives and constraints needs to be selected based on actual requirements.

7. The method for designing an acoustic metamaterial structure with a pre-stressed membrane according to claim 6, characterized in that, The optimization variables include the thickness of the honeycomb panel, the mechanical parameters of the honeycomb panel material, the honeycomb side length, the honeycomb thickness, the honeycomb height, the mechanical parameters of the thin film material, the thin film thickness, the thin film pre-tension, the size of the additional mass block, the bonding position of the additional mass block, and the weight of the additional mass block.

8. The method for designing an acoustic metamaterial structure with a pre-stressed membrane according to claim 7, characterized in that, The mechanical parameter of the honeycomb panel material is the density of the honeycomb panel, and the mechanical parameter of the thin film material is the density of the thin film.

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