Design method of underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness

Abstract

The present invention provides a design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness. The steps are as follows: Step 1, establish a first model, which is a quasi-zero stiffness lattice pressure-resistant sound insulation material model; Step 2, establish a second model, which is a quasi-zero stiffness curved beam constraint condition calculated according to the first model and the pressure-resistant sound insulation requirements; Step 3, establish a third model, which is a quasi-zero stiffness curved beam structure designed by using the genetic algorithm and the finite element simulation method and combining with the second model; according to the third model, obtain the lattice material unit cell; Step 4, establish a fourth model, which is an equivalent sound insulation model of the quasi-zero stiffness lattice material under hydrostatic pressure established by using the third model and the lattice material unit cell and adopting finite element software; Step 5, according to the fourth model, process a cylindrical pressure-resistant sound insulation material suitable for a standing wave tube, and measure the sound insulation performance of the material under the target hydrostatic pressure to verify the pressure-resistant sound insulation performance of the material.

Description

Technical Field

[0001] The present invention relates to a lightweight material for underwater acoustic insulation using a quasi-zero stiffness mechanism, belonging to the field of underwater acoustic propagation control technology. Specifically, it particularly relates to a design method for an underwater pressure-resistant and wide low-frequency acoustic insulation material based on quasi-zero stiffness. Background Art

[0002] Acoustic insulation materials are widely used in fields such as aerospace, transportation, and construction. Generally, they block sound waves by generating impedance mismatch with the environmental medium, and the acoustic insulation effect enhances with the increase in the degree of impedance mismatch. Traditional high-stiffness (usually high-impedance) pressure-resistant materials have a high degree of impedance mismatch with air and can achieve good air-borne sound insulation; however, they have a low degree of impedance mismatch with water and poor underwater acoustic insulation effect.

[0003] Underwater acoustic insulation materials are an important component of the acoustic insulation system in marine equipment such as ships and submarines and play a crucial role. Existing underwater acoustic materials are mainly gas cavity materials with high porosity. The gas inside the materials can significantly reduce the equivalent impedance of the materials, and their underwater acoustic insulation performance will gradually improve with the increase in porosity. However, such high-porosity materials have low stiffness performance, resulting in the inability of the materials to adapt to the working environment under high pressure. This is because there is a strong coupling between the impedance and stiffness of traditional underwater acoustic insulation materials, making it impossible for them to have both high pressure resistance and high impedance mismatch characteristics.

[0004] In recent years, the development of metamaterial technology has enabled material properties to break through the limitations of traditional materials. Scholars have designed new underwater acoustic insulation materials using metamaterial technologies such as Bragg scattering, local resonance, and extreme properties. Among them, Bragg scattering can achieve coherent cancellation of waves, but the working frequency band is equivalent to the material period length and is difficult to be used for low-frequency underwater acoustic insulation; the local resonance mechanism suppresses sound wave transmission by forming negative stiffness / density near the resonance frequency, and the effective frequency band is relatively narrow; extreme materials can weaken the coupling relationship between material impedance and stiffness, but the necessary microstructures inside them cause concentrated stress or buckling during the loading process, greatly limiting the pressure resistance performance of the materials. In summary, there is currently a lack of an underwater acoustic material that combines pressure resistance and underwater acoustic insulation.

[0005] The present invention proposes a design method. Based on quasi-zero stiffness materials, it realizes the decoupling of material impedance and stiffness and designs an underwater pressure-resistant and wide low-frequency acoustic insulation material. Summary of the Invention

[0006] According to the above-mentioned technical problems, a design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness is provided. The present invention can design a wide low-frequency underwater sound insulation material according to the requirements of the use environment (hydrostatic pressure). This material overcomes the narrow-frequency characteristics of resonance mechanism sound insulation materials and the weak load-bearing performance of extreme property materials, and can achieve wide low-frequency sound insulation under high hydrostatic pressure. The present invention is based on the design of a quasi-zero stiffness curved beam, realizing the separation of the dynamic stiffness and static stiffness of the material, and breaking the inherent conflict between pressure resistance and sound insulation performance. The pressure-resistant sound insulation material is composed of upper and lower panels and an intermediate quasi-zero stiffness curved beam. Under the action of hydrostatic pressure, the curved beam tends to quasi-zero stiffness, and the equivalent impedance of the material decreases significantly, forming a high impedance mismatch with water, thereby achieving wide low-frequency sound insulation.

[0007] The technical means adopted by the present invention are as follows:

[0008] A design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness, comprising the following steps:

[0009] Step 1: Establish a first model, which is a quasi-zero stiffness lattice pressure-resistant sound insulation material model. This model is a lattice structure composed of several lattice material unit cells, and each lattice material unit cell is composed of an upper panel, a lower panel, and a quasi-zero stiffness curved beam in the middle;

[0010] Step 2: Establish a second model, which is the constraint conditions of the quasi-zero stiffness curved beam calculated according to the first model and the pressure-resistant sound insulation requirements, that is, the geometric design space of the required curved beam and the load and deformation under quasi-zero stiffness; the constraint conditions include a first constraint condition and a second constraint condition. The first constraint condition is to design the quasi-zero stiffness and the height before and after deformation of the curved beam according to the sound insulation and material thickness requirements by the first model; the second constraint condition is to design the side length and load-bearing performance of the lattice material unit cell according to the pressure resistance requirements.

[0011] Step 3: Establish a third model, which is a quasi-zero stiffness curved beam structure designed by using the genetic algorithm and the finite element simulation method and combined with the second model. The curved beam structure shows quasi-zero stiffness under the required pressure; according to the third model, based on the relationship between the curved beam material, geometric parameters, and quasi-zero stiffness bearing capacity, adjust the curved beam size to obtain the lattice material unit cell.

[0012] Step 4: Establish a fourth model, which is an equivalent sound insulation model of the quasi-zero stiffness lattice material under hydrostatic pressure established by using the third model and the lattice material unit cell, and calculate the sound insulation performance of the material of this model and compare it with the expected result; if they are consistent, enter step 5, otherwise repeat steps 2 to 4;

[0013] Step 5: According to the fourth model, process cylindrical pressure-resistant sound insulation materials applicable to a standing wave tube, measure the sound insulation performance of the materials under the target hydrostatic pressure, and verify the pressure-resistant sound insulation performance of the materials.

[0014] Further, in the above Step 1, the unit cell of the lattice material is of Kagome type, pyramid type or hourglass type. In the pyramid lattice, 4 curved beams intersect at one point and are connected to the upper panel.

[0015] Further, in the above Step 2, in the calculation of the constraint conditions of the quasi-zero stiffness curved beam: taking the sound insulation performance as the goal and based on the double-panel cavity structure, initially calculate the required compression thickness of the material, and then determine the height of the curved beam after compression. Multiply it by the deformation coefficient to obtain the height d of the curved beam. Calculate the bearing capacity according to the side length L of the structural unit cell, and take 1 / 4 as the external force borne by a single curved beam, that is, the acting force in the quasi-zero stiffness state. Thus, the design range of the quasi-zero stiffness curved beam and the external force it bears are obtained according to the pressure-resistant sound insulation requirements.

[0016] Further, in the above Step 3, associate Matlab with the finite element simulation software, use the genetic algorithm to design the size of the curved beam, and input it into the finite element simulation software to calculate its force-displacement curve and perform simulation optimization.

[0017] Further, in the above Step 3, during the simulation optimization process, the optimization variables include the control point coordinates of the spline curve of the curved beam, the characteristic weight, and the cross-sectional area of the curved beam. The constraint conditions are the deformation height and acting force under quasi-zero stiffness, that is, the second model obtained in Step 2. The optimization goal is the deviation degree between the actual deformation and the corresponding acting force in the quasi-zero stiffness state and the required pressure-resistant performance.

[0018] Further, in the above Step 3, when the force-displacement curve of the simulation optimization result shows a negative slope, that is, the curved beam shows negative stiffness, then this result should be discarded.

[0019] When the optimization results do not meet the goals, return to Step 2 to adjust the deformation coefficient of the curved beam and the side length of the unit cell, and change the base material of the curved beam; assemble the optimized curved beams to form a lattice material, and calculate the force-displacement curve of the material under compression through the finite element simulation software to check its bearing performance.

[0020] Further, in the above Step 4, when establishing the fourth model using the finite element software, the background media on both sides of the material is water, and the middle cavity of the material is air; the material deforms under the water pressure. Under this condition, a plane wave in the water is normally incident on the surface of the material; by calculating the intensity of the transmitted sound wave, the sound insulation performance of the material is obtained.

[0021] Further, in the above Step 5, use 3D printing technology to process experimental samples of cylindrical pressure-resistant sound insulation materials, and seal the side of the samples with flexible rubber.

[0022] Further, in the fifth step, the processed cylindrical pressure-resistant sound insulation material is placed in a standing wave tube for underwater sound insulation performance testing under pressure; if the test result has the same trend as the simulation result and the average error is less than 30%, the design of the pressure-resistant sound insulation material is completed; otherwise, steps two to five are repeated.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The design method of underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness provided by the present invention proposes a design method of multifunctional underwater pressure-resistant sound insulation material based on quasi-zero stiffness metamaterials, solves the pressure resistance problem of traditional underwater sound insulation materials, and breaks through the performance conflict between the natural high pressure resistance and high sound insulation of traditional materials.

[0025] 2. The design method of underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness provided by the present invention has the sound insulation performance of the designed multifunctional material not affected by frequency. Compared with the narrow frequency characteristics of existing resonance-type sound insulation materials, wide-frequency sound insulation can be achieved; the pressure resistance performance is clearly characterized, and rapid reverse design can be carried out according to the pressure resistance requirements.

[0026] 3. The design method of underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness provided by the present invention has the designed quasi-zero stiffness material based on a non-linear curved beam structure. Compared with the design method of spring-mechanism quasi-zero stiffness, it has the advantages of simple structure, low complexity, and small mass.

[0027] 4. The design method of underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness provided by the present invention has the designed quasi-zero stiffness material composed of metal materials. Compared with existing sound insulation materials such as rubber, it has the advantages of high safety performance, corrosion resistance, and long service life.

[0028] In summary, applying the technical solution of the present invention can solve the problems of poor pressure resistance performance and narrow effective frequency band of existing underwater sound insulation materials, and can significantly improve the acoustic performance of equipment in deep water high-pressure environments.

[0029] The present invention has high engineering application value and potential, and can be promoted in the field of acoustic performance regulation of marine equipment. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1Several typical quasi-zero stiffness lattice structures related to the present invention are shown. Among them, (a) is the Kagome type, (b) is the pyramid type, and (c) is the hourglass type. Subsequently, the pyramid-shaped pressure-resistant and sound-insulating material will be used as an example for illustration.

[0032] Figure 2 This is the flowchart for the optimal design of the quasi-zero stiffness curved beam in the present invention.

[0033] Figure 3 This is the schematic diagram of the optimized unit cell and its compression performance (force-displacement) curve of the example of the present invention. Among them, (a) is the schematic diagram of the optimized unit cell, and (b) is the compression performance (force-displacement) curve.

[0034] Figure 4 This is the schematic diagram of the model and the simulated sound insulation effect of the pressure-resistant and sound-insulating material of the example of the present invention under an external hydrostatic pressure of 1 MPa. Specific Embodiments

[0035] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment is actually only illustrative and in no way restricts the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0039] The present invention provides a design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness. The specific implementation steps to realize this solution are as follows:

[0040] Step 1: Establish a quasi-zero stiffness lattice pressure-resistant sound insulation material model. The lattice material unit cell consists of upper and lower panels and curved beams in the core.

[0041] Step 2: According to the sound insulation and material thickness requirements, design the quasi-zero stiffness and the heights before and after deformation of the curved beams from the model in Step 1; according to the pressure-resistant requirements, design the side length and load-bearing performance of the lattice material unit cell. Thus, the geometric design space of the required curved beams and the loads and deformations under quasi-zero stiffness are obtained.

[0042] Step 3: Design quasi-zero stiffness curved beams. Use the genetic algorithm and the finite element simulation method to design the quasi-zero stiffness curved beam structure so that it exhibits quasi-zero stiffness under the required pressure. According to the design results, based on the relationship between the curved beam material, geometric parameters, and quasi-zero stiffness bearing capacity, adjust the curved beam dimensions to ensure that it can form a lattice material unit cell.

[0043] Step 4: Establish an equivalent sound insulation model of the quasi-zero stiffness lattice material under hydrostatic pressure, calculate the sound insulation performance of the material, and compare it with the expected results. If they are consistent, proceed to the next step; otherwise, repeat Step 2 and subsequent steps.

[0044] Step 5: Process the cylindrical pressure-resistant sound insulation material designed in Step 4 and applicable to the standing wave tube, measure the sound insulation performance of the material under the target hydrostatic pressure, and verify the pressure-resistant sound insulation performance of the material.

[0045] Example 1

[0046] As Figures 1-4 shown, a design method for an underwater pressure-resistant wide low-frequency sound insulation material provided by the present invention includes the following steps:

[0047] Step 1: Establish a pressure-resistant and sound-insulating material model. The dot-matrix material designed in the present invention is composed of upper and lower panels and intermediate quasi-zero stiffness curved beams. Different arrangements of the curved beams result in different pressure-resistant and sound-insulating materials. Since the structural pressure resistance is mainly borne by the curved beams, the load-bearing performance of the material with a high density of curved beams is relatively stronger. The example will be described with Figure 1 the (b) pyramid material in p . It should be noted that in order to facilitate observing the internal curved beam structure and distribution of the material, the upper panel in the schematic diagram is made transparent. The characteristic dimensions of the lattice structure include the thickness h of the upper and lower panels b , the height d of the curved beam, the side length L of the unit cell, and the cross-sectional area w of the curved beam b ×h

[0048] . In the pyramid lattice, 4 curved beams intersect at a point and are connected to the panel.

[0049] Step 2: Calculate the constraint conditions of the quasi-zero stiffness curved beam according to the pressure-resistant and sound-insulating requirements. First, taking the sound-insulating performance as the goal and based on the double-panel cavity structure, initially calculate the required compression thickness of the material, and then determine the height of the curved beam after compression. Multiply it by the deformation coefficient to obtain the height d of the curved beam; calculate the bearing capacity according to the side length L of the structural unit cell, and take 1 / 4 as the external force borne by a single curved beam, that is, the acting force in the quasi-zero stiffness state. Thus, the design range of the quasi-zero stiffness curved beam and the acting force it receives are obtained according to the pressure-resistant and sound-insulating requirements. Figure 2 As shown. It should be pointed out that if the force-displacement curve of the optimization result shows a negative slope, that is, the curved beam exhibits negative stiffness, then this result should be discarded. If the optimization results do not meet the target, return to Step 2 to adjust the deformation coefficient of the curved beam and the side length of the unit cell, and change the base material of the curved beam. Assemble the optimized curved beams to form a lattice material, and calculate the force-displacement curve of the material under compression through the finite element simulation software to check its load-bearing performance, as Figure 3 shown.

[0050] Step 4: Calculate the equivalent sound insulation model of the lattice material. Use finite element software to establish the sound insulation model of the material. The background media on both sides of the material is water, and the middle cavity of the material is filled with air. The material deforms under water pressure. Under this condition, a plane wave in water is normally incident on the surface of the material. By calculating the intensity of the transmitted sound wave, the sound insulation performance of the material can be obtained. The schematic diagram of the model and the simulated sound insulation results (under a water pressure of 1 MPa) are as Figure 4 shown. It can be seen from the figure that as the water pressure increases, the sound insulation performance of the material gradually increases and reaches the maximum value at quasi-zero stiffness; its sound insulation efficiency is slightly inferior to that of the double-plate cavity structure because the curved beam is not perfectly zero-stiffness, but its result is much higher than that of the existing sound insulation materials.

[0051] Step 5: Use 3D printing technology to process cylindrical experimental samples, and seal the sides of the samples with flexible rubber. Place the test piece in a standing wave tube and conduct the underwater sound insulation performance test under pressure. If the test results are the same as the trend of the simulation results and the average error is less than 30%, the design of the pressure-resistant sound insulation material is completed; otherwise, repeat Step 2 and subsequent steps.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness, characterized in that, it includes the following steps: Step 1: Establish a first model, which is a quasi-zero stiffness lattice pressure-resistant sound insulation material model. This model is a lattice structure composed of several lattice material unit cells. The lattice material unit cell consists of an upper panel, a lower panel, and a quasi-zero stiffness curved beam in the middle; Step 2: Establish a second model, which is the constraint conditions of the quasi-zero stiffness curved beam calculated according to the first model and the pressure-resistant sound insulation requirements, that is, the geometric design space of the required curved beam and the load and deformation under quasi-zero stiffness; the constraint conditions include a first constraint condition and a second constraint condition. The first constraint condition is to design the quasi-zero stiffness and the height before and after deformation of the curved beam according to the sound insulation and material thickness requirements by the first model; The second constraint condition is to design the side length and bearing performance of the lattice material unit cell according to the pressure resistance requirements; Step 3: Establish a third model, which is a quasi-zero stiffness curved beam structure designed by using the genetic algorithm and the finite element simulation method and combined with the second model. The curved beam structure presents quasi-zero stiffness under the required pressure; According to the third model, based on the relationship between the curved beam material, geometric parameters and quasi-zero stiffness bearing capacity, adjust the curved beam size to obtain the lattice material unit cell; Step 4: Establish a fourth model, which is an equivalent sound insulation model of the quasi-zero stiffness lattice material under hydrostatic pressure established by using the third model and the lattice material unit cell and adopting finite element software. Calculate the sound insulation performance of the material of this model and compare it with the expected result; if they are consistent, enter Step 5, otherwise repeat Steps 2 to 4; Step 5: According to the fourth model, process a cylindrical pressure-resistant sound insulation material suitable for a standing wave tube, and measure the sound insulation performance of the material under the target hydrostatic pressure to verify the pressure-resistant sound insulation performance of the material.

2. The design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 1, characterized in that, in the said Step 1, the lattice material unit cell is of Kagome type, pyramid type or hourglass type. In the pyramid lattice, 4 curved beams meet at a point and are connected to the upper panel.

3. The design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 1, characterized in that, in the calculation of the constraint conditions of the quasi-zero stiffness curved beam in the said Step 2: Taking the sound insulation performance as the goal and based on the double-plate cavity structure, initially calculate the required compression thickness of the material, and then determine the height of the curved beam after compression. Multiply it by the deformation coefficient to obtain the height d of the curved beam; Calculate the bearing capacity according to the side length L of the structural unit cell, and take 1 / 4 as the external force received by a single curved beam, that is, the acting force under the quasi-zero stiffness state; Thus, the design range and the external force received by the quasi-zero stiffness curved beam are obtained according to the pressure-resistant sound insulation requirements.

4. The design method for an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 1, characterized in that, in the said Step 3, associate Matlab with the finite element simulation software, use the genetic algorithm to design the size of the curved beam, and input it into the finite element simulation software to calculate its force-displacement curve and perform simulation optimization.

5. The design method of an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 4, characterized in that, in the third step, during the simulation optimization process, the optimization variables include the spline curve control point coordinates, characteristic weights, and cross-sectional area of the curved beam, and the constraint conditions are the deformation height and acting force under quasi-zero stiffness, that is, the second model obtained in the second step. The optimization goal is the deviation degree between the actual deformation and the corresponding acting force in the quasi-zero stiffness state and the required pressure-resistant performance.

6. The design method of an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 5, characterized in that, in the third step, when the force-displacement curve of the simulation optimization result shows a negative slope, that is, the curved beam exhibits negative stiffness, then this result should be discarded; when the optimization results do not meet the goals, return to the second step to adjust the curved beam deformation coefficient and the unit cell side length, and change the base material of the curved beam; assemble the optimized curved beams to form a lattice material, and calculate the force-displacement curve of the material under compression through a finite element simulation software to check its load-bearing performance.

7. The design method of an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 1, characterized in that, in the fourth step, when establishing the fourth model using finite element software, the background media on both sides of the material is water, and the middle cavity of the material is air; the material deforms under water pressure, and under this condition, a plane wave in water is normally incident on the material surface; by calculating the transmitted sound wave intensity, the sound insulation performance of the material is obtained.

8. The design method of an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 1, characterized in that, in the fifth step, a cylindrical pressure-resistant sound insulation material experimental sample is processed using 3D printing technology, and the side of the sample is sealed with flexible rubber.

9. The design method of an underwater pressure-resistant wide low-frequency sound insulation material based on quasi-zero stiffness according to claim 1 or 8, characterized in that, in the fifth step, the processed cylindrical pressure-resistant sound insulation material is placed in a standing wave tube to conduct a pressurized underwater sound insulation performance test; if the test result has the same trend as the simulation result and the average error is less than 30%, then the design of the pressure-resistant sound insulation material is completed; otherwise, repeat steps two to five.

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