Pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS and its design method

Abstract

The present invention relates to the technical field of underwater low-frequency sound insulation superstructures, and discloses a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS and a design method thereof. A two-dimensional cross-section cell is cut along the direction of sound wave incidence on a Gyroid lattice cell model to obtain a two-dimensional cross-section cell. Low impedance is achieved by utilizing the characteristic that the modulus in the direction of sound wave incidence is reduced and easily deformed. The internal structural distribution of the cell is changed by stretching, so that the cell has anisotropy, the modulus of the cell in the direction of sound wave incidence is reduced, and the impedance is further reduced. A deflection angle of the material principal axis is introduced to excite quasi-longitudinal waves and quasi-transverse waves inside the structure, and longitudinal waves incident in water are converted into transverse waves in the structure through longitudinal-transverse wave conversion, thereby improving sound insulation performance. The structure is arranged in a periodic array, and a core layer configuration in a two-dimensional plane is cut from the core layer, and the structure is materialized to obtain a sound insulation layer. Cover plates are covered on both sides of the sound insulation layer to obtain a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater low-frequency sound-isolating superstructures, and in particular, to a design method for a pressure-resistant underwater low-frequency sound-isolating superstructure based on a TPMS. Furthermore, the present invention also relates to a pressure-resistant underwater low-frequency sound-isolating superstructure based on a TPMS that incorporates the aforementioned design method. Background Art

[0002] The acoustic stealth performance of underwater equipment is one of the key factors affecting its concealment and survivability. In order to suppress the radiation noise of the equipment and improve its acoustic stealth performance, sound insulation materials are usually laid on its surface. At present, the sound insulation mechanisms of sound insulation materials mainly include the following two types: (1) damping dissipation sound insulation, that is, through the vibration damping or sound wave scattering effect inside the material, the sound wave energy is dissipated and the sound waves radiated outward are reduced; (2) impedance mismatch sound insulation, that is, by designing the acoustic structure, the internal noise of the equipment is strongly reflected on the surface of the sound insulation material, thereby reducing the energy of the transmitted sound waves. In underwater environments, low impedance structures are usually used to achieve impedance mismatch with the water medium to improve the sound insulation effect.

[0003] Existing sound insulation structures mainly include cavity structures embedded in rubber and mesh lattice structures. However, these structures have certain limitations in practical applications:

[0004] 1. Due to the existence of internal cavities, the rubber cavity structure has poor pressure resistance and is difficult to adapt to deepwater high-pressure environments;

[0005] 2. The mesh lattice structure has a cross-sectional mutation at the connection between the rods, which is prone to stress concentration effect. It may cause premature failure under high hydrostatic pressure conditions, affecting the stability and service life of the structure.

[0006] Furthermore, the current design of sound insulation structures primarily relies on topology optimization methods. However, the mechanical behavior of lattice structures exhibits significant nonlinear characteristics, and their performance is influenced by multiple factors, including cellular configuration, internal deformation patterns, and failure mechanisms. This makes it difficult to accurately predict and optimize using traditional parametric design. Therefore, relying solely on individual design parameters for topology optimization often fails to achieve an ideal structure with both excellent mechanical and sound insulation properties. Summary of the Invention

[0007] This invention provides a TPMS-based pressure-resistant underwater low-frequency sound-isolating metastructure and its design method. Starting from the quasi-static impedance mismatch mechanism, this design employs a low-impedance (much lower than the impedance of water) sound-isolating structure. Based on a three-periodic minimal surface (TPMS) structure, cross-section design, cellular stretching design, and material principal axis deflection angle design are introduced. Through parameter optimization, a pressure-resistant underwater low-frequency sound-isolating metamaterial is designed. Leveraging its unique geometric characteristics and excellent mechanical properties, this metamaterial exhibits excellent pressure resistance in deepwater, high-pressure environments and can withstand high hydrostatic pressures. It also effectively blocks low-frequency (200Hz-3500Hz) underwater acoustic waves, meeting the requirements of underwater equipment acoustic stealth technology. This approach addresses the technical issue of existing sound-isolating structures, which struggle to achieve an ideal structure with both excellent mechanical and sound-isolating properties.

[0008] According to one aspect of the present invention, a design method for a pressure-resistant underwater low-frequency sound-isolating superstructure based on a TPMS is provided, comprising the following steps: S100, establishing a Gyroid lattice cell model in the TPMS; S200, intercepting and obtaining a two-dimensional cross-sectional cell along the direction of sound wave incidence on the Gyroid lattice cell model, utilizing the characteristic that the two-dimensional cross-sectional cell has a reduced modulus and is easily deformed in the direction of sound wave incidence to reduce the sound wave velocity inside the two-dimensional cross-sectional cell, thereby achieving low impedance; S300, performing a cell stretching design on the two-dimensional cross-sectional cell, changing the internal structural distribution of the cell by stretching, so that the cell has anisotropy. The modulus of the cell in the direction of sound wave incidence is reduced to further reduce the impedance; S400, the principal axis angle design of the deflected cellular material is used to excite quasi-longitudinal waves and quasi-transverse waves inside the structure by changing the stiffness distribution of the cell, and the incident longitudinal waves in the water are converted into transverse waves in the structure through longitudinal-transverse wave conversion, thereby improving the sound insulation performance; S500, the two-dimensional cross-sectional cells after the principal axis angle of the deflected cellular material are arranged in a periodic array, from which the core layer configuration under the two-dimensional plane is obtained, and the structure is solidified by stretching to obtain a sound insulation layer; S600, the sound insulation layer is covered with cover plates on both sides, and the two cover plates are arranged in parallel to obtain a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS.

[0009] Furthermore, step S100 establishes a Gyroid lattice cell model in the TPMS, specifically: establishing a Gyroid lattice cell model in the TPMS, where the lattice is defined by the following implicit function:

[0010] (1)

[0011] (2)

[0012] in, , , , Lx, Ly, and Lz are lattice constants, corresponding to the side lengths in the x-axis direction, the y-axis direction, and the z-axis direction of the cell, respectively; is the lattice wall thickness, and C is the surface offset.

[0013] Furthermore, step S200 is specifically as follows: a cell section on the xy plane is intercepted along the z-axis direction of the cell, and the interception position is defined as , parameter a determines the interception position, and the range of parameter a is determined according to the actual cell configuration. The principle of range determination follows that the cell structure after interception must be continuous and there are no isolated islands. After interception design, a two-dimensional cross-section cell with periodic continuity in the x-axis and y-axis directions is obtained; or a cell cross-section on the yz plane is intercepted along the x-axis direction of the cell, and the interception position is defined as , parameter a determines the interception position, and the range of parameter a is determined according to the actual cell configuration. The principle of range determination follows that the cell structure after interception must be continuous and there are no isolated islands. After interception design, a two-dimensional cross-section cell with periodic continuity in the y-axis and z-axis directions is obtained; or a cell cross-section on the xz plane is intercepted along the y-axis direction of the cell, and the interception position is defined as , parameter a determines the interception position, and the range of parameter a is determined according to the actual cell configuration. The principle of range determination must be to ensure that the cell structure after interception is continuous and there are no isolated islands. After the interception design, a two-dimensional cross-section cell with periodic continuity in the x-axis and z-axis directions is obtained.

[0014] Furthermore, step S300 performs a cell stretching design on the two-dimensional cross-section cell, specifically: after intercepting the design, a two-dimensional cross-section cell with periodic continuity in the x-axis and y-axis directions is obtained, and the cell size Lx in the x-axis direction is kept unchanged. By defining the stretching parameter b, b is the ratio of the size in the x-axis direction to the size in the y-axis direction, that is, the size in the y-axis direction after stretching is , thereby changing the size in the y-axis direction, the stretched cell still maintains continuity in the two periodic directions of the x-axis and y-axis; or after intercepting the design, a two-dimensional cross-section cell with periodic continuity in the y-axis and z-axis directions is obtained, keeping the cell size Ly in the y-axis direction unchanged, by defining the stretching parameter b, b is the ratio of the size in the y-axis to the size in the z-axis direction, that is, the size in the z-axis direction after stretching is , thereby changing the size in the z-axis direction, the stretched cell still maintains continuity in the two periodic directions of the y-axis and the z-axis; or after intercepting the design, a two-dimensional cross-section cell with periodic continuity in the z-axis and x-axis directions is obtained, keeping the cell size Lz in the z-axis direction unchanged, by defining the stretching parameter b, b is the ratio of the size in the z-axis to the size in the x-axis direction, that is, the size in the x-axis direction after stretching is , thereby changing the size in the x-axis direction, and the stretched cells still maintain continuity in the two periodic directions of the z-axis and x-axis.

[0015] Furthermore, step S400 deflects the principal axis angle of the cellular material to design the cellular configuration in a new local coordinate system by deflecting the principal axis angle of the cellular material in the global coordinate system. The deflection angle is defined as ; When the two-dimensional cross-section cell is in the coordinate system , by deflecting the global coordinate system The principal axis angle of the cellular material under the The cellular configuration under the deflection angle is defined as , ranging from 0° to 90°; or when the two-dimensional cross-section cell is in the coordinate system , by deflecting the global coordinate system The principal axis angle of the cellular material under the The cellular configuration under the deflection angle is defined as , ranging from 0° to 90°; or when the two-dimensional cross-section cell is in the coordinate system , by deflecting the global coordinate system The principal axis angle of the cellular material under the The cellular configuration under the deflection angle is defined as , ranging from 0°-90°.

[0016] Furthermore, step S500 is specifically as follows: the two-dimensional cross-sectional element cells are periodically arrayed along the two axial directions of the plane where the coordinate system is located, and a predetermined area is intercepted; the sound insulation layer configuration in the two-dimensional plane of the sound insulation structure is obtained after interception.

[0017] Furthermore, the structure is solidified by stretching in the direction of the vertical axis of the plane in which it is located, thereby forming a solid sound insulation layer; the stretching distance L is determined according to the area requirement of the actual sound insulation superstructure.

[0018] Furthermore, the specific configuration of the three-dimensional sound insulation cell obtained by materialization further forms a solid sound insulation layer, and the three-dimensional sound insulation cell as a whole presents periodic symmetry.

[0019] Furthermore, the three-dimensional sound insulation cell includes a first profile, a second profile, a third profile, a fourth profile, a fifth profile, a sixth profile, a seventh profile, and an eighth profile; the first profile and the second profile are in the same plane, the fifth profile and the fourth profile are in the same plane, the first profile and the fifth profile are periodically symmetrical, and the second profile and the fourth profile are periodically symmetrical; the third profile is perpendicular to and intersects with the second profile, and the third profile and the sixth profile are periodically symmetrical; the seventh profile is perpendicular to the third profile, the fourth profile, the fifth profile, and the sixth profile, respectively, and the seventh profile and the eighth profile have the same shape and are in a parallel positional relationship; the width of the first profile is a2, and the distance between one side of the first profile and the sixth profile is a1; the width of the second profile is a4, and the distance between one side of the second profile and the first profile is a3; the width of the third profile is a5, and the distance between one side of the third profile and the fourth profile is a6.

[0020] According to another aspect of the present invention, a TPMS-based pressure-resistant underwater low-frequency sound-insulating superstructure is provided, which is obtained by adopting the above-mentioned design method of the TPMS-based pressure-resistant underwater low-frequency sound-insulating superstructure.

[0021] The present invention has the following beneficial effects:

[0022] 1. Low impedance characteristics enhance the sound insulation effect. By cutting the two-dimensional cross-section of the Gyroid lattice cell and taking advantage of its reduced modulus in the direction of sound wave incidence, the structure is easily deformed, reducing the speed of sound wave propagation, forming an impedance mismatch, thereby reducing sound wave transmission and improving sound insulation performance. Further, through cell stretching design, the internal structure distribution is adjusted, the anisotropy is enhanced, the equivalent modulus in the direction of sound wave incidence is further reduced, the impedance matching is optimized, and the reflection and attenuation of low-frequency sound waves are enhanced.

[0023] 2. Longitudinal-to-transverse wave conversion improves sound insulation efficiency. By deflecting the principal axis angles of the cellular material, the stiffness distribution is altered, and quasi-longitudinal and quasi-transverse waves are excited within the structure, converting incident longitudinal waves in the water into transverse waves. Because transverse waves are difficult to propagate in water, this conversion mechanism effectively improves the sound insulation layer's ability to dissipate sound energy, enhancing low-frequency sound insulation.

[0024] 3. Structural pressure resistance is optimized. The TPMS structure itself has high specific strength and good mechanical stability. Combined with the tensile solidification design, the sound insulation layer has high pressure resistance while maintaining lightweight, adapting to deep-water high-pressure environments.

[0025] 4. The low-frequency sound insulation performance is optimized. Through periodic array arrangement and core layer configuration design, the structure forms an effective sound wave blocking mechanism in the low-frequency range of 200Hz-3500Hz, meeting the needs of underwater equipment for low-frequency noise suppression.

[0026] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 1 is a schematic diagram of the overall structure of the TPMS underwater sound insulation superstructure according to a preferred embodiment of the present invention;

[0029] Figure 2 This is a schematic structural diagram of a rectangular cover structure according to a preferred embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the design process of the TPMS underwater sound insulation superstructure according to the preferred embodiment of the present invention. Figure 3 (1) is a schematic diagram of a Gyroid cell. Figure 3 (2) is the cross-section design diagram, Figure 3 (3) is a schematic diagram of a cross-section cell. Figure 3 (4) is a schematic diagram of the stretching design. Figure 3 (5) is the schematic diagram of the material principal axis deflection angle design, Figure 3 (6) is a schematic diagram of the array. Figure 3 (7) is a schematic diagram of the sound insulation layer area. Figure 3 (8) is a schematic diagram of the sound insulation layer. Figure 3 (9) A schematic diagram of the cover plate;

[0031] Figure 4 2 is a schematic structural diagram of a three-dimensional cell of a sound insulation structure according to a preferred embodiment of the present invention;

[0032] Figure 5 1 is a schematic structural diagram of a hexagonal honeycomb underwater sound insulation superstructure for comparison according to a preferred embodiment of the present invention;

[0033] Figure 6 3. This is a comparison chart of the sound insulation coefficients of the TPMS underwater sound insulation superstructure and the hexagonal honeycomb underwater sound insulation superstructure in the frequency range of 200Hz-3500Hz in a simulation example of a preferred embodiment of the present invention;

[0034] Figure 7 This is a comparison diagram of stress-strain curves in uniaxial compression simulation of a TPMS underwater sound insulation superstructure and a hexagonal honeycomb underwater sound insulation superstructure in a simulation example of a preferred embodiment of the present invention.

[0035] Legend:

[0036] 10. Cover plate; 20. Sound insulation layer; 301. First profile; 302. Second profile; 303. Third profile; 304. Fourth profile; 305. Fifth profile; 306. Sixth profile; 307. Seventh profile; 308. Eighth profile. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0038] Figure 1 1 is a schematic diagram of the overall structure of the TPMS underwater sound insulation superstructure according to a preferred embodiment of the present invention; Figure 2 This is a schematic structural diagram of a rectangular cover structure according to a preferred embodiment of the present invention; Figure 3 1. It is a schematic diagram of the design process of the TPMS underwater sound insulation superstructure according to the preferred embodiment of the present invention; Figure 4 2 is a schematic structural diagram of a three-dimensional cell of a sound insulation structure according to a preferred embodiment of the present invention; Figure 5 1 is a schematic structural diagram of a hexagonal honeycomb underwater sound insulation superstructure for comparison according to a preferred embodiment of the present invention; Figure 6 3. This is a comparison chart of the sound insulation coefficients of the TPMS underwater sound insulation superstructure and the hexagonal honeycomb underwater sound insulation superstructure in the frequency range of 200Hz-3500Hz in a simulation example of a preferred embodiment of the present invention; Figure 7 This is a comparison diagram of stress-strain curves in uniaxial compression simulation of a TPMS underwater sound insulation superstructure and a hexagonal honeycomb underwater sound insulation superstructure in a simulation example of a preferred embodiment of the present invention.

[0039] like Figure 1 、 Figure 2 and Figure 3As shown, the design method of the pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS of this embodiment includes the following steps: S100, establishing a Gyroid lattice cell model in the TPMS; S200, intercepting and obtaining a two-dimensional cross-section cell along the sound wave incident direction on the Gyroid lattice cell model, utilizing the characteristic that the modulus of the two-dimensional cross-section cell is reduced and it is easy to deform in the sound wave incident direction, so as to reduce the sound wave velocity inside the two-dimensional cross-section cell, thereby achieving low impedance; S300, performing cell stretching design on the two-dimensional cross-section cell, changing the internal structure distribution of the cell by stretching, so that the cell has anisotropy, and reducing the cell's deformation when the sound wave enters. The modulus in the radiation direction is increased to further reduce the impedance; S400, the principal axis angle of the deflected cellular material is designed to excite quasi-longitudinal waves and quasi-transverse waves inside the structure by changing the stiffness distribution of the cells, and the incident longitudinal waves in the water are converted into transverse waves in the structure through longitudinal-transverse wave conversion, thereby improving the sound insulation performance; S500, the two-dimensional cross-sectional cells after the principal axis angle of the deflected cellular material are arranged in a periodic array, from which the core layer configuration in the two-dimensional plane is obtained, and the structure is solidified by stretching to obtain the sound insulation layer 20; S600, the sound insulation layer 20 is covered with cover plates 10 on both sides, and the two cover plates 10 are arranged in parallel to obtain a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS.The present invention discloses a design method for a pressure-resistant underwater low-frequency sound-insulating superstructure based on TPMS. A pressure-resistant underwater low-frequency sound-insulating superstructure is designed based on the TPMS (three-periodic minimal surface) structure. Excellent sound insulation performance and pressure resistance are achieved through specific geometric configuration optimization and mechanical regulation. By intercepting the two-dimensional cross-section of the Gyroid lattice cell and utilizing its characteristic of reduced modulus in the direction of sound wave incidence, the structure is made easy to deform, the sound wave propagation speed is reduced, and impedance mismatch is formed, thereby reducing sound wave transmission and improving sound insulation performance. Further, through cell stretching design, the internal structure distribution is adjusted, the anisotropy is enhanced, the equivalent modulus in the direction of sound wave incidence is further reduced, the impedance matching is optimized, and the reflection and attenuation of low-frequency sound waves are enhanced. By deflecting the principal axis angle of the cell material, the stiffness distribution is changed, and the quasi-longitudinal waves and quasi-transverse waves inside the structure are excited, so that the longitudinal waves incident in the water are converted into transverse waves in the structure. Since transverse waves are difficult to propagate in water, this conversion mechanism effectively improves the sound insulation layer. Energy dissipation capacity, enhancing low-frequency sound insulation effect; the TPMS structure itself has high specific strength and good mechanical stability. Combined with the tensile solidification design, the sound insulation layer maintains lightweight while having high compressive resistance, adapting to deep-water high-pressure environments. Compared with traditional rubber cavity or mesh lattice structures, the solution of the present invention avoids the problem of premature failure caused by cavity collapse or stress concentration, and improves the reliability of the structure under water pressure loads; through periodic array arrangement and core layer configuration optimization, the stress concentration problem existing in traditional sound insulation structures is avoided, and the stability of the structure in high hydrostatic pressure environments is enhanced; through periodic array arrangement and core layer configuration design, the structure forms an effective sound wave blocking mechanism in the low-frequency range of 200Hz-3500Hz, meeting the requirements of underwater equipment for low-frequency noise suppression; in terms of material selection and structural optimization, the synergistic improvement of sound insulation performance and mechanical properties is achieved, solving the technical contradictions of traditional sound insulation structures in terms of pressure resistance and low-frequency sound insulation effect. Through geometric optimization and mechanical control of the TPMS structure, the combined effects of low impedance, longitudinal-to-transverse wave conversion, enhanced pressure resistance and improved low-frequency sound insulation performance are achieved, providing an efficient and reliable solution for the acoustic stealth technology of underwater equipment with both excellent low-frequency sound insulation performance and pressure resistance.

[0040] In practice, a TPMS underwater sound insulation superstructure is provided, comprising two cover plates 10 and a sound insulation layer 20 (such as Figure 1 shown);

[0041] The two cover plates 10 are parallel to each other, and the sound insulation layer 20 is composed of m×n sound insulation cells arranged in an array periodically, wherein m≥1, n≥1;

[0042] The design process of the sound insulation cell is as follows:

[0043] 1. Establish the Gyroid lattice cell model in TPMS. The lattice is defined by the following implicit function:

[0044] (1)

[0045] (2)

[0046] in, , , , Lx, Ly, and Lz are lattice constants, corresponding to the side lengths in the x-axis direction, the y-axis direction, and the z-axis direction of the cell, respectively. is the cell wall thickness, C is the surface offset. The Gyroid cell model is obtained by implicit function modeling (such as Figure 3 (1)); The main reason for choosing Gyroid cells as the design basis is that Gyroid cells have been confirmed in a large number of studies to have the mechanical property of high energy absorption. This is due to its internal continuous and smoothly transitioned curved surface structure, which greatly reduces the stress concentration effect and improves the strength of the structure. Therefore, the subsequent sound insulation structure design based on Gyroid cells can fully utilize the excellent mechanical properties of the Gyroid cell structure, making the designed sound insulation structure pressure-resistant.

[0047] 2. Design the cross section of the cell obtained in step 1 (e.g. Figure 3 (2)). A cell section on the xy plane is intercepted along the z-axis of the cell, and the interception position is defined as , parameter a determines the interception position. The range of parameter a is determined according to the actual cellular configuration. The principle of range determination is to ensure that the cellular structure after interception is continuous and there are no isolated islands. Figure 3 As shown in (3), after the interception design, a two-dimensional cross-sectional cell with periodic continuity in the x-axis and y-axis directions can be obtained. The cross-sectional design in the present invention is not limited to interception along the z-axis direction, and interception along the x-axis and y-axis directions is also within the scope of the present invention. The design principle of this step is: the three-dimensional configuration cell does not have the conditions to achieve low impedance. Through calculation, it is found that its structural impedance is not much different from that of water, and it is difficult to achieve efficient underwater sound insulation through impedance mismatch. Therefore, a two-dimensional cross-sectional cell is obtained through cross-sectional design based on the Gyroid three-dimensional cell. The cross-sectional design introduces an easy deformation mode for the cell along the direction of sound wave incidence (this direction is defined as the positive direction of the x-axis), that is, the modulus of the cell in the direction of sound wave incidence is reduced, and it is easy to deform. This feature can reduce the speed of sound waves inside the cell, thereby achieving low impedance, laying the foundation for the subsequent design of low-impedance sound insulation structures.

[0048] 3. Perform cell stretching design on the two-dimensional cell obtained in step 2. Cell stretching design means changing the size ratio of the cell in the horizontal and vertical directions, specifically by maintaining the cell size in the x-axis direction. By defining the stretching parameter b (the ratio of the dimensions in the x-axis to the y-axis directions), the dimension in the y-axis direction after stretching is , thereby changing the size in the y-axis direction. Figure 3 As shown in (4), a rectangular cellular structure is obtained by stretching the design. After stretching, the cell still maintains continuity in the two periodic directions. The principle of this step is to change the internal structure distribution of the cell by stretching, making the cell anisotropic, reducing the modulus of the cell in the x-axis direction, and further reducing the impedance.

[0049] 4. Design the principal axis angle of the deflection material for the cell obtained by stretching design. Figure 3 As shown in (5), the principal axis angle design of the deflected cellular material is achieved by deflecting the global coordinate system counterclockwise. The principal axis angle of the cellular material under , and obtain a new local coordinate system The principle of this step is to change the stiffness distribution of the cells, excite quasi-longitudinal and quasi-transverse waves within the structure, and convert incident longitudinal waves in water into transverse waves within the structure through longitudinal-transverse wave conversion, thereby improving sound insulation performance (transverse waves cannot propagate in liquids). Another important function of deflecting the principal axis angle of the material is to increase the modulus of the structure in the direction of sound wave incidence, thereby improving pressure resistance.

[0050] 5. Extend the cell obtained in step 4 axis, Axis carries out periodic array ( Figure 3 (6)), and intercept a length × width The rectangular area. Since the structure is obtained by periodic array, the interception position does not affect the sound insulation performance of the structure in theory, so the interception position is not required. The sound insulation layer configuration in the two-dimensional plane of the sound insulation structure is obtained after interception ( Figure 3 (7)). Further, Figure 3 As shown in (8), the structure is solidified by stretching along the z-axis to form a solid sound insulation layer structure. The stretching distance L can be determined according to the area requirement of the actual sound insulation superstructure. This step is mainly to form a real sound insulation structure.

[0051] The specific configuration of the three-dimensional sound insulation cell obtained by materialization is as follows: Figure 4As shown in the figure, the cell exhibits periodic symmetry as a whole. The first and second surfaces 301 and 302 are coplanar, and the fifth and fourth surfaces 305 and 304 are coplanar. The first and fifth surfaces 301 and 305 are periodically symmetrical, and the second and fourth surfaces 302 and 304 are periodically symmetrical. The third surface 303 is perpendicular to and intersects with the second surface 302 and is periodically symmetrical with the sixth surface 306. The seventh surface 307 is perpendicular to the third, fourth, fifth, and sixth surfaces 303 and 306, and is of the same shape as the eighth surface 308, with the two surfaces being parallel to each other. The first surface 301 has a width a2, and a distance a1 from one side to the sixth surface 306. The second surface 302 has a width a4, and a distance a3 from one side of the second surface 302 to the first surface 301. The third surface 303 has a width a5, and a distance a6 from one side to the fourth surface 304.

[0052] The sound insulation layer 20 of the structure can be obtained through the design process of steps 1 to 5.

[0053] like Figure 3 As shown in (9), a cover plate 10 is provided on both sides of the sound insulation layer 20. The cover plate is a rectangular plate structure, and its length and width are consistent with the W and L dimensions of the sound insulation layer 20. The thickness of the cover plate 10 is The cover plate 10 is connected to the sound insulation layer 20 to form the final sound insulation superstructure.

[0054] Finally, the parameters: cell wall thickness , interception position a, cell stretching parameter b, material principal axis deflection angle , the thickness of the sound insulation layer h2, the thickness of the cover plate h1 and the pressure resistance (modulus in the direction of sound wave incidence) are used as design variables, and the differential evolution algorithm is used for optimization to obtain the optimal result within the ideal frequency range.

[0055] The cover plate 10 and the sound insulation layer 20 are made of metal or non-metal materials, and the physical parameters of the materials are:

[0056] The elastic modulus E range satisfies 0.1GPa≤E≤220GPa, the Poisson's ratio η range satisfies 0.2≤η≤0.5, and the density ρ range satisfies 800kg / m³≤ρ≤12000kg / m³.

[0057] This TPMS-based, pressure-resistant underwater low-frequency sound-isolating superstructure is designed based on the quasi-static impedance mismatch mechanism and the TPMS structure through configuration changes, parameter adjustments, and parameter optimization. It effectively blocks low-frequency sound insulation issues in the 200Hz-3500Hz range. The smooth transitions within the superstructure reduce stress concentration effects, resulting in excellent mechanical performance under external pressure. It can withstand 3MPa water pressure and achieves low-frequency sound insulation performance for sound waves between 200Hz and 3500Hz. It can be applied to noise control in underwater equipment and other fields, and has promising engineering applications.

[0058] Example 1:

[0059] like Figure 1-Figure 2 The following figure shows a TPMS low-frequency, pressure-resistant, underwater sound-isolating superstructure disclosed in this embodiment. Specifically, the superstructure includes two cover plates 10 and a sound-isolating layer 20 located between the two cover plates 10. The two cover plates 10 are parallel to each other, and the sound-isolating layer 20 is composed of m×n sound-isolating components arranged in a periodic array, where m ≥ 1 and n ≥ 1. The sound-isolating cell design process is as follows:

[0060] 1. Establish the Gyroid lattice cell model in TPMS. The lattice is defined by the following implicit function:

[0061] (1)

[0062] (2)

[0063] in, , , , Lx, Ly, and Lz are lattice constants, corresponding to the side lengths in the x-axis direction, the y-axis direction, and the z-axis direction of the cell, respectively. is the lattice wall thickness, and C is the surface offset.

[0064] In this embodiment, C is not used as a design variable, so it is set .

[0065] Other parameter settings: , .

[0066] By using the commercial mathematical programming software MATLAB for implicit function modeling, a square gyroid cell with a size of 14 mm × 14 mm × 14 mm can be obtained.

[0067] It should be noted that the cell size can be adjusted as needed. In this embodiment, 14 mm is selected considering the size of the overall sound insulation structure. If it is too large, the number of cells in the sound insulation layer will be insufficient, affecting the sound insulation performance. If it is too small, it will affect subsequent processing and manufacturing.

[0068] 2. Design the cross section of the cell obtained in step 1. In this embodiment, a cross section of the cell on the xy plane is cut along the z-axis direction, and the cut position is defined as , parameter a determines the interception position.

[0069] The range of parameter a is determined according to the actual cellular configuration. The principle of range determination is to ensure that the cellular structure after interception is continuous and there are no isolated islands. In this embodiment, it is defined as .

[0070] In this embodiment, it is set to .

[0071] After the interception design, a two-dimensional cross-section cell with periodic continuity in the x-axis and y-axis directions can be obtained.

[0072] The cross-section design in the present invention is not limited to interception along the z-axis direction, and interception along the x-axis and y-axis directions is also within the scope of the present invention.

[0073] 3. Perform cell stretching design on the two-dimensional cell obtained in step 2.

[0074] Cell stretching design changes the size ratio of the cell in the horizontal and vertical directions by maintaining the cell size in the x-axis direction. By defining the stretching parameter b (the ratio of the dimensions in the x-axis to the y-axis directions), the dimension in the y-axis direction after stretching is , thereby changing the size in the y-axis direction. In this embodiment, the x-axis direction is kept The size remains unchanged and the stretching parameter is defined as , that is, the size in the y-axis direction after stretching is A rectangular cellular structure is obtained through stretching design, and the stretched cells still maintain continuity in two periodic directions.

[0075] 4. Design the principal axis angle of the deflected material for the cell obtained in step 3. The principal axis angle design of the deflected cell material is to deflect the global coordinate system. The principal axis angle of the cellular material under the The cellular configuration under the deflection angle is defined as , the range is In this embodiment, it is defined .

[0076] 5. Extend the cell obtained in step 3 axis, Axis to periodic array, and intercept a long ,Width Since the structure is obtained by periodic array, the interception position does not affect the sound insulation performance of the structure in theory, so the interception position is not required. The core layer configuration in the two-dimensional plane of the sound insulation structure is obtained after interception. Further, a solid core layer structure is formed by stretching along the z-axis direction. The stretching distance L can be determined according to actual needs. In this embodiment, it is defined as .

[0077] The three-dimensional sound insulation cell obtained through materialization exhibits periodic symmetry overall. The first and second surfaces 301 and 302 are coplanar, and the fifth and fourth surfaces 305 and 304 are coplanar. The first and fifth surfaces 301 and 305 are periodically symmetrical, and the second and fourth surfaces 302 and 304 are periodically symmetrical. The third surface 303 is perpendicular to and intersects the second surface 302, and is periodically symmetrical with the sixth surface 306. The seventh surface 307 is perpendicular to the third, fourth, fifth, and sixth surfaces 303 and 306, and is identical in shape to the eighth surface 308, with the two surfaces being parallel. The first surface 301 has a width a2 = 2.8 mm, and a distance a1 = 5.9 mm from one side to the sixth surface 306. The second surface 302 has a width a4 = 2.7 mm, and a distance a3 = 6.1 mm from one side to the first surface 301. The width of the third profile 303 is a5=5.5 mm, and the distance between one side and the fourth profile 304 is a6=5.6 mm.

[0078] The sound insulation layer 20 of the structure can be obtained through the design process of steps 1 to 5.

[0079] 6. The first and second profiles 301 and 302 of the sound insulation layer 20 are respectively provided with a cover plate 10. The cover plate 10 is a rectangular plate structure, and its length and width are consistent with the W and L dimensions of the sound insulation layer 20. The thickness of the cover plate 10 is The cover plate 10 and the sound insulation layer 20 are connected to form the final sound insulation metamaterial.

[0080] In this embodiment, the cover plate 10 and the sound insulation layer 20 are made of a metal material or a non-metallic material. The metal material may be aluminum, carbon steel, alloy steel, or the like. The non-metallic material may be nylon, ABS, or the like. The physical parameters of the materials are as follows: an elastic modulus E in the range of 0.1 GPa ≤ E ≤ 220 GPa, a Poisson's ratio ν in the range of 0.2 ≤ ν ≤ 0.5, and a density ρ in the range of 800 kg / m³ ≤ ρ ≤ 12000 kg / m³.

[0081] In this embodiment, the cover plate 10 and the sound insulation layer 20 can be integrally printed and manufactured using 3D printing technology, or can be manufactured using machining methods such as wire-cut electric discharge machining.

[0082] The following is a simulation example of the low-frequency pressure-resistant underwater sound insulation metamaterial in this embodiment. Figure 5 The TPMS low-frequency pressure-resistant underwater sound insulation superstructure in this embodiment is further explained by comparing it with the hexagonal honeycomb structure sound insulation superstructure in the embodiment.

[0083] In this example, the cover plate 10 and the sound insulation layer 20 are both made of PA6 / 66, a common nylon (polyamide) blend, a mixture of polyamide 6 (PA6) and polyamide 66 (PA66). The material parameters are Young's modulus of 2.6 GPa, Poisson's ratio of 0.35, and density of 1250 kg / m³. The entire structure is produced using 3D printing. The relevant generation parameters of the cell and the overall dimensions of the structure are reflected in the specific implementation steps of the embodiment. Based on the above-mentioned dimensional parameters, a finite element analysis model of the material's sound insulation performance is established, and the sound insulation coefficient is obtained by simulation calculation as follows: Figure 6 shown. Figure 6 The sound insulation coefficients of the hexagonal honeycomb structure sound insulation material and the thin layer low-frequency underwater sound insulation superstructure of this embodiment are compared under the conditions of the same material, overall thickness, equivalent density and modulus. Figure 6 It can be seen that the embodiment of the present invention has an average sound insulation of greater than 11 dB in the frequency range of 200-3500 Hz under the condition of an overall thickness of 45 mm, showing excellent sound insulation effect. Compared with the 9.2 dB of the hexagonal honeycomb sound insulation superstructure, the sound insulation performance of this embodiment is improved to a certain extent.

[0084] In order to demonstrate the pressure resistance performance of the TPMS sound insulation superstructure, a mechanical finite element analysis model was established for the same structure and a uniaxial compression simulation was performed. Figure 7 The stress-strain curves of the TPMS sound insulation superstructure and the hexagonal honeycomb sound insulation superstructure were further compared. Figure 7 It can be seen that although the elastic stage modulus of the two is the same, the TPMS sound insulation superstructure has a higher destructive strength and can withstand a maximum stress of more than 3MPa.

[0085] In summary, the TPMS low-frequency pressure-resistant underwater sound insulation superstructure in this embodiment has the following technical effects:

[0086] 1. Excellent low-frequency sound insulation performance. Compared with the hexagonal honeycomb sound insulation superstructure, the TPMS underwater sound insulation superstructure has an average sound insulation of more than 11dB in the frequency range of 200Hz-3500Hz with an overall thickness of 45mm, achieving high-efficiency low-frequency sound insulation.

[0087] 2. Excellent pressure resistance. The TPMS underwater sound insulation superstructure has excellent pressure resistance due to its internal continuous and smooth transition structural characteristics and good stress distribution characteristics. It can maintain robust sound insulation performance in deep water environments and can withstand 3MPa water pressure.

[0088] 3. The sound insulation material of this embodiment has good structural design. By optimizing and adjusting parameters such as the lattice constant, wall thickness, curved surface offset, cross-sectional position, and material principal axis deflection angle of the sound insulation layer unit cells, as well as the thickness and manufacturing materials of the overall structure, it can meet the sound insulation and mechanical performance requirements of different practical applications.

[0089] Matters not covered by the present invention are known technologies.

[0090] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0092] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A design method for a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS, characterized in that: The following steps are involved: S100, establish the Gyroid lattice cell model in TPMS; S200, intercepting and obtaining a two-dimensional cross-sectional cell along the incident direction of the sound wave on the Gyroid lattice cell model, utilizing the characteristic that the modulus of the two-dimensional cross-sectional cell decreases in the incident direction of the sound wave and is easily deformed, so as to reduce the speed of the sound wave inside the two-dimensional cross-sectional cell, thereby achieving low impedance; S300, performing a cell stretching design on the two-dimensional cross-section cell, changing the internal structure distribution of the cell by stretching, making the cell anisotropic, reducing the modulus of the cell in the direction of the incident sound wave, and further reducing the impedance; S400, the deflection cellular material principal axis angle design, by changing the stiffness distribution of the cellular, excites quasi-longitudinal waves and quasi-transverse waves inside the structure. Through longitudinal-transverse wave conversion, the incident longitudinal waves in the water are converted into transverse waves in the structure, thereby improving the sound insulation performance; S500, after deflecting the principal axis angle of the cellular material, the two-dimensional cross-sectional cells are arranged in a periodic array, from which the core layer configuration under the two-dimensional plane is obtained, and the structure is solidified by stretching, thereby obtaining a sound insulation layer (20); S600, the sound insulation layer (20) is covered with cover plates (10) on both sides, and the two cover plates (10) are arranged in parallel to obtain a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS.

2. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 1 is characterized in that: Step S100 establishes a Gyroid lattice cell model in the TPMS, specifically: The Gyroid lattice cell model in TPMS is established. The lattice is defined by the following implicit function: （1） （2） in, , , , Lx, Ly, and Lz are Lattice constants, corresponding to the cell x Side length in the axial direction, y The length of the side in the axial direction and z Side length in the axial direction; is the lattice wall thickness, and C is the surface offset.

3. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 2 is characterized in that: Step S200 is specifically as follows: A cell section on the xy plane is intercepted along the z-axis of the cell, and the interception position is defined as ,parameter a Determine the interception position and parameters a The range is determined according to the actual cellular configuration. The principle of range determination is to ensure that the cellular structure after interception is continuous and there are no isolated islands. After interception design, a two-dimensional cross-section cell with periodic continuity in the x-axis and y-axis directions is obtained; or A cell section on the yz plane is intercepted along the x-axis direction of the cell, and the interception position is defined as ,parameter a Determine the interception position, parameters a The range is determined according to the actual cellular configuration. The principle of range determination is to ensure that the cellular structure after interception is continuous and there are no isolated islands. After interception design, a two-dimensional cross-section cell with periodic continuity in the y-axis and z-axis directions is obtained; or A cell section on the xz plane is intercepted along the y-axis of the cell, and the interception position is defined as ,parameter a Determine the interception position, parameters a The range is determined according to the actual cellular configuration. The principle of range determination is to ensure that the cellular structure after interception is continuous and there are no isolated islands. After interception design, a two-dimensional cross-section cell with periodic continuity in the x-axis and z-axis directions is obtained.

4. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 2 is characterized in that: Step S300 performs cell stretching design on the two-dimensional cross-section cell, specifically: After the interception design, a two-dimensional cross-section cell with periodic continuity in the x-axis and y-axis directions is obtained, keeping the cell size Lx in the x-axis direction unchanged. By defining the stretching parameter b, b is the ratio of the size in the x-axis to the size in the y-axis direction, that is, the size in the y-axis direction after stretching is , thereby changing the size in the y-axis direction, and the stretched cells still maintain continuity in the two periodic directions of the x-axis and y-axis; or After the design is intercepted, a two-dimensional cross-section cell with periodic continuity in the y-axis and z-axis directions is obtained, and the cell size Ly in the y-axis direction is kept unchanged. By defining the stretching parameter b, b is the ratio of the size in the y-axis to the size in the z-axis direction, that is, the size in the z-axis direction after stretching is , thereby changing the size in the z-axis direction, and the stretched cell still maintains continuity in the two periodic directions of the y-axis and z-axis; or After the design is intercepted, a two-dimensional cross-section cell with periodic continuity in the z-axis and x-axis directions is obtained, keeping the cell size Lz in the z-axis direction unchanged. By defining the stretching parameter b, b is the ratio of the size in the z-axis to the size in the x-axis direction, that is, the size in the x-axis direction after stretching is , thereby changing the size in the x-axis direction, and the stretched cells still maintain continuity in the two periodic directions of the z-axis and x-axis.

5. The design method of a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to any one of claims 2 to 4, characterized in that: Step S400 is to design the principal axis angle of the deflection cellular material, specifically: By deflecting the principal axis angle of the cellular material in the global coordinate system, a cellular configuration in a new local coordinate system is obtained. The deflection angle is defined as ; When the two-dimensional cross-section cell is in the coordinate system , by deflecting the global coordinate system The principal axis angle of the cellular material under the The cellular configuration under the deflection angle is defined as , ranging from 0° to 90°; or When the two-dimensional cross-section cell is in the coordinate system , by deflecting the global coordinate system The principal axis angle of the cellular material under the The cellular configuration under the condition of , ranging from 0° to 90°; or When the two-dimensional cross-section cell is in the coordinate system , by deflecting the global coordinate system The principal axis angle of the cellular material under the The cellular configuration under the deflection angle is defined as , ranging from 0°-90°.

6. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 5 is characterized in that: Step S500 is specifically as follows: The two-dimensional cross-section element cell is periodically arrayed along the two axis directions of the plane where the coordinate system is located, and a predetermined area is intercepted; What is obtained after interception is the configuration of the sound insulation layer in the sound insulation structure in a two-dimensional plane.

7. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 6, characterized in that: The structure is solidified by stretching in a direction perpendicular to the plane in which it is located, thereby forming a solid sound insulation layer (20); The stretching distance L is determined according to the area requirement of the actual sound insulation superstructure.

8. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 7 is characterized in that: The specific configuration of the three-dimensional sound insulation cell obtained by solidification further forms a solid sound insulation layer (20), and the three-dimensional sound insulation cell as a whole presents periodic symmetry.

9. The design method of the TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure according to claim 8, characterized in that: The three-dimensional sound insulation cell includes a first profile (301), a second profile (302), a third profile (303), a fourth profile (304), a fifth profile (305), a sixth profile (306), a seventh profile (307), and an eighth profile (308); The first profile (301) and the second profile (302) are in the same plane, the fifth profile (305) and the fourth profile (304) are in the same plane, the first profile (301) and the fifth profile (305) are periodically symmetrical, and the second profile (302) and the fourth profile (304) are periodically symmetrical; The third profile (303) is perpendicular to and intersects the second profile (302), and the third profile (303) is periodically symmetrical to the sixth profile (306); The seventh profile (307) is perpendicular to the third profile (303), the fourth profile (304), the fifth profile (305), and the sixth profile (306), respectively. The seventh profile (307) and the eighth profile (308) are of the same shape and are in a parallel position relationship. The first profile (301) has a width a2, and a distance a1 between one side of the first profile (301) and the sixth profile (306); The width of the second profile (302) is a4, and the distance between one side of the second profile (302) and the first profile (301) is a3; The width of the third profile (303) is a5, and the distance between one side of the third profile (303) and the fourth profile (304) is a6.

10. A pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS, characterized in that: The method for designing a pressure-resistant underwater low-frequency sound-isolating superstructure based on TPMS is adopted as described in any one of claims 1 to 9.

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