TPMS-based pressure-resistant underwater low-frequency sound insulation superstructure and design method thereof

Abstract

The 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 a TPMS (Tire Pressure Monitor System) and a design method thereof, a two-dimensional section cell is intercepted and obtained on a Gyandroid lattice cell model along a sound wave incidence direction, and the characteristic that the modulus in the sound wave incidence direction is reduced and is easy to deform is utilized, so that the sound insulation performance of the sound insulation superstructure is improved, and the sound insulation performance of the sound insulation superstructure is improved. Low impedance is realized; the internal structure distribution of the cells is changed through stretching, so that the cells have anisotropy, the modulus of the cells in the sound wave incidence direction is reduced, and the impedance is further reduced; by introducing a material main shaft deflection angle, quasi longitudinal waves and quasi transverse waves in the structure are excited, and the longitudinal waves incident in water are converted into transverse waves in the structure through longitudinal-transverse wave conversion, so that the sound insulation performance is improved; performing periodic array arrangement, intercepting to obtain a core layer configuration under a two-dimensional plane, and performing structure materialization to obtain a sound insulation layer; the two sides of the sound insulation layer are covered with cover plates, and the pressure-resistant underwater low-frequency sound insulation superstructure based on the TPMS is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater low-frequency sound insulation superstructures, and in particular, to a design method of a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS. In addition, the present invention also relates to a pressure-resistant underwater low-frequency sound insulation superstructure including the above 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 radiated noise of the equipment and improve the 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: (1) Damping dissipation sound insulation, that is, by the vibration damping or acoustic wave scattering effect inside the material, the acoustic wave energy is dissipated, and the acoustic wave radiated outward is reduced; (2) Impedance mismatch sound insulation, that is, by designing an 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 acoustic wave. In the underwater environment, a low-impedance structure is usually adopted to achieve impedance mismatch with the water medium to improve the sound insulation effect.

[0003] The existing sound insulation structures mainly include a rubber structure with an embedded cavity and a reticular lattice structure. However, these structures have certain limitations in practical applications: 1. Due to the existence of the internal cavity in the rubber cavity structure, its pressure resistance performance is poor, and it is difficult to adapt to the deep water high-pressure environment; 2. There is a cross-section mutation at the connection of the rods in the reticular lattice structure, which is prone to the stress concentration effect and may be damaged in advance under high hydrostatic pressure conditions, affecting the stability and service life of the structure.

[0004] In addition, the current design of sound insulation structures mainly relies on topological optimization methods. However, the mechanical behavior of the lattice structure has significant non-linear characteristics, and its performance is affected by various factors such as the unit cell configuration, internal deformation mode, and failure mechanism, and it is difficult to accurately predict and optimize through traditional parametric design. Therefore, relying solely on individual design indicators for topological optimization often makes it difficult to obtain an ideal structure with both excellent mechanical properties and sound insulation performance. Summary of the Invention

[0005] The present invention provides a pressure-resistant underwater low-frequency sound insulation metamaterial based on TPMS and a design method thereof. Starting from the quasi-static impedance mismatch mechanism, that is, by designing a sound insulation structure with low impedance (much smaller than the impedance of water). Based on the structure of the triply periodic minimal surface (TPMS), cross-section design, unit cell stretching design, and material principal axis deflection angle design are introduced, and a pressure-resistant underwater low-frequency sound insulation metamaterial is designed through parameter optimization. Utilizing its unique geometric characteristics and excellent mechanical properties, it has good pressure resistance in the deep-water high-pressure environment, can withstand high hydrostatic pressure, and at the same time can effectively block low-frequency (200 Hz - 3500 Hz) underwater sound waves to meet the requirements of underwater equipment acoustic stealth technology, so as to solve the technical problem that it is difficult for existing sound insulation structures to obtain an ideal structure with both excellent mechanical properties and sound insulation performance.

[0006] According to one aspect of the present invention, a design method of a pressure-resistant underwater low-frequency sound insulation metamaterial based on TPMS is provided, including the following steps: S100. Establish a Gyroid lattice unit cell model in TPMS; S200. Intercept and obtain a two-dimensional cross-section unit cell on the Gyroid lattice unit cell model along the sound wave incident direction. Utilize the characteristic that the modulus of the two-dimensional cross-section unit cell decreases and it is prone to deformation in the sound wave incident direction to reduce the sound wave velocity inside the two-dimensional cross-section unit cell, thereby realizing low impedance; S300. Perform unit cell stretching design on the two-dimensional cross-section unit cell. By stretching, change the internal structure distribution of the unit cell to make the unit cell anisotropic and reduce the modulus of the unit cell in the sound wave incident direction, further reducing the impedance; S400. Perform deflection of the unit cell material principal axis angle design. By changing the stiffness distribution of the unit cell, excite the quasi-longitudinal wave and quasi-transverse wave inside the structure, and convert the longitudinal wave incident in water into a transverse wave in the structure through longitudinal-transverse wave conversion to improve the sound insulation performance; S500. Arrange the two-dimensional cross-section unit cells after deflecting the unit cell material principal axis angle in a periodic array, intercept a core layer configuration in a two-dimensional plane therefrom, and perform structure solidification through stretching to obtain a sound insulation layer; S600. Cover the two sides of the sound insulation layer with cover plates, and the two cover plates are arranged in parallel to obtain a pressure-resistant underwater low-frequency sound insulation metamaterial based on TPMS.

[0007] Further, step S100 of establishing a Gyroid lattice unit cell model in TPMS is specifically: Establish a Gyroid lattice unit cell model in TPMS, and the lattice is defined by the following implicit function: (1) (2) Among them, is the lattice constant, corresponding to the side length in the x-axis direction, the side length in the y-axis direction, and the side length in the z-axis direction of the unit cell respectively; is the lattice wall thickness, and C is the surface offset.

[0008] Further, step S200 is specifically as follows: Cut a cell cross-section on the x-y plane along the cell z-axis direction, and the cutting position is defined as , where the parameter a determines the cutting position, and the range of the parameter a is determined according to the actual cell configuration. The range determination principle is to ensure that the cell structure after cutting is continuous and there are no isolated islands. After the cutting design, a two-dimensional cross-section cell that is periodically continuous in the x-axis and y-axis directions is obtained; or cut a cell cross-section on the y-z plane along the cell z-axis direction, and the cutting position is defined as , where the parameter a determines the cutting position, and the range of the parameter a is determined according to the actual cell configuration. The range determination principle is to ensure that the cell structure after cutting is continuous and there are no isolated islands. After the cutting design, a two-dimensional cross-section cell that is periodically continuous in the y-axis and z-axis directions is obtained; or cut a cell cross-section on the x-z plane along the cell z-axis direction, and the cutting position is defined as , where the parameter a determines the cutting position, and the range of the parameter a is determined according to the actual cell configuration. The range determination principle is to ensure that the cell structure after cutting is continuous and there are no isolated islands. After the cutting design, a two-dimensional cross-section cell that is periodically continuous in the x-axis and z-axis directions is obtained.

[0009] Further, step S300 performs a cell stretching design on the two-dimensional cross-section cell, specifically as follows: After the cutting design, a two-dimensional cross-section cell that is periodically continuous in the x-axis and y-axis directions is obtained. Keep the cell size Lx in the x-axis direction unchanged. By defining the stretching parameter b, where b is the ratio of the sizes in the x-axis and y-axis directions, that is, the size in the y-axis direction after stretching is , so as to change the size in the y-axis direction. The stretched cell still maintains the continuity in the two periodic directions of the x-axis and y-axis; or after the cutting design, a two-dimensional cross-section cell that is periodically continuous in the y-axis and z-axis directions is obtained. Keep the cell size Ly in the y-axis direction unchanged. By defining the stretching parameter b, where b is the ratio of the sizes in the y-axis and z-axis directions, that is, the size in the z-axis direction after stretching is , so as to change the size in the z-axis direction. The stretched cell still maintains the continuity in the two periodic directions of the y-axis and z-axis; or after the cutting design, a two-dimensional cross-section cell that is periodically continuous in the z-axis and x-axis directions is obtained. Keep the cell size Lz in the z-axis direction unchanged. By defining the stretching parameter b, where b is the ratio of the sizes in the z-axis and x-axis directions, that is, the size in the x-axis direction after stretching is , so as to change the size in the x-axis direction. The stretched cell still maintains the continuity in the two periodic directions of the z-axis and x-axis.

[0010] Further, step S400 is the design of deflecting the principal axis angle of the cell material, specifically as follows: By deflecting the principal axis angle of the cell material in the global coordinate system, a cell configuration in a new local coordinate system is obtained, and the deflection angle is defined as ; When the two-dimensional cross-section cell is in the coordinate system By deflecting the principal axis angle of the unit cell material in the global coordinate system a new local coordinate system is obtained for the unit cell configuration The deflection angle is defined as with a range of 0° - 90°; or when the two-dimensional cross-section unit cell is in the coordinate system By deflecting the principal axis angle of the unit cell material in the global coordinate system a new local coordinate system is obtained for the unit cell configuration The deflection angle is defined as with a range of 0° - 90°; or when the two-dimensional cross-section unit cell is in the coordinate system By deflecting the principal axis angle of the unit cell material in the global coordinate system a new local coordinate system is obtained for the unit cell configuration The deflection angle is defined as with a range of 0° - 90°.

[0011] Furthermore, step S500 is specifically as follows: The two-dimensional cross-section unit cells are periodically arrayed along the two axial directions of the plane where the coordinate system is located, and a predetermined area is intercepted; what is obtained after interception is the sound insulation layer configuration of the sound insulation structure in the two-dimensional plane.

[0012] Furthermore, the structure is solidified by stretching along the vertical axis direction of the plane where it is located to form a solid sound insulation layer; the stretching distance L is determined according to the area requirement of the actual sound insulation superstructure.

[0013] Furthermore, the specific configuration of the three-dimensional sound insulation unit cells obtained through solidification is used to form a solid sound insulation layer, and the three-dimensional sound insulation unit cells as a whole exhibit periodic symmetry.

[0014] Furthermore, the three-dimensional sound insulation unit cells include a first surface, a second surface, a third surface, a fourth surface, a fifth surface, a sixth surface, a seventh surface, and an eighth surface; the first surface and the second surface are in the same plane, the fifth surface and the fourth surface are in the same plane, the first surface and the fifth surface are periodically symmetric, and the second surface and the fourth surface are periodically symmetric; the third surface is perpendicular to and intersects the second surface, and the third surface and the sixth surface are periodically symmetric; the seventh surface is perpendicular to the third surface, the fourth surface, the fifth surface, and the sixth surface respectively, the seventh surface and the eighth surface have the same shape, and the two are in a parallel positional relationship; the width of the first surface is a2, and the distance between one side of the first surface and the sixth surface is a1; the width of the second surface is a4, and the distance between one side of the second surface and the first surface is a3; the width of the third surface is a5, and the distance between one side of the third surface and the fourth surface is a6.

[0015] According to another aspect of the present invention, there is also provided a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS, which is obtained by using the design method of the above-mentioned pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS.

[0016] The present invention has the following beneficial effects: 1. The low-impedance characteristic enhances the sound insulation effect. By intercepting the two-dimensional cross-section of the Gyroid lattice unit cell and utilizing the characteristic that its modulus decreases in the sound wave incident direction, the structure is easy to deform, the sound wave propagation speed is reduced, impedance mismatch is formed, thereby reducing sound wave transmission and improving the sound insulation performance; further through the cell stretching design, the internal structure distribution is adjusted, anisotropy is enhanced, the equivalent modulus in the sound wave incident direction is further reduced, impedance matching is optimized, and the reflection and attenuation effects on low-frequency sound waves are enhanced.

[0017] 2. The longitudinal-transverse wave conversion improves the sound insulation efficiency. By deflecting the main axis angle of the cell material, the stiffness distribution is changed, and quasi-longitudinal waves and quasi-transverse waves inside the structure are excited, so that the longitudinal wave incident in water is converted into a transverse wave in the structure. Since transverse waves are difficult to propagate in water, this conversion mechanism effectively improves the sound energy dissipation ability of the sound insulation layer and enhances the low-frequency sound insulation effect.

[0018] 3. The 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 compressive capacity while maintaining light weight, adapting to the deep-water high-pressure environment.

[0019] 4. The low-frequency sound insulation performance is optimized. Through the periodic array arrangement and the core layer configuration design, the structure forms an effective sound wave blocking mechanism in the low-frequency range of 200 Hz - 3500 Hz, meeting the requirements of underwater equipment for low-frequency noise suppression.

[0020] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 is the overall structure schematic diagram of the TPMS underwater sound insulation superstructure of the preferred embodiment of the present invention; Figure 2 is the structure schematic diagram of the rectangular cover plate structure of the preferred embodiment of the present invention; Figure 3 is the schematic diagram of the design flow of the TPMS underwater sound insulation superstructure of the preferred embodiment of the present invention, Figure 3 (1) is the schematic diagram of the Gyroid unit cell,Figure 3 (2) is a schematic diagram of the cross-section design, Figure 3 (3) is a schematic diagram of the cross-sectional unit cell, Figure 3 (4) is a schematic diagram of the tensile design, Figure 3 (5) is a schematic diagram of the design of the deflection angle of the material principal axis, Figure 3 (6) is a schematic diagram of the array, Figure 3 (7) is a schematic diagram of intercepting the sound insulation layer area, Figure 3 (8) is a schematic diagram of forming the sound insulation layer entity, Figure 3 (9) is a schematic diagram of endowing the cover plate; Figure 4 is a schematic diagram of the structure of the three-dimensional unit cell of the sound insulation structure of the preferred embodiment of the present invention; Figure 5 is a schematic diagram of the structure of the hexagonal honeycomb underwater sound insulation superstructure for comparison in the preferred embodiment of the present invention; Figure 6 is a comparison diagram 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 200 Hz - 3500 Hz in the simulation example of the preferred embodiment of the present invention; Figure 7 is a comparison diagram of the stress-strain curves in the uniaxial compression simulation of the TPMS underwater sound insulation superstructure and the hexagonal honeycomb underwater sound insulation superstructure in the simulation example of the preferred embodiment of the present invention.

[0022] Legend: 10. Cover plate; 20. Sound insulation layer; 301. First surface; 302. Second surface; 303. Third surface; 304. Fourth surface; 305. Fifth surface; 306. Sixth surface; 307. Seventh surface; 308. Eighth surface. Specific implementation mode

[0023] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings, but the present invention can be implemented in many different ways defined and covered by the following.

[0024] Figure 1 is a schematic diagram of the overall structure of the TPMS underwater sound insulation superstructure of the preferred embodiment of the present invention; Figure 2 is a schematic diagram of the structure of the rectangular cover plate of the preferred embodiment of the present invention; Figure 3 is a schematic diagram of the design flow of the TPMS underwater sound insulation superstructure of the preferred embodiment of the present invention; Figure 4 is a schematic diagram of the structure of the three-dimensional unit cell of the sound insulation structure of the preferred embodiment of the present invention; Figure 5 is a schematic diagram of the structure of the hexagonal honeycomb underwater sound insulation superstructure for comparison in the preferred embodiment of the present invention; Figure 6It is a comparison diagram of the sound insulation coefficients of the TPMS underwater sound insulation superstructure and the hexagonal honeycomb underwater sound insulation superstructure in the 200Hz - 3500Hz frequency range in the simulation example of the preferred embodiment of the present invention; Figure 7 It is a comparison diagram of the stress-strain curves in the uniaxial compression simulation of the TPMS underwater sound insulation superstructure and the hexagonal honeycomb underwater sound insulation superstructure in the simulation example of the preferred embodiment of the present invention.

[0025] Such as Figure 1 , Figure 2 and Figure 3As shown, the design method of the pressure-resistant underwater low-frequency sound insulation metamaterial based on TPMS in this embodiment includes the following steps: S100. Establish a Gyroid lattice unit cell model in TPMS; S200. Intercept and obtain a two-dimensional cross-sectional unit cell on the Gyroid lattice unit cell model along the sound wave incident direction. Utilize the characteristic that the modulus of the two-dimensional cross-sectional unit cell decreases and it is prone to deformation in the sound wave incident direction to reduce the sound wave velocity inside the two-dimensional cross-sectional unit cell, thereby achieving low impedance; S300. Conduct unit cell stretching design on the two-dimensional cross-sectional unit cell. By stretching, change the internal structure distribution of the unit cell to make the unit cell anisotropic and reduce the modulus of the unit cell in the sound wave incident direction, further reducing the impedance; S400. Conduct the design of deflecting the principal axis angle of the unit cell material. By changing the stiffness distribution of the unit cell, excite the quasi-longitudinal wave and quasi-transverse wave inside the structure, and convert the longitudinal wave incident in water into a transverse wave in the structure through longitudinal-transverse wave conversion to improve the sound insulation performance; S500. Arrange the two-dimensional cross-sectional unit cells after deflecting the principal axis angle of the unit cell material in a periodic array, intercept the core layer configuration in the two-dimensional plane from it, and conduct structure solidification through stretching to obtain the sound insulation layer 20; S600. Cover the two sides of the sound insulation layer 20 with the cover plates 10, and arrange the two cover plates 10 in parallel to obtain the pressure-resistant underwater low-frequency sound insulation metamaterial based on TPMS.Design method of pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS. A pressure-resistant underwater low-frequency sound insulation superstructure is designed based on the TPMS (triply periodic minimal surface) structure. Through specific geometric configuration optimization and mechanical regulation, excellent sound insulation performance and pressure resistance are achieved. By intercepting the two-dimensional cross-section of the Gyroid lattice unit cell and utilizing the characteristic of the modulus reduction in the sound wave incident direction, the structure is easily deformed, the sound wave propagation speed is reduced, impedance mismatch is formed, thereby reducing sound wave transmission and improving sound insulation performance. Further, through the design of cell stretching, the internal structure distribution is adjusted, anisotropy is enhanced, the equivalent modulus in the sound wave incident direction is further reduced, impedance matching is optimized, and the reflection and attenuation effects on low-frequency sound waves are enhanced. By deflecting the principal axis angle of the cell material, the stiffness distribution is changed, and quasi-longitudinal waves and quasi-transverse waves inside the structure are excited, so that the longitudinal wave incident in water is converted into a transverse wave in the structure. Since transverse waves are difficult to propagate in water, this conversion mechanism effectively improves the sound energy dissipation ability of the sound insulation layer and enhances the 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 has high compressive capacity while maintaining light weight, adapting to the deep-water high-pressure environment. Compared with the traditional rubber cavity or reticular lattice structure, 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 load. Through periodic array arrangement and core layer configuration optimization, the problem of stress concentration existing in the traditional sound insulation structure is avoided, and the stability of the structure in a high hydrostatic pressure environment is enhanced. Through periodic array arrangement and core layer configuration design, an effective sound wave blocking mechanism is formed in the low-frequency range of 200 Hz - 3500 Hz, meeting the requirements of underwater equipment for low-frequency noise suppression. The synergistic improvement of sound insulation performance and mechanical performance is realized in terms of material selection and structure optimization, and the technical contradiction in terms of pressure resistance and low-frequency sound insulation effect of the traditional sound insulation structure is solved. Through the geometric optimization and mechanical regulation of the TPMS structure, the comprehensive effects of low impedance, longitudinal-transverse wave conversion, enhanced pressure resistance and improved low-frequency sound insulation performance are achieved, providing an efficient and reliable solution with excellent low-frequency sound insulation performance and pressure resistance for the acoustic stealth technology of underwater equipment.

[0026] During implementation, a TPMS underwater sound insulation superstructure is provided, including two cover plates 10 and a sound insulation layer 20 located between the two cover plates (as Figure 1 shown); The two cover plates 10 are parallel to each other, and the sound insulation layer 20 is composed of m×n sound insulation unit cells arranged in an array period, where m≥1 and n≥1; The design process of the sound insulation unit cell is as follows: 1. Establish a Gyroid lattice unit cell model in TPMS. The lattice is defined by the following implicit function: (1) (2) Among them, are the lattice constants, corresponding to the side lengths in the x-axis direction, y-axis direction, and z-axis direction of the unit cell respectively. is the unit cell wall thickness, and C is the surface offset. The Gyroid unit cell model is obtained through implicit function modeling (as Figure 3 (1)); The main reason for selecting the Gyroid unit cell as the design basis is that the Gyroid unit cell has been proven to have high energy absorption mechanical properties in a large number of studies. This benefits from its internal continuous and smoothly transitioning surface structure, which greatly reduces the stress concentration effect and improves the strength of the structure. Therefore, based on the Gyroid unit cell, the following sound insulation structure design can make full use of the excellent mechanical properties of the Gyroid unit cell structure, making the designed sound insulation structure have pressure resistance.

[0027] 2. Perform cross-section design on the unit cell obtained in step 1 (as Figure 3 (2)). Cut a unit cell cross-section on the x-y plane along the z-axis direction of the unit cell, and the cutting position is defined as , and the parameter a determines the cutting position. The range of the parameter a is determined according to the actual unit cell configuration, and the principle for determining the range is to ensure that the unit cell structure after cutting is continuous and there are no isolated islands. As shown in Figure 3 (3), a two-dimensional cross-section unit cell that is periodically continuous in the x-axis and y-axis directions can be obtained after the cutting design. In the present invention, the cross-section design is not limited to cutting along the z-axis direction, and cutting along the x-axis and y-axis directions is also within the scope covered by the present invention. The design principle of this step is: The three-dimensional configuration unit cell does not meet the conditions for achieving 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 sound insulation underwater through impedance mismatch. Therefore, a two-dimensional cross-section unit cell is obtained through cross-section design on the basis of the Gyroid three-dimensional unit cell. The cross-section design introduces an easily deformable mode for the unit cell along the sound wave incident direction (this direction is defined as the positive x-axis direction), that is, the modulus of the unit cell in the sound wave incident direction decreases and it is easy to deform. This characteristic can reduce the sound wave velocity inside the unit cell, thereby achieving low impedance, laying a foundation for further designing a low-impedance sound insulation structure.

[0028] 3. Perform unit cell stretching design on the two-dimensional unit cell obtained in step 2. The unit cell stretching design is to change the size ratio of the unit cell in the horizontal and vertical directions. The specific method is to keep the unit cell size in the x-axis direction unchanged, and by defining the stretching parameter b (the ratio of the sizes in the x-axis and y-axis directions), that is, the size in the y-axis direction after stretching is , thereby changing the size in the y-axis direction. As Figure 3As 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.

[0029] 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.

[0030] 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.

[0031] The specific configuration of the three-dimensional sound insulation cell obtained by materialization is as follows: Figure 4As shown in the figure. The unit cell as a whole shows periodic symmetry. The first type of surface 301 and the second type of surface 302 are in the same plane. The fifth type of surface 305 and the fourth type of surface 304 are in the same plane. The first type of surface 301 and the fifth type of surface 305 are periodically symmetric. The second type of surface 302 and the fourth type of surface 304 are periodically symmetric. The third type of surface 303 is perpendicular to and intersects with the second type of surface 302, and is periodically symmetric with the sixth type of surface 306. The seventh type of surface 307 is perpendicular to the third type of surface 303, the fourth type of surface 304, the fifth type of surface 305, and the sixth type of surface 306, and has the same shape as the eighth type of surface 308, and the two are in a parallel position relationship. The width of the first type of surface 301 is a2, and the distance from one side to the sixth type of surface 306 is a1. The width of the second type of surface 302 is a4, and the distance from one side of the second type of surface 302 to the first type of surface 301 is a3. The width of the third type of surface 303 is a5, and the distance from one side to the fourth type of surface 304 is a6.

[0032] The sound insulation layer 20 of the structure can be obtained through the design process of steps 1 - 5.

[0033] As Figure 3 shown in (9), cover plates 10 are respectively given to both sides of the sound insulation layer 20. The cover plates are rectangular plate structures, and their length and width are the same as 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 superstructure.

[0034] Finally, the parameters: the cell wall thickness , the intercept position a, the cell stretching parameter b, the deflection angle of the material principal axis , the thickness h2 of the sound insulation layer, the thickness h1 of the cover plate, and the pressure resistance (modulus in the sound wave incident direction) are used as design variables, and the differential evolution algorithm is used for optimization to obtain the optimal result within the ideal frequency range.

[0035] The cover plate 10 and the sound insulation layer 20 are made of metal materials or non - metal materials, and the physical parameters of the materials are: =1]] The range of the elastic modulus E satisfies 0.1 GPa ≤ E ≤ 220 GPa, and the Poisson's ratio range satisfies , and the density range satisfies .

[0036] The present invention is a pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS. Starting from the quasi-static impedance mismatch mechanism and based on the TPMS structure, the design is completed through configuration changes, parameter adjustment, and parameter optimization. It can effectively block the sound insulation problem in the low-frequency band of 200 Hz - 3500 Hz. The smooth transition characteristics inside the superstructure weaken the stress concentration effect, and it has good mechanical performance under external pressure, can withstand a water pressure of 3 MPa, and realizes the low-frequency sound insulation performance for sound waves of 200 Hz - 3500 Hz. It can be applied to underwater equipment and noise control in other fields, and has good engineering application prospects.

[0037] Example 1: As Figure 1 - Figure 2 shown is a TPMS low-frequency pressure-resistant underwater sound insulation superstructure disclosed in this embodiment. It specifically includes two cover plates 10 and a sound insulation layer 20 located between the two cover plates 10. The two cover plates 10 are parallel to each other, and the sound insulation layer 20 is composed of m × n sound insulation components arranged in an array period. Among them, m ≥ 1, n ≥ 1. The design process of the sound insulation unit cell is as follows: 1. Establish a Gyroid lattice unit cell model in TPMS. The lattice is defined by the following implicit function: (1) (2) Among them, is the lattice constant, corresponding to the side length in the x-axis direction, the side length in the y-axis direction, and the side length in the z-axis direction of the unit cell respectively. is the lattice wall thickness, and C is the surface offset.

[0038] In this embodiment, C is not used as a design variable, so is set.

[0039] Other parameter settings: .

[0040] By performing implicit function modeling through the commercial mathematical programming software MATLAB, a square gyroid unit cell with a size of 14 mm × 14 mm × 14 mm can be obtained.

[0041] It should be noted that the size of the unit cell can be adjusted arbitrarily according to needs. Selecting 14 mm in this embodiment is considered in view of the size of the overall sound insulation structure. If it is too large, the number of unit 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.

[0042] 2. Perform cross-section design on the unit cell obtained in step 1. In this embodiment, a unit cell cross-section in the x - y plane is intercepted along the z-axis direction, and the interception position is defined as , and the parameter a determines the interception position.

[0043] The range of parameter a is determined according to the actual cell configuration. The principle for determining the range is to ensure that the intercepted cell structure is continuous and there are no isolated islands. In this embodiment, it is defined as .

[0044] In this embodiment, it is set as .

[0045] After the interception design, a two-dimensional cross-sectional cell that is periodically continuous in the x-axis and y-axis directions can be obtained.

[0046] In the present invention, the cross-section design is not limited to interception along the z-axis direction. Interception along the x-axis and y-axis directions is also within the scope covered by the present invention.

[0047] 3. Perform a cell stretching design on the two-dimensional cell obtained in step 2.

[0048] The cell stretching design is to change the size ratio of the cell in the horizontal and vertical directions. The specific method is to keep the cell size in the x-axis direction unchanged. By defining the stretching parameter b (the ratio of the sizes in the x-axis and y-axis directions), that is, the size in the y-axis direction after stretching is , so as to change the size in the y-axis direction. In this embodiment, keep the size in the x-axis direction unchanged, and the stretching parameter is defined as , that is, the size in the y-axis direction after stretching is . Through the stretching design, a rectangular cell structure is obtained, and the stretched cell still maintains continuity in the two periodic directions.

[0049] 4. Perform a design of deflecting the material principal axis angle of the cell obtained in step 3. The design of deflecting the material principal axis angle of the cell is to obtain a new local coordinate system by deflecting the material principal axis angle of the cell in the global coordinate system . The deflection angle is defined as , and the range is . In this embodiment, it is defined as .

[0050] 5. Periodically array the cell obtained in step 3 along the axis and the axis, and intercept a rectangle with a length of and a width of . Since the structure is obtained by periodic array, the interception position theoretically does not affect the sound insulation performance of the structure, so the interception position is not required. What is obtained after interception is the core layer configuration in the two-dimensional plane of the sound insulation structure. 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 .

[0051] The three-dimensional sound insulation unit cell obtained through materialization is globally periodically symmetric. The first type of surface 301 and the second type of surface 302 are on the same plane. The fifth type of surface 305 and the fourth type of surface 304 are on the same plane. The first type of surface 301 and the fifth type of surface 305 are periodically symmetric. The second type of surface 302 and the fourth type of surface 304 are periodically symmetric. The third type of surface 303 is perpendicular to and intersects the second type of surface 302, and is periodically symmetric with the sixth type of surface 306. The seventh type of surface 307 is perpendicular to the third type of surface 303, the fourth type of surface 304, the fifth type of surface 305, and the sixth type of surface 306, and has the same shape as the eighth type of surface 308, and the two are in a parallel positional relationship. The width of the first type of surface 301 is a2 = 2.8 mm, and the distance from one side to the sixth type of surface 306 is a1 = 5.9 mm. The width of the second type of surface 302 is a4 = 2.7 mm, and the distance from one side of the second type of surface 302 to the first type of surface 301 is a3 = 6.1 mm. The width of the third type of surface 303 is a5 = 5.5 mm, and the distance from one side to the fourth type of surface 304 is a6 = 5.6 mm.

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

[0053] 6. Covers 10 are respectively provided at the first type of surface 301 and the second type of surface 302 of the sound insulation layer 20. The cover 10 is a rectangular plate structure, and its length and width are the same as the W and L dimensions of the sound insulation layer 20. The thickness of the cover 10 . The cover 10 is connected to the sound insulation layer 20 to form the final sound insulation metamaterial.

[0054] In this embodiment, the cover 10 and the sound insulation layer 20 are made of metal materials or non-metal materials. Among them, the metal materials can be selected from aluminum, carbon steel, alloy steel, etc., and the non-metal materials can be selected from nylon, ABS, etc. The physical parameters of the materials are as follows: the elastic modulus E ranges from 0.1 GPa ≤ E ≤ 220 GPa, the Poisson's ratio ν ranges from 0.2 ≤ ν ≤ 0.5, and the density ρ ranges from 800 kg / m³ ≤ ρ ≤ 12000 kg / m³.

[0055] In this embodiment, the cover 10 and the sound insulation layer 20 can be integrally printed and formed by 3D printing technology, or can be formed by machining methods such as wire electrical discharge machining.

[0056] Next, combined with specific simulation examples, the low-frequency pressure-resistant underwater sound insulation metamaterial in this embodiment is compared with Figure 5 the hexagonal honeycomb structure sound insulation superstructure in, and the TPMS low-frequency pressure-resistant underwater sound insulation superstructure in this embodiment is further described.

[0057] In this example, the materials of the cover plate 10 and the sound insulation layer 20 are both PA6 / 66, which is a common nylon (polyamide) blend and a mixed material of polyamide 6 (PA6) and polyamide 66 (PA66). The material parameters are a Young's modulus of 2.6 GPa, a Poisson's ratio of 0.35, and a density of 1250 kg / m³. The overall structure is prepared by 3D printing. The relevant generation parameters of the unit cell and the overall size of the structure have been reflected in the specific implementation steps of the embodiment. According to the above size parameters, a finite element analysis model of the sound insulation performance of the material is established, and the sound insulation coefficient is obtained through simulation calculation as 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. From Figure 6 it can be seen that in the embodiment of the present invention, under the condition that the overall thickness is 45 mm, the average sound insulation amount is greater than 11 dB in the frequency range of 200 - 3500 Hz, having excellent sound insulation effect. Compared with the 9.2 dB of the hexagonal honeycomb structure sound insulation superstructure, the sound insulation performance of this embodiment is improved to a certain extent.

[0058] In order to demonstrate the pressure resistance performance of the TPMS sound insulation superstructure, a mechanical finite element analysis model of the same structure is established and uniaxial compression simulation is carried out. Figure 7 Furthermore, the stress-strain curves of the TPMS sound insulation superstructure and the hexagonal honeycomb structure sound insulation superstructure are compared. From Figure 7 it can be seen that although the moduli in the elastic stage of the two are the same, the TPMS sound insulation superstructure has a higher failure strength, and the maximum stress it can withstand can reach more than 3 MPa.

[0059] To sum up, the technical effects of the TPMS low-frequency pressure-resistant underwater sound insulation superstructure in this embodiment are specifically as follows: 1. It has excellent low-frequency sound insulation performance. Compared with the hexagonal honeycomb structure sound insulation superstructure, under the condition that the overall thickness of the TPMS underwater sound insulation superstructure is 45 mm, the average sound insulation amount is greater than 11 dB in the frequency range of 200 Hz - 3500 Hz, realizing efficient low-frequency sound insulation.

[0060] 2. It has good pressure resistance performance. Due to its internal continuously smooth transition structural characteristics and good stress distribution characteristics, the TPMS underwater sound insulation superstructure has good pressure resistance performance, can maintain stable sound insulation performance in deep water environments, and can withstand a water pressure of 3 MPa.

[0061] 3. The sound insulation material of this embodiment has good structural designability. By optimizing and adjusting parameters such as the lattice constant, wall thickness, surface offset, cross-section position, and principal axis deflection angle of the sound insulation layer unit cell, as well as the thickness and manufacturing material of the overall structure, the requirements for sound insulation and mechanical properties in different actual application scenarios can be met.

[0062] Matters not covered by this invention are well-known technologies.

[0063] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

[0064] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

[0065] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope 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, It includes the following steps: S100. Establish a Gyroid lattice unit cell model in TPMS; S200. Intercept and obtain a two-dimensional cross-sectional unit cell on the Gyroid lattice unit cell model along the sound wave incident direction. Utilize the characteristic that the modulus of the two-dimensional cross-sectional unit cell decreases in the sound wave incident direction and is prone to deformation to reduce the sound wave velocity inside the two-dimensional cross-sectional unit cell, thereby achieving low impedance; S300. Conduct a unit cell stretching design on the two-dimensional cross-sectional unit cell. By stretching, change the internal structure distribution of the unit cell to make the unit cell anisotropic, reduce the modulus of the unit cell in the sound wave incident direction, and further reduce the impedance; S400. Design the deflection of the principal axis angle of the unit cell material. By changing the stiffness distribution of the unit cell, excite the quasi-longitudinal wave and quasi-transverse wave inside the structure, and convert the longitudinal wave incident in water into a transverse wave in the structure through longitudinal-transverse wave conversion to improve the sound insulation performance; S500. Arrange the two-dimensional cross-sectional unit cells after deflecting the principal axis angle of the unit cell material in a periodic array, intercept to obtain the core layer configuration in the two-dimensional plane, and conduct structure solidification through stretching to obtain the sound insulation layer (20); S600. Cover the two sides of the sound insulation layer (20) with cover plates (10). 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 pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to claim 1, characterized in that, Step S100 of establishing a Gyroid lattice unit cell model in TPMS is specifically as follows: Establish a Gyroid lattice unit cell model in TPMS. The lattice is defined by the following implicit function: （1） （2） Among them, For The lattice constants respectively correspond to the side lengths in the x axis direction, y the side length in the z axis direction, and is the lattice wall thickness, and C is the surface offset.

3. The design method of the pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to claim 2, wherein, Step S200 is specifically as follows: A cell cross-section on the x-y plane is intercepted along the z-axis direction of the cell, and the interception position is defined as , the parameter a determines the interception position, and the parameter a The range is determined according to the actual cell configuration. The principle for determining the range is that it is necessary to ensure the continuity of the cell structure after interception and there are no isolated islands. After the interception design, a two-dimensional cross-section cell that is periodically continuous in the x-axis and y-axis directions is obtained; or A cell cross-section on the y-z plane is intercepted along the z-axis direction of the cell, and the interception position is defined as , and the parameter a determines the interception position, and the parameter a The range is determined according to the actual cell configuration. The principle for determining the range is that it is necessary to ensure the continuity of the cell structure after interception, without islands. After the interception design, a two-dimensional cross-section cell that is periodically continuous in the y-axis and z-axis directions is obtained; Or A cell cross-section on the x-z plane is intercepted along the z-axis direction of the cell, and the interception position is defined as , and the parameter a determines the interception position. The range of the parameter a is determined according to the actual cell configuration. The range determination principle follows that the cell structure after interception should be continuous and there should be no isolated islands. After the interception design, a two-dimensional cross-section cell that is periodically continuous in the x-axis and z-axis directions is obtained.

4. The design method of the pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to claim 2, wherein, Step S300 of conducting a unit cell stretching design on the two-dimensional cross-sectional unit cell is specifically as follows: After intercepting the design, a two-dimensional cross-sectional unit cell that is periodically continuous in the x-axis and y-axis directions is obtained. Keeping the unit cell size Lx in the x-axis direction unchanged, by defining a stretching parameter b, where b is the ratio of the sizes in the x-axis and y-axis directions, i.e., the size in the y-axis direction after stretching is , thus changing the size in the y-axis direction, and the unit cell after stretching still maintains continuity in the two periodic directions of the x-axis and y-axis; or After the truncation design, a two-dimensional cross-sectional unit cell that is periodically continuous in the y-axis and z-axis directions is obtained. Keeping the unit cell size Ly in the y-axis direction unchanged, by defining the stretching parameter b, where b is the ratio of the sizes in the y-axis and z-axis directions, that is, the size in the z-axis direction after stretching is , so as to change the size in the z-axis direction, and the stretched unit cell still maintains continuity in the two periodic directions of the y-axis and z-axis; or After the truncation design, a two-dimensional cross-sectional unit cell that is periodically continuous in the z-axis and x-axis directions is obtained. Keeping the unit cell size Lz in the z-axis direction unchanged, by defining the stretching parameter b, where b is the ratio of the size in the z-axis direction to that in the x-axis direction, i.e., the size in the x-axis direction after stretching is , thereby changing the size in the x-axis direction, and the unit cell after stretching still maintains the continuity in the two periodic directions of the z-axis and x-axis.

5. The design method of the 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 of designing the deflection of the principal axis angle of the unit cell material is specifically as follows: By deflecting the principal axis angle of the cell material in the global coordinate system, a cell configuration in a new local coordinate system is obtained, and the deflection angle is defined as ; When the two-dimensional cross-sectional cell is in the coordinate system , by deflecting the principal axis angle of the cell material in the global coordinate system , a new local coordinate system is obtained for the cell configuration. The deflection angle is defined as , with a range of 0° - 90°; or When the two-dimensional cross-sectional cell is in the coordinate system , by deflecting the principal axis angle of the cell material in the global coordinate system , a new local coordinate system is obtained for the cell configuration, and the deflection angle is defined as , with a range of 0° - 90°; or When the two-dimensional cross-sectional cell is in the coordinate system , by deflecting the principal axis angle of the cell material in the global coordinate system , a new local coordinate system is obtained for the cell configuration. The deflection angle is defined as , with a range of 0° - 90°.

6. The design method of the pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to claim 5, characterized in that, Step S500 is specifically as follows: The two-dimensional cross-sectional unit cells are arranged in a periodic array 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 sound insulation layer configuration in the two-dimensional plane in the sound insulation structure.

7. The design method of the pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to claim 6, characterized in that, Conduct structure solidification through stretching along the vertical axis direction of the plane where it is located to form 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 pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS according to claim 7, characterized in that, Through the specific configuration of the three-dimensional sound insulation unit cell obtained by solidification, further form a solid sound insulation layer (20). The three-dimensional sound insulation unit cell as a whole presents periodic symmetry.

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

10. A pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS, characterized in that, It is obtained by using the design method of the pressure-resistant underwater low-frequency sound insulation superstructure based on TPMS described in any one of claims 1 to 9.

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