An underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit

Abstract

The present invention belongs to the technical field of acoustic structures or materials, and particularly relates to an underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit. It includes a surface composite material layer, a sound-absorbing core layer, and a mass distribution structure arranged in the sound-absorbing core layer; the surface composite material layer covers the outside of the sound-absorbing core layer; a number of tower-shaped sound-absorbing cavities are evenly arranged in the sound-absorbing core layer; the mass distribution structure is composed of an inner ring, an outer ring, and a free ring; the structure of the present invention is simple. By using the internal sound-absorbing core material and the sound-absorbing structure formed by the combination of cylindrical cavities - frustum-shaped cavities - mass distribution structure, a multi-layer array structural unit with good mechanical load-bearing performance and low-frequency broadband sound-absorbing performance is formed. This structural unit is compact and stable, has a small density, and can be widely applied to various pressure-bearing and sound-absorbing structures, enabling it to achieve sound-absorbing stealth. At the same time, it has a strong load-bearing capacity and outstanding pressure-resistant performance, and can be applied to the lightweight stealth structures of various underwater devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of acoustic structures or materials, and particularly relates to an underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit. Background Art

[0002] Fiber-reinforced resin matrix composites have the advantages of high specific strength, high specific stiffness, strong specific energy absorption, and good designability, and have received increasing attention in the field of structural engineering. However, in some special or extreme usage environments, not only excellent mechanical properties of the structure are required, but also good environmental adaptability and other special properties are needed. For example, in the design of underwater structural platforms, not only high requirements are put forward for the mechanical properties of the structural platform, but also the structural platform needs to have good acoustic stealth performance underwater. Existing composite materials cannot meet the requirements during application. Summary of the Invention

[0003] The purpose of the present invention is to provide an underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit that can meet the mechanical load-bearing requirements of an underwater structural platform and can provide good acoustic performance for the underwater structural platform.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions.

[0005] An underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit includes a surface composite material layer 1, a sound-absorbing core layer 2, and a mass distribution structure 3 arranged in the sound-absorbing core layer 2;

[0006] The surface composite material layer 1 is coated outside the sound-absorbing core layer 2;

[0007] A number of tower-shaped sound-absorbing cavities are uniformly arranged in the sound-absorbing core layer 2; the tower-shaped sound-absorbing cavity is composed of three combined cavities;

[0008] The combined cavity is composed of a cylindrical cavity 20 at the top and a frustum-shaped cavity 21 at the bottom, and the diameter of the cylindrical cavity 20 is the same as the diameter of the frustum top of the frustum-shaped cavity; the three combined cavities are coaxially arranged, and adjacent combined cavities are connected through the cylindrical cavity;

[0009] The distance R between the top of the cylindrical cavity 20 and the top of the sound-absorbing core material 2 is not less than 2 mm; the frustum bottom of the lowermost frustum-shaped cavity 21 penetrates through the bottom of the sound-absorbing core material 2 to form a sound-transmitting opening;

[0010] The mass distribution structure 3 is composed of an inner ring 30, an outer ring 31, and a free ring 32;

[0011] The inner ring 30 and the outer ring 31 are arranged in groups between all coaxial and adjacent two combined cavities; the inner ring 30 and the outer ring 31 in each group are coaxial with the combined cavity;

[0012] The inner diameter of the inner ring 30 is consistent with the diameter of the cylindrical cavity adjacent to its lower side; the outer diameter is smaller than the cone bottom diameter of the frustum cavity adjacent to its upper side; the inner diameter of the outer ring 31 is consistent with the cone bottom diameter of the frustum cavity above it; and the free rings 32 are evenly arranged between the outer rings 31.

[0013] A further improvement or preferred implementation scheme of the aforementioned underwater lightweight pressure-resistant sound-absorbing multi-layer array structure unit is as follows: the thickness H1 of the cylindrical cavity: the thickness H2 of the frustum cavity: the thickness H3 of the mass distribution structure 3 = 1~1.5:1.5~2:1~1.5.

[0014] As a further improvement or preferred embodiment of the aforementioned underwater lightweight pressure-resistant sound-absorbing multi-layer array structure unit, the inner ring 30 and the outer ring 31 are made of steel material.

[0015] As a further improvement or preferred implementation scheme of the aforementioned underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit, the tower-shaped sound-absorbing cavities are evenly arranged in a circular array or a rectangular array.

[0016] A further improvement or preferred implementation scheme of the aforementioned underwater lightweight pressure-resistant sound-absorbing multi-layer array structure unit, wherein the sound-absorbing core layer is made of polyurethane damping sound-absorbing material with a density of 900 to 1000 kg / m 3 , hydrostatic compressive strength 1~2MPa, linear elastic strain range 0~0.3;

[0017] The surface composite material layer 1 is obtained by a wet winding molding process; during the processing, the winding angle is 10°~30°, the winding thickness is 1~2mm, and the tension is 5~35N; a tension wet winding molding process is adopted, and an optimized winding line is used to evenly wind the surface of the internal core material optimized line to obtain better restraint bearing capacity and energy absorption efficiency, and improve the pressure resistance and bearing performance of the structural unit.

[0018] The molding fiber uses glass fiber or aramid fiber; the resin matrix uses low water absorption resin, which refers to polyester resin or vinyl ester or a combination thereof; the mass ratio of the molding fiber to the resin matrix is ​​1.5 to 1.0; the composite material uses a marine environment-adaptable fiber and resin system and optimizes the fiber-resin mass ratio to achieve better process molding quality and composite interface performance, while enabling it to obtain better underwater adaptability and service life.

[0019] A further improvement or preferred implementation scheme of the aforementioned underwater lightweight pressure-resistant sound-absorbing multilayer array structural unit, wherein the two large end surfaces of the underwater lightweight pressure-resistant sound-absorbing multilayer array structural unit are respectively a sound-facing surface and a fixed surface; the cylindrical cavity in the combined cavity faces the sound-facing surface, the cone bottom of the frustum cavity faces the fixed surface, the surface composite material layer 1 located on the sound-facing surface side has a thickness of 2 mm, and the surface composite material layer 1 located on the fixed surface side has a thickness of 4 mm;

[0020] The thicknesses of the three combined cavities in the tower-shaped sound-absorbing cavity and the mass distribution structure therebetween are: the thickness of the top combined cavity is 15 mm, the thickness of the first layer inner ring, outer ring and free ring is 2 mm, the thickness of the middle combined cavity is 20 mm, the thickness of the second layer inner ring, outer ring and free ring is 3 mm, and the thickness of the bottom combined cavity is 15 mm.

[0021] As a further improvement or preferred implementation scheme of the aforementioned underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit, the cone angles of the frustum in the three combined cavities of the tower-shaped sound-absorbing cavity are 83.89°, 73.74°, and 106.62° from top to bottom, respectively.

[0022] Its beneficial effects are:

[0023] The present invention has a simple structure. By utilizing an internal sound-absorbing core material in combination with a sound-absorbing structure formed by a cylindrical cavity, a frustum cavity, and a mass distribution structure, a multi-layer array structural unit with good mechanical bearing performance and low-frequency broadband sound absorption performance is formed. The structural unit has a compact and stable structure and a low density. It can be widely used in various pressure-bearing and sound-absorbing structures to achieve sound absorption and stealth. At the same time, it has a strong bearing capacity and outstanding pressure-resistant performance, and can be used in lightweight stealth structures of various underwater equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional view of an underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit;

[0025] Figure 2 It is a schematic diagram of the internal structure of an underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit;

[0026] Figure 3 It is a schematic diagram of the process assembly of underwater lightweight pressure-resistant sound-absorbing multi-layer array structural units;

[0027] Figure 4 This is a comparison chart of the sound absorption performance of the composite structure and the sound-absorbing core material under 3MPa water pressure. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments.

[0029] The underwater lightweight pressure-resistant sound-absorbing multi-layer array structural unit of the present invention is mainly used to prepare surface sound-absorbing protective layers / materials for various types of submersible equipment or instruments, and is used to improve the sound absorption and pressure-resistant bearing performance of the equipment protective layer. It is suitable for specific occasions that require stealth, impact resistance or vibration reduction performance.

[0030] The underwater lightweight pressure-resistant sound-absorbing multilayer array structural unit mainly comprises a surface composite material layer 1, a sound-absorbing core layer 2, and a mass distribution structure 3 arranged in the sound-absorbing core layer 2;

[0031] The surface composite material layer 1 is coated on the outside of the sound absorbing core layer 2;

[0032] Several tower-shaped sound-absorbing cavities are evenly arranged in the sound-absorbing core layer 2; the tower-shaped sound-absorbing cavity is composed of three combined cavities; the combined cavity is composed of a cylindrical cavity 20 at the top and a frustum cavity 21 at the bottom, and the diameter of the cylindrical cavity 20 is consistent with the diameter of the cone top of the frustum cavity; the three combined cavities are coaxially arranged, and adjacent combined cavities are connected by the cylindrical cavity;

[0033] The distance R between the top of the cylindrical cavity 20 and the top of the sound-absorbing core material 2 is not less than 2 mm; the bottom of the lowermost cone cavity 21 passes through the bottom of the sound-absorbing core material 2 to form a sound-permeable opening;

[0034] The mass distribution structure 3 is composed of an inner ring 30, an outer ring 31, and a free ring 32;

[0035] The inner ring 30 and the outer ring 31 are arranged in groups between all two coaxial and adjacent combined cavities; the inner ring 30 and the outer ring 31 in each group are coaxial with the combined cavity;

[0036] The inner diameter of the inner ring 30 is consistent with the diameter of the cylindrical cavity adjacent to its lower side; the outer diameter is smaller than the cone bottom diameter of the frustum cavity adjacent to its upper side; the inner diameter of the outer ring 31 is consistent with the cone bottom diameter of the frustum cavity above it; and the free rings 32 are evenly arranged between the outer rings 31.

[0037] In the present application, the sound-absorbing core material and its internal channels are generally made by casting and molding. In order to facilitate the installation of the internal mass distribution structure, a better solution is to use the area where the mass distribution structure of the sound-absorbing core material is located as the dividing line, divide the sound-absorbing core material into multiple sections and cast them separately to obtain multi-layered core materials containing the first layer, the second layer, and the third layer of cavities, respectively. Then, the inner ring, the outer ring and the free ring are respectively installed between the corresponding layers. After determining the position and quantity, the heated fluid polyurethane is filled between the inner ring, the outer ring and the free ring. Finally, the layered core materials are butt-jointed and bonded. After the polyurethane is cooled and stabilized, the core materials of each layer constitute the completed sound-absorbing core material. The above method is simple to implement, and the internal mass distribution structure can be conveniently assembled. At the same time, after the processing is completed, the integrity is good, the internal material is evenly distributed, and the performance is good.

[0038] In the present application, the surface composite material is mainly used to bear water pressure, so that the compression deformation of the structure under deep water pressure load is reduced. At the same time, the physical and chemical properties of the composite material are easy to control. By matching its impedance with that of water, sound waves can pass through the composite material layer more smoothly and enter the interior of the sound-absorbing structure.

[0039] The sound-absorbing core material is a mixture of polymer viscoelastic resin, hollow glass beads and flexible additives. After the sound wave enters the sound-absorbing core material, the sound wave energy is converted into material heat for dissipation, thereby suppressing the reflection and projection of the sound wave. Since the strength and modulus of the sound-absorbing core material itself are relatively low, in order to solve the problem that the sound absorption performance decreases rapidly due to its deformation under high pressure load, a tower-shaped sound-absorbing cavity and a mass distribution structure are specially set up. The sound transmission and reflection of the tower-shaped sound-absorbing cavity structure are utilized to evenly distribute the sound waves to the inside of the sound-absorbing core material, so that it can be absorbed more stably and smoothly. The mass distribution structure utilizes the difference in density between the high-density mass ring and the sound-absorbing material to increase the oscillation loss of the sound wave when it is transmitted between the materials, thereby achieving sound absorption and noise reduction.

[0040] Based on the above, the performance of the above structure and its parameter optimization process are explained below with reference to specific examples:

[0041] 1. According to the requirements of the underwater environment and the design target requirements, in this embodiment, the surface composite material layer 1 is obtained by a wet winding molding process; during the processing, the winding angle is 10°~30°, the winding thickness is 1~2mm, and the tension is 5~35N; the tension wet winding molding process is adopted, and the optimized winding line is used to evenly wind the surface of the internal core material optimized line to obtain better constraint bearing capacity and energy absorption efficiency, and improve the pressure resistance and bearing performance of the structural unit. The molding fiber uses glass fiber or aramid fiber; the resin matrix uses a low water absorption resin, which refers to polyester resin or vinyl ester or a combination thereof; the mass ratio of the molding fiber and the resin matrix is ​​1.5~1.0; the layer composite material uses a marine environment-adaptable fiber and resin system and optimizes the fiber resin mass ratio, so as to achieve better process molding quality and composite interface performance, while enabling it to obtain better underwater adaptability and service life.

[0042] In the specific implementation, the fiber resin system of the surface composite material layer is SW220 high-strength glass fiber produced by Nanjing Glass Fiber Research Institute and 430LV epoxy-modified vinyl ester resin produced by Nanjing Jinling DSM Company;

[0043] 2. The sound-absorbing core layer is made of polyurethane damping sound-absorbing material with a density of 900-1000kg / m 3 , hydrostatic compressive strength 1 ~ 2MPa, linear elastic strain range 0 ~ 0.3; in specific implementation, the internal core material uses HXR-X335 lightweight and high-strength polyurethane damping and sound-absorbing material produced by Hubei Xianning Haixingrui Composite Materials Co., Ltd.

[0044] 3. Preparation process: Before production, a polytetrafluoroethylene casting mold for the internal tower-shaped sound-absorbing cavity is first processed on a CNC lathe. After the core material is cast, a steel metal mass ring is pasted. The three-layer array structure is superimposed to form an internal core material 2 structure. Resin materials need to be prepared before winding molding. The mass ratio of vinyl ester resin, methyl ethyl ketone peroxide curing agent and cobalt cyclopentaneate accelerator is 100:2:1, and the room temperature curing time is 4 hours. The surface composite material 1 adopts a spiral winding line type, the number of winding layers is one layer, the winding angle is 25 degrees, and the fiber resin mass ratio of the surface composite material 1 after final curing is about 1:1, and the total thickness T of the winding layer is 2mm. After winding, the sample can be completely cured and formed in 4 hours at room temperature.

[0045] The underwater lightweight pressure-resistant sound-absorbing multilayer array structure unit product obtained based on the above-mentioned preparation process and structure was compared with the pure sound-absorbing core product to obtain the comparison of the sound absorption performance of the composite structure and the sound-absorbing core under 3MPa water pressure. Figure 1 As shown in the figure, it can be seen that the underwater lightweight pressure-resistant sound-absorbing multilayer array structure of the present application presents better sound absorption performance under high hydrostatic pressure load. In the full frequency range of 1 to 10KHZ under 3MPa water pressure load, the sound absorption performance of the composite structure is better than that of pure sound-absorbing materials, and its average sound absorption coefficient is increased by 20% to 30%, and the sound absorption coefficient of a specific frequency band can be increased by more than 90%. In the further implementation process, by further optimizing the structure and material parameters, adaptive design can be carried out to prepare materials and structures that meet high sound absorption performance in different frequency bands to meet the sound absorption performance under high hydrostatic pressure load.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An underwater lightweight pressure-resistant sound-absorbing metamaterial multi-layer array structural unit, Characterized in that, It includes a surface composite material layer (1), a sound-absorbing core layer (2), and a mass distribution structure (3) arranged in the sound-absorbing core layer (2); The surface composite material layer (1) covers the outside of the sound-absorbing core layer (2); A number of tower-shaped sound-absorbing cavities are evenly arranged in the sound-absorbing core layer (2); the tower-shaped sound-absorbing cavity is composed of three combined cavities; the combined cavity is composed of a cylindrical cavity (20) at the top and a frustum-shaped cavity (21) at the bottom, and the diameter of the cylindrical cavity (20) is the same as the cone top diameter of the frustum-shaped cavity; the three combined cavities are coaxially arranged, and adjacent combined cavities are connected by the cylindrical cavity; The distance R between the top of the cylindrical cavity (20) and the top of the sound-absorbing core material (2) is not less than 2 mm; the cone bottom of the lowermost frustum-shaped cavity (21) penetrates through the bottom of the sound-absorbing core material (2) to form a sound-permeable opening; The mass distribution structure (3) is composed of an inner ring (30), an outer ring (31), and a free ring (32); The inner ring (30) and the outer ring (31) are arranged in groups between all coaxial and adjacent two combined cavities; the inner ring (30) and the outer ring (31) in each group are coaxial with this combined cavity; The inner diameter of the inner ring (30) is the same as the diameter of the cylindrical cavity adjacent to its lower side; the outer diameter is smaller than the cone bottom diameter of the frustum-shaped cavity adjacent to its upper side; the inner diameter of the outer ring (31) is the same as the cone bottom diameter of the frustum-shaped cavity on its upper side; the free rings (32) are evenly arranged between the outer rings (31).

2. The underwater lightweight pressure-resistant sound-absorbing metamaterial multi-layer array structural unit according to claim 1, Characterized in that, The thickness H1 of the cylindrical cavity: the thickness H2 of the frustum-shaped cavity: the thickness H3 of the mass distribution structure (3) = 1 to 1.5: 1.5 to 2: 1 to 1.

5.

3. The underwater lightweight pressure-resistant sound-absorbing metamaterial multi-layer array structural unit according to claim 1, Characterized in that, The inner ring (30), the outer ring (31), and the free ring (32) are made of steel material.

4. The underwater lightweight pressure-resistant sound-absorbing metamaterial multi-layer array structural unit according to claim 1, Characterized in that, The tower-shaped sound-absorbing cavities are evenly arranged in a circular array or a rectangular array.

5. The underwater lightweight pressure-resistant sound-absorbing metamaterial multi-layer array structural unit according to claim 1, Characterized in that, The sound-absorbing core layer is made of polyurethane damping sound-absorbing material with a density of 900 - 1000 kg / m 3 , a hydrostatic pressure resistance strength of 1 - 2 MPa, and a linear elastic strain range of 0 - 0.3; The surface composite material layer (1) is obtained by a wet winding molding process; during the processing, the winding angle is 10° to 30°, the winding thickness is 1 to 2 mm, and the tension is 5 to 35 N; The forming fiber uses glass fiber or aramid fiber; the resin matrix uses a low water absorption resin, and the low water absorption resin refers to polyester resin or vinyl ester or a combination thereof; the mass ratio of the forming fiber to the resin matrix is 1.5 to 1.0.

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