Pressure-resistant underwater sound absorption composite structure, material and application

Abstract

The application discloses a pressure-resistant underwater sound absorption composite structure, material and application, and belongs to the technical field of underwater sound absorption materials. The structure comprises a rigid backing and a plurality of frames arranged in an array along x and y directions above the rigid backing. Adjacent frames are connected through a reduced diameter section. The frame is a hollow sleeve. The hollow sleeve and the reduced diameter section are filled with a double-component polyurethane / urea polymer material. A conical body of an open-cell foam metal material is embedded in the double-component polyurethane / urea polymer material in the frame. The structure fills the double-component polyurethane / urea polymer material with the conical open-cell foam aluminum structure, so that the structure has a good underwater sound absorption effect in a wide frequency band, has effective sound absorption performance under different hydrostatic pressures, and has pressure resistance, waterproofness and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater equipment noise control, and particularly relates to a pressure-resistant underwater sound absorption composite structure, material and application. BACKGROUND

[0002] The underwater sound absorption material needs to have a sound absorption mechanism in its interior. If the sound absorption material cannot effectively attenuate the incoming sound waves, the sound waves will be transmitted to the reflection interface at the end of the material without loss, and then be reflected back to the water, so that the purpose of underwater sound absorption cannot be achieved. Therefore, the underwater sound absorption material requires that the specific impedance is matched with water to minimize the reflection at the surface, and that a high loss factor is required to effectively absorb most of the incident sound waves. In addition, the underwater sound absorption material used in the marine environment also needs to have pressure resistance and other properties, which increases the difficulty of designing the underwater sound absorption material.

[0003] At present, the sound absorption structure mainly includes a microparticle filling type, a cavity resonance type, a sandwich composite type and an impedance gradient type. The underlying physical mechanisms include viscoelastic loss sound absorption, scattering sound absorption, wave mode conversion sound absorption and resonance sound absorption. However, two key problems have not been completely solved, one of which is the structure design based on low-frequency broadband performance, and the other of which is the pressure resistance design for deep sea environment.

[0004] With the continuous reduction of the working frequency of the active detection sonar, the continuous increase of the diving depth, and the continuous updating and improvement of the sonar signal processing technology, the traditional underwater acoustic material cannot effectively absorb low-frequency sound waves without increasing the thickness, and cannot meet the application requirements. Designing the underwater sound absorption composite structure applied to the surface of the underwater equipment is of great significance to the acoustic concealment of the underwater equipment in the deep sea environment. SUMMARY

[0005] To solve the problems in the prior art, the purpose of the present application is to provide a pressure-resistant underwater sound absorption composite structure, which fills the open-cell foam aluminum structure in the shape of a cone in the double-component polyurethane / urea high molecular material, so as to have good underwater sound absorption effect in a wide frequency band of 0.2-3 kHz, and has pressure resistance, waterproofness and corrosion resistance.

[0006] The present application is realized by the following technical solutions.

[0007] In one aspect, the present application provides a pressure-resistant underwater sound absorption composite structure, which comprises a rigid backing and a plurality of frames arranged in an array along the x and y directions above the rigid backing, the adjacent frames are connected by a reduced diameter section, the frame is a hollow sleeve, the hollow sleeve and the reduced diameter section are filled with a double-component polyurethane / urea high molecular material, and the double-component polyurethane / urea high molecular material in the frame is embedded with a cone-shaped body of open-cell foam metal material.

[0008] Preferably, the frames are arranged in a staggered manner, and the number of even rows n is m-1 more than the number of odd rows m.

[0009] Preferably, the frames are arranged in a square lattice or a triangular lattice.

[0010] Preferably, the height of the cone is slightly lower than the height of the frame, and the diameter of the cone is the same as the diameter of the frame; the axis of the cone and the axis of the cylinder coincide in space.

[0011] Preferably, the open-cell foam metal includes aluminum foam, nickel foam, iron foam, or copper foam.

[0012] In another aspect of the present application, a preparation method of the open-cell foam metal material for the structure is provided, in which high-temperature-resistant polyurethane sponge and gypsum are heated and fused with molten liquid metal at a temperature of 600-750°C, and the molten liquid metal is fused into the polyurethane sponge under a pressure of 5-10 MPa, and the gypsum is removed to obtain the porous foam metal.

[0013] In another aspect of the present application, a two-component polyurethane / urea polymer material for the structure is provided, which is prepared by mixing component A and component B at a mass ratio of 2:1.

[0014] Component A: polyether polyol: diisocyanate is (8-12):(0.5-2);

[0015] Component B: polyether polyol: amino chain extender is (20-30):(0.5-2).

[0016] The preparation method of the two-component polyurethane / urea polymer material includes mixing component A and component B at a mass ratio of 2:1.

[0017] Component A:

[0018] The polyether polyol is heated, pressure-maintained, dehydrated under negative pressure, cooled, and mixed with 8-12 parts of polyether polyol and 0.5-2 parts of diisocyanate at a mass ratio under normal pressure, heated, maintained, and then cooled to room temperature to obtain component A.

[0019] Component B:

[0020] Component B is obtained by mixing and stirring 20-30 parts of polyether polyol and 0.5-2 parts of amino chain extender at a mass ratio.

[0021] The polyether polyol is one of glycerol and pentaerythritol or a mixture of the two in any ratio.

[0022] The amino chain extender is a mixture of diethyl toluene diamine E-100 and secondary amine chain extender 6200 in a mass ratio of 1:(1.5-3).

[0023] The damping modifier is a mixture of phenolic resin and amino-terminated polyether in a mass ratio of 1:(1-2).

[0024] In the preparation of the A component, the polyether polyol is heated to 120-130 DEG C, and pressure is maintained at 0.1-0.2 MPa, and the pressure is reduced to 1.5-2 h, and the temperature is lowered to 50-60 DEG C, and the diisocyanate is added, and the temperature is raised to 85-95 DEG C, and the temperature is maintained for 1.5-2.5 h;

[0025] In the preparation of the B component, the polyether polyol and the amino chain extender are mixed and stirred at a speed of 200-500 rpm, and dispersed for 20-40 min.

[0026] The structure provided by the application can be applied in underwater sound absorption in the deep sea.

[0027] The application has the following beneficial effects due to the above technical scheme:

[0028] The high-loss factor of the two-component polyurethane / urea polymer material as the base material in the application can improve the shear energy consumption formed by the waveform conversion in the underwater sound absorption composite structure, and can enable the underwater equipment to have waterproof and corrosion-resistant properties. The open-cell aluminum foam as the scatterer plays the role of a lightweight skeleton, greatly improving the pressure resistance of the underwater sound absorption composite structure. The lightweight skeleton can improve the pressure resistance of the cover layer, so that the application object is more suitable for the combat requirements of the deep sea. The technical feature is that the material formula can be adjusted to flexibly design the frequency and temperature, and the open-cell aluminum foam can be processed into different shapes, showing different mechanical pressure resistance.

[0029] The two-component polyurethane / urea polymer material in the application belongs to the polyurethane damping material, and contains both urethane bonds and urea bonds in the molecular structure. By using raw materials with a large number of side groups, formula design, controlling the microphase separation degree of soft and hard segments, and increasing the internal friction of molecular chain segments, the damping performance of the material is realized. The conical open-cell aluminum foam as the metal scatterer embedded in the high polymer material has a metal skeleton matrix and an interpenetrating network structure, and the physical connection between the structural base units greatly increases the resonance mode and widens the resonance sound absorption frequency band range.

[0030] Unlike traditional sound absorption materials, the pressure-resistant underwater sound absorption composite structure has multiple sound absorption mechanisms such as resonance sound absorption, intramolecular friction sound absorption, and interface energy consumption. In addition, the two-component polyurethane / urea polymer material coated on the surface of the open-cell foam metal can also protect the open-cell foam metal from corrosion by seawater.

[0031] The present application is a pressure-resistant underwater sound absorption composite structure, which utilizes the wave fluctuation law and spatial fluctuation characteristics of sound wave transmission in viscoelastic damping material, embeds conical open-cell aluminum foam to enhance the wave form conversion mechanism and greatly reduce the incident sound energy. In the medium and low frequency range, the pressure-resistant underwater sound absorption composite structure can achieve high-efficiency underwater sound absorption, and still has effective sound absorption performance under different hydrostatic pressures. The geometric shape of the open-cell aluminum foam forces the two-component polyurethane / urea polymer material to perform wave form conversion on the sound waves inside the structure, further utilizing its sound energy loss. The internal through holes of the open-cell aluminum foam have multiple sound absorption mechanisms such as resonance sound absorption, intramolecular friction sound absorption, and interface energy consumption.

[0032] The present application has an average sound absorption coefficient of 0.57 in a wideband frequency of 0.2-3 kHz, an average sound absorption coefficient of 0.51, 0.47 and 0.43 under hydrostatic pressures of 1 MPa, 2 MPa and 4 MPa respectively, realizes effective sound absorption in the sub-wavelength scale range of underwater sound, meets the physical environment of impedance matching and pressure resistance, overcomes the problems of poor pressure resistance and reduced sound absorption performance in medium and low frequencies of traditional underwater sound materials, provides a new choice for the development of underwater sound materials or structures and underwater cover layers, and can effectively reduce the target strength of ships, underwater vehicles and underwater structures, has a wide application prospect in improving the anti-detection ability and acoustic stealth design. BRIEF DESCRIPTION OF DRAWINGS

[0033] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0034] Figure 1 It is a perspective view of the pressure-resistant underwater sound absorption composite structure of the present application;

[0035] Figure 2 It is a perspective view of the pressure-resistant underwater sound absorption composite structure of the present application cut along the axial direction;

[0036] Figure 3 It is a physical picture of the two-component polyurethane / urea polymer material in the pressure-resistant underwater sound absorption composite structure of the present application;

[0037] Figure 4 It is a physical picture of the open-cell aluminum foam in the pressure-resistant underwater sound absorption composite structure of the present application;

[0038] Figure 5 It is a partial X-ray computed tomography image of the open-cell aluminum foam sample in the pressure-resistant underwater sound absorption composite structure of the present application;

[0039] Figure 6 It is a partial electron microscope scanning image of the open-cell aluminum foam sample in the pressure-resistant underwater sound absorption composite structure of the present application;

[0040] Figure 7 The displacement modal diagram of the pressure-resistant underwater sound absorption composite structure of the present application is simulated by the finite element method;

[0041] Figure 8 The embodiments provided by the present application are compared with the underwater sound absorption coefficient experimental test results of open-cell aluminum foam and two-component polyurethane / urea polymer materials.

[0042] Figure 9 The embodiments provided by the present application are compared with the underwater sound absorption coefficient experimental test results under the conditions of static water pressure of 0 MPa, 3 MPa and 5 MPa.

[0043] In the drawings, the marks are respectively: 1 - reduced diameter section; 2 - frame; 3 - rigid backing; 4 - cone. DETAILED DESCRIPTION

[0044] The present application will be described in detail below with reference to the drawings and specific embodiments. The schematic embodiments and descriptions of the present application are used to explain the present application, but are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0045] As shown in Figures 1-2 The pressure-resistant underwater sound absorption composite structure provided by the present embodiment includes a rigid backing 3 and a plurality of frames 2 arranged in an array along the x and y directions above the rigid backing 3. In the present embodiment, the frame is a cylinder, and the frames 2 are staggered, with the number of even rows n being m-1 of the number of odd rows m. The adjacent frames 2 are connected by a reduced diameter section 1, the frame 2 is a hollow cylindrical sleeve, the frame 2 is filled with two-component polyurethane / urea polymer material, and the reduced diameter section 1 is two-component polyurethane / urea polymer material. The two-component polyurethane / urea polymer material in the frame 2 is embedded with a cone 4, and the cone 4 is made of open-cell aluminum foam material. The height of the cone is slightly lower than the height of the frame 2, and the diameter of the cone is the same as the diameter of the frame 2.

[0046] According to the wave shape conversion principle of viscoelastic damping material, the sound waves entering the composite structure are converted from longitudinal waves to shear waves, thereby being dissipated by the two-component polyurethane / urea polymer material, and thus achieving the effect of consuming incident sound energy.

[0047] In this embodiment, the outer circle diameter of the frame is 120 mm, the inner circle diameter is 118 mm, and the height is 60 mm; the geometric shape of the two-component polyurethane / urea high polymer material is a cylinder, the diameter is 118 mm, and the height is 60 mm; the thickness of the rigid backing is 15 mm; the geometric shape of the cone is a cone, the diameter of the cone base is 116 mm, the height of the cone is 56 mm, the central angle of the cone is 125°, and the cone generatrix is 80.6 mm. The design of the cone geometry maximizes the wave conversion mechanism of the two-component polyurethane / urea high polymer material, thereby being able to consume as much acoustic energy as possible.

[0048] The material attribute parameters of the two-component polyurethane / urea high polymer material are as follows: the density is 1150 kg / m 3 , the Young's modulus is 53 MPa, the loss factor is 0.47, and the Poisson's ratio is 0.43.

[0049] The materials of the frame and the rigid backing are Q235A3 steel, the density of the Q235A3 steel is 7850 kg / m 3 , the Young's modulus is 210 GPa, and the Poisson's ratio is 0.29; the areal density of the open-cell aluminum foam is 540 kg / m 3 , the porosity is 75%, as shown in Figure 5 、 6 , the diameter of the through hole inside is 1-5 mm.

[0050] The open-cell aluminum foam material is able to maximize the immersion of the two-component polyurethane / urea high polymer material into the pores during the preparation of the composite structure sample due to the open-cell structure on the surface and inside. Since the material is aluminum, it has certain pressure resistance, which can guarantee the sound absorption performance of the underwater sound absorption composite structure in a large depth environment.

[0051] The arrangement mode of the plurality of frames in this embodiment can be a square lattice or a triangular lattice. The number of the frames in this embodiment can be determined according to the actual laying surface area size.

[0052] The embodiment of the application gives a preparation method of the two-component polyurethane / urea high polymer material, including the preparation method of the A component and the B component and the pouring mode.

[0053] The A component is a semi-prepolymer generated by the reaction of diisocyanate and polyether polyol, and the B component is a mixture composed of an amino-terminated chain extender, polyether polyol, and an organic hybrid small molecule damping modifier.

[0054] The preparation method of the A component is as follows:

[0055] The polyether polyol is added into a four-necked flask, heated to 120-130°C, kept at a pressure of 0.1-0.2 MPa, vacuum dehydration for 1.5-2 h, cooled to 50-60°C, and then diisocyanate is added under normal pressure according to a mass ratio of polyether polyol: diisocyanate = (8-12):(0.5-2), heated to 85-95°C after the addition is completed, kept for 1.5-2.5 h, and then the heating is stopped after the titration value of the isocyanate group content reaches the theoretical value, and the product is discharged after cooling to room temperature, to obtain the required A component.

[0056] The preparation method of the B component is as follows:

[0057] The polyether polyol and the amino chain extender are added into a dispersion container according to a mass ratio of polyether polyol: amino chain extender = (20-30):(0.5-2), kept at a constant rotation speed of 200-500 rpm, heated and melted after the organic hybrid small-molecule damping modifier is fully mixed, added into the dispersion container, and dispersed for 20-40 min, to stop the stirring, and obtain the required B component.

[0058] The polyether polyol is one of glycerol and pentaerythritol or a mixture of the two in any ratio.

[0059] The amino chain extender is a mixture of diethyl toluene diamine E-100 and secondary amine chain extender 6200 according to a mass ratio of 1:(1.5-3).

[0060] The damping modifier is a mixture of phenolic resin and amino-terminated polyether according to a mass ratio of 1:(1-2).

[0061] Different embodiments of the preparation of the two-component polyurethane / urea polymer material are given below.

[0062] Example 1

[0063] The preparation method of the A component is as follows:

[0064] The pentaerythritol is added into a four-necked flask, heated to 120°C, kept at a pressure of 0.2 MPa, vacuum dehydration for 1.5 h, cooled to 60°C, and then diisocyanate is added under normal pressure according to a mass ratio of pentaerythritol: diisocyanate = 9:2, heated to 85°C after the addition is completed, kept for 1 h, to obtain the A component.

[0065] The preparation method of the B component is as follows:

[0066] The pentaerythritol and the amino chain extender are added into a dispersion container according to a mass ratio of pentaerythritol: amino chain extender = 30:1, fully mixed at a rotation speed of 200 rpm, added into the dispersion container, and dispersed for 40 min, to obtain the B component.

[0067] The amino chain extender is a mixture of diethyl toluene diamine E-100 and secondary amine chain extender 6200 in a mass ratio of 1:1.5.

[0068] The damping modifier is a mixture of phenolic resin and amino-terminated polyether in a mass ratio of 1:1.5.

[0069] Example 2

[0070] The preparation method of the A component is as follows:

[0071] The polyether polyol is added into a four-necked flask, the temperature is raised to 125°C, the pressure is kept at 0.1 MPa, and the polyether polyol is dehydrated under negative pressure for 2 h. The temperature is lowered to 50°C, and the diisocyanate is added in a mass ratio of polyether polyol: diisocyanate of 12:1,5 under normal pressure. After the addition is completed, the temperature is raised to 95°C, and the mixture is kept at this temperature for 1.5 h to obtain the A component.

[0072] The preparation method of the B component is as follows:

[0073] The polyether polyol and the amino chain extender are added into a dispersion container in a mass ratio of polyether polyol: amino chain extender of 25:2, and they are mixed well at a speed of 500 r / min. The mixture is added into the dispersion container, and is dispersed for 20 min to obtain the B component.

[0074] The polyether polyol is a mixture of glycerol and pentaerythritol.

[0075] The amino chain extender is a mixture of diethyl toluene diamine E-100 and secondary amine chain extender 6200 in a mass ratio of 1:3.

[0076] The damping modifier is a mixture of phenolic resin and amino-terminated polyether in a mass ratio of 1:2.

[0077] Example 3

[0078] The preparation method of the A component is as follows:

[0079] The glycerol is added into a four-necked flask, the temperature is raised to 130°C, the pressure is kept at 0.1 MPa, and the glycerol is dehydrated under negative pressure for 2 h. The temperature is lowered to 55°C, and the diisocyanate is added in a mass ratio of glycerol: diisocyanate of 8:0.5 under normal pressure. After the addition is completed, the temperature is raised to 90°C, and the mixture is kept at this temperature for 2 h to obtain the A component.

[0080] The preparation method of the B component is as follows:

[0081] The glycerol and the amino chain extender are added into a dispersion container in a mass ratio of glycerol: amino chain extender of 20:0.5, and they are mixed well at a speed of 300 r / min. The mixture is added into the dispersion container, and is dispersed for 30 min to obtain the B component.

[0082] The amino chain extender is a mixture of diethyltoluenediamine E-100 and secondary amine chain extender 6200 in a mass ratio of 1:2.

[0083] The damping modifier is a mixture of phenolic resin and amino-terminated polyether in a mass ratio of 1:1.

[0084] When using, mix component A and component B in a mass ratio of 2:1.

[0085] Preheat before use to reduce viscosity and make mixing more uniform; ensure the material is dry and sealed.

[0086] During pouring: The material will harden as the proportion of component A increases; the air humidity should be controlled within 30%-80%, and the material temperature should be controlled within 50±5℃; it is forbidden to add any solvent or diluent to the material.

[0087] After filling: Seal the remaining material strictly; clean the equipment thoroughly, paying special attention to cleaning the end agitator.

[0088] like Figure 3 The image shown is a physical diagram of the two-component polyurethane / urea polymer material in the pressure-resistant underwater acoustic absorption composite structure of this invention.

[0089] The present invention further provides a method for preparing open-cell foam metal, which employs a melt infiltration method.

[0090] In the preparation of the material of this invention, high-temperature resistant polyurethane foam and gypsum, used as filler particles, are first fused with molten liquid metal at a mass ratio of 0.2:(1-1.5). Then, the gypsum is heated and hardened at a high temperature of 600℃-750℃, causing the polyurethane foam to vaporize. The molten metal can then be maximally melted into the polyurethane foam under a pressure of 5-10 MPa. Finally, the gypsum is removed to obtain porous foamed metal.

[0091] The material for open-cell foamed metal can be foamed nickel, foamed iron, or foamed copper.

[0092] The following are different examples of preparing open-cell aluminum foam, nickel foam, iron foam, or copper foam.

[0093] Example 1

[0094] First, high-temperature resistant polyurethane foam and gypsum, used as filler particles, are fused with molten liquid aluminum at a mass ratio of 0.2:1.5. Then, the gypsum is heated to harden at 600°C, causing the polyurethane foam to vaporize. The molten aluminum then melts into the polyurethane foam to a maximum extent under a pressure of 5 MPa. Finally, the gypsum is removed to obtain porous aluminum foam.

[0095] like Figure 4As shown, the porosity of the open-cell aluminum foam prepared by the present application is 75%, and the internal channels are mutually penetrated.

[0096] Example 2

[0097] First, the high-temperature-resistant polyurethane sponge used as the filling particles and the gypsum are fused with the molten liquid nickel in a mass ratio of 0.2:1, and then the gypsum is hardened by heating at a high temperature of 700 DEG C, so that the polyurethane sponge is gasified, and the nickel liquid can be maximally fused into the polyurethane sponge under a pressure of 10 MPa. Finally, the gypsum is removed to obtain the porous foam nickel.

[0098] Example 3

[0099] First, the high-temperature-resistant polyurethane sponge used as the filling particles and the gypsum are fused with the molten liquid iron in a mass ratio of 0.2:1.2, and then the gypsum is hardened by heating at a high temperature of 650 DEG C, so that the polyurethane sponge is gasified, and the iron liquid can be maximally fused into the polyurethane sponge under a pressure of 8 MPa. Finally, the gypsum is removed to obtain the porous foam iron.

[0100] Example 4

[0101] First, the high-temperature-resistant polyurethane sponge used as the filling particles and the gypsum are fused with the molten liquid copper in a mass ratio of 0.2:1.4, and then the gypsum is hardened by heating at a high temperature of 750 DEG C, so that the polyurethane sponge is gasified, and the copper liquid can be maximally fused into the polyurethane sponge under a pressure of 7 MPa. Finally, the gypsum is removed to obtain the porous foam copper.

[0102] The working principle of the present application is as follows:

[0103] The characteristic impedance of the two-component polyurethane / urea high polymer material prepared by the present application is similar to that of water, so that as many acoustic waves in water as possible can enter into the structure. In addition, the polyurea high polymer material has good waterproof and corrosion-resistant properties, which provides protection for the long-term work of the acoustic material in seawater. Therefore, the material selection of the two-component polyurethane / urea high polymer material combines the impedance matching, waterproof and corrosion-resistant characteristics, and has a larger loss factor, which can dissipate the incident acoustic wave energy.

[0104] When the incident sound wave in water enters the surface of the pressure-resistant underwater sound absorption composite structure, due to the characteristic impedance of the double-component polyurethane / urea high polymer material being close to that of water, no obvious reflection phenomenon occurs at the interface; the sound wave entering the interior of the structure propagates in the form of a longitudinal wave, the open-cell aluminum foam (nickel foam, iron foam or copper foam) can convert the sound wave propagating in the form of a longitudinal wave into a shear wave, the design of the conical shape of the sound propagation path gradually enhances the degree of conversion of the wave shape of the sound wave, and due to the double-component polyurethane / urea high polymer material having a large loss factor, energy is consumed by shear loss, and the molecular internal friction sound absorption and interface energy consumption of the double-component polyurethane / urea high polymer material can further improve the shear loss. The open-cell aluminum foam (nickel foam, iron foam or copper foam) has through holes in the interior, a plurality of cavities of different sizes exist, and a resonant sound absorption structure can be formed to further consume the sound energy incident into the interior of the structure.

[0105] Next, a simulation model is established by using the acoustic-solid coupling module in the Comsol Mutiphysics 5.6 finite element simulation software to calculate the displacement modal of the unit cell in the pressure-resistant underwater sound absorption composite structure.

[0106] As shown in Figure 7 , when the frequency of the incident sound wave is 500 Hz and the amplitude of the sound wave is 10 Pa, in the displacement modal of the unit cell in the pressure-resistant underwater sound absorption composite structure, the displacement deformation maximum is concentrated at the top of the open-cell aluminum foam (nickel foam, iron foam or copper foam), and the arrow indicates the displacement deformation direction, which can show that the greater the displacement deformation and the deeper the direction into the structure, the worse the consistency of the displacement deformation direction. The greater the displacement deformation, the more dispersed the displacement deformation direction, the more sufficient the coupling between the open-cell aluminum foam (nickel foam, iron foam or copper foam) and the double-component polyurethane / urea high polymer material 1, the higher the degree of wave shape conversion, the greater the sound absorption coefficient, and the better the sound absorption performance.

[0107] Next, the sound absorption performance of the unit cell in the pressure-resistant underwater sound absorption composite structure is tested by using the underwater acoustic tube test system. The underwater acoustic tube test system includes a double-channel signal filter, a signal amplifier, an oscilloscope, a transducer and a power amplifier. The experimental test uses the transfer function method to obtain the reflection coefficient β, thereby obtaining the sound absorption coefficient α. The test standard is Acoustic-determination of sound absorption coefficient and impedance in impedance tubes, part 2: transfer-function method, BS EN ISO (2001) 10534-10542.

[0108]

[0109] As shown in the figure, the cell in the pressure-resistant underwater sound absorption composite structure realizes excellent underwater sound absorption effect in the frequency range of 200-3000Hz, the average value of the sound absorption coefficient is 0.57, the first sound absorption peak appears within 1000Hz, and the maximum sound absorption coefficient corresponding to the first sound absorption peak is more than 0.7. Figure 8 As shown in the figure, the cell in the pressure-resistant underwater sound absorption composite structure realizes excellent underwater sound absorption effect in the frequency range of 200-3000Hz, the average value of the sound absorption coefficient is 0.57, the first sound absorption peak appears within 1000Hz, and the maximum sound absorption coefficient corresponding to the first sound absorption peak is more than 0.7.

[0110] Figure 9 As shown in the figure, the cell in the pressure-resistant underwater sound absorption composite structure realizes excellent underwater sound absorption effect in the frequency range of 200-3000Hz, the average value of the sound absorption coefficient is 0.57, the first sound absorption peak appears within 1000Hz, and the maximum sound absorption coefficient corresponding to the first sound absorption peak is more than 0.7.

[0111] The pressure-resistant underwater sound absorption composite structure provided by the application effectively solves the sound absorption problem in the frequency range of 200-3000Hz and under different hydrostatic pressures, the structure thickness is 75mm, relative to the wavelength of the underwater sound wave of the same frequency, the pressure-resistant underwater sound absorption composite structure can realize subwavelength efficient underwater sound absorption, still has effective sound absorption performance under different hydrostatic pressures, the pressure-resistant underwater sound absorption composite structure has the technical advantages of simple structure and excellent sound absorption effect, and has wide application prospect in the research of underwater sound materials or structures and underwater cover layer, target strength control of ships, underwater vehicles and underwater structures.

[0112] The application is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the application, those skilled in the art can make some substitutions and modifications to some technical features without creative labor, and the substitutions and modifications are all within the protection scope of the application.​

Claims

1. A pressure-resistant underwater sound-absorbing composite structure, characterized by comprising: The rigid backing and the array of frames arranged along the x and y directions above the rigid backing, the adjacent frames are connected by the reduced diameter section, the frame is a hollow sleeve, the inside of the hollow sleeve and the reduced diameter section are the two-component polyurethane / urea polymer material, and the cone-shaped body of the open-cell foam metal material is embedded in the two-component polyurethane / urea polymer material in the inside of the frame.

2. The pressure-resistant underwater sound absorbing composite structure according to claim 1, characterized in that, The frame is a cylinder, the frames are staggered, and the number of even rows n is m-1 more than the number of odd rows m. The arrangement mode of the frames is a square lattice or a triangular lattice.

3. The pressure-resistant underwater sound absorbing composite structure according to claim 1, characterized in that, The height of the cone-shaped body is slightly lower than the height of the frame, and the diameter of the cone-shaped body is the same as the diameter of the frame. The axis of the cone-shaped body and the cylinder coincide in space.

4. The pressure-resistant underwater sound absorbing composite structure according to claim 1, characterized in that, The open-cell foam metal is foam aluminum, foam nickel, foam iron or foam copper.

5. The pressure-resistant underwater sound absorbing composite structure according to claim 1, characterized in that, The preparation method of the open-cell foam metal material is as follows: The high-temperature-resistant polyurethane sponge, gypsum and molten liquid metal are heated and fused at a temperature of 600-750 DEG C, and the molten liquid metal is fused into the polyurethane sponge under a pressure of 5-10 MPa, and the gypsum is removed to obtain the open-cell foam metal material.

6. The pressure-resistant underwater sound absorbing composite structure according to claim 1, characterized in that, The two-component polyurethane / urea polymer material comprises A component and B component mixed in a mass ratio of 2:

1. The A component is polyether polyol and diisocyanate in a mass ratio of (8-12):(0.5-2). The B component is polyether polyol and amino chain extender in a mass ratio of (20-30):(0.5-2).

7. The pressure-resistant underwater sound absorbing composite structure according to claim 1, characterized in that, The preparation method of the two-component polyurethane / urea polymer material comprises mixing A component and B component in a mass ratio of 2:

1. The A component is polyether polyol and diisocyanate in a mass ratio of (8-12):(0.5-2). The B component is polyether polyol and amino chain extender in a mass ratio of (20-30):(0.5-2). The preparation method of the two-component polyurethane / urea polymer material comprises mixing A component and B component in a mass ratio of 2:

1. The A component is polyether polyol and diisocyanate in a mass ratio of (8-12):(0.5-2).

8. The pressure-resistant underwater sound absorbing composite structure according to claim 7, characterized in that, The B component is polyether polyol and amino chain extender in a mass ratio of (20-30):(0.5-2). The polyether polyol is a mixture of one or two of glycerol and pentaerythritol in any ratio. The amino chain extender is a mixture of diethyl toluene diamine E-100 and secondary amine chain extender 6200 in a mass ratio of 1:(1.5-3).

9. The pressure-resistant underwater sound absorbing composite structure according to claim 7, characterized in that, The organic hybrid small molecule damping modifier is a mixture of phenolic resin and amino-terminated polyether in a mass ratio of 1:(1-2). In the preparation of the A component, the polyether polyol is heated to 120-130 DEG C, the pressure is maintained at 0.1-0.2 MPa, the negative pressure dehydration is performed for 1.5-2 h, the temperature is lowered to 50-60 DEG C, the diisocyanate is added and the temperature is raised to 85-95 DEG C, and the temperature is maintained for 1.5-2.5 h. In the preparation of the B component, the polyether polyol and the amino chain extender are mixed and stirred at a speed of 200-500 r / min for 20-40 min.

10. The pressure-resistant underwater sound absorption composite structure according to any one of claims 1-9 is applied to underwater sound absorption in the deep sea.

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