CN111696509B - Damping material filled double-pore open-cell foam metal underwater sound absorption structure - Google Patents
Damping material filled double-pore open-cell foam metal underwater sound absorption structure Download PDFInfo
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- CN111696509B CN111696509B CN202010486474.7A CN202010486474A CN111696509B CN 111696509 B CN111696509 B CN 111696509B CN 202010486474 A CN202010486474 A CN 202010486474A CN 111696509 B CN111696509 B CN 111696509B
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
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Abstract
The invention discloses a damping material filled double-pore open-cell foam metal underwater sound absorption structure which comprises an open-cell foam metal framework, wherein hard damping material covering layers are respectively arranged on the upper surface and the lower surface of the open-cell foam metal framework, the open-cell foam metal framework and the hard damping material covering layers form a sealing structure, a plurality of pores are periodically arranged in the sealing structure to form cavities, and soft damping materials are filled in the cavities. The underwater sound absorption material has excellent mechanical property and good underwater sound absorption performance, has more adjustable parameters in design, comprises structural parameters and material parameters, can be correspondingly adjusted according to the requirements of actual working conditions, and is simple in structure and easy to manufacture.
Description
Technical Field
The invention belongs to the technical field of underwater sound absorption composite structures, and particularly relates to a damping material filled double-pore open-pore foam metal underwater sound absorption structure.
Background
With the continuous deep detection of human beings on the ocean, various underwater mechanical equipment continuously emerge, vibration and noise have great influence on the service life of the equipment and the precision of instruments, and the underwater sound absorption and noise reduction problem increasingly becomes a complex and urgent problem to be solved. Most of the existing underwater sound absorption and noise reduction technologies adopt macromolecular damping materials such as rubber, polyurethane and the like. The materials can play a certain role in sound absorption and noise reduction when applied underwater, but have some defects: with the increasing of the water depth, the pressure will increase to lose its elasticity, and then lose the function of absorbing vibration and noise. In addition, such materials cannot achieve good sound absorption at low frequencies due to limitations in the sound absorption mechanism. Therefore, the underwater sound absorption structure with the pressure bearing capacity and the better low-frequency sound absorption performance is realized through the design of the structure, and the underwater sound absorption structure has important engineering application prospect.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a dual-pore open-cell foam metal underwater sound absorption structure filled with damping material, which is a composite material of foam metal and damping material, i.e. a functional structure integrated material with high damping performance and good mechanical performance, wherein the through-hole foam metal is used as a base, and the holes are filled with the damping material, so as to obtain an interwoven complex of the metal and the damping material.
The invention adopts the following technical scheme:
the utility model provides a damping material fills two hole trompil foam metal sound absorbing structure under water, includes trompil foam metal skeleton, and the porosity of trompil foam metal skeleton is 70% ~90%, and the pore diameter is 0.8~2mm, and the upper surface and the lower surface of trompil foam metal skeleton are provided with hard damping material overburden respectively, and trompil foam metal skeleton constitutes seal structure with hard damping material overburden, and the inside periodicity of seal structure is opened has a plurality of holes to form the cavity, and the cavity intussuseption is filled with soft damping material.
Specifically, the diameter of the hole of the cavity is larger than the diameter of the foam metal hole of the open-cell foam metal framework, and the height of the cavity is the same as the thickness of the open-cell foam metal framework.
Specifically, the shape of the cavity is one or more of a cylinder shape, a cone shape, a ball shape, an ellipsoid shape or a horn shape.
Furthermore, the aperture of the cavity is 15-30 mm.
Specifically, the thickness of the open-cell foam metal framework 1 is 30-50 mm.
Specifically, the open-cell foam metal skeleton is made of foamed iron, copper or aluminum material.
Specifically, the Young modulus of the soft damping material is 2-10 MPa, and the loss factor is more than or equal to 0.3.
Specifically, the Young modulus of the hard damping material covering layer is 30-100 MPa, and the thickness is 1-3 mm.
Furthermore, the sound absorption frequency of the sound absorption structure is 2-20 kHz, and the average sound absorption coefficient is more than or equal to 0.8.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention relates to a double-pore open-cell foam metal underwater sound absorption structure filled with damping materials. Due to the existence of holes with different sizes, the sound absorption range of the structure is widened. And because the foam metal framework exists, the structure has certain bearing capacity, and the sound absorption performance and the water pressure resistance performance of the structure are improved.
Further, the shape of the holes punched in the metal foam may be cylindrical, conical or trumpet-shaped, and the diameter of the holes is exemplified by cylindrical holes, and the diameter of the holes is between 15 and 30mm.
Furthermore, in order to ensure the content of the damping material in the structure and the bearing capacity of the structure to hydrostatic pressure, the content of the foam metal is controlled to be between 70 and 90 percent, and in order to ensure the mechanical property of the structure and the enhancement effect on the acoustic property, the opening size of the foam metal is between 5 and 15 mm.
Further, in order to ensure that the structure has enough sound absorption capacity, the total thickness of the foam metal filled damping material structure is 30-50 mm.
Furthermore, the foam metal material can be selected from aluminum, steel or copper and other metals with good mechanical properties.
Furthermore, the damping material is a polyurethane viscoelastic material, such as polyurethane or rubber, and plays a main sound absorption role in the structure, and the isotropic loss factor is 0.3 or more, so as to ensure that the damping material has enough loss capacity for sound wave energy.
Furthermore, after the foam metal is filled with the damping material, the upper surface and the lower surface of the open-pore structure are covered with a hard damping material covering layer so as to play a role in sealing and protecting the metal material from being corroded.
In conclusion, the underwater sound absorption structure has excellent mechanical properties and good underwater sound absorption performance, has more adjustable parameters in the design aspect, including structural parameters and material parameters, can be correspondingly adjusted according to the requirements of actual working conditions, and is simple in structure and easy to manufacture.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
Fig. 1 is a schematic structural diagram of the present invention, wherein (a) is an overall schematic structural diagram, (b) is a front view of an open cell of a metal foam, and (c) is a sectional view of a tapered cell in the structure.
FIG. 2 is a comparison graph of sound absorption coefficients of three different structures of pure polyurethane, foamed aluminum filled polyurethane and open-cell foamed aluminum filled polyurethane after a conical cavity is formed.
FIG. 3 is a graph comparing sound absorption coefficient curves for structures of different damping layer thicknesses.
FIG. 4 is a graph comparing sound absorption coefficient curves for structures of different cell sizes.
Fig. 5 is a graph comparing sound absorption coefficient curves of structures with different foamed metal materials.
FIG. 6 is a graph comparing sound absorption coefficient curves for structures of different polyurethane moduli.
Wherein: 1. an open-cell foam metal skeleton; 2. a soft damping material; 3. a hard damping material cover layer; 4. a cavity.
Detailed Description
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one side", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The foam metal is a functional material which develops rapidly in recent years, is compounded by a metal matrix and mutually communicated pores, and shows excellent characteristics of integrating structure and function. Compared with the traditional dense metal, the foam metal has a plurality of excellent characteristics in structure, such as light weight, high specific strength, high specific rigidity, high damping and the like; as a functional material, it has the advantages of sound absorption/insulation, heat insulation/dissipation, electromagnetic wave shielding and the like.
The invention provides a damping material filled double-pore open-cell foam metal underwater sound absorption structure, which is characterized in that holes are periodically punched in open-cell foam metal, then viscoelastic damping material is filled in the holes, and finally hard polyurethane covers the upper surface and the lower surface of the obtained structure to seal and protect the structure. The damping material is compounded with the double-pore foam metal, so that the mechanical property of the structure is improved, and the sound absorption performance of the damping material is greatly improved. Thereby realized one kind and can bear, had the underwater sound absorption structure of wide band sound absorption effect again.
Referring to fig. 1, the underwater sound absorption structure of dual-pore open-cell foam metal filled with damping material of the present invention includes an open-cell foam metal skeleton 1 for bearing, a soft damping material 2 as a sound absorption material, a hard damping material covering layer 3 and cavities 4, wherein the hard damping material covering layer 3 is disposed on the upper surface and the lower surface of the open-cell foam metal skeleton 1, so as to ensure the sealing performance of the whole underwater sound absorption structure and protect the open-cell foam metal skeleton 1 from seawater corrosion, the open-cell foam metal skeleton 1 is periodically provided with holes to form a plurality of cavities 4, and the soft damping material 2 is disposed in the cavities 4 to improve the low-frequency sound absorption performance of the structure.
The open-cell foam metal framework 1 is made of metal materials such as iron, copper or aluminum through foaming, the porosity is 70-90%, the pore diameter of pores is 0.8-2 mm, and the thickness is 30-50%.
The diameter of the hole of the cavity 4 is larger than the diameter of the foam metal hole of the open-cell foam metal framework 1,
the height is consistent with the thickness of the open-cell foam metal framework 1, and the shape is one or more of a cylinder shape, a cone shape, a ball shape, an ellipsoid shape or a horn shape.
The soft damping material 2 is a viscoelastic material, such as soft rubber or soft polyurethane, and has a young's modulus of 2-10 MPa and a loss factor of more than 0.3, and completely fills the gap of the open-cell foam metal 1.
The hard damping material covering layer 3 is a viscoelastic material, such as hard rubber or hard polyurethane, the Young modulus of the hard damping material covering layer is 30-100 MPa, the thickness of the hard damping material covering layer is 1-3 mm, and the hard damping material covering layer covers the lower surface of the structure and mainly plays a role in protection.
The underwater sound absorption structure of the double-pore open-pore foam metal filled with the damping material can realize a good sound absorption effect between 2 kHz and 20kHz, and is considered as a network interpenetrating composite material because the damping material and the double-pore open-pore foam metal are mutually permeated, the two materials are not simply superposed any more, the vibration of the structure is caused when sound waves are transmitted to the surface of the structure under the existence of the foam metal, and at the moment, because acoustic impedance is not coordinated, the transmission speed of the sound waves in the damping material is far less than that in a foam metal framework, a very strong shearing action is generated near the interface of the two materials, longitudinal waves are converted into transverse waves, and the transverse waves cannot be transmitted into water from the structure, so the transverse waves are scattered and reflected continuously in the structure and are dissipated finally. In addition, compared with single-porosity foam metal, the double-porosity material can effectively widen the sound absorption frequency band, so that the sound absorption curve moves to low frequency. In addition, the foam metal framework has a scattering effect on the ground propagation of the sound waves in the damping material, so that the ground propagation direction of the sound waves is changed, and the propagation distance of the sound waves is increased. In addition, the structure also meets the requirement of maintaining the sound absorption performance under high hydrostatic pressure without reduction; simple structure, maneuverability are strong.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples
Materials for examples:
metal aluminum: it is characterized by having a density of 2700kg/m 3 Young's modulus 70GPa and Poisson's ratio 0.33.
Damping material: it is characterized in that the density is 980kg/m 3 Young's modulus 6MPa, poisson's ratio 0.497, and loss factor 0.5.
Hard polyurethane: it is characterized by a density of 1100kg/m 3 Young's modulus 30MPa, poisson's ratio 0.493, and loss factor 0.3.
Water: it is characterized by a density of 1000kg/m 3 The speed of sound is 1500m/s.
Structural dimensions of the examples:
the simulation calculation uses an open-cell foamed aluminum tetrakaidecahedron model, the side length of a cell is 8mm, the diameter of a foamed aluminum framework is 2mm, the porosity is 70.1%, and the thickness of foamed aluminum is 50mm; the hard damping material covering layers are the same from top to bottom, and the thickness is 2mm; referring to fig. 1 (c), the perforation pattern has a diameter of 10mm at the upper surface and 20mm at the lower surface, and a lattice size of 30mm in a periodic arrangement.
Numerical simulations using the above materials and structural dimensions gave the following results for the examples:
referring to fig. 2, fig. 2 is a graph comparing sound absorption coefficient curves of three different structures, namely a pure polyurethane structure, a foamed aluminum-filled polyurethane structure, and a damping material-filled dual-porosity foamed aluminum structure. The sound absorption coefficient of the pure rubber structure is mainly concentrated on about 0.65 within the frequency range of 2-20 kHz, the sound absorption coefficient of the structure after the foamed aluminum is filled with the polyurethane can reach more than 0.95 at 8kHz, and the open-cell foamed aluminum is below 5.6kHz and even has an inhibiting effect on the sound absorption performance of the polyurethane. The invention can widen the bandwidth of the structure and improve the sound absorption performance of the low-frequency structure. The sound absorption coefficient of the structure reaches more than 0.8 after 6 kHz.
In addition, using the methods and materials described above, to further illustrate the rules of the influence of the structural dimensions on the acoustic performance of the invention, the following comparative examples are provided for the invention:
comparative example 1
Please refer to fig. 3, which is a comparison of sound absorption coefficients of different foamed aluminum filled polyurethane structure thicknesses. During the calculation, the thicknesses of the structures were taken as 30mm, 40mm and 50mm, respectively, while keeping the other parameters unchanged. It can be seen from the figure that the thicker the damping layer, the higher the low frequency sound absorption coefficient of the structure.
Comparative example 2
FIG. 4 shows the comparison of sound absorption coefficients of structures with different foamed aluminum pore sizes. During calculation, the pore diameters of the foamed aluminum are respectively 8mm, 10mm and 12mm, and other parameters are kept unchanged. It can be seen from the figure that as the diameter of the opening increases, the low frequency sound absorption performance is improved, because the restriction of the internal polyurethane is weakened due to the increase of the aperture, the flexibility is increased, and the natural vibration frequency is reduced. Meanwhile, the sound absorption coefficient of a high-frequency area is reduced, because the content of the foamed aluminum is reduced due to the increase of the pore size of the foamed aluminum, and the enhancement of the shearing effect is reduced.
Comparative example 3
Please refer to fig. 5, which is a comparison of sound absorption coefficients of different foam metal structures. In the calculation process, respectivelyThe metal framework is made of aluminum, iron and copper. Wherein the iron is characterized by a density of 7850kg/m 3 Young's modulus 200GPa, poisson's ratio 0.27 and loss factor 0. The copper is characterized by a density of 8960kg/m 3 Young's modulus 120GPa, poisson's ratio 0.34 and loss factor 0. It can be seen from the figure that the sound absorption coefficient of the composite structure of copper and iron is improved compared to foamed aluminium, especially at low frequencies, because copper and iron interact more strongly with polyurethane due to their higher acoustic impedance compared to aluminium.
Comparative example 4
FIG. 6 is a comparison of sound absorption coefficients of structures with different moduli of the flexible polyurethane. In the calculation process, the Young modulus of the soft polyurethane is respectively 2MPa, 6MPa and 10MPa, and other parameters are kept unchanged. It can be seen from the figure that, as the modulus of the soft polyurethane increases, the sound absorption curve moves to a high frequency, and the sound absorption coefficient is improved because the modulus becomes larger to increase the natural vibration frequency of the structure, and the modulus increases to increase the loss modulus at the same time, so the sound absorption coefficient is improved.
According to the data, the technical effects achieved by the invention are as follows:
1. the simulation calculation result of the invention is that the sound absorption coefficient is about 0.8 at 2-20 kHz, the average sound absorption coefficient is more than 0.8, and the requirement of perfect sound absorption in a certain frequency band is met;
2. compared with the traditional sound absorption material, the sound absorption material not only improves the integral sound absorption performance, but also solves the problem of poor low-frequency sound absorption performance;
3. the structure is simple, and the processing is convenient;
4. the mechanical property and the acoustic property of the structure can be changed by changing the parameters of the foam metal, such as the porosity, the pore diameter and the like, so that the requirements of different occasions are met.
According to the characteristics of the underwater sound absorption structure of the dual-pore open-pore foam metal filled with the damping material, the underwater sound absorption structure can be used for manufacturing underwater non-pressure-resistant structures or some bearing structures, such as sound absorption covering layers, non-pressure-resistant shells and the like, and has wide engineering application prospects.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (3)
1. The underwater sound absorption structure is characterized by comprising an open-cell foam metal framework (1), wherein the thickness of the open-cell foam metal framework (1) is 30-50mm, the porosity of the open-cell foam metal framework (1) is 70-90%, the pore diameter of the pores is 0.8-2mm, hard damping material covering layers (3) are respectively arranged on the upper surface and the lower surface of the open-cell foam metal framework (1), the Young modulus of the hard damping material covering layer (3) is 30-100MPa, the thickness of the hard damping material covering layer is 1-3mm, the open-cell foam metal framework (1) and the hard damping material covering layer (3) form a sealing structure, a plurality of holes are periodically arranged in the sealing structure to form a cavity (4), the pore diameter of the cavity (4) is 15-30mm, a soft damping material (2) is filled in the cavity (4), the Young modulus of the soft damping material (2) is 2-10MPa, the loss factor is greater than or equal to 0.3, the frequency of the sound absorption structure is 2-2kHz, and the average sound absorption coefficient is greater than or equal to 0.8.
2. The underwater sound absorption structure filled with dual-pore open-cell foam metal by the damping material as claimed in claim 1, wherein the diameter of the pores of the cavity (4) is larger than the diameter of the foam metal pores of the open-cell foam metal skeleton (1), and the height of the cavity (4) is the same as the thickness of the open-cell foam metal skeleton (1).
3. The underwater sound absorbing structure of a double pore open cell foam metal filled with a damping material according to claim 1, wherein the shape of the cavity (4) is one or more of a cylinder type, a cone type, a sphere type, an ellipsoid type or a horn type.
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