RU2528356C1 - Kochetov's sound-absorbing structure - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: sound-absorbing structure comprises perforated surfaces, between which the multilayer sound-absorbing element is placed. The structure consists from symmetrically located perforated walls, between which the multilayer sound-absorbing element made in the form of five layers, two of which, adjoining to perforated walls, are sound-absorbing layers from materials of various density. Three central layers are combined, and the axial layer is made as sound-absorbing, and two symmetrically located layers are made from sound reflecting material from complex profile. As a sound-absorbing material the plates from mineral wool are used. The sound-absorbing element is lined by an acoustically transparent material.

EFFECT: enhanced efficiency of sound absorption and reliability of the structure in general.

4 cl, 1 dwg, 1 tbl

Description

The invention relates to industrial acoustics.

The closest technical solution to the technical nature and the achieved result is a sound-absorbing element used as a facing of industrial premises, known from the RF patent No. 2463412 (prototype).

The disadvantage of the technical solution adopted as a prototype is the relatively low noise reduction due to the presence of voids between the layers, where there is no sound absorption between the layers of the sound absorber.

The technical result is an increase in the efficiency of sound attenuation and the reliability of the structure as a whole.

This is achieved by the fact that in a sound-absorbing structure containing perforated surfaces between which a multilayer sound-absorbing element is placed, the structure consists of symmetrically arranged perforated walls, between which a multilayer sound-absorbing element is made in the form of five layers, two of which are adjacent to the perforated walls are sound-absorbing layers of materials of different densities, and the three central layers are combined, and the axial layer is made n sound-absorbing, and two symmetrically adjacent layers adjacent to it are made of sound-reflecting material of a complex profile, while each of the perforated walls has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, and the shape of the hole can be made in the form of holes of a round, triangular, square, rectangular or rhomboid profile, while in the case of non-circular holes, the maximum diameter inscribed in a polygon should be considered as a conditional diameter to the circumference, and as sound-absorbing material, slabs made of rockwool basalt type mineral wool or URSA type mineral wool or P-75 basalt wool or glass wool lined with glass wool are used as sound absorbing material, the sound-absorbing element along its entire surface lined with an acoustically transparent material, such as fiberglass type E3-100 or polymer type "poviden."

The drawing shows a diagram of a sound-absorbing structure.

The sound-absorbing design is made in the form of symmetrically arranged perforated 1 and 7 walls, between which there is a multilayer sound-absorbing element made in the form of five layers, two of which adjacent to the perforated 1 and 7 walls are sound-absorbing layers 2 and 6 of materials of different densities, and the three central layers 3,4,5 are combined, and the axial layer 4 is made sound-absorbing, and two symmetrically adjacent adjacent layers 3 and 5 are made of sound-reflecting material of complex A profile consisting of uniformly distributed hollow tetrahedra, which allow reflecting sound waves incident in all directions. Each of the perforated walls has the following perforation parameters: the diameter of the holes is 3 ÷ 7 mm, the percentage of perforation is 10% ÷ 15%, and the shape of the holes can be made in the form of holes of a round, triangular, square, rectangular or diamond-shaped profile, in this case non-circular holes as the conditional diameter should be considered the maximum diameter of the circle inscribed in the polygon.

Each of the perforated walls 1 and 7 can be made of structural materials with a layer of soft vibration-damping material deposited on their surfaces from one or two sides, for example, VD-17 mastic or “Gerlen-D” type material, while the ratio between the thicknesses of the material and vibration-damping coating lies in the optimal range of values: 1 / (2.5 ... 3.5).

Each of the perforated walls 1 and 7 can be made of stainless steel or galvanized sheet with a thickness of 0.7 mm with a protective and decorative polymer coating of 50 μm thick or Polyester 25 μm thick, or aluminum sheet 1.0 mm thick and a coating thickness of 25 microns. The perforation coefficient of perforated sheets is taken to be equal to or more than 0.25.

Each of the perforated walls 1 and 7 can be made of solid, decorative vibration damping materials, such as plastic compound type "Agate". “Anti-vibration”, “Shvim”, the inner surface of the perforated surface facing the sound-absorbing structure, lined with an acoustically transparent material, such as fiberglass type E3-100 or polymer type “visible”, or non-woven materials, such as “lutrasil”.

As the material of the sound-reflecting layers 3 and 5, a material based on aluminum-containing alloys can be used, followed by filling them with titanium hydride or air with a density in the range of 0.5 ... 0.9 kg / m ³ with the following strength properties: compressive strength in the range of 5 ... 10 MPa, bending strength within 10 ... 20 MPa, for example foam aluminum, or soundproofing boards based on glass staple fiber of the “Shumostop” type with a material density of 60 ÷ 80 kg / m ^{3 were used} .

As sound-absorbing material of layers 2, 4 and 6, rockwool-type mineral wool or URSA-type mineral wool, or P-75-type basalt wool, or glass wool lined with glass wool, or foamed polymer, for example, can be used. polyethylene or polypropylene. Moreover, the sound-absorbing material over its entire surface is lined with an acoustically transparent material, for example, EZ-100 fiberglass or a “visible” polymer, or the surface of the fibrous sound absorbers is treated with special porous paints that allow air to pass through (for example, Acutex T) or coated with breathable fabrics or non-woven materials, e.g. Lutrasil. In addition, as the sound-absorbing material of layers 2 and 4, a porous sound-absorbing material, for example, foam aluminum, or cermets, or a shell rock with a porosity degree in the range of optimal values of 30–45%, or metal foam, or a pressed material can be used crumbs from solid vibration-damping materials, for example elastomer, polyurethane, or plastic compound such as Agate, Anti-Vibrate, Shvim, and the size of the fractions of the crumb lies in the optimal range of values: 0.3 ... 2.5 mm, and can also be used porous mineral piece materials were used, for example pumice, vermiculite, kaolin, slag with cement or other binder, or synthetic fibers, while the surface of the fibrous absorbers is treated with special porous paints that allow air to pass through, for example, Acutex T or coated with breathable fabrics or non-woven materials e.g. Lutrasil.

To reduce or correct the reverberation time of premises, sound-absorbing materials and structures (sound absorbers) are used in its decoration.

Porous sound absorbers are made in the form of plates that are attached to the enclosing surfaces directly or on the basis of light and porous mineral piece materials - pumice, vermiculite, kaolin, slags, etc. with cement or other binder. Such materials are strong enough and can be used to reduce noise in corridors, foyers, staircases of public and industrial buildings.

The raw materials for their production are wood fibers, mineral wool, glass wool, synthetic fibers. The surface of the fibrous sound absorbers is treated with special porous paints that allow air to pass through (for example, Acutex T), or covered with breathable fabrics or non-woven materials, such as Lutrasil.

Currently, fibrous sound absorbers are the most common in construction practice. They not only proved to be the most effective from an acoustic point of view in a wide frequency range, but also meet the increased requirements for room design.

Table 1 Material, object 125 250 500 1000 2000 4000 Unpainted concrete 0.01 0.012 0.016 0.019 0.023 0.035 Painted concrete 0.009 0.011 0.014 0.016 0.017 0.018 Marble 0.01 0.01 0.01 0.013 0.015 0.017 Brick unpainted 0.024 0.025 0.031 0.042 0.049 0.07 Painted brick 0.012 0.013 0.017 0.02 0.023 0.025 Gypsum plaster 0.02 0.026 0.04 0.062 0.058 0.028 Lime plaster 0.024 0.046 0.06 0.085 0.043 0.056 Wood-fiber boards (MDF), 12 mm 0.22 0.3 0.34 0.32 0.41 0.42 Gypsum panel 10 mm to 100 mm from the wall 0.41 0.28 0.15 0.06 0.05 0.02 Parquet floor 0.04 0.04 0.07 0.06 0.06 0.07 Boardwalk Floor 0.2 0.15 0.12 0.1 0.08 0.07 Metlakh tile 0.01 0.01 0.02 0.02 0.02 0.03 Glazed Window Bindings 0.35 0.25 0.18 0.12 0.07 0.04 Lacquered Doors 0.03 0.02 0.05 0.04 0.04 0.04 Wool carpet 9 mm thick for concrete 0.02 0.08 0.21 0.26 0.27 0.37

In fiber absorbers, the dispersion of the energy of air vibrations and its transformation into heat occurs at several physical levels. Firstly, due to the viscosity of the air, and there is a lot of it in the interfiber space, the oscillation of air particles inside the absorber leads to friction. In addition, there is air friction on the fibers, the surface of which is also large. Thirdly, the fibers rub against each other and, finally, energy dissipation occurs due to the friction of the crystals of the fibers themselves. This explains that at medium and high frequencies the sound absorption coefficient of fibrous materials is in the range of 0.4 ... 1.0. The sound absorption coefficient α is equal to the ratio of the energy of the air vibration not reflected (absorbed inside and passed through) from the surface to the total energy acting on the surface. Sound absorption coefficients for most building materials are shown in table 1.

Sound-absorbing design works as follows.

Sound energy from equipment located in the room, or other object emitting intense noise, passing through the perforated walls 1 and 7 falls on layers 2 and 6 from soft sound-absorbing material of different densities, and then it encounters layers 3 and 5 of sound-reflecting material, respectively a complex profile consisting of uniformly distributed hollow tetrahedra, allowing to reflect sound waves incident in all directions, but part of the sound energy passes through layers 3 and 5 of sound-reflecting materials ala, and it interacts with the axial layer of sound absorbing material 4, where the final dissipation of the sound energy.

Layers 2 and 6 of soft sound-absorbing material of different densities can be made, for example, of basalt or glass fiber. In fibrous absorbers, the dissipation of the energy of air vibrations and its transformation into heat occurs at several physical levels. Firstly, due to the viscosity of the air, and there is a lot of it in the interfiber space, the oscillation of air particles inside the absorber leads to friction. The transition of sound energy into thermal energy (dissipation, energy dissipation) occurs in the pores of a sound absorber, which are the Helmholtz resonator model, where energy losses occur due to friction of the mass of air in the resonator neck oscillating with the frequency of excitation on the neck wall, which has the form of a branched sound absorber pore network. In addition, there is air friction on fibers, the surface of which is also large. Thirdly, the fibers rub against each other and, finally, energy dissipation occurs due to the friction of the crystals of the fibers themselves. This explains that at medium and high frequencies the sound absorption coefficient of fibrous materials is in the range of 0.4 ... 1.0.

Claims (4)

1. A sound-absorbing structure containing perforated surfaces between which a multilayer sound-absorbing element is placed, characterized in that it is made in the form of symmetrically arranged perforated walls, between which a multilayer sound-absorbing element is made in the form of five layers, two of which are adjacent to the perforated walls are sound-absorbing layers of materials of different densities, and the three central layers are combined, and the axial layer is made of sound absorption and two symmetrically adjacent layers adjacent to it are made of sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedrons, which allow reflecting sound waves incident in all directions, each of the perforated walls has the following perforation parameters: hole diameter - 3 ÷ 7 mm, the percentage of perforation 10% ÷ 15%, and the shape of the holes can be made in the form of holes of a round, triangular, square, rectangular or rhomboid profile, while in the case of For open holes, the maximum diameter of the circle inscribed in the polygon should be considered as the conditional diameter, and as sound absorbing material, slabs made of rockwool based mineral wool or URSA type mineral wool or P-75 basalt wool, or glass wool with glass fiber lining, and the sound-absorbing element over its entire surface is lined with an acoustically transparent material, such as fiberglass type E3-100 or polymer type "see". 2. The sound-absorbing structure according to claim 1, characterized in that the porous sound-absorbing material, for example, foam aluminum, or cermets, or a shell rock with a degree of porosity in the range of optimal values: 30 ÷ 45%, or metal porol, is used as the sound-absorbing material. or a material in the form of compressed crumb from solid vibration-damping materials, for example elastomer, polyurethane or plastic compound such as Agate, Anti-Vibrate, Shvim, and the size of the fractions of the crumb lies in the optimal range of values 0.3 ... 2.5 mm, and also porous mineral piece materials can be used, for example pumice, vermiculite, kaolin, slags with cement or other binder, or synthetic fibers, while the surface of the fibrous absorbers is treated with special porous paints that allow air to pass through, for example, type Acutex T or coated with breathable fabrics or non-woven materials, such as Lutrasil. 3. The sound-absorbing structure according to claim 1, characterized in that the material based on aluminum-containing alloys is used as a sound-reflecting material, followed by filling them with titanium hydride or air with a density in the range of 0.5 ... 0.9 kg / m ³ with the following strength properties : compressive strength in the range of 5 ... 10 MPa, bending strength in the range of 10 ... 20 MPa, for example foamed aluminum, or soundproofing boards based on glass staple fiber of the “Shumostop” type with a material density of 60 ÷ 80 kg / m ³ . 4. The sound-absorbing structure according to claim 1, characterized in that each perforated wall can be made of structural materials with a layer of soft vibration-damping material deposited on their surface from one or two sides, for example, VD-17 mastic or “Gerlen-D” type material the ratio between the thicknesses of the material and the vibration damping coating lies in the optimal range of 1 / (2.5 ... 3.5), either from stainless steel or a galvanized sheet 0.7 mm thick with a polymer protective and decorative coating of the Pural type t with a thickness of 50 microns or Polyester 25 microns thick, or an aluminum sheet 1.0 mm thick and a coating thickness of 25 microns, or from hard decorative vibration damping materials, such as plastic compounds such as Agate, Anti-Vibrate, Shvim.

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