RU2531154C1 - Sound-absorbing structure - Google Patents

Abstract

FIELD: physics, acoustics.

SUBSTANCE: invention relates to industrial acoustics and can be used to reduce machine drive noise, in facing industrial facilities and in other sound-absorbing structures. The sound-absorbing structure has perforated surfaces with a multilayer sound-absorbing element placed in between said surfaces. The structure is in the form of symmetrically arranged perforated walls, between which there is a sound-absorbing element which is the form of three layers: a centre layer made of sound-reflecting material with a complex shape, consisting of uniformly distributed hollow tetrahedrons, and symmetrically adjacent thereto sound-absorbing layers made of materials of different density. The perforations can be circular, triangular, square, rectangular or rhomboid. The sound-absorbing material used is in the form of Rockwool mineral wool boards on a basalt base or URSA mineral wool or P-75 basalt wool or glass wool lined with glass felt.

EFFECT: high efficiency of noise-absorption and reliability of the structure.

4 cl, 1 tbl, 1 dwg

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, it is made in the form of symmetrically arranged perforated walls, between which there is a sound-absorbing element made in the form of three layers: a central layer of sound-reflecting material, a complex profile, consisting of uniformly distributed hollow tetrahedra, allowing to reflect sound waves incident in all directions, and symmetrically adjoining them to it sound-absorbing layers of materials of different densities, each of the perforated walls has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage 10% ÷ 15%, and the shape of the holes can be made in the form of round, triangular, square holes , rectangular or diamond-shaped profile, while in the case of non-circular holes, the maximum diameter of the circle inscribed in the polygon should be considered as the conditional diameter, and plates made of m are used as sound-absorbing material rockwool type basalt wool or URSA type mineral wool or P-75 basalt wool or glass wool lined with glass wool, and the sound-absorbing element is lined with acoustically transparent material over its entire surface, such as E3-100 fiberglass or “poviden” polymer.

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

The sound-absorbing structure is made in the form of symmetrically arranged perforated walls 1 and 5, between which there is a sound-absorbing element made in the form of three layers: the central layer 3 of sound-reflecting material, a complex profile consisting of uniformly distributed hollow tetrahedrons, which allow reflecting sound waves incident in all directions , and symmetrically adjacent to it sound-absorbing layers 2 and 4 of materials of different densities. 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 5 can be made of structural materials, with a layer of soft vibration-damping material, for example, VD-17 mastic or “Gerlen-D” type material applied on their surface from one or two sides, and 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 5 can be made of stainless steel or a 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 5 can be made of solid, decorative vibration-damping materials, such as plastic compounds such as Agate, Anti-Vibrate, Shvim, and the inner surface of the perforated surface facing the sound-absorbing structure is lined with an acoustically transparent material, for example fiberglass type E3-100 or polymer type "poviden", or non-woven materials, such as "lutrasil."

As the material of the sound-reflecting layer 3, 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 and 4, 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, such as polyethylene or polypropylene. Moreover, the sound-absorbing material is lined with an acoustically transparent material over its entire surface, for example, E3-100 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 degree of porosity in the range of optimal values: 30–45%, or metal foam, or a material in the form of pressed crumbs from solid vibration-damping materials, for example elastomer, polyurethane, or plastic compound like “Agate”, “Anti-vibration”, “Shvim”, and the size of the crumbs fractions lies in the optimal range of values: 0.3 ... 2.5 mm, and they could also 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 absorbers is treated with special porous air-permeable paints (e.g. Acutex T) or coated 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 Fiberboard (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 0.03 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 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. In addition, there is air friction on the fibers, the surface of which is also large. Secondly, 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 another object that emits intense noise, passing through the perforated walls 1 and 6, enters layers 2 and 5 of the sound-reflecting material of a complex profile, consisting of uniformly distributed hollow tetrahedrons that allow reflecting incident in all directions sound waves, and which are located respectively at the perforated walls 1 and 6, and then falls on layers 3 and 4 of soft sound-absorbing material of different densities located in two layers (for example, nnogo basalt or glass fibers). 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. Secondly, 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. 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 there is a sound-absorbing element made in the form of three layers: a central layer of sound-reflecting material of a complex profile, consisting of from uniformly distributed hollow tetrahedra, allowing to reflect sound waves incident in all directions, and symmetrically adjacent it of sound-absorbing layers of materials of different densities, each of the perforated walls has the following perforation parameters: hole diameter - 3 ÷ 7 mm, perforation percentage - 10% ÷ 15%, and the shape of the holes can be made in the form of round, triangular, square holes, a rectangular or diamond-shaped profile, while in the case of non-circular holes, the maximum diameter of the circle inscribed in the polygon should be considered as a conditional diameter, and mines made of mines are used as sound-absorbing material rockwool-type basalt wool or URSA-type mineral wool or P-75 basalt wool or glass wool lined with glass wool, and the sound-absorbing element is lined with acoustically transparent material over its entire surface, such as fiberglass type E3-100 or "poviden" polymer. 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 material in the form of compressed 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 also porous mineral piece materials, for example pumice, vermiculite, kaolin, slags with cement or other binder, or synthetic fibers can be used, 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 nonwoven 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, for example, VD-17 mastic or Gerlen-type material, deposited on their surface D ", while the ratio between the thicknesses of the material and the vibration damping coating lies in the optimal range of values: 1 / (2.5 ... 3.5), or stainless steel, or a galvanized sheet 0.7 mm thick with a polymer protective and decorative coating of the type Pural with a thickness of 50 μm, or Polyester with a thickness of 25 μm, or an aluminum sheet with a thickness of 1.0 mm and a coating thickness of 25 μm, or from solid, decorative vibration-damping materials, such as plastic compounds such as Agate, Anti-Vibrate, Shvim, and the inner surface of the perforated surface facing the sound-absorbing structure is lined with an acoustically transparent non-woven material, for example Lutrasil.

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