EP-4740205-A2 - A METHOD AND A METAMATERIAL FOR COLLECTING SOUND WAVES

Abstract

The invention relates to a method for collecting sound waves from the environment and/or changing their characteristics and a metamaterial for this process.

Inventors

• BAYGUN, Tuba

Assignees

• Metadyna Mühendislik Sanayi ve Ticaret Anonim Sirketi

Dates

Publication Date

20260513

Application Date

20240625

Claims (20)

1. 1. A method for collecting sound waves from the environment to an acoustic metamaterial (1), characterized in that normal incident waves (n) and random incident waves (r) arriving independently on the metamaterial (1) are guided through two independent paths to a common point in the cell
2. 2. A method according to claim 1, characterized in that said normal incident waves (n) and random incident waves (r) are guided to a common point by a collector (2) generating independent normal wave input (Rn) and random wave input (Rr).
3. 3. A method according to claim 1, characterized in that said normal incident waves (n) and random incident waves (r) are directed to a common point by means of a collector (2) generating independent normal wave inlet (Rn) and random wave inlet (Rr), and a normal wave channel (Cn) and a random wave channel (Cr), respectively, connected to the inputs.
4. 4. A method according to any one of claims 1-3, characterized in that said common point is within a metamaterial inlet (1.1) connected to a cell (H) comprising a metamaterial (1) or within a channel comprising the cell (H).
5. 5. A method according to any of one the preceding claims, characterized in that said common point is an interference zone (z) where normal incident waves (n) and random incident waves (r) will be interfered.
6. 6. A method according to claim 5, characterized in that; the primary distance (Ln) and the secondary distance (Lr) are selected in accordance with the following formula r = to - s^/2 wherein the primary distance (Ln) is the distance from said normal wave inlet (Rn) to the interference zone (z), the secondary distance (Lr) is the distance from said random wave inlet (Rr) to the interference zone (z), and the s is a user-selected wavelength adjustment parameter.
7. 7. A method according to claim 6, characterized in that said s value is selected in such a way that it is Q.68 s 1.32.
8. 8. A method according to claim 6, characterized in that said s value is selected in such a way that it it is s < 0.68 or s > 1.32 .
9. 9. A device for collecting sound waves from an environment, characterized in that it comprises the following: a metamaterial (1) having a metamaterial input (1.1) and at least one cell (H) connected to the metamaterial input (1.1) through which the waves are introduced, a collector (2) placed in the metamaterial inlet (1.1), having an opening (2.3) positioned in connection with said metamaterial inlet (1.1), having a surface so as to form a normal wave inlet (Rn) for the transmission of normal incident waves (n) from said opening (2.3) to a point in said metamaterial (1) and a random wave inlet (Rr) for the transmission of random incident waves (r) to said same point by a different path than said normal wave inlet (Rn).
10. 10. A device according to claim 9, characterized in that said collector (2) comprises a surface such that said collector lower surface (2.2) and said metamaterial upper surface (1.3) of said metamaterial (1) together form a random wave inlet (Rr).
11. 11. A device according to claim 9 or 10, characterized in that said collector (2) comprises a surface such that the collector lower surface (2.2) and the metamaterial upper surface (1.1) of said metamaterial (1) form a random inlet section (Cr) to guide random incident waves (r) towards said common point.
12. 12. A device according to any one of claims 9-11, characterized in that it comprises guides (2.5) to be connected from said random wave inlet (Rr) to said common point.
13. 13. A device according to claim 9, characterized in that said collector (2) comprises a surface at the end of the opening (2.3) together with the base of said metamaterial inlet (1.1) to form a normal wave inlet (Rn).
14. 14. A device according to claim 9 or 13, characterized in that said collector (2) comprises a surface at the end of the opening (2.3) and together with the base of said metamaterial inlet (1.1) to form a normal inlet channel (Cr) for guiding normal incident waves (n) towards said common point.
15. 15. A device according to claim 9 or 12, characterized in that said cell (H) comprises a channel with at least a part of the surface of said cell (H) discharged and a layer (4) positioned in said discharged part, said layer (4) being positioned on said collector (2) with said collector inner surface (2.2).
16. 16. A device according to claim 15 , characterized in that said layer (4) consists of multiple parts to form said opening (2.3) when said metamaterial is placed in the discharged part.
17. 17. A device according to claim 9, characterized in that said collector (2) has a collector outer surface (2.1) curved towards said opening (2.3).
18. 18. A device according to claim 9, characterized in that the guiding the normal incidence wave (n) is curved from said opening (2.3) towards said common point.
19. 19. A device according to claim 9, characterized in that it comprises a router (3) positioned in said opening (2.3) and increasing its cross-sectional area towards its base.
20. 20. A device according to claim 18, characterized in that it comprises a surface extending inclined towards the base of said router (3).

Description

A METHOD AND A METAMATERIAL FOR COLLECTING SOUND WAVES Technical Field The invention relates to a method for collecting sound waves from the environment and/or changing their characteristics and a metamaterial for this process. The present invention relates to a normal and random sound waves router, collector and thus a method of directing and collecting sound waves from different angles, which can be used for passive, resonating or meta-based materials developed for the purpose of directing, isolating, or damping/absorbing sound waves in areas such as construction, architecture, automotive, aviation, space, white goods, machinery industry, etc. State of the Art Traditional materials such as sponge, felt, textile wastes, glass wool, rock wool, etc. are generally used for sound absorption in the field of acoustics. However, these materials are fairly inefficient due to wavelength constraints, especially at low frequencies (in the range of about 50 Hz-800 Hz). The effective thickness of the material increases as the frequency increases, and the performances of these materials increase as the effective thickness reaches values comparable to the wavelength of the sound. Sound absorption is provided by the conversion of sound energy into heat energy in the insulation material. Traditional materials generally provide this energy conversion in three ways. The first is the visco-thermal and scattering effects of the sound in the material as a result of the friction in the cavity and structure, the second is the visco-elastic energy losses caused by the sound pressure in the material due to the deformation elasticity on the elastic particles, and the third is the tortuosity formed by the penetration path length of the sound in the material. However, all these energy conversions are directly related to the effective thickness of the material. The low-frequency sound wave easily passes through the material by partially creating these effects in the material. Therefore, these materials cannot be very efficient at low frequencies. Therefore, researchers are trying to develop effective metamaterials at low frequencies. Metamaterials are artificial structures that do not exist in nature, usually containing micro- or macro-resonance cells of periodic and lower wavelength sizes. The metamaterials can be tuned to the desired frequency (frequency-tuning) depending on the appropriate geometry design and the characteristics of the main materials used. However, metamaterials can generally perform in the narrow band in terms of sound absorption. In order for metamaterials to operate in a wider band, they need to be developed in order to prevent their effects such as having different multi-cell architectures, therefore containing intricate and complex structures that make mass production difficult and decreasing absorption ability at higher frequencies. Therefore, research has been carried out on metamaterials, especially in recent years, and various developments have been made on these materials for low frequencies, although they are not yet widely used industrially. Researchers working in the field of acoustics are trying to develop various materials that are effective at low frequencies. Metamaterials, which are one of them, are artificial structures that do not exist in nature, usually containing micro- or macro-resonance cells of periodic and lower wavelength sizes. The metamaterials can be tuned to the desired frequency (frequency-tuning) depending on the appropriate geometry design and the characteristics of the main materials used. However, metamaterials can generally perform in the narrow band in terms of sound absorption. In order for metamaterials to operate in a wider band, further developments need to be made in order to eliminate problems such as the necessity of having different multi-cell architectures, therefore the necessity of containing intricate and complex structures that make mass production difficult, and the decrease in absorption ability at higher frequencies. In order for metamaterials to provide high performance, the sound pressure must be strong enough to resonate the material cells, that is, to overcome cell structural inertia (cell mass resistance). Cells designed specifically for lower frequencies operate with less efficiency because they have greater cell mass resistance and/or cannot resonate strongly enough if exposed to low-amplitude sound waves. In relation to this, the sound wave must be applied directly to the material cells in order for the metamaterial cells to be efficient. The sound waves with the random incidence angle, which constitute the majority of the sound energy, cannot be effectively covered by the metamaterial. CN114255723A discloses a metamaterial for sound reduction. Said metamaterial contains a circular and concentric double case, and while one of these cases is filled with soundabsorbing materials, the other case is arranged to form a labyrinth structure within itself. A