Method and metamaterial for collecting acoustic waves

Abstract

The invention relates to a method for collecting sound waves from an environment and / or changing the properties thereof and to a metamaterial for use in such a process.

Description

Technical Field

[0001] The present invention relates to a method for collecting sound waves from the environment and / or altering their properties, and metamaterials for the process.

[0002] This invention relates to a normal and random acoustic wave circuit, collector, and therefore to a method for guiding and collecting acoustic waves from different angles, which can be used with passive, resonant or element-based materials. This method has been developed for guiding, isolating or damping / absorbing acoustic waves in areas such as architecture, construction, automotive, aviation, aerospace, white goods, and machinery industries. Background Technology

[0003] Traditional materials such as sponge, felt, textile waste, glass wool, and rock wool are commonly used for sound absorption in the acoustics field. However, these materials are quite inefficient due to wavelength limitations, especially at low frequencies (approximately 50Hz-800Hz). The effective thickness of the material increases with increasing frequency, and the performance of these materials improves as the effective thickness reaches a value comparable to the wavelength of the sound.

[0004] Sound absorption is achieved by converting acoustic energy into heat energy within insulating materials. Traditional materials typically provide this energy conversion in three ways. The first is the viscous heating and scattering effect of sound within the material due to friction in cavities and structures; the second is the viscoelastic energy loss caused by sound pressure within the material due to the deformation elasticity of elastic particles; and the third is the tortuosity formed by the length of the sound's penetration path within the material. However, all these energy conversions are directly related to the effective thickness of the material. Low-frequency sound waves easily penetrate materials by partially generating these effects. Therefore, these materials are not very effective at low frequencies.

[0005] Therefore, researchers are attempting to develop effective metamaterials at low frequencies. Metamaterials are artificial structures that do not exist in nature, typically comprising periodic micro-resonant units or macro-resonant units with low wavelength dimensions. Depending on the appropriate geometry and the properties of the primary materials used, metamaterials can be tuned to desired frequencies (frequency tuning). However, metamaterials typically perform sound absorption in a narrow band. To enable metamaterials to operate over a wider frequency band, they need to be developed to prevent problems such as those caused by different multi-unit architectures, resulting in intricate structures that hinder large-scale production and reduce absorption capacity at higher frequencies.

[0006] Therefore, metamaterials have been studied, especially in recent years, and various developments have been made for these materials used at low frequencies, although they are not yet widely used in industry. Researchers working in the field of acoustics are attempting to develop a variety of materials that are effective at low frequencies. One such material is a man-made structure that does not exist in nature, typically containing periodic micro-resonant units or macro-resonant units with low wavelength dimensions. Depending on the appropriate geometric design and the properties of the main materials used, metamaterials can be tuned to a desired frequency (frequency tuning).

[0007] However, metamaterials typically perform sound absorption in narrow bands. To enable metamaterials to operate over wider frequency bands, further development is needed to address issues such as the need for different multi-unit architectures, and therefore the inclusion of intricate structures that hinder mass production, as well as the reduction in absorption capacity at higher frequencies. For metamaterials to deliver high performance, the sound pressure must be strong enough to make the material units resonate, i.e., to overcome the unit structure inertia (unit mass drag). Units specifically designed for lower frequencies operate with lower efficiency because they have greater unit mass drag and / or do not resonate strongly enough when exposed to low-amplitude sound waves.

[0008] Relatedly, sound waves must be applied directly to the material unit in order for the metamaterial unit to be effective. Sound waves with random incident angles, which constitute the majority of sound energy, cannot be effectively covered by the metamaterial.

[0009] CN114255723A discloses a metamaterial for sound reduction. The metamaterial comprises a circular and concentric double shell, and while one of these shells is filled with a sound-absorbing material, the other shell is arranged to form a labyrinth structure within itself.

[0010] CN218243835U discloses another metamaterial. Here, channels extending radially through a body surrounding a center are used. The invention can perform multi-directional, multi-band damping at lower wavelengths in this structure.

[0011] A sound-absorbing metamaterial is disclosed in WO2017093693A1. Here, according to the inlet provided on the upper surface of the cylindrical structure, there are channels extending in the axial and radial directions in the form of grooves.

[0012] Therefore, all of the above problems require innovation in the relevant fields.

[0013] The purpose of this invention

[0014] The main objective of this invention is to provide a method for acquiring / collecting normal sound waves and random sound waves from the environment, as well as metamaterial structures associated with this method.

[0015] The purpose of this invention is to provide a method for altering properties by interfering with normal and random sound waves from the environment, and metamaterial structures associated with this method.

[0016] The objective of this invention is to improve the sound absorption performance of metamaterials. In particular, it provides efficiency especially in the low-frequency region without exhibiting performance degradation at high frequencies.

[0017] The purpose of this invention is to improve filtering performance.

[0018] The purpose of this invention is to provide more compact metamaterials by reducing the thickness requirements in metamaterials. Summary of the Invention

[0019] The present invention essentially relates to a method for guiding both non-directional (i.e., random sound waves) and normal sound waves to a common point (e.g., a metamaterial arranged for the sound waves, particularly an absorption / damping / filtering channel of the metamaterial), and a collector that provides such guidance.

[0020] In the metamaterial, the collector is located at the unit entrance of the metamaterial, thereby creating at least two distinct entrances: one for normally incident waves and the other for randomly incident waves. These entrances preferably guide the sound waves to the same point within the metamaterial, specifically to the same channel, through a channel created by the metamaterial and the collector.

[0021] Therefore, in addition to normal sound waves, random sound waves are also acquired / collected from the environment.

[0022] Furthermore, the collector ensures that normal and random sound waves are interfered with by specifically directing the sound waves to a common metamaterial channel with an entrance provided by it.

[0023] The interference mentioned here can occur constructively or destructively based on the adjustment of the distance between the point where the normal and random acoustic waves enter the metamaterial and the point where they reach the unit channel. Therefore, significant performance improvements in absorption or filtering properties can be achieved. Consequently, the need for larger metamaterials to improve these properties is eliminated, and the performance can be achieved with a much smaller structure. Attached Figure Description

[0024] The accompanying drawings and related descriptions are provided below for better explanation of the present invention.

[0025] Figure 1 It is an isometric image of the collector and the metamaterial assembly.

[0026] Figure 1a These are isometric images of the implementation of the collector.

[0027] Figure 1b yes Figure 1a The top image.

[0028] Figure 1c yes Figure 1b A cross-sectional view along the AA axis.

[0029] Figure 1d This is a cross-sectional image of another implementation of the collector.

[0030] Figure 1e It is shown along the AA axis. Figure 1 A cross-sectional view of the acoustic inlet.

[0031] Figure 1f yes Figure 1 A cross-sectional view along the AA axis.

[0032] Figure 2 This is a side view of another embodiment of the collector and metamaterial assembly.

[0033] Figure 3 It is an isometric image of the acoustic circuit.

[0034] Figure 4 This is an isometric image of an assembly of another embodiment of a collector with metamaterials.

[0035] Figure 4a yes Figure 4 The lower isometric image of the collector in the image.

[0036] Figure 4b yes Figure 4 The upper isometric image of the collector in the image.

[0037] Figure 4c yes Figure 4b A cross-sectional view along the AA axis.

[0038] Figure 5 It is a dashed isometric image of a metamaterial used as a masking layer.

[0039] Figure 5a yes Figure 5 Isometric images of the masking layer of the metamaterial in the image.

[0040] Figure 5b yes Figure 4 The collector will be placed on the isometric image of the segment on the metamaterial.

[0041] Figure 5c yes Figure 5 The upper part of the image.

[0042] Figure 5d This is an image of a circular-square inlet piece mounted on a metamaterial, which allows... Figure 4The collector is placed in Figure 5 On metamaterials.

[0043] Figure 6 It is shown Figure 2 and Figure 4 A cross-sectional image of the absorption / damping / filtration mechanism in the embodiment described above.

[0044] Figure 6a It is shown Figure 5 A schematic cross-sectional image of the absorption / damping / filtration mechanism in the embodiment.

[0045] Figure 6b It is shown Figure 5c A schematic cross-sectional image of the absorption / damping / filtration mechanism in the embodiment.

[0046] Figure 7 This shows the amplitude-wavelength diagram of destructive interference for various s values.

[0047] Figure 8 This shows the amplitude-wavelength diagram of constructive interference for various s values.

[0048] Figure 9 This is when there is a device with metamaterials (n+r waves) and no device with metamaterials (n only) and experimental sound absorption coefficients.

[0049] Definition of components / parts / components in this invention

[0050] To better explain the invention, the components and parts in the accompanying drawings are numbered, and the corresponding numbers are given below.

[0051] 1. Metamaterials

[0052] 1.1. Metamaterials Entry Point

[0053] 1.2. Unit Entrance

[0054] 1.3. Metamaterial Upper Surface

[0055] 2. Collector

[0056] 2.1. Collector outer surface

[0057] 2.2. Inner surface of the collector

[0058] 2.3. Entrance Opening

[0059] 2.4. Collector inlet surface

[0060] 2.5. Guide

[0061] 3. Acoustic circuit breaker

[0062] 3.1. Acoustic circuit tip

[0063] 3.2. Acoustic circuit base

[0064] 4. Layer

[0065] 5. Opening layer

[0066] Rn. Normal wave entrance

[0067] Rr. Random Wave Entrance

[0068] Cn. Normal Entry Section

[0069] Cr. Random Entry Section

[0070] Ln. Main distance

[0071] Lr. Secondary Distance

[0072] Lc. Total length

[0073] Lcn. Normal entrance channel length

[0074] Cp. Cutoff point

[0075] n. normal wave

[0076] r. random wave

[0077] z. Interference region

[0078] H. Unit

[0079] A. AA axis Detailed Implementation

[0080] The subject of this invention relates to a method for collecting sound waves from the environment and / or altering their properties, and metamaterials for this process.

[0081] In the method described, normal incident waves (n) and random incident waves (r) are collected. Throughout the specification, a normal wave (n) is defined as a wave perpendicular to the surface into which it will enter. A random incident wave (r) is a wave at a different angle to the perpendicular to the surface.

[0082] The normal incident wave (n) and the random incident wave (r) originate from different inlets, and the surfaces provided along the continuation of these inlets act as barriers and alter the direction of the sound waves, carrying both the normal incident wave (n) and the random incident wave (r) to a common collection point. In this invention, the inlets of the normal incident wave (n) and the random incident wave (r) are defined as the normal wave inlet (Rn) and the random wave inlet (Rr), respectively.

[0083] Here, guidance is performed by two distinct sound waves that are independent of each other, and preferably, no interference occurs between the normal incident wave (n) and the random incident wave (r) until the common point is reached.

[0084] In a preferred embodiment, the normal incident wave (n) and the random incident wave (r) carried by the two different paths can interfere at the common point. In this case, the common point can be referred to as the interference region (z).

[0085] As a result of the interference, the characteristics of the wave may change. When the changes in wave characteristics are manipulated as needed, they can be used for absorption / damping and filtering processes.

[0086] During the disclosure of this invention, it was surprisingly observed that after sound waves, normal incident waves (n), and random incident waves (r) carried by independent paths are acquired from different inlets, the interference of the waves can be controlled to be destructive or constructive by manipulating the distances they travel when reaching the interference region (z), and absorption / damping or filtering can be performed as needed.

[0087] It has been observed that constructive interference increases absorption / damping performance by increasing the amplitude at low frequencies, while destructive interference provides better filtering performance at higher frequencies.

[0088] The performance of the destructive and constructive interference can be controlled by the following formula:

[0089] here and This refers to the distance a sound wave travels after entering the interference region (z). It refers to the wavelength of the normal incident wave (n) and the random incident wave (r). It means The wavelengths are equal, and the normal incident wave (n) and the random incident wave (r) have the same wavelength. The wavelength setting parameters are selected by the user. Based on the wavelength adjustment parameters, the direction of interference (destructive or constructive) is controlled. Using this distance adjustment, the desired interference is provided by changing the phase of the normal incident wave (n) and the random incident wave (r).

[0090] In the studies conducted, it was observed that the interference was selected as The time is canceling, and when it has the property of being divisible Values ​​other than or When the method is selected, it exhibits complementary characteristics.

[0091] Here, the maximum destructive interference... =1, constructive interference =0 and =2, s=4 appear as values ​​of 2n, 4n, and multiples thereof. Intermediate values ​​can be changed according to design objectives.

[0092] The collector (2) and the metamaterial (1) comprising at least one unit, preferably multiple units, can be used to perform the above-described acoustic wave collection and absorption / damping / filtering process.

[0093] refer to Figure 1 The metamaterial (1) is preferably arranged diagonally, especially rectangular or square, but the area of ​​use may also be provided in different forms depending on the structure of one or more units (H) to be used (if any) or for aesthetic reasons. Preferably, the metamaterial (1) consists of multiple units (H) (MQWM) of a quarter wavelength, and preferably, the units (H) have a suitable channel structure. Preferably, a helical channel structure is used. This choice contributes positively to the thickness of the metamaterial.

[0094] The metamaterial is equipped with a large number of quarter-wave resonance (QWR) units (H) with a smooth and continuous spiral design, so that they do not reflect back. Using these units, absorption can be provided at the desired low frequencies.

[0095] Metamaterials (1) equipped with quarter-wave resonant (QWR) units (H) and collectors (2) provide a novel Herschel-Quincke (HQ)-based structure with a compatible design at the inlet. In the sense of multiple QW and HQ metamaterials, the meta-in-meta structure obtained with these two new metamaterials is called mQWHQM.

[0096] A collector (2) is placed in the inlet component of the metamaterial (1). The collector (2) includes an opening (2.3) through which sound waves can enter. The opening (2.3) allows sound waves to enter the metamaterial inlet (1.1) of the metamaterial (1). Preferably, the opening (2.3) is concentrically placed in the metamaterial inlet (1.1).

[0097] Preferably, the opening (2.3) and the metamaterial inlet (1.1) are located at the center of the metamaterial (1), but this is not necessary, and the two structures can be located at different points from the center. In an embodiment of the invention, the metamaterial inlet (1.1) is provided as a square. The characteristic dimension of the metamaterial inlet (1.1) (the edge length of the square) is experimentally selected as one-quarter of the physical length of the metamaterial. These dimensions and forms are given as examples, and the metamaterial inlet (1.1) can be of different geometries, such as angled (triangle, square, trapezoid, parallelogram, etc.) or curved (circle, ellipse, etc.).

[0098] Preferably, the collector (2) and / or opening (2.3) are provided in a circular form, but this geometry may also be provided in different forms depending on the field of use or for aesthetic reasons.

[0099] The collector (2) also forms a normal wave inlet (Rn) for the acoustic wave from the opening (2.3) to reach the unit (H) of the metamaterial (1). Here, the acoustic wave from the opening (2.3) is a normal incident wave (n).

[0100] Furthermore, the collector (2) also forms a random wave inlet (Rr) with the metamaterial (1) itself. The random wave inlet (Rr) is also arranged to allow acoustic waves (such as normal wave inlets (Rn)) from the opening (2.3) to reach the unit (H) of the metamaterial (1), preferably to its channel (if any). Here, the acoustic waves from the random wave inlet (Rr) are random incident waves (r).

[0101] Preferably, the normal wave inlet (Rn) and the random wave inlet (Rr) are arranged to send sound waves to the unit (H) independently of each other without interfering with each other, especially to the channel.

[0102] The normal wave inlet (Rn) and the random wave inlet (Rr) are arranged to send the normal sound wave (n) and the random sound wave (r) to the same point, preferably to the same unit (H), and especially to the same channel of the metamaterial (1).

[0103] In a metamaterial (1) having multiple channels or units (H), the normal wave inlet (Rn) and random wave inlet (Rr) are also arranged to send acoustic waves to at least some, preferably all, of the channels or units (H).

[0104] refer to Figures 1a to 1cThe collector (2) includes an opening (2.3) and a body surrounding the opening (2.3). The body includes an outer surface (2.1) and an inner surface (2.2). Here, the outer surface (2.1) refers to the surface in the direction from which the sound waves (especially the normal wave (n)) originate, and the inner surface (2.2) refers to the surface in the direction from which the random sound waves (r) originate.

[0105] Preferably, the outer surface (2.1) of the collector is provided in a curved, particularly convex, form toward the opening (2.3), so that the incident wave can be reflected toward the opening (2.3). Furthermore, although the outer surface (2.1) of the collector can be provided in a planar manner, this is disadvantageous in guiding and reflecting the wave back to the opening (2.3). Additionally, the body can be perforated to minimize reflection.

[0106] refer to Figure 1c and Figure 1d The normal incident wave (n) passing through the opening (2.3) in the collector (2) is guided by the collector inlet surface (2.4) arranged in the lower part of the opening (2.3).

[0107] Furthermore, the collector inner surface (2.2) guides the random incident wave (r). Here, the collector inlet surface (2.4) and the collector inner surface (2.2) are configured to carry the normal incident wave (n) and the random incident wave (r) to the same point, respectively.

[0108] Preferably, the surface extending from the opening (2.3) to the collector inlet surface (2.4) is provided in a curved, particularly convex, manner.

[0109] refer to Figure 1e and Figure 1f As previously described, the collector (2) is positioned in an opening (2.3) within the metamaterial inlet (1.1) of the metamaterial (1). A normal wave inlet (Rn) is formed to transmit a normal incident wave (n) between the end of the opening (2.3) and the base of the metamaterial inlet (1.1) within the metamaterial (1).

[0110] Preferably, the collector inlet surface (2.4) is arranged to extend along the base of the metamaterial inlet (1.1). The surface mentioned herein forms a normal inlet segment (Cn) for transmitting a normal incident wave (n) within the metamaterial (1) (preferably a metamaterial (1) unit (H)).

[0111] The collector lower surface (2.2) of the collector (2) is shaped such that another inlet is formed on the opening (2.3) and the metamaterial inlet (1.1).

[0112] A random wave inlet (Rr) is formed to send a random incident wave (r) between the lower surface of the collector (2.2) and the upper surface of the metamaterial (1.3) into the metamaterial (1).

[0113] Preferably, the lower surface (2.2) of the collector is arranged to extend along the upper surface (1.3) of the metamaterial. A random inlet segment (Cr) is formed to transmit the surface and a random incident wave (r) into the metamaterial (1).

[0114] The normal wave inlet (Rn), the random wave inlet (Rr), the normal inlet segment (Cn), and the random inlet segment (Cr) are arranged to ensure that the normal incident wave (n) and the random incident wave (r) reach the same point within the metamaterial.

[0115] Preferably, the wave from the normal wave inlet (Rn) is transmitted to the metamaterial (1) through the normal inlet section (Cn), and in particular to the element inlet (1.2) of the element (H) of the metamaterial (1).

[0116] Preferably, the wave from the random wave inlet (Rr) is transmitted to the metamaterial (1) through the random inlet segment (Cr), and in particular to the unit inlet (1.2) of the unit (H) of the metamaterial (1).

[0117] refer to Figure 1e and Figure 3 In this invention, preferably, the guide (3) is placed in the opening (2.3), especially in the metamaterial inlet (1.1). The router (3) is useful in ensuring that the normal sound wave (n) impacts the base of the metamaterial (1) and is reflected less and that the normal sound wave (n) is guided to the metamaterial (1) (especially the unit (H)).

[0118] The acoustic circuit (3) is a structure that extends from its end to its base. Preferably, the cross-sectional area increases from the tip to the base. When the acoustic circuit tip (3.1) portion of the acoustic circuit (3) is a narrow structure, the acoustic circuit base (3.2) is wider than the acoustic circuit tip (3.1).

[0119] In a preferred embodiment, a curved, preferably recessed surface is provided from the tip (3.1) of the acoustic circuit towards the base (3.2) of the acoustic circuit. Alternatively, the surface may be provided as planar, but a curved surface is advantageous in terms of better guiding sound waves. For example, triangular prisms may also be arranged in a prismatic shape in the acoustic circuit (3). The acoustic circuit (3) mentioned herein may be provided as hollow or solid.

[0120] refer to Figures 4 to 4cIn a preferred embodiment of the invention, a plurality of guides (2.5) are arranged on the inner surface (2.2) of the collector. The guides (2.5) provide guidance for transmitting the random incident wave (r) into the metamaterial (1), and in particular into the channel of the unit (H), after entering from the random wave inlet (Rr).

[0121] The guide (2.5) preferably extends from the edge of the collector (2) toward the metamaterial inlet (1.1). Furthermore, the guide (2.5) extends from the inner surface (2.2) of the collector toward the upper surface (1.3) of the metamaterial. Figure 6 As can be seen from the implementation, the guide (2.5) can be disposed in the random entry section (Cr). Here, the guided random entry section (Cr) is formed by assembling the guide (2.5) into the random entry section (Cr).

[0122] Alternatively, the guide (2.5) can be formed on the upper surface (1.3) of the metamaterial and can form a channel from the random wave inlet (Rr) to the metamaterial inlet (1.1) in the random inlet section.

[0123] Although the guides (2.5) are preferably linearly extended, they may also be provided in a curved or convex form.

[0124] By using guides (2.5) of varying lengths added to a sub-region of the collector (2) to guide the sound at random incident angles, the sound is directed to the metamaterial inlet (1.1), which provides an advantage in terms of interference control. The random sound wave (r) travels further than the normal sound wave and undergoes constructive or destructive interference with the normal sound wave in the interference region (z) depending on the selected parameters.

[0125] As previously explained, the current metamaterial (1) can include channels that define QW units (H).

[0126] In this embodiment of the invention, at least a portion of the upper surface (1.3) of the metamaterial is discharged, and the collector inner surface (2.2) of the collector (2) is positioned in the discharge portion, particularly in its guide (2.5).

[0127] As previously explained, see reference. Figure 5 and Figure 5a The current metamaterial (1) comprises units (H), preferably units (H) having channels. In an alternative embodiment of the invention, the channels extend to the metamaterial inlet (1.1), or the units (H) are exposed by cutting the upper surface (1.3) of the metamaterial. Preferably, at least the upper portion of the channel is exposed in a section of the upper surface (1.3) of the metamaterial that has been cut.

[0128] In this embodiment, a passivation process is performed in the exposed portion of the channel. During the passivation process, at least a portion of the channel surface is preferably cut from its tip to a cutoff point (Cp) on the channel. A layer (4) is placed on the cut surface to fit the cut surface.

[0129] Then, the collector (2) with the guide (2.5) is placed in such a way that its guide (2.5) is adapted to the upper surface (1.3) of the metamaterial. Thus, the random entry segment (Cr) is transformed into a channel structure.

[0130] The dimensions of the layer (4) do not prevent random incident waves (r) guided by the guide (2.5) from entering the cell (H). Here, if the length of the layer (4) is shorter than the cutoff point (Cp), such as Figure 5a As shown, or if the length of layer (4) is longer than the cutoff point (Cp), then layer (4) will not remain completely stable, and thus the entry of random waves (r) is possible.

[0131] In this configuration, when the normal incident wave (n) enters at the end of the channel, due to the channel's cut and the placement of the layer (4), the random incident wave (r) enters the unit (H) from the exposed portion via the guide (2.5). Therefore, the normal wave inlet (Rn) and the random wave inlet (Rr) are positioned separately from each other. The waves converge at a common point in the channel.

[0132] In this embodiment, as in Figures 5 to 5c As can also be seen, layer (4) can be composed of multiple parts. When said layer (4) is properly positioned, they form an opening (2.3) in the middle. Figures 5a to 5c In the middle, although these layers (4) are shown in the form of triangular prisms, they can also be formed in different geometries depending on the form of the cut-off point (Cp) or the metamaterial inlet (1.1).

[0133] refer to Figure 5d ,for Figure 5 and 5c In the embodiment described, the opening layer (5) is preferably placed on the layer (4) so ​​that the metamaterial inlet (1.1) adapts to the opening (2.3) of the collector (2). Here, since the geometry between the layers (4) is square, the opening layer (5) includes a circular opening thereon. Here, the shape of the body can also be changed according to the geometry formed between the layers (4).

[0134] The collector (2) and the metamaterial (1) can be configured to interfere with the normal incident wave (n) and the random incident wave (r) at a common point in the metamaterial (1) in the interference region (z). For this purpose, the dimensions of the collector (2) and the metamaterial (1) should respectively provide the distance from the normal wave inlet (Rn) to the interference region (z) and the distance from the random wave inlet (Rr) to the interference region (z) according to the following formulas.

[0135]

[0136] Here, the wavelength is selected based on whether the wavelength s is expected to be destructive or constructive, as determined by the user as a setting parameter.

[0137] Here, the primary distance (Ln) also refers to the normal wave emission length, and the secondary distance (Lr) refers to the random wave emission length.

[0138] refer to Figure 6 The normal wave (n) enters from the normal wave inlet (Rr) formed by the collector (2) and the metamaterial inlet (1.1). A collector inlet surface (2.4) is located in the lower part of the opening (2.3) and extends along the base of the metamaterial inlet (1.1). The collector inlet surface (2.4) and the metamaterial inlet (1.1) together form a normal inlet segment (Cn), wherein the distance extending from the normal wave inlet (Rn) to the interference region (z) and including the normal inlet segment (Cn) forms the principal length (Ln).

[0139] Furthermore, the main body of the collector (2) extends outward from the metamaterial inlet (1.1). The inner surface (2.2) of the collector and the upper surface (1.3) of the metamaterial extend outward from the random wave inlet (Rr) and the random wave segment (Cr) in this portion, allowing the random incident wave (r) to enter the metamaterial (1) together. Preferably, the random wave segment (Cr) is provided with a channel structure having a guide (2.5) below the collector (2), and the wave from the random wave inlet (Rr) is sent to the interference region (z) by means of the guide (2.5). In this embodiment, the collector (2) does not completely close the metamaterial inlet (1.1), and the random wave segment (Cr) connects to the interference region (z) from this opening and enters the metamaterial (1). The distance extending from the random wave inlet (Rr) to the interference region (z) and including the random inlet channel (Rr) forms a secondary distance (Lr).

[0140] refer to Figure 6a , showed Figures 5 to 5c Interference mechanism in. Here, random incident wave (r) enters the metamaterial (1) directly from the exposed part of the unit (H) by means of the cutting / passivation of the unit (H) and / or channel and the layer (4) placed in these parts and guide (2.5).

[0141] Furthermore, the inner surface of the collector (2.2) and the metamaterial inlet (1.1) together form a normal inlet segment (Cn), wherein the distance extending from the normal wave inlet (Rn) to the interference region (z) and including the normal inlet segment (Cn) forms the main length (Ln).

[0142] The distance from the center of the opening (2.3) to the end of the metamaterial (1) is defined as the total length (Lc). The total length (Lc) and the normal wave channel length (Lcn) overlap each other. That is, the normal wave channel length (Lcn) is the length representing a portion of the total length (Lc).

[0143] refer to Figure 6b The collector layer (4) and the collector inner surface (2.2) placed thereon, together with the metamaterial inlet (1.1), form the normal inlet section (Cn), wherein the distance from the normal wave inlet (Rn) to the interference region (z) and including the normal inlet channel (Cn) forms the main length (Ln).

[0144] In both implementations, constructive and destructive interference can be manipulated by changing the length of the cut portion of the channel using a passivation process.

[0145] In the metamaterial of this invention, all structures can be individually produced using the same or different main materials in an integrated manner. The structures can be easily assembled through mass production using different methods, such as plastic injection molding and CNC machining.

[0146] exist Figure 7 In the diagram, destructive interference is shown, and... Figure 8 In this study, constructive interference is illustrated by simulating different s-values. By overcoming the mass inertia of the low-frequency units and amplifying the amplitude of low-frequency waves through constructive interference (amplitude amplification), stronger resonance can be obtained. Therefore, better absorption of small-amplitude sound waves at low frequencies can be achieved. Furthermore, at high frequencies, due to destructive interference, high-frequency sound waves lose energy due to interference before they can reach the units. This process can be termed high-frequency filtering. This makes the resonant system and metamaterials effective broadband systems at high frequencies. Therefore, all units can be designed and integrated into the system according to the desired purpose using both constructive and destructive interference.

[0147] exist Figure 9 The experimental sound absorption coefficients measured in the impedance absorption system components are shown in the figure. Metamaterial (1) with a unit width of 4 mm and a unit thickness of 20 mm was used in the test. As an example of the system of the present invention, these results were obtained using (n) and (n+r) when a device without the metamaterial (1) was not available, providing approximately 80% and 90% sound absorption in the broadband range of 200 Hz-1000 Hz, respectively.

Claims

1. A method for collecting sound waves from the environment into an acoustic metamaterial (1), characterized in that: Normal incident waves (n) and random incident waves (r) that independently reach the metamaterial (1) are guided through two independent paths to reach a common point in the cell.

2. The method according to claim 1, characterized in that, The normal incident wave (n) and the random incident wave (r) are guided to a common point by the collector (2), thereby generating independent normal wave input (Rn) and random wave input (Rr).

3. The method according to claim 1, characterized in that, The normal incident wave (n) and the random incident wave (r) are guided to a common point by means of a collector (2), which generates independent normal wave inlets (Rn) and random wave inlets (Rr), as well as normal wave channels (Cn) and random wave channels (Cr) connected to the normal wave input and the random wave input, respectively.

4. The method according to any one of claims 1 to 3, characterized in that, The common point is located within the metamaterial inlet (1.1) connected to the unit (H) including the metamaterial (1) or within the channel including the unit (H).

5. The method according to any one of the preceding claims, characterized in that, The common point is the interference region (z), where the normal incident wave (n) and the random incident wave (r) will interfere.

6. The method according to claim 5, characterized in that: Select the primary distance (Ln) and secondary distance (Lr) according to the following formula: Wherein, the primary distance (Ln) is the distance from the normal wave inlet (Rn) to the interference region (z), the secondary distance (Lr) is the distance from the random wave inlet (Rr) to the interference region (z), and s is the wavelength adjustment parameter selected by the user.

7. The method according to claim 6, characterized in that, The s value is based on the s value. The method was selected.

8. The method according to claim 6, characterized in that, The s value is based on the s value. or The method was selected.

9. A device for collecting sound waves from the environment, characterized in that, The device includes: - Metamaterial (1), the metamaterial having a metamaterial input (1.1) and at least one unit (H) connected to the metamaterial input (1.1), through which the wave is introduced. - Collector (2), which is placed in the metamaterial inlet (1.1), It has an opening (2.3) that is connected and positioned to the metamaterial inlet (1.1). It has a surface to form a normal wave inlet (Rn) for sending a normal incident wave (n) from the opening (2.3) to a point in the metamaterial (1) and a random wave inlet (Rr) for sending a random incident wave (r) to the same point via a different path than the normal wave inlet (Rn).

10. The device according to claim 9, characterized in that, The collector (2) includes a surface such that the lower surface (2.2) of the collector and the upper surface (1.3) of the metamaterial (1) together form a random wave inlet (Rr).

11. The device according to claim 9 or 10, characterized in that, The collector (2) includes a surface such that the lower surface (2.2) of the collector and the upper surface (1.1) of the metamaterial (1) form a random entry segment (Cr) to guide a random incident wave (r) toward the common point.

12. The device according to any one of claims 9 to 11, characterized in that, The device includes a guide (2.5) that connects from the random wave inlet (Rr) to the common point.

13. The device according to claim 9, characterized in that, The collector (2) includes a surface at the end of the opening (2.3) and a base of the metamaterial inlet (1.1) to form a normal wave inlet (Rn).

14. The device according to claim 9 or 13, characterized in that, The collector (2) includes a surface at the end of the opening (2.3) and together with the base of the metamaterial inlet (1.1) forms a normal inlet channel (Cr) for guiding the normal incident wave (n) toward the common point.

15. The device according to claim 9 or 12, characterized in that, The unit (H) includes a channel through which at least a portion of the surface of the unit (H) is discharged, and a layer (4) is positioned in the discharge portion, the layer (4) being positioned on the collector (2) together with the inner surface (2.2) of the collector.

16. The device according to claim 15, characterized in that, The layer (4) consists of multiple parts to form the opening (2.3) when the metamaterial is placed in the discharge portion.

17. The device according to claim 9, characterized in that, The collector (2) has an outer collector surface (2.1) that is curved toward the opening (2.3).

18. The device according to claim 9, characterized in that, The normal incident wave (n) is guided to bend from the opening (2.3) toward the common point.

19. The device according to claim 9, characterized in that, The device includes a sound circuit (3) positioned in the opening (2.3) and the cross-sectional area of ​​the sound circuit increases toward the base of the sound circuit.

20. The device according to claim 18, characterized in that, The device includes a surface that extends at an angle toward the base of the acoustic circuit (3).

21. The device according to claim 9, characterized in that, The unit (H) is a quarter-wavelength multi-unit (MQWM).

22. The device according to any one of claims 9 to 21, characterized in that, The unit (H) includes at least one channel associated with the metamaterial inlet (1.1).

23. The device according to claim 22, characterized in that, The collector (2) or the metamaterial (1) is configured such that the common point is formed in the channel or unit entrance (1.2).

24. The device according to claim 9, 22, or 23, characterized in that, The common point is the interference region (z), in which the normal incident wave (n) and the random incident wave (r) interfere.

25. The device according to claim 24, characterized in that: The primary distance (Ln) and secondary distance (Lr) are configured according to the following formula: Wherein, the primary distance (Ln) is the distance from the normal wave inlet (Rn) to the interference region (z), the secondary distance (Lr) is the distance from the random wave inlet (Rr) to the interference region (z), and s is the wavelength adjustment parameter selected by the user.

26. The device according to claim 25, characterized in that, The s value is based on the s value. The method was selected.

27. The device according to claim 25, characterized in that, The s value is based on the s value. or The method was selected.

Images