A multi-gradient pressure-resistant sound-absorbing covering layer

Abstract

This disclosure discloses a multi-gradient pressure-resistant sound-absorbing covering layer, comprising: a substrate, on which are arranged a first array of heavy cores, the radius of each row of heavy cores varying gradient along the direction of sound wave incidence; the substrate is also provided with a second array of cavities arranged intersecting with the heavy cores to form an assembly, the radius of each row of cavities varying gradient along the direction of sound wave incidence; each heavy core is provided with an outer covering layer, the inner radius of which is the same as the radius of the heavy core it covers.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of sound absorption and noise reduction, and particularly relates to a multi-gradient pressure-resistant sound absorption cover layer. BACKGROUND

[0002] The concealment performance of underwater vehicles mainly depends on the acoustic stealth performance against sound wave detection. The sound absorption cover layer can effectively dissipate sound energy and reduce the detection distance of the opponent sonar, and is currently the main means to improve the acoustic stealth performance of underwater vehicles. At present, the known sound absorption cover layer is mainly a sound absorption cover layer containing a cavity and an extended gradient cavity sound absorption cover layer. The sound absorption peak frequency of the sound absorption cover layer containing a cavity is related to the cavity resonance frequency, and the cavity resonance frequency is related to the structural parameters and shear modulus of the base body. The research on the sound absorption cover layer containing a cavity mainly focuses on the shape (such as cylindrical, spherical, etc.), size / mixed size, and micro-perforated material of the cavity.

[0003] In addition, research shows that local resonance materials based on heavy cores can also be used for underwater sound absorption. Typical research on local resonance sound absorption cover layers includes the position of heavy cores and multiple local resonance bodies, but the realization of local resonance in existing research relies on multiple single-degree-of-freedom local resonance modes, which has the problem of too narrow sound absorption frequency band.

[0004] Sonar technology and sound absorption cover layer technology are like "spear" and "shield", and develop in constant mutual surpassing. The increasingly developed modern sonar technology requires the sound absorption cover layer to have stronger sound absorption capacity. Modern underwater vehicles dive to a depth of more than 300 meters, and the resulting underwater high static pressure environment also requires the sound absorption cover layer to have pressure resistance.

[0005] Existing sound absorption cover layers mainly consider improving the sound absorption capacity of the sound absorption cover layer and ignore its pressure resistance. Therefore, it is of great significance to design a sound absorption cover layer that can improve the sound absorption capacity and at the same time has certain pressure resistance. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present disclosure is to provide a multi-gradient pressure-resistant sound absorption cover layer. The heavy cores and cavities in the sound absorption cover layer change with the gradient of the sound wave incidence direction, so that the sound absorption capacity and pressure resistance of the sound absorption cover layer are both improved.

[0007] To achieve the above purpose, the present disclosure provides the following technical solutions:

[0008] A multi-gradient pressure-resistant sound absorption cover layer comprises:

[0009] a base body,

[0010] The base body is provided with a first array of heavy cores, and the radius of each column of heavy cores changes with the gradient of the sound wave incidence direction;

[0011] The base body is further provided with a second array of cavities arranged crosswise to the heavy cores to form a combination, the radius of each column of cavities varying along the direction of sound wave incidence;

[0012] The outer layer of each heavy core is provided with a cladding layer, the inner radius of the cladding layer being the same as the radius of the heavy core it wraps.

[0013] Preferably, the cavities are located below the heavy cores, and the included angle between the cavities and the normal of the surface of the base body is less than 90°.

[0014] Preferably, the gap between the cavities and the heavy cores is less than the diameter of the cavities.

[0015] Preferably, the number of heavy cores and cavities is adjusted according to the thickness of the base body.

[0016] Preferably, the radius of the heavy cores is 2-5 mm.

[0017] Preferably, the radius of the cavities is 2-5 mm.

[0018] Preferably, the material of the heavy cores comprises copper, steel or high-density alloy.

[0019] Preferably, the base body is made of rubber material.

[0020] Preferably, the inner radius of the cladding layer is 2-5 mm, and the outer radius is 3-6 mm.

[0021] Preferably, the cladding layer is made of viscoelastic material.

[0022] Compared with the prior art, the present disclosure has the following beneficial effects:

[0023] 1. Near the interface between water and the sound-absorbing cover layer, the size of the heavy cores, soft cladding layer and cavities is small, so as to reduce the impedance mismatch with water, thereby reducing the reflection of incident sound waves.

[0024] 2. The local resonance of the heavy cores can dissipate sound energy; the soft cladding layer wrapped outside the heavy cores can strengthen the local resonance of the heavy cores, and the soft cladding layer also has viscoelastic dissipation effect on sound energy; the resonance of the cavities can dissipate sound energy. The multiple gradient changes of the heavy cores, soft cladding layer and cavities can couple gradient size resonance, gradient size local resonance and other sound energy dissipation effects, thereby improving the sound absorption capacity of the sound-absorbing cover layer.

[0025] 3. The local equivalent stiffness of the heavy cores, soft cladding layer and the cavities closest to them is higher than that without heavy cores, thereby making the sound-absorbing cover layer have certain pressure resistance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of a multi-gradient pressure-resistant sound-absorbing cover layer provided by one embodiment of the present disclosure;

[0027] Figure 2 is a structural schematic diagram of the I part of the sound-absorbing cover layer shown in Figure 1

[0028] Figure 3 is a structural schematic diagram of the II part of the sound-absorbing cover layer shown in Figure 1

[0029] Figure 4 is a diagram of sound-absorbing coefficients of a multi-gradient pressure-resistant sound-absorbing cover layer and a single-cavity gradient sound-absorbing cover layer varying with frequency, provided by another embodiment of the present disclosure;

[0030] The marks in the drawings are explained as follows:

[0031] 1, base body; 2, heavy core; 3, cladding layer; 4, cavity. DETAILED DESCRIPTION

[0032] The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Although specific embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. Figures 1 to 4 The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Although specific embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0033] It should be noted that certain terms are used in the specification and claims to refer to certain components. Those skilled in the art will understand that the same component can be referred to by different names. The present specification and claims should not be limited by the names of the components. Rather, the criterion for distinguishing components is their functional differences. As mentioned throughout the specification and claims, “comprising” or “including” is an open term, which should be interpreted as “comprising but not limited to”. The subsequent description is a preferred embodiment for implementing the present disclosure, which is for the purpose of the general principles of the specification, and not to limit the scope of the present disclosure. The scope of protection of the present disclosure is defined by the appended claims.

[0034] For the sake of understanding the embodiments of the present disclosure, further explanation and description will be made below with reference to specific embodiments as examples, and each of the drawings does not constitute a limitation on the embodiments of the present disclosure.

[0035] In one embodiment, as shown in Figure 1 The present disclosure provides a multi-gradient pressure-resistant sound-absorbing cover layer, comprising: ​​

[0036] The base body 1,

[0037] The base body 1 is provided with a first array of heavy cores 2, wherein the radius of each row of heavy cores is the same, and the radius of each column of heavy cores 2 changes in gradient along the sound wave incident direction;

[0038] The base body 1 is also provided with a second array of cavities 4 arranged in cross with the heavy cores 2 to form a combination, wherein the radius of each row of cavities is the same, and the radius of each column of cavities 4 changes in gradient along the sound wave incident direction;

[0039] As shown in Figure 2 The outer layer of each heavy core 2 is provided with a cladding layer 3, and the inner radius of the cladding layer 3 is the same as the radius of the heavy core 2 it wraps.

[0040] The above embodiment constitutes the basic technical scheme of the present disclosure. In the embodiment, the heavy core wrapped with the cladding layer and the cavity are arranged alternately, so that the heavy core, the cladding layer and the cavity form a combination, and the equivalent elastic modulus of the combination is greater than that of the cavity alone, so that the equivalent stiffness of the combination is greater than that of the cavity alone, and thus the sound absorption cover layer of the embodiment can obtain higher pressure resistance performance compared with the existing sound absorption cover layer. It should be noted that the cladding layer is wrapped on the outside of the heavy core, so that the heavy core vibrates slightly when the sound wave is incident, so that the local resonance effect of the heavy core inside is strengthened, and the viscoelastic dissipation effect on sound energy is also produced.

[0041] In addition, since the radius of the heavy core and the cavity changes in gradient along the sound wave incident direction Figure 1 Only the case where the radius of the heavy core and the cavity gradually increases along the sound wave incident direction is shown, and in specific applications, the radius of the heavy core and the cavity can also be designed to gradually decrease along the sound wave incident direction, or the radius of the heavy core and the cavity changes in the opposite direction along the sound wave incident direction, so that the combination formed by the two can reduce the impedance mismatch with water near the water-sound absorption cover layer interface, thereby reducing the reflection of incident sound waves.

[0042] In addition, the local resonance effect of the heavy core can dissipate sound energy; the soft cladding layer wrapped outside the heavy core can strengthen the local resonance effect of the heavy core, and the soft cladding layer also has a viscoelastic dissipation effect on sound energy; the resonance effect of the cavity can dissipate sound energy. The multiple gradient changes of the heavy core, the soft cladding layer and the cavity can couple gradient size resonance, gradient size local resonance and other sound energy dissipation effects, thereby improving the sound absorption capacity of the sound absorption cover layer.

[0043] In another embodiment, the cavity is located below the heavy core, and the included angle between the cavity and the normal to the surface of the base body is less than 90°.

[0044] In this embodiment, to cope with the case of vertical incidence of sound waves, the cavity can be located directly below the heavy core; to cope with the case of oblique incidence of sound waves, the cavity can be offset from the heavy core by a certain angle; to cope with more complex cases of sound wave incidence, those skilled in the art can further optimize the specific positions of the cavity and the heavy core according to the present disclosure.

[0045] In another embodiment, the gap between the cavity and the heavy core is less than the diameter of the cavity.

[0046] In this embodiment, the resonance effect of the cavity mainly acts on the wavelength range of the sound waves in the same order of magnitude as the diameter. The action scale of the heavy core includes its diameter and the wavelength range of the sound waves which is greater than the diameter by 2 orders of magnitude. Both the heavy core and the cavity have a certain effect on the sound waves smaller than their diameters. Assuming that the wavelength of the incident sound wave is the same as the diameter of the cavity, to achieve the coupling effect of the heavy core and the cavity in the combination, the gap between the two should not be too far, otherwise the coupling will be decoupled, and the gap distance should be measured by the diameter of the cavity, so as to ensure that the cavity and the heavy core produce coupling dissipation effect on the incident sound wave.

[0047] In another embodiment, the number of heavy cores and cavities is adjusted according to the thickness of the substrate.

[0048] In this embodiment, the number of heavy cores and cavities is not limited to Figure 1 As shown, the number of heavy cores and cavities can be increased according to the thickness of the substrate, that is, the greater the thickness of the substrate, the more heavy cores and cavities can be set, and the better the sound absorption effect. For example, when the thickness of the substrate is 40 mm, the heavy core and the cavity are set to 2 layers; when the thickness of the substrate is 80 mm, the heavy core and the cavity are set to 3 layers.

[0049] In another embodiment, the radius of the heavy core is 2-5 mm.

[0050] For example, as shown in Figure 1 Along the direction of sound wave incidence, the heavy core is divided into 3 layers, and the radius of each layer is set to 2 mm, 3.5 mm and 5 mm in turn. Setting the radius of the heavy core to 2-5 mm can reduce the thickness of the sound absorption cover layer to a certain extent, thereby reducing the potential impact of the introduction of the heavy core on the increase in the thickness of the sound absorption cover layer.

[0051] In another embodiment, as shown in Figure 3 The radius of the cavity is 2-5 mm.

[0052] Similarly, as shown in Figure 1 Along the direction of sound wave incidence, the cavity is also divided into 3 layers, and is arranged in cross with the heavy core, and the radius of each layer is set to 2 mm, 3.5 mm and 5 mm in turn. Setting the radius of the cavity to 2-5 mm has the same reason as the heavy core.

[0053] It should be noted that the radius of the cavity can also be different from the radius of the heavy core, and the specific design needs to be optimized according to the thickness of the defined base body and the material selection.

[0054] In another embodiment, the preparation material of the heavy core is copper, steel or high-density alloy.

[0055] In another embodiment, the base body is prepared by using rubber material.

[0056] In this embodiment, the density of the base body prepared by rubber material is close to the density of water, which can reduce the reflection of sound waves at the interface between water and the sound-absorbing cover layer, so that more sound waves can pass through the sound-absorbing cover layer, thereby obtaining a better sound-absorbing effect.

[0057] In another embodiment, the inner radius of the cladding layer is 2-5mm, and the outer radius is 3-6mm.

[0058] In this embodiment, as shown in the figure, Figure 1 the cladding layer is also divided into three layers, and the inner radius is the same as that of the heavy core, and along the sound wave incident direction, it is sequentially set to 2mm, 3.5mm and 5mm, and the outer radius is sequentially set to 3mm, 4.5mm and 6mm.

[0059] In another embodiment, the cladding layer is prepared by viscoelastic material.

[0060] In the following, the present disclosure is compared with the sound-absorbing cover layer with a single cavity gradient to further illustrate the technical features of the present disclosure.

[0061] The sound-absorbing cover layer with a single cavity gradient includes a base body and a cavity, the cavity is a sphere, and has three layers; along the sound wave incident direction, the radii of the three layers of cavities are 2mm, 3.5mm and 5mm respectively; the material of the base body is rubber. The cavities are arranged periodically in an array.

[0062] The sound-absorbing performance of the structure of the present disclosure and the sound-absorbing cover layer with a single cavity gradient is simulated and analyzed by using finite element numerical calculation, and the sound-absorbing coefficients of the two with respect to frequency are shown in the figure. Figure 4 Figure 4 In the range of 350-2200Hz, the integral average sound-absorbing coefficient of the structure is improved by 9% compared with the sound-absorbing cover layer with a single cavity gradient, and in the range of 4450-7900Hz, the integral average sound-absorbing coefficient of the structure is improved by 10% compared with the sound-absorbing cover layer with a single cavity gradient. It can be seen that the sound-absorbing capacity of the structure is greatly improved compared with the sound-absorbing cover layer with a single cavity gradient.

[0063] ​In another aspect, the structure has one more absorption peak at 900Hz than the single cavity gradient sound absorption cover. The third absorption peak of the structure is at 2000Hz, and the second sound absorption peak of the single cavity gradient sound absorption cover is at 2850Hz, that is, the left shift of the absorption peak position occurs (the left shift means the movement to low frequency, which indicates the improvement of the low frequency sound absorption capacity).

[0064] As described above, the present disclosure improves the sound absorption capacity of the sound absorption cover by the multiple gradient changes of the heavy core, the soft cover layer and the cavity, and the coupling of the gradient size resonance, the gradient size local resonance and other sound energy dissipation effects, thereby improving the sound absorption capacity of the sound absorption cover. The combination of the heavy core, the soft cover layer and the cavity closest thereto improves the local equivalent stiffness, thereby making the sound absorption cover have certain pressure resistance.

[0065] The above describes the technical solutions provided by the present disclosure in combination with specific embodiments, and the description of the above embodiments is only used to help understand the core idea of the present disclosure. For those skilled in the art, according to the idea of the present disclosure, the specific implementation manner and application range will be changed. Therefore, the content of the specification should not be understood as a limitation of the present disclosure.

Claims

1.A multi-gradient pressure-resistant and sound-absorbing coating, comprising: a substrate, a first array of heavy cores arranged on the substrate, the radius of each column of the heavy cores varying along the sound wave incident direction; a second array of cavities arranged on the substrate and crossing the heavy cores to form a combination, the radius of each column of the cavities varying along the sound wave incident direction; an outer layer of each heavy core is provided with a cladding layer, the inner radius of the cladding layer is the same as the radius of the heavy core wrapped thereby; the heavy core, the cladding layer and the cavity form a combination, the equivalent elastic modulus of the combination is greater than that of the cavity alone, so that the equivalent stiffness of the combination is greater than that of the cavity alone; wherein, the radius of the heavy core and the cavity varies along the sound wave incident direction, so that the combination formed by the heavy core and the cavity can reduce the impedance mismatch with water near the interface between the water and the sound-absorbing coating, thereby reducing the reflection of the incident sound wave, the radius of the heavy core and the cavity varies along the sound wave incident direction, including that the radius of the heavy core and the cavity gradually increases along the sound wave incident direction, the radius of the heavy core and the cavity gradually decreases along the sound wave incident direction, or the radius of the heavy core and the cavity changes in the opposite direction along the sound wave incident direction; the cavity is located below the heavy core, and the included angle between the cavity and the normal of the surface of the substrate is less than 90°; in order to deal with the case of oblique incidence of sound wave, the cavity deviates from directly below the heavy core by a certain angle; the gap between the cavity and the heavy core is less than the diameter of the cavity; the number of the heavy core and the cavity is adjusted according to the thickness of the substrate; the radius of the heavy core is 2-5mm; the radius of the cavity is 2-5mm; the material of the heavy core includes copper, steel or high-density alloy; the substrate is made of rubber material; the inner radius of the cladding layer is 2-5mm, and the outer radius is 3-6mm; the cladding layer is made of viscoelastic material. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The acoustical cover layer of claim 1, wherein, ​ 3. The acoustical coverings of claim 1, wherein, ​ 4. The acoustical coverings of claim 1, wherein, ​ 5. The acoustical coverings of claim 1, wherein, ​ 6. The acoustical coverings of claim 1, wherein, ​ 7. The acoustical coverings of claim 1, wherein, ​ 8. The acoustical coverings of claim 1, wherein, ​ 9. The acoustical coverings of claim 1 or 8 wherein, ​

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