A spiral acoustic black hole structure with enhanced thickness and a ring-ribbed cylindrical shell

Abstract

This invention relates to the field of vibration reduction and noise reduction technology, specifically to a spiral acoustic black hole structure with enhanced thickness and a ring-ribbed cylindrical shell. It includes a spirally coiled portion and a mounting component for mounting the spirally coiled portion onto the structure to be vibration-damped. The spirally coiled portion includes an extended enhanced thickness portion, a damping portion, and a one-dimensional acoustic black hole strip with gradually varying thickness. The damping portion is tightly attached to the inner wall of the extended enhanced thickness portion, and its inner end is flush with the inner end of the extended enhanced thickness portion. The outer end of the extended enhanced thickness portion is connected to the end of the mounting component. A one-dimensional acoustic black hole strip is tightly attached to the inner wall of the extended enhanced thickness portion between the outer end of the damping portion and the end of the mounting component. The thicker end of the one-dimensional acoustic black hole strip is connected to the end of the mounting component, and the thinner end of the one-dimensional acoustic black hole strip is connected to the damping portion. This invention can achieve both low-frequency and wide-frequency vibration reduction with a relatively low space occupancy.

Description

Technical Field

[0001] This invention relates to the field of vibration reduction and noise reduction technology, specifically to a spiral acoustic black hole structure with enhanced thickness and a ring-ribbed cylindrical shell. Background Technology

[0002] Vibration has always been a critical issue in engineering, especially in industries such as aerospace, shipbuilding, and transportation, where structural integrity and comfort are paramount. Vibration not only causes structural fatigue and performance degradation but also discomfort to personnel. Traditional vibration reduction methods, including the use of damping materials and vibration isolators, are effective to some extent, but often come with significant increases in weight, cost, or design complexity, especially in the low-frequency range where vibration reduction is ineffective.

[0003] Acoustic black holes (ABHs), as a novel vibration reduction technology, offer advantages such as small mass, low-frequency vibration reduction, and a wide frequency band. Their principle involves utilizing changes in the internal impedance of a structure to alter the phase velocity and group velocity of flexural waves propagating within it. Currently, the primary method for achieving the ABH effect is through designing the structure's thickness to ensure that the distance to the edge meets certain conditions, namely, that the wavenumber of the flexural wave changes very little on the wavelength scale. Power functions with an exponent greater than 2 are a common form that satisfies these conditions. Theoretically, when the thickness gradually decreases to zero, the wave velocity can drop to zero, preventing reflection. However, in reality, the truncated thickness at the tip of an ABH causes wave energy to concentrate at the tip, severely affecting wave absorption. Therefore, a small amount of uniform damping is often placed at the tip of the ABH to absorb wave energy as much as possible.

[0004] Existing acoustic black hole structures, in order to achieve good results, are often designed to be quite long, occupying a large amount of space. Furthermore, because acoustic black holes generally have high cutoff frequencies, good vibration suppression effects are typically achieved only at higher frequencies. However, in actual production and daily life, the vibration frequencies of many mechanical systems are usually kept at lower frequencies, resulting in insignificant vibration reduction effects. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a spiral acoustic black hole structure with enhanced thickness and a ring-ribbed cylindrical shell, which can achieve both low-frequency vibration reduction and wide-frequency vibration reduction with a low space occupancy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a spiral acoustic black hole structure with enhanced thickness, comprising a spirally coiled portion and a mounting component for mounting the spirally coiled portion onto a structure to be vibration-damped. The spirally coiled portion includes an extended enhanced thickness portion, a damping portion, and a one-dimensional acoustic black hole strip with a gradually varying thickness. The damping portion is tightly attached to the inner wall of the extended enhanced thickness portion, and the inner end of the damping portion is flush with the inner end of the extended enhanced thickness portion. The outer end of the extended enhanced thickness portion is connected to the end of the mounting component. The one-dimensional acoustic black hole strip is tightly attached to the inner wall of the extended enhanced thickness portion between the outer end of the damping portion and the end of the mounting component. The thicker end of the one-dimensional acoustic black hole strip is connected to the end of the mounting component, and the thinner end of the one-dimensional acoustic black hole strip is connected to the damping portion.

[0008] As a further optimization of the present invention, the lower surface of the one-dimensional acoustic black hole slab is a plane and is in close contact with the inner ring wall of the extended reinforcing thickness portion, and the upper surface of the one-dimensional acoustic black hole slab is a wedge surface.

[0009] As a further optimization of the present invention, the thinner end of the one-dimensional acoustic black hole slab is sandwiched between the extended reinforcement thickness portion and the damping portion.

[0010] As a further optimization of the present invention, when the one-dimensional acoustic black hole slab is fully extended, the sum of the thicknesses of the one-dimensional acoustic black hole slab and the corresponding extended reinforcement thickness portion below it, h, is... (x) The expression is:

[0011] h (x) =H t +εx m ;

[0012] Among them, H t The thickness of the extended reinforcement portion; x is the horizontal axis; m is a constant, and m≥2; ε is the thickness coefficient used to scale ABH.

[0013] As a further optimization of the present invention, the spiral curled portion is formed by an extended and reinforced thickness portion, a damping portion, and a one-dimensional acoustic black hole slab, which are curled into a spiral in the form of a standard Archimedean spiral.

[0014] As a further optimization of the present invention, the widths of the extended and reinforced thickness portion, the damping portion, and the one-dimensional acoustic black hole slab are all the same.

[0015] As a further optimization of the present invention, the thickness of the damping portion should be twice the thickness of the extended reinforcing thickness portion.

[0016] As a further optimization of the present invention, both the extended and reinforced thickness portion and the damping portion are strip structures with constant thickness.

[0017] As a further optimization of the present invention, both the extended reinforcing thickness portion and the one-dimensional acoustic black hole slat are made of steel. The mounting component is also made of steel. The extended reinforcing thickness portion, the one-dimensional acoustic black hole slat, and the mounting component are integrally formed.

[0018] As a further optimization of the present invention, the damping part is made of asphalt.

[0019] A ring-ribbed cylindrical shell, wherein the spiral acoustic black hole structure with enhanced thickness is mounted on the web and / or outer shell of the ring-ribbed cylindrical shell.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. The spiral acoustic black hole structure with enhanced thickness proposed in this invention is lightweight and easy to install. It is formed by spirally curling an extended enhanced thickness section, a damping section, and a one-dimensional acoustic black hole slab. As an additional vibration damping element, it can greatly extend the effective length of the acoustic black hole. In the variable thickness region of the one-dimensional acoustic black hole slab, the wave propagation speed gradually decreases as the thickness decreases by a power law, thereby causing the wave to concentrate at the tip of the one-dimensional acoustic black hole slab. Then, it is dissipated through the damping section, so that the wave energy is greatly absorbed, while hardly changing the inherent characteristics of the damped structure.

[0022] 2. In the past, acoustic black holes were often designed to be large in size in order to achieve better results. However, the spiral acoustic black hole structure of this invention breaks this mindset. It can greatly save space and at the same time allow the cutoff frequency of the acoustic black hole to be designed to be extremely low, which can significantly suppress the vibration of the structure being damped in the low frequency range.

[0023] 3. The mounting component of this invention can be flexibly designed and applied to various occasions, with a wide range of application scenarios. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the acoustic black hole structure with enhanced thickness disclosed in the embodiments of the present invention.

[0025] Figure 2 This is a front view of the enhanced thickness spiral acoustic black hole structure disclosed in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the enhanced thickness spiral acoustic black hole structure disclosed in the embodiments of the present invention when it is in a fully deployed state.

[0027] Figure 4 This is a schematic diagram illustrating the spiral curling principle of the spiral acoustic black hole structure with enhanced thickness disclosed in the embodiments of the present invention.

[0028] Figure 5 This is a schematic diagram of the installation of the acoustic black hole structure disclosed in the embodiment of the present invention on the web of a ring-ribbed cylindrical shell.

[0029] Figure 6 This is a schematic diagram of the installation of the acoustic black hole structure disclosed in the embodiment of the present invention on the outer shell of the ring-ribbed cylindrical shell.

[0030] Figure 7 The image shows a comparison of the vibration characteristics of a cylindrical shell with no damping elements installed, a mass block of equal mass installed, and the acoustic black hole structure of this invention installed on its web.

[0031] Figure 8 The image shows a comparison of the vibration characteristics of the outer shell of the ring-ribbed cylindrical shell without vibration damping elements, with a mass block of equal mass, and with the acoustic black hole structure of this invention installed.

[0032] Reference numerals: 1. Spiral coiled portion; 101. Extended and reinforced thickness portion; 102. Damping portion; 103. One-dimensional acoustic black hole slat; 104. Upper surface; 105. Lower surface; 2. Mounting component; 3. Ring-ribbed cylindrical shell; 301. Web plate; 302. Outer shell. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the present patent. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable that some well-known structures and their descriptions may be omitted in the drawings for those skilled in the art. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present patent.

[0034] One of the objectives of this invention is to provide a novel acoustic black hole structure that can solve the problem of vibration reduction and noise reduction in low-frequency and wide-frequency ranges while greatly saving space occupancy.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1-4As shown, the present invention provides a spiral acoustic black hole structure with enhanced thickness, including a spiral coiled portion 1 and a mounting member 2 for connecting the spiral coiled portion 1 to the structure to be damped. A damping portion 102 is tightly disposed on the inner wall of the extended enhanced thickness portion 101, and the inner end of the damping portion 102 is flush with the inner end of the extended enhanced thickness portion 101; the outer end of the extended enhanced thickness portion 101 is connected to the end of the mounting member 2; a one-dimensional acoustic black hole strip 103 is tightly disposed on the inner wall of the extended enhanced thickness portion 101 between the outer end of the damping portion 102 and the end of the mounting member 2, the thicker end of the one-dimensional acoustic black hole strip 103 is connected to the end of the mounting member 2, and the thinner end of the one-dimensional acoustic black hole strip 103 is connected to the damping portion 102.

[0037] The spiral coiled portion 1 is formed by coiling a standard Archimedean spiral, consisting of an extended and reinforced thickness portion 101, a damping portion 102, and a one-dimensional acoustic black hole slab 103. This spiral absorbs and dissipates vibrational energy at any location on the structure to be damped while maximizing space efficiency. The extended and reinforced thickness portion 101 is designed to enhance the acoustic black hole effect by extending the truncated thickness to a certain length, taking into account the truncated thickness of the acoustic black hole. The damping portion 102 is located on the inner wall surface of the one-dimensional acoustic black hole slab 103 and is used to absorb vibrational energy concentrated at the tip of the slab. The loss factor of the damping portion 102 should be chosen to be as large as possible. The mounting component 2 is located at the outer end of the spiral coiled portion 1 and is used to connect the spiral coiled portion 1 to the structure to be damped, thus establishing a connection between the acoustic black hole structure and the structure to be damped. The mounting component 2 can be designed with appropriate curvature based on the location of the damped component.

[0038] The lower surface 105 of the one-dimensional acoustic black hole slat 103 is flat and closely adheres to the inner wall of the extended reinforcing thickness portion 101, while the upper surface 104 of the one-dimensional acoustic black hole slat 103 is a wedge-shaped surface. The upper surface 104 rotates inward along with the lower surface 105 while maintaining a relative distance from the one-dimensional acoustic black hole outline, forming a spiral acoustic black hole structure. The distance between the flat surface and the wedge-shaped surface is the thickness of the one-dimensional acoustic black hole slat 103. When the one-dimensional acoustic black hole slat 103 is fully unfolded, its thickness decreases exponentially from the thicker end to the thinner end; and the thickest end of the one-dimensional acoustic black hole slat 103 is the outer end of the spiral curled portion 1, used for connection with the mounting component 2. The thinner end of the one-dimensional acoustic black hole slab 103 is sandwiched between the extended thickened portion 101 and the damping portion 102, such that the damping portion 102 is disposed on the tip surface of the one-dimensional acoustic black hole slab 103 to dissipate the energy concentrated at the tip.

[0039] When the one-dimensional acoustic black hole slab 103 is fully deployed, the sum of the thicknesses h of the one-dimensional acoustic black hole slab 103 and the corresponding extended reinforcement thickness portion 101 below it is...(x) The expression is:

[0040] h (x) =H t +εx m ;

[0041] Among them, H t To extend the thickness of the reinforced portion; x is the horizontal axis (e.g., Figure 3 As shown, the length direction of the unfolded one-dimensional acoustic black hole slab is the horizontal axis, the thickness direction is the vertical axis, and point O is the origin; m is a constant, and m≥2; ε is the thickness coefficient used to scale ABH.

[0042] The vibration reduction effect of a single-thickness spiral acoustic black hole structure is explained below based on simulation results.

[0043] In the spiral acoustic black hole structure with enhanced thickness, the extended enhanced thickness part, the one-dimensional acoustic black hole strip, and the mounting parts can all be made of steel or other materials; the size of the mounting parts 2 can be appropriately changed according to actual needs; the extended enhanced thickness part 101 should not be too thick; the thickness of the damping part 102 should be greater than twice that of the extended enhanced thickness part 101, and the loss factor should be as large as possible; the damping part and the acoustic black hole are bonded together.

[0044] The length and width of the one-dimensional acoustic black hole slab 103, lower surface 105, and upper surface 104 in the above structure can be changed according to the actual situation. The number of spiral acoustic black holes with increased thickness installed on the structure to be vibration reduced can also be changed appropriately. This demonstration configuration is just a special case.

[0045] This invention will provide a set of parameters and material parameters for a spiral acoustic black hole with enhanced thickness, installed on a ring-ribbed cylindrical shell structure, to demonstrate that the invention can be applied to both planar and curved structures, thereby verifying the beneficial effects of the invention, including the following:

[0046] According to the parametric equation of the Archimedes spiral, the coordinates of the baseline of the spiral are x. b y b for:

[0047]

[0048] The baseline length can be obtained by integration:

[0049]

[0050] Interpreting the arc length l(θ) with the one-dimensional acoustic black hole expression h(x) = Ht + εx m By combining these elements, the acoustic black hole structure model can be constructed.

[0051] (1) In h(x) = Ht + εx m In this case, the reinforcement thickness Ht is 1 mm, m is 2.2, and ε is 0.015.

[0052] (2) The length of the mounting part 2 is 60mm, the width is 30mm, and the thickness is 6mm.

[0053] (3) The length of the one-dimensional acoustic black hole slab 103 is 498 mm and the width is 30 mm.

[0054] (4) The length of the extended and reinforced thickness portion 101 is 550 mm and the width is 30 mm.

[0055] (5) The length of the damping part 102 is 264.5 mm, the width is 30 mm, the thickness is 5 mm, and the material is asphalt damping.

[0056] (6) The outer diameter of the ring rib of the ring-ribbed cylindrical shell 3 is 1000mm, the outer shell 302 is 200mm wide and 9mm thick, the inner shell is 80mm wide and 8mm thick, and the ring rib web 301 is 200mm wide and 5mm thick.

[0057] (7) Material parameters of each material in Table 1

[0058] Material <![CDATA[Density / kg / m 3 > Elastic modulus / Pa Poisson's ratio Loss factor steel 7850 <![CDATA[2.1×10 11 ]]> 0.3 0.0026 Asphalt Damping 1650 <![CDATA[2.25×10 8 ]]> 0.3 0.8

[0059] (8) The mass of the enhanced thickness spiral acoustic black hole structure in this paper is 0.76 kg.

[0060] (9) Apply the acoustic black hole structure model described in the multiphysics coupling analysis software COMSOL Multiphysics.

[0061] (10) The vibration characteristics of the structure are evaluated using the mean square velocity level (MQV), and the formula is as follows:

[0062]

[0063] In the formula, v is the vibration velocity amplitude, which can be directly calculated from the solid mechanics plate, and v0 is the reference velocity amplitude, with a value of 1×10. -9 S is the area of ​​the vibration surface to be monitored.

[0064] like Figure 5 As shown, Figure 5 The acoustic black hole structure is mounted on the web 301 of the annular cylindrical shell 3, and point excitation is applied below the web 301 of the acoustic black hole. Figure 7The figure shows the mean square velocity level curve of the web of a ribbed cylindrical shell. After installing the acoustic black hole, the vibration of the web was significantly suppressed, and its mean square velocity level curve became smoother. Almost all resonance peaks were significantly reduced, while the natural frequency of the web remained almost unchanged. The mass block of equal mass only reduced the peak value of the resonance peaks at high frequencies, because its inertial force in the high-frequency range significantly suppressed the vibration of the web. With a single acoustic black hole structure placed on the web, the peak values ​​of all mean square velocity levels of the web were significantly reduced, with almost all resonance peaks reduced by more than 13 dB. Vibration of the web was also significantly suppressed in the low-frequency range, demonstrating a significant vibration reduction effect.

[0065] like Figure 6 As shown, Figure 6 The acoustic black hole structure is installed on the outer shell 302 of the ring-ribbed cylindrical shell 3. Point excitation is performed at the outer shell 302 corresponding to the acoustic black hole structure, and the direction is inward along the normal of the outer shell. Figure 8 The figure shows the mean square velocity level curve of the ring-ribbed cylindrical shell. After installing the acoustic black hole, almost all resonance peaks were significantly suppressed. The mean square velocity level of the resonance peak near 65Hz was reduced by more than 8dB, and the vibration reduction effect was even better at higher frequencies thereafter, while the natural frequency of the shell remained almost unchanged. The mass block of equal mass had almost no effect on vibration reduction.

[0066] Therefore, the spiral acoustic black hole structure described in this invention has the following advantages compared to existing technologies:

[0067] 1. The traditional one-dimensional acoustic black hole is cleverly designed into a spiral structure, which greatly saves space while ensuring that the acoustic black hole is long enough to achieve excellent vibration reduction effect in low frequency and wide frequency range.

[0068] 2. Employing a spiral-shaped acoustic black hole with enhanced thickness can further enhance the vibration reduction effect of the acoustic black hole.

[0069] 3. Adding damping to the tip damping of the acoustic black hole effectively improves the vibration reduction performance of the acoustic black hole.

[0070] 4. The mounting components of the acoustic black hole structure can be flexibly designed according to the installation position of the structure to be vibration-damped, and are no longer limited to flat plates or curved surfaces, so as to adapt to various complex working conditions.

[0071] 5. The thickened spiral acoustic black hole is a fusion design that combines the advantages of three structures: one-dimensional acoustic black hole, dynamic vibration absorber, spiral structure, and constraint damping.

[0072] 6. The thickened spiral acoustic black hole can achieve the goals of being lightweight, space-saving, having good low-frequency vibration reduction effect, and wide-frequency vibration reduction.

[0073] Based on the description and accompanying drawings of this invention, those skilled in the art can readily manufacture or use the enhanced thickness spiral acoustic black hole structure of this invention, and can produce the positive effects described in this invention.

[0074] Unless otherwise specified, in this invention, terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe orientation or positional relationships in this invention are for illustrative purposes only and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0075] Unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0076] The above description is merely a preferred embodiment of the present invention, but the present invention is not limited to the specific embodiments described above. Those skilled in the art can make various modifications, additions, or substitutes with similar methods without departing from the principles of the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A spiral acoustic black hole structure with enhanced thickness, characterized in that: The device includes a spirally coiled portion (1) and a mounting member (2) for mounting the spirally coiled portion (1) onto the structure to be damped. The spirally coiled portion (1) includes an extended reinforcing thickness portion (101), a damping portion (102), and a one-dimensional acoustic black hole strip (103) with a gradually varying thickness. The damping portion (102) is tightly attached to the inner wall of the extended reinforcing thickness portion (101), and the inner end of the damping portion (102) is flush with the inner end of the extended reinforcing thickness portion (101). The outer end of the extended reinforcing thickness portion (101) is connected to the end of the mounting member (2), and the spirally coiled portion (102) is tightly attached to the inner wall of the extended reinforcing thickness portion (101) between the outer end of the damping portion (102) and the end of the mounting member (2). The one-dimensional acoustic black hole slab (103) is provided, with the thicker end of the one-dimensional acoustic black hole slab (103) connected to the end of the mounting member (2), and the thinner end of the one-dimensional acoustic black hole slab (103) connected to the damping portion (102); the thinner end of the one-dimensional acoustic black hole slab (103) is sandwiched between the extended reinforcing thickness portion (101) and the damping portion (102); the spiral curled portion (1) is formed by the extended reinforcing thickness portion (101), the damping portion (102) and the one-dimensional acoustic black hole slab (103) curled in a plane according to the form of a standard Archimedean spiral; the thickness of the damping portion (102) should be more than twice the thickness of the extended reinforcing thickness portion (101).

2. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: The lower surface (105) of the one-dimensional acoustic black hole slab (103) is a plane and is in close contact with the inner ring wall of the extended reinforced thickness portion (101), while the upper surface (104) of the one-dimensional acoustic black hole slab (103) is a wedge surface.

3. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: When the one-dimensional acoustic black hole slab (103) is fully extended, the sum of the thicknesses of the one-dimensional acoustic black hole slab (103) and the corresponding extended reinforcing thickness portion (101) below it is... h (x) The expression is: ； in, To extend the thickness of the reinforced portion; x The x-axis is the horizontal axis. m It is a constant, and m≥2; This is the thickness factor used to scale ABH.

4. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: The widths of the extended thick portion (101), the damping portion (102), and the one-dimensional acoustic black hole slat (103) are all the same.

5. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: Both the extended and reinforced thickness portion (101) and the damping portion (102) are strip structures with constant thickness.

6. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: The extended and reinforced thickness portion (101) and the one-dimensional acoustic black hole slab (103) are both made of steel, and the damping portion (102) is made of asphalt.

7. A ring-ribbed cylindrical shell, characterized in that: The spiral acoustic black hole structure with enhanced thickness as described in any one of claims 1-6 is installed on the web (301) and / or the outer shell (302) of the ring-ribbed cylindrical shell (3).

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