Thickness-enhanced spiral acoustic black hole structure and annular rib cylindrical shell

Abstract

The invention relates to the technical field of vibration and noise reduction, in particular to a thickness-enhanced spiral acoustic black hole structure and an annular rib cylindrical shell, which comprise a spiral curling part and a mounting piece for mounting the spiral curling part on a structure to be subjected to vibration reduction, the spiral curling part comprises an extension thickness enhancing part, a damping part and a one-dimensional acoustic black hole batten with the gradually-changed thickness, the damping part is tightly attached to the inner ring wall of the extension thickness enhancing part, and the inner end of the damping part is flush with the inner end of the extension thickness enhancing part; the outer end of the extending and thickness-enhancing part is connected with the end part of the mounting piece, a one-dimensional acoustic black hole batten is tightly attached to the inner ring wall of the extending and thickness-enhancing part between the outer end of the damping part and the end part of the mounting piece, and the thicker end of the one-dimensional acoustic black hole batten is connected with the end part of the mounting piece; and the thinner end of the one-dimensional acoustic black hole batten is connected with the damping part. According to the invention, low-frequency vibration reduction and broadband vibration reduction can be realized at the same time under the condition of relatively low space occupancy.

Description

Technical Field

[0001] The invention relates to the technical field of vibration reduction and noise reduction, and in particular to a spiral acoustic black hole structure with enhanced thickness and a ring-ribbed cylindrical shell. Background Art

[0002] In the field of engineering, vibration has always been a critical issue, especially in industries such as aerospace, shipping and transportation that have extremely high requirements for structural integrity and comfort. Vibration not only causes structural fatigue and performance degradation, but also causes discomfort to personnel. Traditional vibration reduction methods include the use of damping materials, vibration isolators and other methods. Although effective to a certain extent, they are often accompanied by significant weight increase, cost increase or design complexity increase, especially the poor vibration reduction effect in the low frequency band.

[0003] As a new vibration reduction technology, Acoustic Black Hole (ABH) has the advantages of small mass, low-frequency vibration reduction, and wide frequency band. Its principle is to use the change of internal impedance of the structure to change the phase velocity and group velocity of the bending wave propagating in the structure. The current way to achieve the effect of ABH is mainly to design the thickness of the structure so that the distance to the edge meets certain conditions, that is, the wave number of the bending wave changes very little on the wavelength scale. A power function with an exponent greater than 2 is one of the common forms that meets the conditions. In theory, when the thickness gradually decreases to 0, the wave velocity can be reduced to 0, and no reflection will occur. However, since the actual ABH tip has a certain truncation thickness, the wave energy is concentrated at the tip, which seriously affects the absorption of the wave. Therefore, a small amount of uniform damping is often arranged at the ABH tip to absorb the wave energy as much as possible.

[0004] In order to achieve better results, the existing attached acoustic black hole structures are often designed to be longer and occupy more space. At the same time, since the general acoustic black hole has a higher cutoff frequency, it can usually achieve better vibration suppression effects in higher frequency bands. However, in actual production and life, the vibration frequencies of many mechanical systems are usually kept in lower frequency bands, resulting in insignificant vibration reduction effects. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a spiral acoustic black hole structure and a ring-ribbed cylindrical shell with enhanced thickness, which can achieve low-frequency vibration reduction and broadband vibration reduction at the same time with a lower space occupancy.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] The present invention provides a spiral acoustic black hole structure with enhanced thickness, comprising a spirally curled portion and a mounting member for mounting the spirally curled portion on a structure to be damped, wherein the spirally curled portion comprises an extended enhanced thickness portion, a damping portion and a one-dimensional acoustic black hole slat with a gradually varying thickness, wherein the damping portion is tightly arranged on the inner ring 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 member, and the one-dimensional acoustic black hole slat is tightly arranged on the inner ring wall of the extended enhanced thickness portion between the outer end of the damping portion and the end of the mounting member, the thicker end of the one-dimensional acoustic black hole slat is connected to the end of the mounting member, and the thinner end of the one-dimensional acoustic black hole slat is connected to the damping portion.

[0008] As a further optimization scheme 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 enhanced thickness portion, and the upper surface of the one-dimensional acoustic black hole slab is a wedge surface.

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

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

[0011] h (x) =H t +εx m ;

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

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

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

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

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

[0017] As a further optimization scheme of the present invention, the extended enhanced thickness portion and the one-dimensional acoustic black hole slat are made of steel. The material of the mounting piece is steel. The extended enhanced thickness portion, the one-dimensional acoustic black hole slat and the mounting piece are an integrated structure.

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

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

[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 the present invention is lightweight and easy to install. It is formed by extending the enhanced thickness part, the damping part and the one-dimensional acoustic black hole slab and spirally curling it. 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 propagation speed of the wave gradually decreases with the power-law decrease of the thickness, thereby causing the wave to gather at the tip of the one-dimensional acoustic black hole slab, and then dissipate through the damping part, so that the wave energy is greatly absorbed, while the inherent characteristics of the damped structure are hardly changed.

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

[0023] 3. The mounting part of the present invention can be flexibly designed and can be applied to a variety of occasions and has a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0027] Figure 4 Schematic diagram of the spiral curling principle of the spiral acoustic black hole structure with enhanced thickness disclosed in an embodiment of the present invention.

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

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

[0030] Figure 7 The diagram is a comparison of vibration characteristics when no vibration-damping element is installed on the web of the ring-ribbed cylindrical shell, when a mass block of equal mass is installed, and when the acoustic black hole structure of the present invention is installed.

[0031] Figure 8 The vibration characteristics comparison diagram is when no vibration reduction element is installed on the outer shell of the ring-ribbed cylindrical shell, a mass block of equal mass is installed, and the acoustic black hole structure of the present invention is installed.

[0032] Figure numerals: 1. spiral curled portion; 101. extended enhanced thickness portion; 102. damping portion; 103. one-dimensional acoustic black hole slat; 104. upper surface; 105. lower surface; 2. mounting member; 3. ring-ribbed cylindrical shell; 301. web; 302. outer shell. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for exemplary description and cannot be understood as a limitation on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only for exemplary description and cannot be understood as a limitation on this patent.

[0034] One of the purposes of the present invention is to provide a new acoustic black hole structure, which can solve the vibration and noise reduction problems of the structure at low frequencies and wide frequencies, while greatly saving space occupancy.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is 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, comprising a spiral curled portion 1 and a mounting member 2 for connecting the spiral curled portion 1 to a structure to be damped. The damping portion 102 is closely arranged on the inner ring 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, and a one-dimensional acoustic black hole slat 103 is closely arranged on the inner ring 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 slat 103 is connected to the end of the mounting member 2, and the thinner end of the one-dimensional acoustic black hole slat 103 is connected to the damping portion 102.

[0037] The spiral curling part 1 is formed by an extended enhanced thickness part 101, a damping part 102 and a one-dimensional acoustic black hole slat 103, and is formed by curling the spiral in the form of a standard Archimedean spiral line, and is used to absorb and dissipate the vibration energy at any position of the structure to be damped while greatly saving the space occupancy. The extended enhanced thickness part 101 is considered to have a certain truncation thickness of the acoustic black hole, and the truncation thickness is extended to a certain length, which can better enhance the acoustic black hole effect; the damping part 102 is arranged on the inner wall surface of the one-dimensional acoustic black hole slat 103, and is used to absorb the vibration energy gathered at the tip of the one-dimensional acoustic black hole slat 103. The loss factor of the damping part 102 should be selected as large as possible. The mounting part 2 is arranged at the outer end of the spiral curling part 1, and is used to connect the spiral curling part 1 to the structure to be damped, thereby establishing a connection between the acoustic black hole structure and the structure to be damped, and the mounting part 2 can reasonably design the curvature according to the position of the part to be damped.

[0038] The lower surface 105 of the one-dimensional acoustic black hole slat 103 is a plane and is in close contact with the inner wall of the extended enhanced thickness portion 101, and the upper surface 104 of the one-dimensional acoustic black hole slat 103 is a wedge surface. The upper surface 104 rotates inwardly with the lower surface 105 while maintaining a relative distance from the lower surface 105 to form a spiral acoustic black hole structure. The distance between the plane and the wedge 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 curling portion 1, which is used to connect with the mounting member 2. The thinner end of the one-dimensional acoustic black hole slab 103 is sandwiched between the extended enhanced thickness portion 101 and the damping portion 102, so that the damping portion 102 is arranged on the tip surface of the one-dimensional acoustic black hole slab 103 to consume the energy accumulated at the tip.

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

[0040] h (x) =H t +εx m ;

[0041] Among them, H t is the thickness of the extended enhanced thickness part; x is the horizontal coordinate (such as Figure 3 As shown, the length direction of the spread-out 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 the ABH.

[0042] The vibration reduction effect of a single enhanced thickness spiral acoustic black hole structure is explained below in combination with simulation results.

[0043] In the spiral acoustic black hole structure with enhanced thickness, the extended enhanced thickness part, the one-dimensional acoustic black hole slats and the mounting parts can all be made of steel or other materials; the size of the mounting part 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 the extended enhanced thickness part 101, and the loss factor should be as large as possible, and the damping part and the acoustic black hole are glued.

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

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

[0046] According to the parametric equation of the Archimedean spiral, the coordinate of the spiral baseline is x b ,y b for:

[0047]

[0048] The baseline length can be integrated to obtain:

[0049]

[0050] The arc length l(θ) and the one-dimensional acoustic black hole expression h(x) = Ht + εx m Combined, the acoustic black hole structure model can be constructed.

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

[0052] (2) The mounting member 2 has a length of 60 mm, a width of 30 mm, and a thickness of 6 mm.

[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 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 used is asphalt damping.

[0056] (6) The outer diameter of the ring rib of the ring rib cylindrical shell 3 is 1000 mm, the outer shell 302 is 200 mm wide and 9 mm thick, the inner shell is 80 mm wide and 8 mm thick, and the ring rib web 301 is 200 mm wide and 5 mm 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 multi-physics field coupling analysis software COMSOL Multiphysics to describe the acoustic black hole structure model.

[0061] (10) The vibration characteristics of the structure are evaluated using the mean square velocity (MQV) formula:

[0062]

[0063] Where v is the vibration velocity amplitude, which can be directly calculated from the solid mechanics section, and v0 is the reference velocity amplitude, which is 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 installed on the web 301 of the ring-stiffened cylindrical shell 3, and the point excitation is below the web 301 of the acoustic black hole. Figure 7It is the mean square velocity level curve of the web of the ring-ribbed cylindrical shell. After installing the acoustic black hole, the vibration of the web is significantly suppressed, and its mean square velocity level curve is smoother. Almost all the resonance peaks are significantly reduced. At the same time, the natural frequency of the web has hardly changed, while the mass block of equal mass only reduces the peak value of the resonance peak at high frequency. This is because its inertial force in the high frequency band significantly suppresses the vibration of the web. When a single acoustic black hole structure is arranged on the web, the mean square velocity level peaks of the web are significantly reduced, and almost all the resonance peaks are reduced by more than 13dB. The vibration of the web is also significantly suppressed in the low frequency band, and the vibration reduction effect is significant.

[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, and the point excitation is performed at the outer shell 302 corresponding to the acoustic black hole structure, and the direction is inward excitation along the normal direction of the outer shell. Figure 8 The mean square velocity level curve of the outer shell of the ring-ribbed cylindrical shell. After installing the acoustic black hole, almost all resonance peaks were significantly suppressed, and the mean square velocity level of the resonance peak near the low frequency of 65Hz was reduced by more than 8dB. After that, the vibration reduction effect of higher frequencies was better, and the natural frequency of the shell hardly changed. The mass block of equal mass had almost no effect on vibration reduction.

[0066] It can be seen that the spiral acoustic black hole structure described in the present invention has the following advantages compared with the prior art:

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

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

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

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

[0071] 5. The spiral acoustic black hole with enhanced thickness is designed by combining the advantages of one-dimensional acoustic black hole, dynamic vibration absorber, spiral structure and constrained damping.

[0072] 6. The spiral acoustic black hole with enhanced thickness can achieve the purpose of light weight, space saving, good low-frequency vibration reduction effect and wide-band vibration reduction.

[0073] According to the description and drawings of the present invention, those skilled in the art can easily manufacture or use a spiral acoustic black hole structure with enhanced thickness of the present invention, and can produce the positive effects described in the present invention.

[0074] Unless otherwise specified, in the present invention, the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood in conjunction with the drawings and according to specific circumstances.

[0075] Unless otherwise clearly specified and limited, in the present invention, the terms "disposed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] The above is only a preferred embodiment of the present invention, but the present invention is not limited to the above specific embodiments. Those skilled in the art may make some modifications, supplements or use similar methods instead without departing from the principle of the present invention, which should also be regarded as the protection scope of the present invention.

Claims

1. A spiral acoustic black hole structure with enhanced thickness, characterized in that: The invention comprises a helical curled portion (1) and a mounting member (2) for mounting the helical curled portion (1) on a structure to be subjected to vibration reduction, wherein the helical curled portion (1) comprises an extended enhanced thickness portion (101), a damping portion (102) and a one-dimensional acoustic black hole slat (103) with a gradually varying thickness, wherein the damping portion (102) is closely arranged 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); the one-dimensional acoustic black hole slat (103) is tightly arranged on the inner ring 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 slat (103) is connected to the end of the mounting member (2), and the thinner end of the one-dimensional acoustic black hole slat (103) is connected to the damping portion (102).

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 wall of the extended enhanced thickness portion (101), and 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: The thinner end of the one-dimensional acoustic black hole slab (103) is sandwiched between the extended enhanced thickness portion (101) and the damping portion (102).

4. 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 expanded, the sum of the thicknesses of the one-dimensional acoustic black hole slab (103) and the corresponding extended enhanced thickness portion (101) below is h (x) The expression is: h (x) =H t +εx m ; Among them, H t is the thickness of the extended enhanced thickness portion; x is the abscissa; m is a constant, and m≥2; ε is the thickness coefficient used to scale the ABH.

5. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: The spirally curled portion (1) is formed by an extended enhanced thickness portion (101), a damping portion (102) and a one-dimensional acoustic black hole slab (103), and is spirally curled in the form of a standard Archimedean spiral.

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

7. The spiral acoustic black hole structure with enhanced thickness according to claim 1, characterized in that: The thickness of the damping portion (102) should be greater than twice the thickness of the extended enhanced thickness portion (101).

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

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

10. A ring-ribbed cylindrical shell (3), characterized in that: The web (301) and / or the outer shell (302) of the ring-ribbed cylindrical shell (3) is / are installed with a spiral acoustic black hole structure with enhanced thickness as described in any one of claims 1 to 9.

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