An additional acoustic black hole combination structure

Abstract

This invention discloses an additional acoustic black hole assembly structure, relating to the field of vibration reduction and noise reduction technology. It includes a vibration damping component and a protective shell. The protective shell has a protective cavity and is used for fixed connection with the controlled structure. The vibration damping component is disposed within the protective cavity and includes a connecting column and a damping disk fixedly wrapped around the outer periphery of the connecting column. The connecting column is used for fixed connection with the protective shell or the controlled structure. The thickness of the longitudinal section of the damping disk decreases exponentially from the side attached to the connecting column away from the connecting column. The additional acoustic black hole assembly structure provided by this invention can reduce the interference of external conditions and better reduce vibration and noise in the controlled structure.

Description

Technical Field

[0001] This invention relates to the field of vibration reduction and noise reduction technology, and in particular to an additional acoustic black hole combination structure. Background Technology

[0002] Vibration is a standing wave generated by multiple reflections at the boundaries of a structure, while noise is the wave energy radiated into the air by structural vibration. Therefore, manipulating the wave behavior within a structure is an effective means of achieving vibration reduction and noise reduction. Currently, wave manipulation is mainly divided into two methods: active and passive. Active methods generally require external power supply and involve complex system design, so they are not widely adopted. For passive methods, the most basic form is the addition of damping materials; some viscoelastic materials can effectively absorb vibration energy. However, for some heavy equipment, a large amount of damping material needs to be pasted onto the surface for vibration reduction. While this achieves vibration reduction and noise reduction, it is detrimental to structural lightweighting, increasing economic costs and adding excessive mass.

[0003] The concept of the acoustic black hole (ABH) effect has opened a new chapter in the research of artificially manipulating the propagation of flexural waves in elastic media and structures. As a novel passive control method, the acoustic black hole controls wave propagation by designing and optimizing the shape of the structure itself. It has the advantages of simple and flexible implementation, small mass, and great potential and broad application prospects in thin-walled structures. Currently, the main way to achieve the acoustic black hole effect by changing the structural impedance is to change the thickness of the structure. Utilizing the propagation characteristics of flexural waves in structures with varying thickness, when the structural thickness decreases in the form of a certain exponential function, the phase velocity and group velocity of the flexural wave also decrease accordingly. Ideally, when the thickness is reduced to zero, the wave velocity at the edge of the structure can be reduced to zero, achieving zero wave reflection. This concentrates all wave energy at the tip of the structure, achieving energy absorption or vibration reduction and noise reduction through the damping of the structure and the damping material attached to it. For example, patent CN108133700B provides an acoustic black hole vibration reduction and noise reduction device. This device includes a disk-shaped structure whose distance between the upper and lower surfaces gradually decreases from the central axis to the outer edge. The disk-shaped structure has a black hole region, and the distance between the upper and lower surfaces of the black hole region changes exponentially from the central axis to the outer edge. By attaching the disk-shaped structure to the structure to be denoised, broadband vibration reduction and noise reduction are achieved by utilizing the ABH effect and dynamic vibration absorption characteristics. However, during use, because the thickness of the disk-shaped structure decreases from the center outward, the acoustic black hole structure is easily affected by external conditions, affecting the vibration reduction and noise reduction effect. Summary of the Invention

[0004] The purpose of this invention is to provide an additional acoustic black hole combination structure to solve the problems existing in the prior art, reduce the interference of external conditions on itself, and better reduce vibration and noise of the controlled structure.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides an additional acoustic black hole assembly structure, including a vibration damping component and a protective shell; the protective shell has a protective cavity and is used for fixed connection with a controlled structure; the vibration damping component is disposed in the protective cavity, and the vibration damping component includes a connecting column and a vibration damping disk fixedly wrapped around the outer peripheral surface of the connecting column; the connecting column is used for fixed connection with the protective shell or the controlled structure; the thickness of the longitudinal section of the vibration damping disk decreases exponentially from the side that is attached to the connecting column along the direction away from the connecting column.

[0007] Preferably, the protective shell includes a detachably connected upper shell and a lower cover. The upper shell is open at one end facing the controlled structure. The lower cover is detachably disposed on the open side of the upper shell to form the protective cavity with the upper shell, and the lower cover is fixedly attached to the controlled structure. The connecting post is fixedly connected to the lower cover.

[0008] Preferably, the connecting post and the lower cover are detachably connected.

[0009] Preferably, a damping layer is provided on the inner wall surface of the upper shell.

[0010] Preferably, an extension ring is fixedly provided on the circumferential edge of the damping disc, and the thickness of the extension ring is the same as the thickness of the circumferential edge of the damping disc.

[0011] Preferably, the vibration damping assembly further includes an annular damping pad, which is fixedly disposed on the side of the extension ring facing the controlled structure, and the outer circumferential edge of the annular damping pad is flush with the outer circumferential edge of the extension ring.

[0012] Preferably, the perpendicular bisector of the end face of the damping disc that is away from the center of gravity of the controlled structure and is perpendicular to the end face is parallel to and not collinear with the center line of the connecting column.

[0013] Preferably, the cross-sections of the damping disc and the extension ring are both rectangular rings, the connecting column is a rectangular column, and the cross-section of the protective shell is rectangular.

[0014] Preferably, the expression for the exponent is h(w) i ) = aw i m ,i=1,2,3,4, where h(w i) represents the thickness of the damping disc, w i i = 1, 2, 3, 4 represent the distances from any point on the four edges of the end face of the connecting column away from the controlled structure to the corresponding parallel edge on the end face of the damping disk away from the controlled structure, a represents a coefficient, and m is greater than or equal to 2.

[0015] Preferably, the vibration damping component and the protective shell are made of aluminum.

[0016] The present invention achieves the following technical effects compared to the prior art:

[0017] The present invention provides an additional acoustic black hole combination structure, in which a vibration damping component and a protective shell are attached to the controlled structure. Waves of a certain frequency emitted by the controlled structure are transmitted to the vibration damping disk through the connecting column of the vibration damping component. Since the thickness of the vibration damping disk decreases exponentially, an acoustic black hole region is formed between the vibration damping disk and the controlled structure. The wave propagation speed decreases as the thickness decreases, the wavelength decreases, and the wave vibration amplitude increases, concentrating in the region with decreasing thickness. Utilizing the ABH effect and the characteristics of dynamic vibration absorption, broadband vibration damping and noise reduction are achieved for the controlled structure. In addition, since the vibration damping component is set in the protective cavity of the protective shell, the protective shell can protect the vibration damping disk, preventing external interference and damage to the vibration damping component, which would affect the vibration damping and noise reduction effect of the vibration damping component. Moreover, the protective shell can shield the noise and vibration generated by the vibration damping disk itself during the vibration damping and noise reduction process, thereby further improving the vibration damping and noise reduction effect on the controlled structure. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the additional acoustic black hole combination structure provided in Embodiment 1;

[0020] Figure 2 A top view schematic diagram of the additional acoustic black hole combination structure provided in Embodiment 1;

[0021] Figure 3 A schematic diagram illustrating the propagation of elastic waves in the damping disk structure provided in Embodiment 1;

[0022] Figure 4 A perspective view of an additional acoustic black hole combination structure provided for an embodiment;

[0023] Figure 5A comparison diagram of the damping characteristics of the additional acoustic black hole combination structure and the uniform plate provided in Example 1.

[0024] Figure 6 The diagram shows a comparison of the vibration characteristics of the additional acoustic black hole combination structure and the uniform plate provided in Example 1.

[0025] Icons: 100 - Additional acoustic black hole assembly structure; 110 - Vibration damping component; 111 - Connecting column; 112 - Vibration damping disc; 113 - Extension ring; 114 - Annular damping pad; 120 - Protective shell; 121 - Protective cavity; 122 - Upper shell; 1221 - Folding area; 123 - Lower cover; 1231 - Snap-fit ​​column; 1232 - Connecting boss; 200 - Controlled structure. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The purpose of this invention is to provide an additional acoustic black hole combination structure to solve the problems existing in the prior art, reduce the interference of external conditions on itself, and better reduce vibration and noise of the controlled structure.

[0028] 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.

[0029] Example 1

[0030] This embodiment provides an additional acoustic black hole combination structure. Please refer to [link / reference]. Figures 1-4 Specifically, it includes a vibration damping component 110 and a protective shell 120; the protective shell 120 has a protective cavity 121 and is used to be fixedly connected to the controlled structure 200; the vibration damping component 110 is disposed in the protective cavity 121 and includes a connecting column 111 and a vibration damping disk 112 fixedly wrapped on the outer peripheral surface of the connecting column 111. The connecting column 111 is used to be fixedly connected to the protective shell 120 or the controlled structure 200, and the thickness of the longitudinal section of the vibration damping disk 112 decreases exponentially from the side that is attached to the connecting column 111 along the direction away from the connecting column 111.

[0031] The vibration damping component 110 and the protective shell 120 are attached to the controlled structure 200. Waves of a certain frequency emitted by the controlled structure 200 are transmitted to the vibration damping disk 112 through the connecting post 111 of the vibration damping component 110. Since the thickness of the vibration damping disk 112 decreases exponentially, an acoustic black hole region is formed between the vibration damping disk 112 and the controlled structure 200. The wave propagation speed decreases as the thickness decreases, the wavelength decreases, and the wave vibration amplitude increases, concentrating in the region with decreasing thickness. Please refer to [link to relevant documentation]. Figure 3 By utilizing the ABH effect and the characteristics of dynamic vibration absorption, broadband vibration reduction and noise reduction are achieved on the controlled structure 200. In addition, since the vibration damping component 110 is set inside the protective cavity 121 of the protective shell 120, the protective shell 120 can protect the vibration damping disk 112, preventing external interference and damage to the vibration damping component 110, which would affect the vibration reduction and noise reduction effect of the vibration damping component 110. Furthermore, the protective shell 120 can shield the noise and vibration generated by the vibration damping disk 112 itself during the vibration reduction and noise reduction process, thereby further improving the vibration reduction and noise reduction effect on the controlled structure 200.

[0032] In the optional solutions of this embodiment, a more preferred option is described in the following description: Figure 1 and Figure 2 The protective shell 120 includes an upper shell 122 and a lower cover 123 that can be detachably connected. The upper shell 122 is open at one end facing the controlled structure 200. The lower cover 123 is detachably disposed on the open side of the upper shell 122 to form a protective cavity 121 with the upper shell 122. The lower cover 123 is fixedly attached to the controlled structure 200. Specifically, the lower cover 123 is fixedly bonded to the controlled structure 200. Multiple snap-fit ​​posts 1231 can be provided circumferentially along the outer edge of the lower cover 123. The open side of the upper shell 122 is provided with a folding area 1221 along the circumferential direction to facilitate connection with the lower cover 123. Multiple snap-fit ​​holes that are interference-fitted with the snap-fit ​​posts 1231 are provided circumferentially along the upper edge of the folding area 1221 to facilitate installation and disassembly. The connecting post 111 is fixedly connected to the lower cover 123. The wave of the controlled structure 200 is transmitted to the lower cover 123 and then to the connecting post 111.

[0033] More preferably, the connecting post 111 and the lower cover 123 are detachably connected, facilitating installation and disassembly. Specifically, the lower cover 123 has a connecting boss 1232 on the portion opposite to the connecting post 111. The connecting post 111 and the connecting boss 1232 have the same cross-sectional dimensions, and the connecting post 111 and the connecting boss 1232 are detachably fixed together by studs. Alternatively, the connecting post 111 can be directly fixed to the controlled structure 200, and the controlled structure 200 can directly transmit waves to the connecting post 111.

[0034] More preferably, a damping layer is provided on the inner wall surface of the upper shell 122. By providing the damping layer, noise can be absorbed and the noise reduction effect can be improved. Specifically, the damping layer can be made of butyl rubber material.

[0035] In the optional scheme of this embodiment, more preferably, an extension ring 113 is fixedly provided on the circumferential edge of the damping disk 112. The thickness of the extension ring 113 is the same as the thickness of the circumferential edge of the damping disk 112. The wave gathers in the area where the thickness of the damping disk 112 decreases. When it reaches the cut-off point, the wave continues to propagate at a low wave speed due to the extension ring 113. The weak point of the structure is located at the outermost end of the structure, and the deformation at the outer end is easier. The acoustic black hole effect is more likely to occur, thereby achieving high-efficiency broadband vibration reduction and noise reduction.

[0036] Specifically, the connecting column 111, the damping plate 112, and the extension ring 113 can be integrally formed to ensure stability.

[0037] In an optional embodiment, more preferably, the vibration damping component 110 further includes an annular damping pad 114. The annular damping pad 114 is fixedly disposed on the side of the extension ring 113 facing the controlled structure 200, and the outer circumferential edge of the annular damping pad 114 is flush with the outer circumferential edge of the extension ring 113. The annular damping pad 114 can consume most of the bending wave energy, thereby achieving the purpose of high-efficiency energy absorption or vibration reduction and noise reduction. Specifically, the annular damping pad 114 is bonded to the extension ring 113 or extended and bonded to the lower surface of the vibration damping disc 112. The annular damping pad 114 can be made of butyl rubber material, and the thickness can be specifically determined according to different materials. For example, if butyl rubber material is used, it can be set to 2mm. The bonding width does not exceed the acoustic black hole area, and more damping material can be bonded without exceeding the rated mass.

[0038] In the optional scheme of this embodiment, more preferably, the center of gravity of the end face of the damping disk 112 that is away from the controlled structure 200 and the perpendicular line of the end face is parallel to and not collinear with the center line of the connecting column 111. That is, the entire damping component 110 is eccentrically set. The eccentric design, compared with the symmetrical structure, makes it easier for the additional acoustic black hole combination structure 100 to form a strong coupling with the controlled structure 200, and better transfers the wave energy to the additional acoustic black hole combination structure 100 and consumes it, giving full play to the advantages of the acoustic black hole energy gathering effect.

[0039] In the optional schemes of this embodiment, it is more preferred that the vibration damping component 110 and the protective shell 120 are made of aluminum, which has low mass and good strength.

[0040] In the optional solutions of this embodiment, a more preferred option is described in the following description: Figure 2 and Figure 4The cross-sections of the damping disc 112 and the extension ring 113 are both rectangular rings, the connecting column 111 is a rectangular column, the cross-section of the protective shell 120 is rectangular, and the expression for the exponential change of the wall thickness of the damping disc 112 is h(w i ) = aw i m ,i=1,2,3,4, where h(w i ) indicates the thickness of the damping disc 112, w i i = 1, 2, 3, 4 represent the distances from any point on the four edges of the end face of the connecting column 111 away from the controlled structure 200 to the corresponding parallel edge on the end face of the damping disk 112 away from the controlled structure 200, respectively. a represents a coefficient, and m is greater than or equal to 2.

[0041] The dimensions of the additional acoustic black hole composite structure 100 provided in this embodiment are determined according to actual requirements. The following provides an additional acoustic black hole composite structure 100 with specific dimensions, and a model is established in ABAQUS using the finite element method. The damping level and vibration response of the structure are calculated through steady-state dynamic analysis and modal superposition method. Please refer to [link to relevant documentation]. Figure 2 The four edges of the upper end face of the connecting column 111 are perpendicular to the four edges of the upper end face of the damping plate 112 and have four sizes in a clockwise direction, namely w ABH1 =103.5mm, w ABH2 =60.2539mm, w ABH3 =62.5mm, w ABH4 =39.75mm; the four edges of the lower end face of the connecting column 111 are perpendicular to the four edges of the folded area 1221 and have four dimensions in a clockwise direction, namely w ABH5 =126mm, w ABH6 =82.75mm, w ABH7 =85mm, w ABH8= 62.25mm; the cross-sectional dimensions of the connecting column 111 are 14mm × 10mm; the upper surface dimensions of the damping disc 112 are 180mm × 110mm, with a maximum thickness of 3mm and a minimum edge thickness of 0.2mm; the width of the extension ring 113 is 10mm and the thickness is 0.2mm; the outer edge dimensions of the annular damping pad 114 are 190mm × 120mm, with a width of 10mm and a thickness of 2mm, and it is made of butyl rubber with a material loss factor set to 0.3; a length of 600mm, a width of 500mm, and a thickness of 5mm are selected. A uniform plate of mm diameter is used as the controlled structure 200. A coordinate system is established with the center of the controlled structure 200 as the origin. An additional acoustic black hole combination structure 100 is attached to the controlled structure 200 at (70, -100mm). To illustrate the superior performance of the rectangular eccentric DVA, a circular eccentric DVA is added as a control. The circular DVA has a diameter of 150mm, a maximum thickness of 3.5mm, and a minimum edge thickness of 0.3mm. The annular damping pad has a width of 10mm, a thickness of 2mm, and an outer diameter of 150mm, and is made of butyl rubber. To eliminate the influence of weight on the effect, the circular eccentric DVA weighs 141g, and the rectangular eccentric DVA weighs 135g.

[0042] Analysis of Calculation Results

[0043] 1. Damping Characteristics Analysis

[0044] like Figure 5 As shown, the additional acoustic black hole combination structure 100 provided in this embodiment can significantly improve the inherent damping of the structure, with a system damping ratio that is 5-75 times higher across the entire frequency band. Compared with the system with the addition of a circular additional ABH, the system damping ratio is also significantly improved. Overall, the additional acoustic black hole combination structure 100 can greatly improve the damping characteristics of the uniform plate, which has potential benefits for the vibration suppression of elastic structures, while not causing damage to the controlled object.

[0045] 2. Vibration Control Characteristics Analysis

[0046] like Figure 6 As shown, to evaluate the vibration level of the system, the system's origin response is selected as the indicator for study. From Figure 6It can be observed that after adding the additional acoustic black hole combination structure 100 provided in this embodiment, the vibration level of the structure before control is reduced by 5-28 dB across all frequencies in the entire broadband range. This is because the additional acoustic black hole combination structure 100 provided in this embodiment has a very high modal damping ratio due to the acoustic black hole effect and dynamic vibration absorption effect, and can make full use of its characteristics to absorb the wave energy on the controlled structure 200, thereby reducing the vibration level of the system. This is because the additional acoustic black hole combination structure 100 is designed in an eccentric form, which to some extent destroys the traditional perfect symmetry, making it easier for the additional structure to form a strong coupling with the controlled object, and better transfer the wave energy to the additional structure and consume it, thus giving full play to the advantages of the acoustic black hole energy concentration effect. Compared with the circular eccentric DVA, it can be seen that, under similar size, weight, and power law, the rectangular eccentric DVA has a significantly better vibration reduction effect on the uniform plate in the broadband range than the circular eccentric DVA.

[0047] The additional acoustic black hole combination structure 100 cleverly combines the characteristics of acoustic black holes and dynamic vibration absorbers, avoiding the limitations of traditional acoustic black holes and breaking the inherent perfect symmetry of traditional disk structures. It can realize the control of multiple modes of the controlled object by a single device, achieving a highly efficient vibration reduction effect.

[0048] The present invention can design parameters based on the frequency characteristics of the controlled object, which can further improve the broadband characteristics.

[0049] The additional eccentric acoustic black hole combination structure of the present invention has a small added mass, which can easily meet the requirements of engineering applications, and at the same time has the characteristics of high efficiency.

[0050] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An additional acoustic black hole combination structure, characterized in that: Includes a vibration damping assembly (110) and a protective housing (120). The protective shell (120) has a protective cavity (121), and the protective shell (120) is used for fixed connection with the controlled structure (200); The vibration damping component (110) is disposed in the protective cavity (121), and the vibration damping component (110) includes a connecting column (111) and a vibration damping disk (112) fixedly wrapped around the outer peripheral surface of the connecting column (111). The connecting column (111) is used to be fixedly connected to the protective shell (120) or the controlled structure (200). The thickness of the longitudinal section of the vibration damping disk (112) decreases exponentially from the side that is attached to the connecting column (111) in the direction away from the connecting column (111). The protective shell (120) includes a detachably connected upper shell (122) and a lower cover (123). The upper shell (122) is open at one end facing the controlled structure (200). The lower cover (123) is detachably disposed on the open side of the upper shell (122) to form the protective cavity (121) with the upper shell (122), and the lower cover (123) is fixedly attached to the controlled structure (200). The connecting post (111) is fixedly connected to the lower cover (123). A damping layer is provided on the inner wall surface of the upper shell (122). An extension ring (113) is fixedly provided on the circumferential edge of the damping disc (112), and the thickness of the extension ring (113) is the same as the thickness of the circumferential edge of the damping disc (112). The center line of the damping disc (112) that is perpendicular to the end face of the controlled structure (200) and is perpendicular to the end face is parallel to the center line of the connecting column (111) and is not collinear. The cross-sections of the damping disc (112) and the extension ring (113) are both rectangular rings, the connecting column (111) is a rectangular column, and the cross-section of the protective shell (120) is rectangular.

2. The additional acoustic black hole assembly structure according to claim 1, characterized in that: The connecting post (111) and the lower cover (123) can be detachably connected.

3. The additional acoustic black hole combination structure according to claim 1, characterized in that: The vibration damping assembly (110) further includes an annular damping pad (114), which is fixedly disposed on the side of the extension ring (113) facing the controlled structure (200), and the outer circumferential edge of the annular damping pad (114) is flush with the outer circumferential edge of the extension ring (113).

4. The additional acoustic black hole assembly structure according to claim 3, characterized in that: The expression for the exponent is: ,in, This indicates the thickness of the damping disc (112). The distances from any point on any of the four edges of the end face of the connecting column (111) away from the controlled structure (200) to the corresponding parallel edge on the end face of the damping disk (112) away from the controlled structure (200) are respectively represented by 'a', 'm', and 'm'.

5. The additional acoustic black hole assembly structure according to claim 1, characterized in that: The vibration damping component (110) and the protective shell (120) are made of aluminum.

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