Buoyant raft vibration isolation device integrated with acoustic black hole and size determination method of buoyant raft vibration isolation device

Abstract

The invention discloses a buoyant raft vibration isolation device integrated with an acoustic black hole and a size determination method of the buoyant raft vibration isolation device. The buoyant raft vibration isolation device comprises a raft frame and a plurality of acoustic black hole units installed in the raft frame, each acoustic black hole unit comprises a plurality of acoustic black hole structures which are sequentially stacked, each acoustic black hole structure is of a rectangular plate structure with the thin edge and the thick middle, and the end face, close to the bottom wall of the raft frame, of each rectangular plate structure is a plane. A through hole is formed in the middle of the rectangular plate structure for a fastener to penetrate through, and the fastener penetrates through all the acoustic black hole structures of the acoustic black hole units and then fastens the acoustic black hole structures in the raft frame. According to the buoyant raft vibration isolation device, on one hand, the structural modal frequency can be reduced, and on the other hand, the broadband and line spectrum vibration noise of a raft frame structure can be reduced.

Description

Technical Field

[0001] This invention relates to the field of ship vibration control technology, and in particular to a floating raft vibration isolation device integrating an acoustic black hole and its size determination method. Background Technology

[0002] Mechanical system noise is one of the main noise sources in ships operating at low speeds. Vibration isolation technology is an efficient means of controlling mechanical system noise. With the application of floating raft vibration isolation technology, broadband vibration noise of mechanical systems has been effectively suppressed and significantly reduced. At the same time, the line spectrum vibration control effect of floating raft vibration isolation technology is limited, and the line spectrum vibration noise of some mechanical systems is still too high, affecting the ship's vibration and noise environment and the operation of precision instruments and equipment, requiring further optimization and improvement.

[0003] Acoustic black hole technology can directionally transmit vibration energy to the center of a black hole and then absorb it through damping, which can effectively reduce the transmission of high-frequency vibrations. However, traditional acoustic black hole structures have high stiffness and high structural modal frequencies. While they have some effect on high-frequency line spectrum control, their effect on low-frequency line spectrum control is limited. Furthermore, a single acoustic black hole structure is difficult to meet the vibration control requirements of marine machinery and equipment, and further optimization and improvement are needed. Summary of the Invention

[0004] The main objective of this invention is to provide a raft vibration isolation device integrating an acoustic black hole and a method for determining its dimensions, which aims to reduce the structural modal frequencies and simultaneously reduce the broadband and line spectrum vibration noise of the raft structure.

[0005] To achieve the above objectives, the present invention provides a floating raft vibration isolation device integrating acoustic black holes, comprising a raft frame and multiple acoustic black hole units installed inside the raft frame. Each acoustic black hole unit includes multiple acoustic black hole structures stacked sequentially. The acoustic black hole structure is a rectangular plate structure with thin edges and thick middle. The end face of the rectangular plate structure near the bottom wall of the raft frame is flat. A through hole is provided in the middle of the rectangular plate structure for fasteners to pass through. After the fasteners pass through all the acoustic black hole structures of the acoustic black hole unit, they are fastened to the inside of the raft frame.

[0006] Preferably, one side of the planar structure of all acoustic black hole structures in the acoustic black hole unit faces the bottom wall of the raft.

[0007] Preferably, the multiple acoustic black hole units inside the raft are arranged in a matrix.

[0008] Preferably, each of the acoustic black hole units comprises 5 to 10 layers of acoustic black hole structure.

[0009] Preferably, the raft frame includes a top plate and a bottom plate arranged opposite to each other, as well as transverse and longitudinal reinforcing ribs connecting the top plate and the bottom plate. The top plate has multiple process holes, and the length and width dimensions of the acoustic black hole structure are smaller than the length and width dimensions of the process holes. The acoustic black hole unit is located between the top plate and the bottom plate.

[0010] Preferably, the acoustic black hole structure is made of aluminum, steel, or composite materials.

[0011] Preferably, the acoustic black hole structure includes a connecting part located in the middle and a vibration damping part arranged around the connecting part. The connecting part has a cylindrical structure, and a through hole is opened in the middle of the cylindrical structure for fasteners to pass through. The top and bottom surfaces of the cylindrical structure are both flat. The bottom surface of the vibration damping part is also flat and flush with the bottom surface of the connecting part. The thickness of the vibration damping part gradually increases from the outer ring side to the inner ring side of the top surface of the top surface, and the thickness of the vibration damping part is an exponential function.

[0012] Preferably, the top surface of the connecting part of the acoustic black hole structure abuts against the bottom surface of the connecting part of the acoustic black hole structure above it, and the thickness of the damping part is 5mm~20mm. Preferably, the modal frequencies of the acoustic black hole structure are consistent with the main excitation frequencies of the equipment on the raft.

[0013] This invention also proposes a method for determining the dimensions of a floating raft vibration isolation device based on the above-mentioned integrated acoustic black hole, comprising the following steps: The dimensions of the raft frame are determined based on the vibration isolation equipment, general layout, weight and space resource requirements; The main excitation frequency of the equipment on the floating raft is determined based on the operating conditions and factory test results of the vibration-isolated equipment. Based on the determined dimensions of the raft frame and the main excitation frequency of the equipment on the floating raft, the dimensions of the acoustic black hole unit are determined, as well as the material, length, width, thickness, and through-hole positions of the acoustic black hole structure, so that the modal frequency of the acoustic black hole unit is consistent with the excitation frequency of the equipment. The number of stacked layers of the acoustic black hole structure is determined based on the main height and weight requirements of the raft frame. Based on the arrangement of the transverse and longitudinal stiffeners and process holes in the raft structure, the number of rows and columns of the acoustic black hole unit is determined.

[0014] The integrated acoustic black hole raft vibration isolation device proposed in this invention has the following beneficial effects: 1. By improving the traditional acoustic black hole structure (which has a high modal frequency and poor low-frequency vibration reduction effect) to a structure with a thin edge and a thick middle, the modal frequency of the black hole structure itself can be significantly reduced, the low-frequency vibration reduction effect of the acoustic black hole can be improved, and the problem of poor low-frequency control effect can be solved. 2. By changing the circular plate to a rectangular plate and adjusting the installation position, the low-frequency modes of the acoustic black hole structure can be optimized, so that the elastic mode frequency of the acoustic black hole structure is consistent with the excitation frequency of the equipment on the raft, which can further improve the low-frequency vibration reduction effect of the acoustic black hole structure. 3. By setting the acoustic black hole unit as a stacked integrated design and installing the stacked acoustic black hole structure inside the raft frame door, the line spectrum vibration noise of the floating raft frame structure can be significantly reduced through the acoustic black hole structure and the periodic stacked bandgap characteristics, thus solving the problem of efficient control of line spectrum vibration noise of the ship's mechanical system and significantly reducing the line spectrum vibration of the ship's mechanical system. 4. This floating raft vibration isolation device can guide the efficient design of ship floating raft vibration isolation systems, significantly reduce the vibration and noise of ship mechanical systems, and provide support for the acoustic design of ship mechanical systems and the preparation of related installation documents. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the front view of the acoustic black hole structure in the raft vibration isolation device integrating an acoustic black hole according to the present invention. Figure 2 This is a three-dimensional structural diagram of the acoustic black hole structure in the raft vibration isolation device integrating an acoustic black hole according to the present invention. Figure 3 This is a three-dimensional structural diagram of the raft frame in the raft vibration isolation device integrating an acoustic black hole according to the present invention. Figure 4 This is a schematic diagram of the structure of the raft vibration isolation device integrating an acoustic black hole according to the present invention. Figure 5 This is a schematic diagram of the structure of the raft vibration isolation device integrating an acoustic black hole according to the present invention. Figure 6 This is a schematic diagram of the acoustic black hole unit in the raft vibration isolation device integrating an acoustic black hole according to the present invention.

[0016] In the figure, 1-raft frame, 11-top plate, 12-bottom plate, 13-transverse stiffener, 14-longitudinal stiffener, 15-process hole, 2-acoustic black hole unit, 21-acoustic black hole structure, 211-connection part, 212-vibration damping part.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] It should be noted that in the description of this invention, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing the invention and for 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, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] This invention proposes a raft vibration isolation device integrating an acoustic black hole.

[0021] Reference Figures 1 to 6 In this preferred embodiment, a floating raft vibration isolation device integrating acoustic black holes includes a raft frame 1 and multiple acoustic black hole units 2 installed inside the raft frame 1. Each acoustic black hole unit 2 includes multiple acoustic black hole structures 21 stacked sequentially. The acoustic black hole structure 21 is a rectangular plate structure with thin edges and thick middle. The end face of the rectangular plate structure near the bottom wall of the raft frame 1 is flat. A through hole is provided in the middle of the rectangular plate structure for fasteners to pass through. After the fasteners pass through all the acoustic black hole structures 21 of the acoustic black hole unit 2, they are fastened to the inside of the raft frame 1.

[0022] Specifically, fasteners can be bolts, which are used to fix the stacked acoustic black hole units 2 to the inside of the raft frame 1. (Refer to...) Figure 1 and Figure 2 The acoustic black hole structure 21 is a solid plate with a through hole in the middle.

[0023] Specifically, in this embodiment, referring to Figure 4 and Figure 6 All acoustic black hole structures 21 in acoustic black hole unit 2 have one side of their plane facing the bottom wall of raft 1. (Refer to...) Figure 4 and Figure 5 The multiple acoustic black hole units 2 inside the raft 1 are arranged in a matrix, that is, the acoustic black hole units 2 are set with multiple rows and columns.

[0024] Furthermore, in this embodiment, each acoustic black hole unit 2 includes 5 to 10 layers of acoustic black hole structures 21. By stacking and integrating the acoustic black hole units 2, the number of stacked layers of acoustic black hole structures 21 is increased as much as possible within the constraints of weight and space resources. The bandgap characteristics of the multi-layer periodic structure are utilized to improve the line spectrum vibration control effect. In this embodiment, a 7-layer configuration is used as an example for specific illustration.

[0025] In this embodiment, refer to Figures 3 to 5The raft frame 1 includes a top plate 11 and a bottom plate 12 arranged opposite to each other, as well as a transverse reinforcing rib 13 and a longitudinal reinforcing rib 14 connecting the top plate 11 and the bottom plate 12. The top plate 11 has multiple process holes 15. The length and width of the acoustic black hole structure 21 are smaller than the length and width of the process holes 15 (so as to facilitate the installation of the acoustic black hole unit 2). The acoustic black hole unit 2 is located between the top plate 11 and the bottom plate 12.

[0026] By installing the acoustic black hole unit 2 between the top plate 11 and the bottom plate 12, this installation does not increase the additional space resources of the raft frame 1 structure, and it is beneficial to use the raft frame 1 structure to protect the acoustic black hole unit 2. In addition, the band gap characteristics of the stacked structure of the acoustic black hole unit 2 can be used to further improve the acoustic performance of the floating raft.

[0027] In this embodiment, the acoustic black hole structure 21 is made of aluminum, steel or composite materials.

[0028] Specifically, refer to Figure 1 and Figure 2 The acoustic black hole structure 21 includes a connecting portion 211 located in the middle and vibration damping portions 212 arranged around the connecting portion 211. The connecting portion 211 has a cylindrical structure with a through hole in the middle for fasteners to pass through. The top and bottom surfaces of the cylindrical structure are flat. The bottom surface of the vibration damping portion 212 is also flat and flush with the bottom surface of the connecting portion 211. The thickness of the vibration damping portion 212 gradually increases from the outer ring side to the inner ring side of the top surface, and the thickness of the vibration damping portion 212 follows an exponential function. The top surface of the connecting portion 211 of the acoustic black hole structure 21 abuts against the bottom surface of the connecting portion 211 of the acoustic black hole structure 21 above it. The thickness of the vibration damping portion 212 is 5mm to 20mm. The length and width of the vibration damping portion 212 are determined according to the size of the process hole 15. Within the range not exceeding the size of the process hole 15, the larger its length and width, the better, in order to reduce its frequency.

[0029] Furthermore, the modal frequencies of the acoustic black hole structure 21 are consistent with the main excitation frequencies of the equipment on the raft 1, thereby improving the vibration reduction effect of the acoustic black hole structure 21.

[0030] The integrated acoustic black hole raft vibration isolation device proposed in this invention has the following beneficial effects: 1. By improving the traditional acoustic black hole structure 21, which is thick at the edges and thin in the middle (resulting in a high modal frequency and poor low-frequency vibration reduction effect), to a structure with thin edges and thick in the middle, the modal frequency of the black hole structure itself can be significantly reduced, the low-frequency vibration reduction effect of the acoustic black hole can be improved, and the problem of poor low-frequency control effect can be solved. 2. By changing the circular plate to a rectangular plate and adjusting the installation position, the low-frequency mode of the acoustic black hole structure 21 can be optimized, so that the elastic mode frequency of the acoustic black hole structure 21 is consistent with the excitation frequency of the equipment on the raft 1, which can further improve the low-frequency vibration reduction effect of the acoustic black hole structure 21. 3. By setting the acoustic black hole unit 2 as a stacked integrated design and installing the stacked acoustic black hole structure 21 inside the raft frame 1, the line spectrum vibration noise of the floating raft frame 1 structure can be significantly reduced through the acoustic black hole structure 21 and the periodic stacked bandgap characteristics, thus solving the problem of efficient control of line spectrum vibration noise of the ship's mechanical system and significantly reducing the line spectrum vibration of the ship's mechanical system. 4. This floating raft vibration isolation device can guide the efficient design of ship floating raft vibration isolation systems, significantly reduce the vibration and noise of ship mechanical systems, and provide support for the acoustic design of ship mechanical systems and the preparation of related installation documents.

[0031] The present invention also proposes a method for determining the dimensions of a floating raft vibration isolation device integrating an acoustic black hole.

[0032] In this preferred embodiment, a method for determining the size of a floating raft vibration isolation device based on the above-mentioned integrated acoustic black hole includes the following steps: Step S10: Determine the dimensions of the raft frame 1 based on the vibration isolation equipment, overall layout, weight and space resource requirements; Step S20: Determine the main excitation frequency of the equipment on the floating raft based on the operating conditions and factory test results of the vibration-isolated equipment. Step S30: Based on the determined dimensions of the raft frame 1 and the main excitation frequency of the equipment on the floating raft, determine the dimensions of the acoustic black hole unit 2, and determine the material, length, width, thickness, and through-hole position of the acoustic black hole structure 21, so that the modal frequency of the acoustic black hole unit 2 is consistent with the excitation frequency of the equipment. Step S40: Determine the number of stacking layers of the acoustic black hole structure 21 based on the main body height and weight resource requirements of the raft 1; Step S50: Based on the arrangement of the transverse reinforcing ribs 13, longitudinal reinforcing ribs 14, and process holes 15 of the raft frame 1 structure, determine the number of rows and columns of the acoustic black hole unit 2.

[0033] When determining the number of stacked layers of an acoustic black hole structure, the number of stacked layers should be increased as much as possible, provided that weight and space resources allow.

[0034] The dimension determination method proposed in this invention can significantly reduce the vibration and noise of marine mechanical systems, providing support for the acoustic design of marine mechanical systems and the preparation of related installation documents.

[0035] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A floating raft vibration isolation device integrating an acoustic black hole, characterized in that, The device includes a raft frame and multiple acoustic black hole units installed inside the raft frame. Each acoustic black hole unit includes multiple acoustic black hole structures stacked sequentially. Each acoustic black hole structure is a rectangular plate structure with thin edges and thick middle. The end face of the rectangular plate structure near the bottom wall of the raft frame is flat. A through hole is provided in the middle of the rectangular plate structure for fasteners to pass through. After the fasteners pass through all the acoustic black hole structures of the acoustic black hole unit, they are fastened to the inside of the raft frame.

2. The raft vibration isolation device integrating an acoustic black hole as described in claim 1, characterized in that, All acoustic black hole structures in the acoustic black hole unit have one side of their plane facing the bottom wall of the raft.

3. The raft vibration isolation device integrating an acoustic black hole as described in claim 1, characterized in that, The multiple acoustic black hole units inside the raft are arranged in a matrix.

4. The raft vibration isolation device integrating an acoustic black hole as described in claim 1, characterized in that, Each of the acoustic black hole units comprises 5 to 10 layers of acoustic black hole structure.

5. The raft vibration isolation device integrating an acoustic black hole as described in claim 1, characterized in that, The raft frame includes a top plate and a bottom plate arranged opposite each other, as well as transverse and longitudinal reinforcing ribs connecting the top plate and the bottom plate. Multiple process holes are provided on the top plate. The length and width dimensions of the acoustic black hole structure are smaller than the length and width dimensions of the process holes. The acoustic black hole unit is located between the top plate and the bottom plate.

6. The raft vibration isolation device integrating an acoustic black hole as described in claim 1, characterized in that, The acoustic black hole structure is made of aluminum, steel, or composite materials.

7. The raft vibration isolation device integrating an acoustic black hole as described in claim 1, characterized in that, The acoustic black hole structure includes a connecting part located in the middle and a vibration damping part arranged around the connecting part. The connecting part has a cylindrical structure with a through hole in the middle for fasteners to pass through. The top and bottom surfaces of the cylindrical structure are both flat. The bottom surface of the vibration damping part is also flat and flush with the bottom surface of the connecting part. The thickness of the vibration damping part gradually increases from the outer ring side to the inner ring side of the top surface of the top surface, and the thickness of the vibration damping part is an exponential function.

8. The raft vibration isolation device integrating an acoustic black hole as described in claim 7, characterized in that, The top surface of the connecting part of the acoustic black hole structure abuts against the bottom surface of the connecting part of the acoustic black hole structure above it; the thickness of the damping part is 5mm~20mm.

9. The raft vibration isolation device for an integrated acoustic black hole as described in any one of claims 1 to 8, characterized in that, The modal frequencies of the acoustic black hole structure are consistent with the main excitation frequencies of the equipment on the raft.

10. A method for determining the dimensions of a floating raft vibration isolation device based on an integrated acoustic black hole according to any one of claims 1 to 9, characterized in that, Includes the following steps: The dimensions of the raft frame are determined based on the vibration isolation equipment, general layout, weight and space resource requirements; The main excitation frequency of the equipment on the floating raft is determined based on the operating conditions and factory test results of the vibration-isolated equipment. Based on the determined dimensions of the raft frame and the main excitation frequency of the equipment on the floating raft, the dimensions of the acoustic black hole unit are determined, as well as the material, length, width, thickness, and through-hole positions of the acoustic black hole structure, so that the modal frequency of the acoustic black hole unit is consistent with the excitation frequency of the equipment. The number of stacked layers of the acoustic black hole structure is determined based on the main height and weight requirements of the raft frame. Based on the arrangement of the transverse and longitudinal stiffeners and process holes in the raft structure, the number of rows and columns of the acoustic black hole unit is determined.

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