Novel vibration and noise reduction flexible connecting pipe

Abstract

The invention provides a novel vibration and noise reduction flexible connecting pipe which is of an annular structure and comprises an outer side surface layer, an inner side surface layer and a zero-Poisson-ratio honeycomb core clamped between the outer side surface layer and the inner side surface layer. The honeycomb core is composed of hexagonal unit cell structures distributed in an array mode, and the Poisson ratio is zero by optimizing geometric parameters such as the length of the bevel edge, the height of the vertical wall, the thickness of the wall and the included angle of each unit cell. And a closed cavity is formed by the surface layer, so that radial deformation can be inhibited, a heat exchange effect can be generated, vibration and noise transmission can be reduced, and displacement compensation and balance can be accurately regulated and controlled. Outer side and inner side surface layer materials can be selected from elastic materials such as rubber and silicone rubber, and flanges are connected to two ends of the structure for pipeline connection. The connecting pipe is compact and reasonable in structure, has remarkable advantages in the aspects of vibration and noise reduction, displacement compensation, balance and the like, is wide in application range, and can meet the requirements of complex working conditions such as a ship pipeline system.

Description

Technical Field

[0001] The present invention relates to the technical field of ship noise, and in particular to a novel vibration damping and noise reduction flexible joint. Background Art

[0002] The vibration and noise transmitted in the ship pipeline system directly affect the stealth and safety of the ship. In addition, when the ship is subjected to underwater impact, the equipment on the pipeline system will generate a large instantaneous displacement due to the impact, which may cause the pipeline system to be damaged in severe cases. Therefore, it is necessary to take effective vibration damping and anti-impulse measures for the ship pipeline system. At present, the flexible joint technology is one of the effective control methods. It can not only isolate and attenuate the vibration and noise of the pipeline structure, but also compensate for the displacement caused by vibration and impact between the equipment and the pipeline system.

[0003] However, although the flexible joint can reduce the vibration and jitter of the medium during transmission to a certain extent, relying solely on the elasticity of the rubber joint still cannot meet the actual requirements, so it is easy to increase the failure rate of the flexible joint. At this time, a flexible joint with good shock absorption effect is needed.

[0004] Therefore, we propose a novel vibration damping and noise reduction flexible joint. Summary of the Invention

[0005] In view of the above-mentioned disadvantages in the existing production technology, the applicant provides a novel vibration damping and noise reduction flexible joint. Through the unique structure of the zero Poisson's ratio honeycomb core and the closed cavity formed with the elastic surface layer, the transmission of vibration and noise is effectively reduced by suppressing radial deformation and generating heat exchange effects. In terms of displacement compensation and balance, the honeycomb core, as the core skeleton, realizes the precise regulation of both through optimizing geometric parameters, solving the problems of traditional designs.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A novel vibration damping and noise reduction flexible joint, comprising a ring-shaped structure of:

[0008] An outer surface layer and an inner surface layer;

[0009] And;

[0010] A zero Poisson's ratio honeycomb core, clamped between the outer surface layer and the inner surface layer;

[0011] The zero Poisson's ratio honeycomb core includes a plurality of hexagonal unit cell structures distributed in an array. Two adjacent unit cell structures share a side in the axial direction. The two adjacent unit cell structures extend and are connected on both sides in the circumferential direction. A gap K is provided in the middle of the two adjacent unit cell structures in the circumferential direction. Among them, the hypotenuse length of the unit cell is l, the height of the axial vertical wall of the unit cell is αl, and the wall thickness of the unit cell is βl; the angle φ between the hypotenuse of the unit cell and the axis satisfies:

[0012] 2*sinφ*l + 2*βl + K = al。

[0013] In one embodiment, the raw material of the zero Poisson's ratio honeycomb core is selected from metals, nylons, resins or composite materials, and the Poisson's ratio is achieved to be 0 through geometric parameter design.

[0014] In one embodiment, the materials of the outer surface layer and the inner surface layer are independently selected from rubbers, silicone rubbers, polyurethanes or elastic plastics, and the thicknesses of the two surface layers can be the same or different.

[0015] In one embodiment, a plurality of sealed cavities are formed between the zero Poisson's ratio honeycomb core and the outer surface layer and the inner surface layer. The air medium in the sealed cavities generates heat exchange under the action of sound waves, and converts sound energy into heat energy.

[0016] In one embodiment, it further includes flanges, and the flanges are connected to both ends of the honeycomb sandwich cylindrical structure for pipeline connection.

[0017] In one embodiment, in the unit cell structure, the thickness of the axial frame is twice the thickness of the circumferential frame.

[0018] In one embodiment, the angle φ between the hypotenuse of the unit cell and the axis satisfies: 15° ≤ φ ≤ 60°.

[0019] In one embodiment, the angle φ between the hypotenuse of the unit cell and the axis is 30°, the ratio α of the height of the vertical wall to the length of the hypotenuse is 2, and the ratio β of the wall thickness to the length of the hypotenuse is 0.1.

[0020] In one embodiment, the materials of the outer surface layer and the inner surface layer are rubber, with a density of 1200 kg / m 3 , a Young's modulus of 3×10^9 Pa, and a Poisson's ratio of 0.48.

[0021] In one embodiment, the matrix material of the zero Poisson's ratio honeycomb core is steel, with a density of 7800 kg / m 3 , a Young's modulus of 200 GPa, and a Poisson's ratio of 0.3.

[0022] The beneficial effects of the present invention are as follows:

[0023] The structure of the present invention is compact, reasonable, and convenient to operate, showing significant advantages in multiple aspects. In terms of vibration and noise reduction performance, the unique structure of the zero Poisson's ratio honeycomb core and the sealed cavity formed with the elastic surface layer effectively reduce the transmission of vibration and noise by suppressing radial deformation and generating heat exchange effects. In terms of displacement compensation and balance, the honeycomb core, as the core framework, realizes precise control of both through optimizing geometric parameters, solving the problems of traditional designs. In terms of structural stability and application scope, the modular structure design, selection of high-quality surface materials, and standardized flange connections improve the overall stability of the pipe joint and broaden its application scenarios. These beneficial effects enable the novel flexible pipe joint of the present invention to better meet the usage requirements under complex working conditions such as ship pipeline systems, providing a more effective solution to solve the vibration and noise problems in pipeline systems, and having broad application prospects and market value.

[0024] Meanwhile, the present invention also has the following advantages:

[0025] The novel flexible pipe joint of the present invention uses a zero Poisson's ratio honeycomb core as the core support component. Its periodically distributed honeycomb structure effectively reduces the Poisson's ratio of the material while providing sufficient strength. During axial deformation, this unique structure can effectively suppress radial deformation and significantly reduce the Poisson coupling effect of the liquid-filled pipeline. By adjusting the geometric parameters of the honeycomb core's unit cell, such as the inclined side length, vertical wall height, wall thickness, and included angle, its mechanical properties and vibration and noise reduction effects can be precisely controlled. For example, when the included angle between the inclined side of the unit cell and the axial direction is within the range of 15° - 45°, the buffering efficiency can be improved. Moreover, the sealed cavity formed between the honeycomb core and the elastic surface layer generates a heat exchange effect under the action of sound waves, converting sound energy into heat energy and further enhancing the noise reduction performance. The impedance comparison experimental data strongly confirm the excellent performance of the novel flexible pipe joint. Compared with traditional straight pipes and ordinary flexible pipe joints, the present invention shows lower impedance values in the low-frequency range, meaning it can more effectively transmit and attenuate vibration energy, thus achieving better vibration and noise reduction and displacement compensation performance.

[0026] By using the honeycomb core as the core framework, the present invention can precisely control the displacement compensation ability and balance of the pipe joint. The contradiction in traditional designs that it is difficult to balance displacement compensation and balance is effectively solved in the present invention. By optimizing the geometric parameters of the honeycomb core, when the pipe joint bears displacement changes, it can not only achieve good displacement compensation but also maintain the balance of the structure. For example, by adjusting parameters such as the unit cell size, wall thickness, and included angle of the honeycomb core, its stiffness and damping characteristics can be precisely controlled, thereby realizing efficient vibration energy dissipation in a wide frequency band and ensuring the stability of the pipe joint during displacement changes. This optimized design enables the novel flexible pipe joint to better adapt to the vibration and displacement changes of ship pipeline systems under complex working conditions, improving the reliability and safety of the pipeline system.

[0027] The novel flexible pipe joint structure design of the present invention has modular characteristics, and each component works together, not only improving the overall stability of the pipe joint, but also effectively suppressing vibration and noise through the unique mechanical properties of the honeycomb core. The outer surface layer and the inner surface layer, as the interfaces directly contacting the pipeline medium, consider both elasticity and durability in material selection. Elastic materials such as rubber, silicone rubber, polyurethane, and elastic plastics are selected to ensure good sealing performance and vibration absorption ability under complex working conditions. The flange design fully considers the convenience and compatibility of installation, and realizes rapid docking with pipelines of different specifications through standardized connection interfaces, further expanding the application scope of the present invention. Whether in the ship pipeline system or other industrial fields requiring vibration and noise reduction, the novel flexible pipe joint of the present invention can play an important role and meet the usage requirements under different working conditions. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the flexible pipe joint structure in the present invention.

[0029] Figure 2 It is a geometric parameter diagram of the flexible pipe joint in the present invention.

[0030] Figure 3 It is a schematic diagram of the honeycomb core model structure in the flexible pipe joint of the present invention.

[0031] Figure 4 It is a schematic diagram of the geometric parameters of the zero Poisson's ratio honeycomb core in the flexible pipe joint of the present invention.

[0032] Figures 5 - 8 It is a comparison diagram of the vibration and noise reduction effects of the flexible pipe joint, rubber pipe, and steel pipe in the present invention.

[0033] In the figure:

[0034] 1. Outer surface layer; 2. Zero Poisson's ratio honeycomb core; 3. Flange; 4. Inner surface layer;

[0035] R. Neutral surface radius of the flexible pipe joint, L. Length of the flexible pipe joint, h. Thickness of the flexible pipe joint, h0. Thickness of the honeycomb core. Detailed Embodiments

[0036] The following combines the drawings to illustrate the detailed embodiments of the present invention.

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inner" and "outer" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the term "connection" 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 a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present invention can be understood according to specific circumstances.

[0039] The technical problem to be solved by this invention patent is that the damping effect of general flexible pipes is poor, and a new type of flexible pipe with good damping and noise reduction effects is provided. This flexible pipe consists of an outer surface layer 1, an inner surface layer 4, a zero Poisson's ratio honeycomb core 2, and a flange 3. The surface layers are bonded to both sides of the honeycomb core to form a honeycomb sandwich cylindrical structure, and both ends of the honeycomb sandwich cylindrical structure are connected to the flange 3. The skin is an elastic material, which can be rubber, silicone rubber, polyurethane, elastic plastic, etc., but is not limited thereto. The thicknesses of the two skin layers can be the same or different. The honeycomb core is any honeycomb core with a zero Poisson's ratio characteristic in a periodic distribution, and the raw materials can be metal materials, nylon materials, resin materials, composite materials, etc., but are not limited thereto. The flange 3 is only used for pipe connection, and the structure and size of the flange 3 are not restricted. The core advantage of this structural design lies in its modular characteristics. The components work together, not only improving the overall stability of the pipe, but also effectively suppressing vibration and noise through the unique mechanical properties of the honeycomb core. The outer surface layer and the inner surface layer, as the interfaces directly contacting the pipeline medium, need to consider both elasticity and durability in material selection to ensure good sealing performance and vibration absorption ability under complex working conditions. The zero Poisson's ratio honeycomb core, as the key supporting component of the entire structure, its periodically distributed honeycomb structure provides sufficient strength while effectively reducing the Poisson's ratio of the material, thus significantly reducing the noise and vibration caused by material deformation. The design of the flange 3 fully considers the installation convenience and compatibility, and realizes the rapid docking with different specifications of pipes through standardized connection interfaces, further expanding the application scope of the present invention.

[0040] Specifically, a flexible pipe with good damping and noise reduction effects in this embodiment includes 1 zero Poisson's ratio honeycomb core 2, 2 elastic surface layers, and 2 flanges 3. The surface layers are bonded to both sides of the honeycomb core to form a honeycomb sandwich cylindrical structure, and both ends of the honeycomb sandwich cylindrical structure are connected to the flange 3.

[0041] The multiple beneficial effects of the novel flexible joint are as follows: Firstly, the honeycomb core, as the core framework, can precisely regulate the displacement compensation ability and balance of the joint. By optimizing the geometric parameters of the honeycomb core, the contradiction between displacement compensation and balance in traditional designs, which is difficult to balance, is effectively solved. Secondly, during axial deformation, the unique structure of the zero Poisson's ratio honeycomb core can effectively suppress radial deformation, significantly reducing the Poisson coupling effect of the liquid-filled pipeline, thereby greatly enhancing the vibration and noise reduction effect. Finally, the sealed cavity formed between the honeycomb core and the elastic surface layer generates a heat exchange effect under the action of sound waves, converting sound energy into heat energy, further enhancing the noise reduction performance.

[0042] The impedance comparison experimental data strongly confirms the excellent performance of the novel flexible joint. Compared with traditional straight pipes and ordinary flexible joints, the present invention exhibits lower impedance values in the low-frequency range, which means it can more effectively transmit and attenuate vibration energy, thereby achieving better vibration and noise reduction and displacement compensation performance. Impedance is a key indicator for evaluating the dynamic performance of pipeline systems, which reflects the propagation and reflection characteristics of the system to vibration waves. A lower impedance value indicates that the system has a stronger ability to attenuate vibration waves, and can effectively reduce the propagation distance and intensity of vibration waves in the pipeline system. Through comparative experiments, it can be clearly observed that the impedance characteristics of the present invention are superior to those of traditional designs at different frequencies. Especially in the low-frequency band, its impedance value is significantly reduced, which provides strong support for improving the overall vibration and noise reduction performance of ship pipeline systems.

[0043] At the same time, the impedance comparison diagrams of the novel flexible joint proposed in the present invention with traditional straight pipes and ordinary flexible joints are shown in Figure 4 as follows. It can be seen that the novel flexible joint in the present invention has a lower impedance value and better vibration and noise reduction and displacement compensation capabilities.

[0044] The present invention provides a novel flexible joint, which includes an outer surface layer 1, a zero Poisson's ratio honeycomb core 2, a flange 3, and an inner surface layer 4. The outer surface layer 1 and the inner surface layer 4 are connected to the zero Poisson's ratio honeycomb core 2 to form a honeycomb flexible sandwich structure (see Appendix Figure 2 ), and both ends of the honeycomb sandwich flexible structure are connected to the flange 3. The zero Poisson's ratio honeycomb core 2 is selected as a double-V honeycomb structure (see Appendix Figure 3 ), that is, the zero Poisson's ratio honeycomb core 2 includes a plurality of hexagonal unit cell structures distributed in an array. Compared with traditional honeycomb structures, the double-V honeycomb structure has higher specific stiffness and specific strength, and can provide better load-bearing capacity and energy absorption performance under the same weight.

[0045] Two adjacent unit cell structures in the axial direction share a common side, and two adjacent unit cell structures in the circumferential direction are connected on both sides, and a gap K is provided in the middle. ，By setting the spacing K, the circumferential interval of the propagation path of sound waves or vibration waves is changed, which can disrupt the continuity of sound / vibration, enhance the structural damping. At the same time, by adjusting the size of K, the acoustic bandgap of the honeycomb structure can be designed to achieve the suppression of specific frequency noise. In addition, the overall weight can be reduced because the honeycomb structure itself has sufficient stiffness and no shared edges, which can reduce the weight of the intermediate honeycomb sandwich; another effect is to increase the intermediate air layer and improve the vibration damping effect. Under impact or compressive loads, the interval K can serve as a deformation buffer to absorb more energy through plastic deformation.

[0046] In this embodiment, in the unit cell structure, the axial frame thickness is twice the circumferential frame thickness. The differential design of the axial and circumferential frame thicknesses realizes the directional dissipation of vibration energy and the active intervention of the sound wave propagation path. The core advantage of this anisotropic honeycomb structure in vibration and noise reduction lies in: the axial direction mainly focuses on "blocking" (suppressing propagation), and the circumferential direction mainly focuses on "diverting" (guiding dissipation). Through the combination of rigidity and flexibility, it covers the collaborative control of low-frequency impact and high-frequency vibration noise.

[0047] Among them, the hypotenuse length of the unit cell is l, the height of the axial vertical wall of the unit cell is αl, and the wall thickness of the unit cell is βl; the angle between the hypotenuse of the unit cell and the axial direction is φ;

[0048] Satisfy: (sinφ * l (the projected height of the hypotenuse of the unit cell in the circumferential direction) + βl + 1 / 2K) * 2 = al, that is: 2 * sinφ * l + 2 * βl + K = al, where 15° ≤ φ ≤ 60°. By adjusting the geometric parameters of the unit cell, such as the hypotenuse length l, the vertical wall height αl, the wall thickness βl, and the angle φ, etc., the mechanical properties and vibration and noise reduction effects of the honeycomb core can be precisely controlled. In addition, by changing the local stiffness distribution of the honeycomb core, the multi-band attenuation of vibration waves is realized, further improving the vibration and noise reduction performance.

[0049] By ensuring that the sum of the circumferential solid part (hypotenuse projection + wall thickness) and the interval K is equal to the axial wall height, the geometric compatibility of the unit cell in the axial and circumferential directions is ensured, and the strength of the unit cell structure is guaranteed.

[0050] By adjusting φ, βl, and K, on the premise of satisfying the formula, the axial and circumferential stiffness ratios can be directionally adjusted. For example:

[0051] Increase φ: Increase the hypotenuse projection, and it is necessary to reduce K or β to maintain the equation, which may lead to an increase in circumferential stiffness and is suitable for scenarios where circumferential vibration needs to be suppressed.

[0052] Increase K: It is necessary to reduce φ or βl, thereby reducing the circumferential stiffness and enhancing the energy dissipation ability.

[0053] Meanwhile, it is beneficial for noise reduction. By adjusting the interval K: Through the formula to relate K with other parameters, the size of the circumferential microchannel can be precisely designed, which affects the reflection, transmission, and scattering of sound waves.

[0054] Hypotenuse angle: Changes the propagation path of sound waves in the honeycomb. A large angle increases the probability of oblique incidence of sound waves and enhances the attenuation of sound energy.

[0055] The formula ensures the geometric difference between the axial wall (αl) and the circumferential structure (K), forming an acoustic impedance gradient to reflect sound waves in a specific frequency band.

[0056] In one embodiment, for two adjacent unit cells, the inner and outer surface layers 1 are made of rubber materials with the same thickness, and its density is 1200 kg / m 3 , and the Young's modulus is 3×10 9 Pa, and the Poisson's ratio is 0.48. The rubber material has good elasticity and damping characteristics, and can effectively attenuate vibration and noise. By adjusting the formula and process parameters of the rubber, its dynamic mechanical properties can be further improved to meet the requirements under specific working conditions. At the same time, the optimization of geometric parameters comprehensively considers factors such as the installation space of the nozzle, working pressure, and vibration characteristics of the nozzle. Through finite element analysis and experimental verification, it is ensured that the nozzle can still maintain stable working performance under complex working conditions.

[0057] In this embodiment, as Figure 4 shown in the figure, in the figure, θ is the circumferential direction of the pipeline in the coordinate system, x is the axial direction in the coordinate system, l is the hypotenuse length of the unit cell; αl is the height of the vertical wall in the x direction of the unit cell; βl is the wall thickness of the unit cell; φ is the angle between the unit cell and the x direction.

[0058] It should be noted that the geometric parameters of the honeycomb core have a decisive influence on its mechanical properties. By adjusting parameters such as the unit cell size, wall thickness, and included angle of the honeycomb core, its stiffness and damping characteristics can be precisely controlled, so as to achieve efficient vibration energy dissipation in a wide frequency band. In addition, the heat exchange effect of the closed cavity not only depends on the geometric shape of the cavity, but also is closely related to the material properties of the surface layer. High-damping elastic materials can enhance the interaction between sound waves and the cavity, promote the conversion of sound energy into heat energy, and further improve the noise reduction effect.

[0059] In a specific embodiment, the geometric parameters of a new type of flexible nozzle in this embodiment are: the length L of the flexible nozzle is 1 m, the neutral surface radius R of the flexible nozzle is 0.05 m, the thickness h of the flexible nozzle is 5 mm, and the thickness h0 of the honeycomb core is 4 mm. The geometric parameters of the honeycomb core are: αl = 2, βl = 0.1, φ = 30°, that is, the ratio α of the height of the vertical wall to the hypotenuse length is 2, and the ratio β of the wall thickness to the hypotenuse length is 0.1. The honeycomb core is made of steel, and its density is 7800 kg / m 3 , and the Young's modulus is 200 GPa, and the Poisson's ratio is 0.3.

[0060] Through impedance calculation and comparison with the impedance characteristics of steel pipes and rubber hoses, see the appendix Figure 4 . It can be seen that in the low-frequency range, the acoustic impedance and mechanical impedance amplitudes of steel pipes are greater than those of rubber hoses and the flexible pipe joints of the present invention. The acoustic impedance amplitude of the rubber hose is less than that of the flexible pipe joints of the present invention, while the mechanical impedance amplitude is greater than that of the flexible pipe joints of the present invention. In addition, the resonance and anti-resonance frequencies of steel pipes are also greater than those of rubber hoses and the flexible pipe joints of the present invention. The acoustic impedance resonance and anti-resonance frequencies of rubber hoses are less than those of the flexible pipe joints of the present invention, while the mechanical impedance resonance and anti-resonance frequencies are greater than those of the flexible pipe joints of the present invention.

[0061] Similarly, as Figures 5 - 8 shown, it can be seen that there are many small burrs in the mechanical impedance amplitude-frequency curves of steel pipes and rubber hoses, which are caused by acoustic resonance of the fluid in the pipes. However, there are no burrs in the mechanical impedance amplitude-frequency curve of the flexible pipe joints of the present invention. The structure and the longitudinal wave of the fluid are independent of each other, and there is no Poisson coupling. It is proved that the flexible pipe joints of the present invention have a more effective vibration and noise reduction effect than ordinary rubber hoses and steel pipes.

[0062] Specifically, the calculation and design method of the zero Poisson's ratio honeycomb structure in this embodiment includes the following steps:

[0063] Since the honeycomb sandwich cylindrical shell is an axisymmetric model, the bending caused by the displacement of any mass point of the sandwich cylindrical shell can be expressed according to the classical shell theory (CST) as:

[0064]

[0065] According to the linear motion relationship, the strain of the sandwich cylindrical shell can be expressed as:

[0066]

[0067] Based on Hooke's law, the stress-strain relationship of the thin-walled sandwich cylindrical shell is as follows:

[0068]

[0069] Among them, is the elastic constant and can be written as:

[0070]

[0071] Among them and are the equivalent moduli of the inner layer, outer layer, and core layer in the x and θ directions. And are equivalent Poisson's ratios. k = 1, 2, and 3 represent the inner layer, core layer, and outer layer respectively.

[0072] Assume that the materials of the isotropic parts are the same, that is, the material properties of the inner and outer layers are the same, and their elastic modulus, density, and Poisson's ratio are E, ρ t and μ, respectively. That is, the material properties of the inner and outer layers are as follows:

[0073]

[0074] According to the literature, the equivalent mechanical properties of the zero Poisson's ratio honeycomb core 2 are:

[0075]

[0076] where and ρ c are the elastic modulus and density of the honeycomb core matrix material, respectively.

[0077] In the present invention, the acoustic impedance matching of the surface layer causes an absorption effect. Since the flexible pipe wall does not adopt a solid sandwich layer, but a hollow honeycomb structure, air will be formed between the upper and lower elastic surface layers and the honeycomb sandwich. Due to the large magnitude difference among the acoustic impedance of the fluid medium in the pipe, the acoustic impedance of the elastic medium of the pipe wall, and the acoustic impedance of the air medium in the sandwich, there is an obvious acoustic impedance mismatch among the three, so that the vibration noise in the pipe can be effectively isolated from being transmitted outward. Because the air layer is a very good acoustic barrier layer.

[0078] In this embodiment, the acoustic impedance matching of the surface layer causes an absorption effect. Since the flexible pipe wall does not adopt a solid sandwich layer, but a hollow honeycomb structure, air will be formed between the upper and lower elastic surface layers and the honeycomb sandwich. Due to the large magnitude difference among the acoustic impedance of the fluid medium in the pipe, the acoustic impedance of the elastic medium of the pipe wall, and the acoustic impedance of the air medium in the sandwich, there is an obvious acoustic impedance mismatch among the three, so that the vibration noise in the pipe can be effectively isolated from being transmitted outward. Because the air layer is a very good acoustic barrier layer.

[0079] The above description is an explanation of the present invention, not a limitation of the invention. The scope defined by the present invention is referred to the claims, and within the protection scope of the present invention, any form of modification can be made.

Claims

1. A new type of vibration and noise reduction flexible joint, characterized in that Including a ring-shaped structure consisting of: An outer surface layer and an inner surface layer; And; A zero Poisson's ratio honeycomb core sandwiched between the outer surface layer and the inner surface layer; The zero Poisson's ratio honeycomb core includes a plurality of hexagonal unit cell structures distributed in an array. Two adjacent unit cell structures share a side in the axial direction, extend and are connected on both sides of two adjacent unit cell structures in the circumferential direction, and a gap K is provided in the middle of two adjacent unit cell structures in the circumferential direction. Among them, the hypotenuse length of the unit cell is l, the height of the axially perpendicular wall of the unit cell is αl, and the wall thickness of the unit cell is βl; the angle φ between the hypotenuse of the unit cell and the axis satisfies: 2*sinφ*l + 2*βl + K = al.

2. The vibration damping and noise reduction flexible joint according to claim 1, wherein: The raw material of the zero Poisson's ratio honeycomb core is selected from metals, nylon, resins or composite materials, and the Poisson's ratio is achieved to be 0 through geometric parameter design.

3. The vibration damping and noise reduction flexible connection pipe according to claim 1, characterized in that: The materials of the outer surface layer and the inner surface layer are independently selected from rubber, silicone rubber, polyurethane or elastic plastics, and the thicknesses of the two surface layers can be the same or different.

4. The vibration damping and noise reduction flexible pipe joint according to claim 1, wherein: A plurality of sealed cavities are formed between the zero Poisson's ratio honeycomb core and the outer surface layer and the inner surface layer. The air medium in the sealed cavities generates heat exchange under the action of sound waves, converting sound energy into heat energy.

5. The vibration damping and noise reduction flexible joint according to claim 1, characterized in that: It further includes flanges connected to both ends of the honeycomb sandwich cylindrical structure for pipeline connection.

6. The vibration damping and noise reduction flexible connection pipe according to claim 1, characterized in that: In the unit cell structure, the thickness of the axial frame is twice the thickness of the circumferential frame.

7. The vibration damping and noise reduction flexible joint according to claim 6, wherein: The angle φ between the hypotenuse of the unit cell and the axis satisfies: 15° ≤ φ ≤ 60°.

8. The vibration damping and noise reduction flexible pipe joint according to claim 7, characterized in that: The angle φ between the hypotenuse of the unit cell and the axis is 30°, the ratio of the height of the perpendicular wall to the hypotenuse length α = 2, and the ratio of the wall thickness to the hypotenuse length β = 0.

1.

9. The vibration damping and noise reduction flexible joint according to claim 1, characterized in that: The materials of the outer surface layer and the inner surface layer are rubber, with a density of 1200 kg / m 3 , a Young's modulus of 3×109 Pa, and a Poisson's ratio of 0.

48.

10. The flexible pipe for vibration reduction and noise reduction according to claim 1, characterized in that: The matrix material of the zero Poisson's ratio honeycomb core is steel, with a density of 7800 kg / m 3 , a Young's modulus of 200 GPa, and a Poisson's ratio of 0.3.

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