Periodic structure-based low-frequency vibration isolation quasi-zero stiffness bracket for pipeline and implementation method

Abstract

The application discloses a kind of based on periodic structure's pipeline low-frequency vibration isolation quasi-zero stiffness support and implementation method, belong to structure vibration isolation technical field, including the hoop being arranged on pipeline, with the quasi-zero vibration isolation unit being connected with the hoop, the support frame body being connected the quasi-zero stiffness vibration isolation unit, the quasi-zero stiffness vibration isolation unit is evenly arranged several along pipeline section, the quasi-zero stiffness vibration isolation unit is hexagonal composite beam structure, and the support frame body is rectangular frame body.The application realizes complete zero stiffness, and then plays the vibration isolation performance of full-band, can realize zero stiffness within wide range of deformation, utilizes periodic structure principle, designs the semi-active vibration control of pipeline, with high static stiffness and low stiffness characteristics, suitable for large-diameter thin-walled pipeline low-frequency vibration control, low in cost, vibration control band is wide, help to realize the statics / dynamics comprehensive optimization design of pipeline support hanger system.

Description

Technical Field

[0001] The present invention relates to the technical field of structural vibration isolation, and more particularly to a pipeline low-frequency vibration isolation quasi-zero stiffness bracket based on a periodic structure and an implementation method thereof. Background Art

[0002] Common pipelines include water supply and drainage, gas, fuel, heating, and refrigeration. Pipeline design requires consideration of numerous factors, including fluid flow, support, vibration, and compensation. Fluids at certain pressures and velocities generate dynamic pressure on the pipe walls, causing vibrations. These vibrations can negatively impact the safety and lifespan of the pipelines, and in severe cases, can have incalculable consequences. For liquid infusion / filling piping systems, static buckling and vibration issues severely impact the operational reliability of the piping system. Low-frequency vibration, in particular, is a pressing issue that needs to be addressed both domestically and internationally.

[0003] Patent document No. CN110185740A discloses a novel low-frequency, high-temperature-resistant, variable-rigidity pipe clamp, comprising a pipe clamp (1), a metal rubber (2), and a coil spring (3); wherein a circular installation space is provided inside the pipe clamp (1), the metal rubber (2) is annular and its outer wall is tightly connected to the inner wall of the pipe clamp (1), the coil springs (3) are arranged in a plurality of arrays and installed inside the metal springs (3), and the coil springs (3) are partially located outside the metal rubber (2). The clamp can absorb low-frequency vibrations of high-temperature pipes through the internal coil springs, and a circular cavity is formed by two semicircular pipe clamps, which are fixed to the pipe by bolts.

[0004] Patent document with publication number CN114623289A discloses an active-passive composite shock-absorbing device and a working method thereof, relating to the field of vibration and noise control technology. The shock-absorbing device is suitable for pipeline vibration isolation, comprising: a pipe clamp, which is sleeved on the outside of the pipeline, and a medium- and high-frequency shock-absorbing unit is provided in the pipe clamp; a drive component, which is connected to the pipe clamp; and an induction drive component, which is connected to the drive component. By arranging the medium- and high-frequency shock-absorbing unit in the pipe clamp, the vibration is converted into heat energy for dissipation, and the medium- and high-frequency broadband vibration of the pipeline is controlled. The medium- and high-frequency shock-absorbing unit is a shock-absorbing material arranged in the pipe clamp.

[0005] The above two methods can achieve vibration isolation effects to a certain extent. However, they do not have a balanced configuration and cannot suppress the specific low-frequency and high-amplitude vibrations of the piping structure in the low-frequency band. Summary of the Invention

[0006] Therefore, the application provides a pipeline low-frequency vibration isolation quasi-zero stiffness support based on a periodic structure and an implementation method, so as to realize low-frequency wide-band vibration isolation and vibration absorption of the pipeline and to realize the static / dynamic service performance requirements of the pipeline.

[0007] To solve the above technical problems, the technical solution adopted by the application is:

[0008] The pipeline low-frequency vibration isolation quasi-zero stiffness support based on the periodic structure comprises a hoop arranged on the pipeline, a quasi-zero vibration isolation unit connected with the hoop, and a support frame body connected with the quasi-zero vibration isolation unit.

[0009] Further, the quasi-zero vibration isolation unit is four, and the quasi-zero vibration isolation unit and the rectangular frame body form a structure symmetrical in up-down and left-right.

[0010] Further, when in a static equilibrium position, the pipeline and the four quasi-zero vibration isolation units are in a static force balance state; when the pipeline vibrates with acceleration in a certain direction, the stiffness characteristics in the direction can be realized by the quasi-zero stiffness characteristics of the adjacent quasi-zero vibration isolation units, so as to realize effective vibration isolation in a given frequency band.

[0011] Further, the edge frame of the quasi-zero vibration isolation unit is provided with a spring.

[0012] Further, the hoop is made of metal and is attached to the outer wall of the pipeline and is fixed by bolts.

[0013] Further, the implementation method of the pipeline low-frequency vibration isolation quasi-zero stiffness support based on the periodic structure comprises the following steps.

[0014] S1: Obtain the cold and hot state equilibrium configurations of the pipeline and the node loads of each support by applying the elastic mechanics thermal stress analysis theory;

[0015] S2: Measure the vibration characteristics of the pipeline system by applying the vibration mechanics and engineering test analysis theory;

[0016] S3: Determine the arrangement mode of the quasi-zero vibration isolation unit according to the vibration characteristics;

[0017] S4: Establish a dynamic finite element model of the quasi-zero vibration isolation unit;

[0018] S5: Design the equilibrium configuration of the quasi-zero stiffness support by comprehensively considering the cold and hot state displacements, stresses and node loads of the pipeline nodes;

[0019] S6: Perform static and dynamic modeling and analyze and evaluate the cold and hot state stresses and inherent vibration characteristics of the system.

[0020] Furthermore, in step S2, the installation position of the quasi-zero stiffness bracket is determined according to the spatial configuration of the main resonance mode and the static load characteristics of the point; at the same time, the frequency spectrum characteristics of the excitation load are determined according to the engineering test analysis theory.

[0021] Furthermore, in step S4, linear modal analysis is then performed to obtain modal parameters of each order of the vibration isolation unit.

[0022] Furthermore, in step S5, the lengths of the sides and the internal angles of the composite beam structure of the pipeline vibration isolation unit are designed to match the equilibrium configuration of the composite beam, thereby achieving high static stiffness characteristics in the equilibrium configuration of the composite beam structure and ensuring the thermal stress and displacement of the pipeline.

[0023] Furthermore, based on the excitation load spectrum characteristics obtained in step S2, the load power spectrum is input to analyze the resonance characteristics of the piping system-quasi-zero stiffness system for evaluation.

[0024] The quasi-zero stiffness vibration isolation system has the characteristics of high static stiffness and low dynamic stiffness. Its basic principle is to utilize the negative stiffness of the post-buckling beam structure in the original equilibrium position and the nonlinear stiffness of the post-buckling configuration to meet the static / dynamic service characteristics of the service pipeline and effectively solve the low-frequency vibration problem of the pipeline.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention involves a low-frequency vibration isolation quasi-zero stiffness support for pipelines based on periodic metamaterials. It mainly integrates a number of quasi-zero stiffness vibration isolation units evenly arranged along the pipeline section on the basis of the original clamp. It has the function of supporting the structural load of the pipeline at that location, while maintaining the static characteristics of the pipeline and achieving vibration isolation of the pipeline in a wider frequency band. The quasi-zero stiffness vibration isolation unit is a hexagonal composite beam structure. Its buckling configuration is achieved by designing the internal angle of the hexagon, utilizing the buckling characteristics of the composite beam structure, considering the cold and hot displacements of the pipeline, and matching the equilibrium configuration of the composite beam to achieve high static stiffness characteristics in the equilibrium configuration of this composite beam structure. Since the equilibrium configuration of the quasi-zero stiffness vibration isolation unit is designed according to the post-buckling characteristics of the beam structure, it has low dynamic stiffness characteristics, which can achieve the suppression of specific low-frequency and high-amplitude vibrations in the low-frequency band of the pipeline structure. When in static equilibrium, the pipeline and its four quasi-zero stiffness isolation units are in a state of static equilibrium. When the pipeline vibrates with acceleration in a certain direction, the stiffness characteristics in that direction can be leveraged by the quasi-zero stiffness characteristics of adjacent isolation units, achieving effective vibration isolation within a given frequency band. By optimizing the static equilibrium configuration of the isolation units, the static characteristics of the pipeline are minimally impacted, meeting the pipeline's static and dynamic service requirements.

[0027] The application realizes complete zero stiffness, and further plays the vibration isolation performance in the full frequency band, can realize zero stiffness in a wide range of deformation, utilizes the periodic structure principle, designs the semi-active vibration control of the pipeline, has high static stiffness and low stiffness characteristics, is suitable for low-frequency vibration control of large-diameter thin-walled pipelines, is low in cost, wide in vibration control frequency band, and is helpful to realize the static / dynamic comprehensive optimization design of the pipeline support and hanger system. BRIEF DESCRIPTION OF DRAWINGS

[0028] The application will be further described in detail below with reference to the drawings.

[0029] Figure 1 is a structural schematic diagram of a pipeline low-frequency vibration isolation quasi-zero stiffness support based on a periodic structure of the application.

[0030] The meanings of the reference signs are as follows:

[0031] 1: pipeline, 2: hoop, 3: hexagonal combined beam structure, 4: support frame body, 5: spring. DETAILED DESCRIPTION

[0032] To make the purpose, technical scheme and advantages of the embodiments of the application more clear, the following will combine the drawings of the embodiments of the application to make a clear and complete description of the technical scheme of the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the described embodiments of the application, all other embodiments obtained by those skilled in the art belong to the protection scope of the application. Figure 1 The technical scheme of the embodiments of the application is clearly and completely described. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the described embodiments of the application, all other embodiments obtained by those skilled in the art belong to the protection scope of the application.

[0033] Embodiment 1

[0034] The embodiment provides a pipeline low-frequency vibration isolation quasi-zero stiffness support based on a periodic structure, which comprises a hoop 2 arranged on a pipeline 1, a quasi-zero vibration isolation unit connected with the hoop 2, and a support frame body 4 connected with the quasi-zero stiffness vibration isolation unit. The quasi-zero stiffness vibration isolation unit is arranged uniformly along the pipeline section and comprises a plurality of hexagonal combined beam structures 3. The statics configuration of the hexagonal combined beam structure 3 is designed to match the cold and hot state balance configuration of the pipeline, has the function of supporting the structural load of the pipeline at this position, maintains the statics characteristics of the pipeline, and realizes the vibration isolation of the pipeline in a wide frequency band. The support frame body 4 is a rectangular frame body, and the hexagonal combined beam structure 3 can be connected with the support frame body 4 in a welding manner.

[0035] The quasi-zero stiffness vibration isolation unit comprises four units, and forms a structure symmetrical in up and down and left and right with the rectangular frame body. Of course, corresponding quasi-zero stiffness vibration isolation units can be added according to design requirements. The edge frame of the quasi-zero stiffness vibration isolation unit is provided with a spring 5. The hoop 2 is made of metal and is attached to the outer wall of the pipeline and is fixed through bolt connection.

[0036] When in static equilibrium, the pipeline and the four quasi-zero stiffness vibration isolation units are in a state of static equilibrium. When the pipeline vibrates with acceleration in a certain direction, the stiffness characteristics in that direction can be effectively isolated in a given frequency band through the quasi-zero stiffness characteristics of the adjacent quasi-zero stiffness vibration isolation units. The design of the geometric configuration needs to be determined in combination with the hot and cold displacements of the piping structure to ensure that the bracket has high static stiffness within the hot and cold displacement ranges. At the same time, by utilizing the post-buckling characteristics of the configuration and designing the configuration angle, the quasi-zero stiffness characteristics of specific frequencies in the low-frequency band can be achieved, effectively completing the suppression of low-frequency, high-amplitude vibrations.

[0037] Example 2

[0038] This embodiment provides a method for implementing the periodic structure-based low-frequency vibration isolation and quasi-zero stiffness support for pipelines described in Example 1, comprising the following steps:

[0039] S1: Apply elastic mechanics thermal stress analysis theory to obtain the hot and cold equilibrium configuration of the pipeline and the node loads of each support;

[0040] S2: Apply vibration dynamics and engineering test analysis theory to measure the vibration characteristics of the piping system. Determine the installation location of the quasi-zero stiffness bracket based on the spatial configuration of the main resonance mode and the static load characteristics of the point. At the same time, determine the frequency spectrum characteristics of the excitation load based on engineering test analysis theory.

[0041] S3: Determine the arrangement of the quasi-zero stiffness vibration isolation unit according to the vibration characteristics;

[0042] S4: Establish a dynamic finite element model of the quasi-zero stiffness vibration isolation unit, and then perform linear modal analysis to obtain the modal parameters of each order of the vibration isolation unit;

[0043] S5: Based on the cold and hot displacements, stresses, and nodal loads of the pipeline nodes, the equilibrium configuration of the quasi-zero stiffness bracket is designed. The lengths of each side and the internal angles of the composite beam structure of the pipeline vibration isolation unit are designed to match the equilibrium configuration of the composite beam. The high static stiffness characteristics of this composite beam structure equilibrium configuration are achieved to ensure the cold and hot stresses and displacements of the pipeline;

[0044] S6: Perform static and dynamic modeling to analyze and evaluate the cold and hot stresses and inherent vibration characteristics of the system; input the load power spectrum based on the excitation load spectrum characteristics obtained in step S2, analyze the resonance characteristics of the piping system-quasi-zero stiffness system, and perform an evaluation.

[0045] Example 3

[0046] The implementation method of the low-frequency vibration isolation quasi-zero stiffness support for pipelines based on a periodic structure provided in this embodiment, based on embodiment 2, further comprises: S7: During subsequent inspection and maintenance, the length l of each beam arm of the combined beam structure of the pipeline vibration isolation unit can be adjusted and replaced according to the node load and displacement of the pipeline support. D-i , thickness h D-i and interior angle ω D-i , repeat steps S2-S6 to calculate the static stiffness and dynamic stiffness of the vibration isolation unit, and further optimize the static / dynamic characteristics of the vibration isolation unit.

[0047] Example 4

[0048] The implementation method of the periodic structure-based low-frequency vibration isolation quasi-zero stiffness support for pipelines provided in this embodiment includes the following steps:

[0049] S1: Apply elastic mechanics thermal stress analysis theory to obtain the pipeline's cold and hot equilibrium configuration, cold and hot stress distribution, and the node loads of each support;

[0050] S2: Apply vibration dynamics and engineering test analysis theory to measure the vibration characteristics of the piping system, including: main vibration frequency, main vibration mode, especially the order i of the main resonance mode, spatial configuration Φ i (x,y,z) and frequency ω i (t) Determine the installation location of the quasi-zero stiffness bracket based on the spatial configuration of the main resonance mode and the static load characteristics of the point; at the same time, determine the frequency spectrum characteristics of the excitation load based on engineering test analysis theory;

[0051] S3: According to the vibration characteristics of the piping system: the order i of the main resonance mode, the spatial configuration Φ i (x,y,z), main resonance frequency ω i (t) and installation position, determine the layout of the vibration isolation unit. The general selection principles are: (1) According to the spatial configuration of the main resonance mode Φ i (x, y, z), determine the installation position of each vibration isolation unit in the fixed frame; (2) according to the main resonance frequency ω i (t), design the internal angle of each vibration isolation unit of the quasi-zero stiffness bracket;

[0052] S4: Based on the shell element, a dynamic finite element model of the vibration isolation unit is established. The material is selected as steel. Then, a linear modal analysis is performed to obtain the modal parameters of each order of the vibration isolation unit: modal frequency ω D-i and the modal vibration shape Φ D-i For this purpose, the first-order modal frequency ω is generally selected. D-1 , used to match the main resonance frequency ω of the piping structure i (t), complete the frequency band near the main resonance frequency ω i(t) Resonance vibration absorption design near the vicinity; specific design, mainly design the internal angle β of the vibration isolation unit i ;

[0053] S5: Design the equilibrium configuration of the quasi-zero stiffness support by integrating the cold and hot displacements, stresses, and nodal loads of the pipeline nodes. Specifically, the lengths of the sides and internal angles of the composite beam structure of the pipeline vibration isolation unit are designed to match the equilibrium configuration of the composite beam, achieving high static stiffness characteristics in this equilibrium configuration of the composite beam structure, and ensuring that the cold and hot stresses and displacements of the pipeline meet the design requirements.

[0054] S6: Perform static and dynamic modeling on the newly designed piping-quasi-zero stiffness system to analyze and evaluate the system's cold and hot stresses and inherent vibration characteristics. Simultaneously, based on the external excitation load spectrum characteristics obtained in step S2, input the load power spectrum and analyze the resonance characteristics of the piping-quasi-zero stiffness system for evaluation. If necessary, repeat steps S3-S6 until the external resonance amplitude of the piping-quasi-zero stiffness system is reduced by 60%-80% of the design index. Because the equilibrium configuration of the isolation unit is designed using the post-buckling configuration of the composite beam structure, it exhibits low stiffness characteristics, achieving low-frequency, broadband vibration isolation of the pipeline.

[0055] S7: In subsequent maintenance, the length of each beam arm of the composite beam structure of the pipeline vibration isolation unit can be adjusted and replaced according to the node load and displacement of the pipeline support. D-i , thickness h D-i and interior angle ω D-i , repeat steps S2-S6 to calculate the static stiffness and dynamic stiffness of the vibration isolation unit, and further optimize the static / dynamic characteristics of the vibration isolation unit.

[0056] The present invention utilizes the principle of periodic structure to design a semi-active vibration control for pipelines. The semi-active vibration control has high static stiffness and low stiffness characteristics, is suitable for low-frequency vibration control of large-diameter thin-walled pipelines, has low cost, and has a wide vibration control frequency band, which helps to achieve the static / dynamic comprehensive optimization design of the pipeline support and hanger system.

[0057] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A low-frequency vibration isolation and quasi-zero stiffness support for pipelines based on a periodic structure, characterized by: It includes a clamp set on the pipe, a quasi-zero stiffness vibration isolation unit connected to the clamp, and a support frame connected to the quasi-zero stiffness vibration isolation unit. The quasi-zero stiffness vibration isolation units are uniformly arranged along the pipe section. The quasi-zero stiffness vibration isolation unit is a hexagonal composite beam structure, and the support frame is a rectangular frame. There are four quasi-zero stiffness vibration isolation units, which form a vertically and horizontally symmetrical structure with the rectangular frame. One vertex of each hexagonal composite beam structure is respectively connected to the outer surface of the clamp, and the other vertex symmetrical to the vertex in each hexagonal composite beam structure is respectively connected to the inner wall of the support frame.

2. The pipeline low-frequency vibration isolation quasi-zero stiffness bracket based on a periodic structure according to claim 1 is characterized by: When in a static equilibrium position, the pipeline and the four quasi-zero stiffness vibration isolation units are in a static equilibrium state; when the pipeline vibrates with acceleration in a certain direction, the stiffness characteristics in that direction can achieve effective vibration isolation in a given frequency band through the quasi-zero stiffness characteristics of adjacent quasi-zero stiffness vibration isolation units.

3. The pipeline low-frequency vibration isolation quasi-zero stiffness bracket based on a periodic structure according to claim 2 is characterized by: A spring is provided on the frame of the quasi-zero stiffness vibration isolation unit.

4. The pipeline low-frequency vibration isolation quasi-zero stiffness bracket based on a periodic structure according to claim 3 is characterized by: The clamp is made of metal, fits the outer wall of the pipe, and is connected and fixed by bolts.

5. The implementation method of the periodic structure-based low-frequency vibration isolation and quasi-zero stiffness support for pipelines according to claim 4 is characterized by: The following steps are involved: S1: Apply elastic mechanics thermal stress analysis theory to obtain the hot and cold equilibrium configuration of the pipeline and the node loads of each support; S2: Apply vibration dynamics and engineering test analysis theory to measure the vibration characteristics of the piping system; S3: Determine the arrangement of the quasi-zero stiffness vibration isolation unit according to the vibration characteristics; S4: Establish the dynamic finite element model of the quasi-zero stiffness vibration isolation unit; S5: Design the equilibrium configuration of the quasi-zero stiffness support by integrating the cold and hot displacements, stresses and node loads of the pipeline nodes; S6: Perform static and dynamic modeling to analyze and evaluate the system's cold and hot stresses and inherent vibration characteristics.

6. The implementation method of the periodic structure-based low-frequency vibration isolation and quasi-zero stiffness support for pipelines according to claim 5 is characterized by: In step S2, the installation position of the quasi-zero stiffness bracket is determined according to the spatial configuration of the main resonance mode and the static load characteristics of the point; at the same time, the frequency spectrum characteristics of the excitation load are determined according to the engineering test analysis theory.

7. The implementation method of the periodic structure-based low-frequency vibration isolation and quasi-zero stiffness support for pipelines according to claim 6 is characterized by: In step S4, linear modal analysis is then performed to obtain modal parameters of each order of the vibration isolation unit.

8. The implementation method of the periodic structure-based low-frequency vibration isolation and quasi-zero stiffness support for pipelines according to claim 7 is characterized by: In step S5, the lengths of the sides and the internal angles of the composite beam structure of the pipeline vibration isolation unit are designed to match the equilibrium configuration of the composite beam, thereby achieving high static stiffness characteristics in the equilibrium configuration of the composite beam structure and ensuring the thermal stress and displacement of the pipeline.

9. The implementation method of the periodic structure-based low-frequency vibration isolation and quasi-zero stiffness support for pipelines according to claim 8 is characterized by: According to the excitation load spectrum characteristics obtained in step S2, the load power spectrum is input to analyze the resonance characteristics of the piping system-quasi-zero stiffness system and perform an evaluation.

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