CN116658692A - Quasi-zero stiffness support for pipeline low-frequency vibration isolation based on periodic structure and its implementation method - Google Patents

Abstract

The invention discloses a low-frequency vibration isolation quasi-zero stiffness support for a pipeline based on a periodic structure and an implementation method, which belong to the technical field of structural vibration isolation and comprise hoops arranged on the pipeline, quasi-zero vibration isolation units connected with the hoops, and support frame bodies connected with the quasi-zero stiffness vibration isolation units, wherein the quasi-zero stiffness vibration isolation units are uniformly distributed along the section of the pipeline, the quasi-zero stiffness vibration isolation units are of a hexagonal combined beam structure, and the support frame bodies are rectangular frame bodies. The vibration isolation device realizes complete zero stiffness, further plays a role in vibration isolation of a full frequency band, can realize zero stiffness in a large-scale deformation, designs semi-active vibration control of the pipeline by utilizing a periodic structure principle, has the characteristics of high static stiffness and low stiffness, is suitable for low-frequency vibration control of a large-caliber thin-wall pipeline, has low cost and wide vibration control frequency band, and is beneficial to realizing static/dynamic comprehensive optimization design of a pipeline support and hanger system.

Description

Quasi-zero stiffness support for pipeline low-frequency vibration isolation based on periodic structure and its implementation method

technical field

The invention relates to the technical field of structural vibration isolation, and more specifically, the invention relates to a quasi-zero-stiffness bracket for low-frequency vibration isolation of pipelines based on a periodic structure and an implementation method.

Background technique

Common pipelines include water supply and drainage pipelines, gas pipelines, fuel pipelines, heat pipelines, refrigeration pipelines, etc. The design of pipelines needs to consider many factors, such as fluid flow, support problems, vibration problems, compensation problems, etc. Under the action of fluid at a certain pressure and flow rate, hydrodynamic pressure will be generated on the walls of these pipes, which will cause the vibration of the pipes. These vibrations will have a certain impact on the safety and life of the pipes. In severe cases, it may cause immeasurable damage. as a result of. For the infusion/filling pipeline system, its static buckling and vibration problems seriously affect the operation reliability of the pipeline system, especially the low-frequency vibration problem is an urgent problem to be solved at home and abroad.

The patent document with the notification number CN110185740A discloses a new type of low-frequency, high-temperature resistant and variable-stiffness pipe clamp, including a pipe clamp (1), metal rubber (2), and a coil spring (3); wherein the pipe clamp (1) is provided with There is a circular installation space, the metal rubber (2) is circular and its outer wall is closely connected to the inner wall of the pipe clamp (1), and the number of the coil springs (3) is installed in multiple arrays on the Inside the metal spring (3), the part of the coil spring (3) is located outside the metal rubber (2). The clamp can absorb the low-frequency vibration of the high-temperature pipeline through the internal coil spring, forms a circular cavity through two semicircular pipe clamps, and is fixed on the pipe by bolts.

The patent document with the publication number CN114623289A discloses an active-passive composite shock-absorbing device and its working method, which relates to the technical field of vibration and noise control. On the outside of the pipeline, a medium-high-frequency shock-absorbing unit is arranged inside the pipe clip; a drive assembly, the drive assembly is connected to the pipe clip; an induction drive assembly, the induction drive assembly is connected to the drive assembly, through the pipe clip A medium-high-frequency shock-absorbing unit is installed inside to convert vibration into heat energy for dissipation, and control the medium-high-frequency broadband vibration of the pipeline. The medium-high frequency shock-absorbing unit is a shock-absorbing material arranged in the pipe clamp.

The above two methods can achieve vibration isolation effect to a certain extent, but they do not have a balanced configuration and cannot achieve specific low-frequency and high-amplitude vibration suppression in the low-frequency range of the piping structure.

Contents of the invention

In view of this, the present invention provides a quasi-zero-stiffness support for pipeline low-frequency vibration isolation based on a periodic structure and an implementation method to realize low-frequency and wide-band vibration isolation and vibration absorption of pipelines, and to meet the static/dynamic service performance requirements of pipelines.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A quasi-zero-stiffness bracket for low-frequency vibration isolation of a pipeline based on a periodic structure, comprising a hoop arranged on the pipeline, a quasi-zero vibration isolation unit connected to the hoop, and a bracket connected to the quasi-zero-stiffness vibration isolation unit Frame body, several 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 body.

Further, there are four quasi-zero-stiffness vibration isolation units, which form a vertically symmetrical structure with the rectangular frame body.

Further, when in the static equilibrium position, 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 this direction can be passed through the adjacent quasi-zero stiffness The quasi-zero stiffness characteristic of the vibration isolation unit realizes effective vibration isolation in a given frequency band.

Further, a spring is provided on the frame of the quasi-zero stiffness vibration isolation unit.

Further, the hoop is made of metal, adheres to the outer wall of the pipeline, and is connected and fixed by bolts.

Further, the implementation method of the periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness support includes the following steps:

S1: Apply the thermal stress analysis theory of elastic mechanics to obtain the cold and hot state equilibrium configuration of the pipeline and the node load of each support;

S2: Apply vibration mechanics and engineering test analysis theory to measure the vibration characteristics of the piping system;

S3: According to the vibration characteristics, determine the arrangement of quasi-zero stiffness vibration isolation units;

S4: Establish the dynamic finite element model of quasi-zero stiffness vibration isolation unit;

S5: Based on the cold and hot state displacement, stress and node load of the pipeline node, design the equilibrium configuration of the quasi-zero stiffness support;

S6: Conduct static and dynamic modeling, analyze and evaluate the cold and hot state stress and inherent vibration characteristics of the system.

Further, in the step S2, according to the spatial configuration of the main resonance mode and the static load characteristics of this point, determine the installation position of the quasi-zero stiffness support; at the same time, according to the engineering test analysis theory, determine the frequency spectrum characteristics of the excitation load .

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

Further, the step S5 is to design the side lengths and internal angles of the composite beam structure of the pipeline vibration isolation unit to match the balanced configuration of the composite beam, so as to realize the high static stiffness characteristics of the balanced configuration of the composite beam structure, and ensure that the pipeline thermal stress and displacement.

Further, according to the excitation load spectrum characteristics obtained in step S2, input the load power spectrum, analyze the resonance characteristics of the piping system-quasi-zero stiffness system, and perform evaluation.

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

Compared with prior art, the beneficial effect of the present invention is:

The quasi-zero-stiffness support for pipeline low-frequency vibration isolation based on periodic metamaterials involved in the present invention mainly integrates several quasi-zero-stiffness vibration isolation units uniformly arranged along the section of the pipeline on the basis of the original hoop, and has the ability to support the The load function of the pipeline structure, while maintaining the static characteristics of the pipeline, and at the same time realizing the vibration isolation of the pipeline in a wider frequency band. The quasi-zero stiffness vibration isolation unit is a hexagonal composite beam structure. The buckling configuration of the hexagonal composite beam is designed to match the equilibrium configuration of the composite beam by using the buckling characteristics of the composite beam structure and considering the cold and hot displacement of the pipeline. The high static stiffness characteristics of the balanced configuration of this composite beam structure are achieved. 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 and realizes specific low-frequency high-amplitude vibration suppression for the low-frequency section of the piping structure. When in the static equilibrium position, the pipeline and the four quasi-zero stiffness vibration isolation units are in a state of static force balance; when the pipeline vibrates with acceleration in a certain direction, the stiffness characteristics in this direction can pass through the quasi-zero stiffness characteristics of the adjacent vibration isolation units , to achieve effective vibration isolation for a given frequency band. By optimizing the design of the static equilibrium configuration of the vibration isolation unit, the impact on the static characteristics of the pipeline is small, and the static/dynamic service characteristics of the pipeline are satisfied.

The present invention realizes complete zero stiffness, and then achieves full-frequency vibration isolation performance, and can realize zero stiffness in a wide range of deformation. Using the periodic structure principle, the semi-active vibration control of the pipeline is designed, and has high static stiffness and low stiffness characteristics. , suitable for low-frequency vibration control of large-diameter thin-walled pipelines, low cost, wide vibration control frequency, and helpful to realize the static/dynamic comprehensive optimization design of the pipeline support and hanger system.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a structural schematic diagram of a quasi-zero-stiffness support for pipeline low-frequency vibration isolation based on a periodic structure in the present invention.

The meaning of each reference mark is as follows:

1: pipe, 2: hoop, 3: hexagonal composite beam structure, 4: bracket frame, 5: spring.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with FIG. 1 of the embodiment of the present invention. Apparently, the described embodiments are some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention belong to the protection scope of the present invention.

Example 1

This embodiment provides a pipeline low-frequency vibration isolation quasi-zero stiffness support based on a periodic structure, which includes a hoop 2 arranged on the pipeline 1, a quasi-zero vibration isolation unit connected to the hoop 2, and a quasi-zero vibration isolation unit connected to the quasi-zero stiffness. The support frame 4 of the zero-stiffness vibration isolation unit, several of the quasi-zero-stiffness vibration-isolation units are evenly arranged along the pipe section, the quasi-zero-stiffness vibration-isolation unit is a hexagonal composite beam structure 3, and its static configuration After design, it matches the cold and hot state balance configuration of the pipeline, and has the function of supporting the structural load of the pipeline, while maintaining the static characteristics of the pipeline, and at the same time realizing the vibration isolation of the pipeline in a wide frequency range. The support frame 4 is a rectangular frame, and the hexagonal composite beam structure 3 can be connected to the support frame 4 by welding.

There are four quasi-zero-stiffness vibration-isolation units, which form a vertical and left-right symmetrical structure with the rectangular frame body. Of course, corresponding quasi-zero-stiffness vibration-isolation units can also be added according to design requirements. A spring 5 is arranged on the frame of the quasi-zero stiffness vibration isolation unit. The hoop 2 is made of metal, fits the outer wall of the pipeline, and is connected and fixed by bolts.

When in the 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 this direction can pass through the adjacent quasi-zero stiffness vibration isolation units The quasi-zero stiffness characteristics achieve effective vibration isolation in a given frequency band. The design of the geometric configuration needs to be determined in combination with the cold and hot state displacement of the piping structure, so as to ensure that the support has a high static stiffness within the range of the cold and hot state displacement; at the same time, by using the post-buckling-like characteristics of the configuration, by designing the configuration angle, the For the quasi-zero stiffness characteristics of specific frequencies in the low-frequency band, it can effectively suppress low-frequency and high-amplitude vibrations.

Example 2

This embodiment provides the implementation method of the periodic structure-based low-frequency vibration isolation quasi-zero stiffness support for pipelines described in Embodiment 1, which includes the following steps:

S1: Apply the thermal stress analysis theory of elastic mechanics to obtain the cold and hot state equilibrium configuration of the pipeline and the node load of each support;

S2: Apply vibration mechanics and engineering test analysis theory to measure the vibration characteristics of the piping system; according to the spatial configuration of the main resonance mode and the static load characteristics of this point, determine the installation position of the quasi-zero stiffness support; at the same time, according to Engineering test analysis theory to determine the spectrum characteristics of the excitation load;

S3: According to the vibration characteristics, determine the arrangement of quasi-zero stiffness vibration isolation units;

S4: Establish the 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;

S5: Comprehensive cold and hot state displacements, stresses and node loads of pipeline nodes, design the balanced configuration of quasi-zero stiffness supports, design the lengths of sides and internal angles of the composite beam structure of the pipeline vibration isolation unit, and match the balanced configuration of the composite beam , realize the high static stiffness characteristics of the balanced configuration of the composite beam structure, and ensure the cold and thermal stress and displacement of the pipeline;

S6: Carry out static and dynamic modeling, analyze and evaluate the cold and hot state stress and natural vibration characteristics of the system; according to the excitation load spectrum characteristics obtained in step S2, input the load power spectrum, analyze the resonance characteristics of the piping system-quasi-zero stiffness system ,to evaluate.

Example 3

The implementation method of the pipeline low-frequency vibration isolation quasi-zero-stiffness bracket based on the periodic structure provided in this embodiment, on the basis of Embodiment 2, also includes: S7: In the follow-up maintenance, according to the node load and displacement of the pipeline bracket, Adjust and replace the beam arm length l _Di , thickness h _Di and internal angle ω _Di of the composite beam structure of the pipeline vibration isolation unit, repeat steps S2-S6, calculate the static stiffness and dynamic stiffness of the vibration isolation unit, and further optimize the static/dynamic vibration isolation unit academic characteristics.

Example 4

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

S1: Apply the thermal stress analysis theory of elastic mechanics to obtain the cold and hot state equilibrium configuration of the pipeline, the cold and hot state stress distribution and the nodal load of each support;

S2: Apply vibration mechanics 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 main resonance mode, spatial configuration Φ _i (x, y, z) and frequency ω _i (t), according to the spatial configuration of the main resonance mode and the static load characteristics of this point, determine the installation position of the quasi-zero stiffness support; at the same time, according to the engineering test analysis theory, determine the excitation load spectral characteristics;

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), the main resonance frequency ω _i (t) and the installation location, determine the arrangement of the vibration isolation unit , the general selection principles are: (1) according to the spatial configuration Φ _i (x,y,z) of the main resonance mode, determine the installation position of each vibration isolation unit in the fixed frame; (2) according to the main resonance frequency ω _i (t), the interior angle of each vibration isolation unit of the designed quasi-zero stiffness support;

S4: Establish the dynamic finite element model of the vibration isolation unit based on the shell element, select steel as the material, and then perform linear modal analysis to obtain the modal parameters of each order of the vibration isolation unit: modal frequency ω _Di and mode shape Φ _Di. For this reason, the first-order modal frequency ω _D-1 is generally selected to match the main resonance frequency ω _i (t) of the piping structure, and the resonance vibration absorption design near the frequency band ω _i (t) near the main resonance frequency is completed; specifically Design, mainly to design the internal angle β _i of the vibration isolation unit;

S5: Based on the cold and hot displacements, stresses and node loads of pipeline nodes, the equilibrium configuration of quasi-zero stiffness brackets is designed. Specifically, the main design is to design the side lengths and internal angles of the composite beam structure of the pipeline vibration isolation unit to match the balanced configuration of the composite beam, to achieve the high static stiffness characteristics of the balanced configuration of the composite beam structure, and to ensure the cold and thermal stress of the pipeline. and displacement meet the design requirements;

S6: Perform static and dynamic modeling on the above-mentioned newly designed piping system-quasi-zero stiffness system, analyze and evaluate the cold and hot state stress and natural vibration characteristics of the system; at the same time, according to the external excitation load spectrum characteristics obtained in step S2, Input the load power spectrum, analyze the resonance characteristics of the piping system-quasi-zero stiffness system, and evaluate it. If necessary, repeat steps S3-S6 until the external resonance amplitude of the pipe system-quasi-zero stiffness system is reduced by 60%-80% of the design index; since the post-buckling configuration of the composite beam structure is used to design the vibration isolation unit Balanced configuration, so it has low stiffness characteristics, and realizes low-frequency broadband vibration isolation of pipelines;

S7: In the follow-up maintenance, according to the nodal load and displacement of the pipe support, the length l _Di , thickness h _Di and inner angle ω _Di of each beam arm of the composite beam structure of the pipe vibration isolation unit can be adjusted and replaced, and steps S2-S6 can be repeated to calculate the vibration isolation The static stiffness and dynamic stiffness of the unit are used to further optimize the static/dynamic characteristics of the vibration isolation unit.

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

Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments we have described are only illustrative, rather than used to limit the scope of the present invention. Equivalent modifications and changes made by skilled personnel in accordance with the spirit of the present invention shall fall within the protection scope of the claims of the present invention.

Claims (10)

1. A pipeline low frequency vibration isolation quasi zero rigidity support based on periodic structure, its characterized in that: including setting up staple bolt on the pipeline, with the quasi-zero vibration isolation unit that the staple bolt is connected, connect the support framework of quasi-zero rigidity vibration isolation unit, quasi-zero rigidity vibration isolation unit is along the even a plurality of that arranges of pipeline section, quasi-zero rigidity vibration isolation unit is hexagon composite beam structure, the support framework is the rectangle framework.

2. The periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness bracket according to claim 1, wherein the bracket is characterized by: the number of the quasi-zero rigidity vibration isolation units is four, and a structure which is symmetrical up and down and left and right is formed between the quasi-zero rigidity vibration isolation units and the rectangular frame body.

3. The periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness bracket according to claim 2, wherein the bracket is characterized by: when the vibration isolator is at a static balance position, the pipeline and the four quasi-zero stiffness vibration isolation units are in a static balance state; when the pipeline vibrates and has acceleration in a certain direction, the rigidity characteristic in the direction can realize effective vibration isolation of a given frequency band through the quasi-zero rigidity characteristic of the adjacent quasi-zero rigidity vibration isolation units.

4. The periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness bracket according to claim 3, wherein the bracket is characterized by: and a spring is arranged on the frame of the quasi-zero stiffness vibration isolation unit.

5. The periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness bracket according to claim 4, wherein the bracket is characterized by: the staple bolt is metal material, laminating pipeline outer wall, through bolted connection and fixed.

6. The implementation method of the periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness bracket is characterized by comprising the following steps of: comprises the following steps:

s1: the method comprises the steps of obtaining a cold-hot state balance configuration of a pipeline and node loads of all brackets by using an elastic mechanical thermal stress analysis theory;

s2: measuring vibration characteristics of the pipe system by using vibration mechanics and engineering test analysis theory;

s3: determining the arrangement mode of the quasi-zero stiffness vibration isolation units according to the vibration characteristics;

s4: establishing a dynamic finite element model of the quasi-zero stiffness vibration isolation unit;

s5: the cold-hot displacement, stress and node load of the pipeline node are synthesized, and the balance configuration of the quasi-zero stiffness bracket is designed;

s6: and (5) carrying out statics and dynamics modeling, and analyzing and evaluating cold-hot state stress and inherent vibration characteristics of the system.

7. The implementation method of the periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness bracket is characterized by comprising the following steps of: step S2, determining the installation position of the quasi-zero stiffness bracket according to the space configuration of the main resonance mode and the static load characteristic of the point; and meanwhile, according to an engineering test analysis theory, determining the frequency spectrum characteristic of the excitation load.

8. The method for implementing the periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness support is characterized by comprising the following steps of: and S4, performing linear modal analysis to obtain modal parameters of each order of the vibration isolation unit.

9. The method for implementing the periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness support is characterized by comprising the following steps of: and S5, designing the length of each side and the angle of the inner angle of the combined beam structure of the pipeline vibration isolation unit, matching the balanced configuration of the combined beam, realizing the high static stiffness characteristic of the balanced configuration of the combined beam structure, and ensuring the cold and hot stress and displacement of the pipeline.

10. The method for implementing the periodic structure-based pipeline low-frequency vibration isolation quasi-zero stiffness support is characterized by comprising the following steps of: and (3) according to the excitation load frequency spectrum characteristic obtained in the step (S2), inputting a load power spectrum, analyzing the resonance characteristic of the piping-quasi-zero stiffness system, and evaluating.