A mobile variable stiffness TMD cable vibration control device and control system

Abstract

The application provides a mobile variable stiffness TMD cable vibration control device and a control system, and belongs to the technical field of cable vibration suppression in bridge wind engineering. The technical problems of high cost, poor applicability, failure to achieve ideal effect and installation limitation of the existing cable vibration reduction are solved. The mobile variable stiffness TMD cable vibration control system is sleeved on the outer periphery of the cable, two power devices are located on the inner side of the body and connected with the control system integrated device, two acceleration sensors are located on the outer side of the body and connected with the power devices, four self-locking devices are located on the inner side of the body and connected with the control system integrated device, and the variable stiffness TMD is installed in the body. The real-time data monitored by the acceleration sensor is used to determine the vibration mode of the cable, and then the position of the mobile variable stiffness TMD cable vibration control system is moved. The application can effectively improve the use safety and stability of the cable, and has high applicability to cables in different environments and under different working conditions.

Description

Technical Field

[0001] This invention belongs to the field of bridge wind engineering cable vibration suppression technology, and specifically relates to a mobile variable stiffness TMD cable vibration control device and control system. Background Technology

[0002] Long-span bridges have large spans and high throughput capacity, and the stability of their cables has a significant impact on their overall stability. Whether it's a long-span cable-stayed bridge or a suspension bridge, the cables have a high slenderness ratio, making them prone to vortex-induced vibrations perpendicular to the wind direction. This type of continuous, repetitive vibration, which can occur even under normal wind speeds, has a high probability of occurrence. Long-term, repeated vibrations can easily lead to cable fatigue failure, loosening and fatigue failure of anchorages and components on the cable seats. These are all significant safety hazards for the normal operation of long-span bridges.

[0003] Currently, common methods for solving the problem of cable vortex-induced vibration include: 1) arranging flow disturbance devices such as passive air-blowing collars on the cable. This method can change the flow field characteristics around the cable surface, thereby suppressing vortex-induced vibration; 2) adding reinforcement measures to weak plates, which can alleviate fatigue damage to metal components caused by vortex-induced vibration, but it consumes a lot of manpower and material resources and cannot fundamentally solve the problem of vortex-induced vibration; 3) arranging tuned mass dampers. However, simply arranging TMDs (tuned mass dampers) in certain locations may not have an ideal control effect and is not cost-effective.

[0004] Among the methods described above, adding flow disturbance devices and installing dampers are relatively simple and easy solutions. However, most existing flow disturbance devices are made of metal, and installing them extensively in steel pipe towers increases the tower's load. Metal flow disturbance devices are also costly to manufacture, have complex processes, and lack versatility and adaptability. Furthermore, the control effectiveness of flow disturbance devices requires extensive experimentation. Traditional annular and spiral TMDs are typically placed at the extreme points of lower-order modes. For example, the first-order mode is placed at 1 / 2 of the cable's centerline length, the second-order mode at 1 / 4 and 3 / 4, and so on, placing TMDs at all amplitude extreme points of different lower-order modes. This method lacks specificity and, in some cases, not only has unsatisfactory control effects but is also costly.

[0005] In summary, traditional TMD control methods suffer from limited applicability to cable vibration and high costs. There is an urgent need to develop a novel mobile variable stiffness TMD cable vibration control system to improve the control efficiency of existing cable vortex-induced vibration control, thereby enhancing the stability and safety of cable structures. Summary of the Invention

[0006] In view of this, in order to solve the technical problems of high cost, limited applicability, failure to achieve ideal results, and installation restrictions of existing cable vibration damping systems, this invention proposes a mobile variable stiffness TMD cable vibration control device and control system, which can automatically adjust the stiffness of the TMD according to the real-time vibration response.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a mobile variable stiffness TMD cable vibration control system, wherein the mobile variable stiffness TMD cable vibration control system is fixed to the outer periphery of the cable, the mobile variable stiffness TMD cable vibration control system includes a main body, two acceleration sensors, two power units, four self-locking devices, a variable stiffness TMD, and a control system integration device. The two power units are located inside the main body and are connected to the control system integration device, the two acceleration sensors are located outside the main body and are connected to the power units, the four self-locking devices are located inside the main body and are connected to the control system integration device, the variable stiffness TMD is installed inside the main body, the vibration mode of the cable is determined according to the real-time data monitored by the acceleration sensors, and then the position of the mobile variable stiffness TMD cable vibration control system is moved.

[0008] Furthermore, when it is necessary to control a single half-wave, the mobile variable stiffness TMD cable vibration control system actively moves to the position of 1 / 2 length of the cable.

[0009] Furthermore, when it is necessary to control the double half-wave, the mobile variable stiffness TMD cable vibration control system actively moves to a position of 1 / 4 or 3 / 4 of the cable length.

[0010] Furthermore, when it is necessary to control the three half-waves, the mobile variable stiffness TMD cable vibration control system actively moves to a position of 1 / 6 or 5 / 6 of the cable length.

[0011] Furthermore, the cable is provided with cable retaining teeth, and the movable variable stiffness TMD cable vibration control system is fitted onto the cable retaining teeth.

[0012] Furthermore, the main body, power unit, and self-locking device are all made of aluminum alloy.

[0013] Furthermore, the self-locking device includes gears, and the movable variable stiffness TMD cable vibration control device moves up and down by the gears on the power unit rolling and meshing with the cable teeth, and the self-locking device is fixed by the cable teeth 1.

[0014] Furthermore, two accelerometers are arranged perpendicular to the center line of the cable teeth, and the two accelerometers point in directions perpendicular to each other. After monitoring real-time data in both directions, the orthogonal decomposition method is used to determine the vibration direction and amplitude, and the signal is transmitted to the control system integration device for processing.

[0015] Furthermore, the stiffness of the variable stiffness TMD is adjusted in segments based on the real-time vibration response amplitude. When the amplitude exceeds a threshold, the stiffness of the variable stiffness TMD is automatically increased. After increasing the stiffness, the vibration response is monitored for a certain period of time to determine whether the stiffness of the variable stiffness TMD needs to be further increased. When the amplitude decreases to a threshold, the adjustment of the stiffness of the variable stiffness TMD is stopped.

[0016] Compared with the prior art, the beneficial effects of the mobile variable stiffness TMD cable vibration control device and control system described in this invention are:

[0017] (1) This invention can obtain the real-time vibration mode of the cable by analyzing the natural frequency of the cable under wind load disturbance in real time through an acceleration sensor, and then adjust the position of the damper under different vibration modes through a toothed device, a power device, and a self-locking device, which is highly targeted.

[0018] (2) The accelerometer can also monitor the vibration response amplitude of the cable and adjust the TMD stiffness in segments based on the real-time vibration response amplitude. When the amplitude is greater than a threshold, the damper stiffness is automatically increased. After the stiffness is increased, the vibration response is monitored for a certain period of time to determine whether the damper stiffness needs to be further increased. When the amplitude decreases to a threshold, the adjustment of the TMD stiffness is stopped. The TMD stiffness can be automatically adjusted according to the real-time vibration response.

[0019] (3) The mobile variable stiffness TMD cable vibration control system of the present invention can effectively improve the safety and stability of cable use and has high applicability to cables in different environments and working conditions. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A schematic diagram of the structure of a mobile variable stiffness TMD cable vibration control system;

[0022] Figure 2 This is a schematic diagram of the structure of a mobile variable stiffness TMD cable vibration control device.

[0023] Markings: 1- Cable clamp; 2- Acceleration sensor; 3- Power unit; 4- Self-locking device; 5- Variable stiffness TMD; 6- Control system integration device. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0025] See Figure 1-2 This embodiment describes a mobile variable stiffness TMD cable vibration control system. The mobile variable stiffness TMD cable vibration control system is fixed to the outer periphery of the cable. The mobile variable stiffness TMD cable vibration control system includes a main body, two acceleration sensors 2, two power units 3, four self-locking devices 4, a variable stiffness TMD 5, and a control system integration device 6. The two power units 3 are located inside the main body and are connected to the control system integration device 6. The two acceleration sensors 2 are located outside the main body and are connected to the power units 3. The four self-locking devices 4 are located inside the main body and are connected to the control system integration device 6. The variable stiffness TMD 5 is installed inside the main body. The vibration mode of the cable is determined based on the real-time data monitored by the acceleration sensors 2, and then the position of the mobile variable stiffness TMD cable vibration control system is moved.

[0026] Two accelerometers 2 are arranged perpendicular to the center line of the cable tooth 1, and the two accelerometers 2 point perpendicular to each other. After monitoring the real-time data in the two directions, the orthogonal decomposition method is used to determine the vibration direction and amplitude, and the signal is transmitted to the control system integration device 6 for processing.

[0027] The mobile variable stiffness TMD cable vibration control system is connected to the cable via cable locking teeth 1. The mobile variable stiffness TMD cable vibration control system uses the up-and-down rolling of gears in the power unit 3 to engage with the locking teeth to achieve position self-adjustment. After determining and moving to the target position, it is fixed in the current position by four self-locking devices 4 engaging with the cable locking teeth 1.

[0028] The self-locking device 4 includes gears. The movable variable stiffness TMD cable vibration control device moves up and down by the gears on the power unit 3 rolling and meshing with the cable locking teeth 1. The self-locking device 4 is fixed by the cable locking teeth 1.

[0029] The stiffness of the variable stiffness TMD5 is adjusted in segments by measuring the vibration response amplitude in real time. When the amplitude exceeds a threshold, the stiffness of the variable stiffness TMD5 is automatically increased. After increasing the stiffness, the vibration response is monitored for a certain period of time to determine whether the stiffness of the variable stiffness TMD5 needs to be further increased. When the amplitude decreases to a threshold, the adjustment of the stiffness of the variable stiffness TMD5 is stopped.

[0030] The power device 3 is used for the up-and-down movement of the device. The power device 3 is a power belt and gear structure. Two are designed because the cable cannot remain completely straight, and setting too many is not conducive to its up-and-down movement.

[0031] Figure 1 In the mobile variable stiffness TMD cable vibration control system, the vibration frequency obtained by real-time monitoring of the acceleration sensor 2 is used to determine the vibration suppression position with the best effect. If it is necessary to control a single half-wave, the control system automatically moves to the 1 / 2 length of the cable; to control a double half-wave, it automatically moves to the 1 / 4 or 3 / 4 length; to control a triple half-wave, it automatically moves to the 1 / 6 or 5 / 6 length, etc. When it is necessary to control other order modes, the mobile variable stiffness TMD cable vibration control system actively moves to the corresponding position.

[0032] Figure 1 In the mobile variable stiffness TMD cable vibration control system, the stiffness adjustment range of the variable stiffness TMD 5 can be determined according to the actual needs of the project and through test results. A larger stiffness adjustment range of the variable stiffness TMD 5 can obtain greater control ability, and setting different stiffness adjustment ranges for different projects can improve the use efficiency of the TMD and avoid waste of performance and materials.

[0033] The mobile variable stiffness TMD cable vibration control system is made of aluminum alloy material, which has the characteristics of light weight, precise preparation and good shape retention. Since this system is integrated by mechanical devices and electronic devices, the structure is slightly complex and the electronic devices are used frequently, and the use environment is complex and changeable. The lightweight system is convenient for maintenance and is beneficial to extending the service life of this system.

[0034] The specific form of the variable stiffness TMD 5 can be selected as a circumferential TMD or a spiral TMD according to the actual situation.

[0035] The present invention adopts the principle of flow separation:

[0036] The flow around a cylinder and the vortex shedding phenomenon accompanying the flow around a cylinder are mainly affected by the Reynolds number (Re). When Re < 5, the fluid flows backward in layers along the cylinder boundary; when 5 < Re < 45, the free shear layer converges at the midline behind the cylinder and a stable symmetric vortex is generated in the near-field wake. As the Reynolds number continues to increase, the wake begins to show unstable periodic fluctuations, vortices shed from the cylinder surface, forming a Karman vortex street, but the boundary layer of the cylinder still remains laminar; when 300 < Re < 1.5×105, this is called the subcritical state, and the transition from laminar flow to turbulent flow in the shear layer begins. Within this range, the laminar boundary layer separates from the cylinder surface, and the vortex shedding process is stable and has strong periodicity; when 1.5×105 < Re < 3.5×106, the laminar boundary layer changes to turbulent flow and the separation point moves downstream; when Re > 3.5×106, a turbulent vortex street and a turbulent boundary layer appear.

[0037] In the subcritical state, the vortex shedding process occurs alternately on both sides of the cylinder, causing periodic fluctuations in the stress around the cylinder. This results in the cylinder being subjected to periodic forces, leading to vibration, known as vortex-induced vibration. For cylinders capable of free vibration or bending deformation, vortex-induced vibration can effectively influence the flow field and improve fluid-structure interaction: for example, by increasing vortex intensity; enhancing the axial correlation of vortex shedding; and bringing the vortex shedding frequency close to the natural frequency, also known as frequency locking. Vortex-induced vibration can cause severe fatigue damage to building structures.

[0038] This invention employs the principles of structural dynamics:

[0039] Structural dynamics studies the theory and methods for calculating the internal forces and displacements of structures under dynamic loads. Compared with static structural calculations, when a structure is subjected to dynamic loads such as cyclic loads, impact loads, and random loads, the general form of the differential equations of motion in structural dynamics is as follows:

[0040] mx"(t) + cx'(t) + kx(t) = F(t)

[0041] Where m is mass, x(t) is the structural vibration response, c is the damping coefficient, k is the stiffness, and F(t) is the generalized force, which is the vortex-induced force in this case. t is time.

[0042] With the magnitude of the generalized force on the right-hand side of the equation remaining constant, adjusting the magnitudes of the inertial force term mx(t) and the damping term cx'(t) on the left-hand side will cause changes in the elastic term. Meanwhile, the structural stiffness k is generally fixed, so only the vibration response x(t) changes in the elastic term. Therefore, adjusting the structural damping is an important method for suppressing structural vibration.

[0043] A tuned mass damper (TMD) is a structural vibration control device primarily used to reduce the vibration amplitude of buildings, bridges, and other large structures. Its principle involves using a vibration system composed of a mass block, springs, dampers, and other components. When the structure vibrates, the TMD generates a counter-vibration, thus counteracting the structural vibration. Its working principle can be simply described as follows: a certain number of mass blocks are connected to the structure. When the structure vibrates, the mass blocks also vibrate. Because springs and dampers connect the mass blocks to the structure, the vibration of the mass blocks produces a counter-vibration, thereby reducing the vibration amplitude of the structure. By adjusting the parameters of the mass blocks, springs, and dampers, the TMD can be synchronized with the vibration frequency of the structure to achieve optimal vibration control.

[0044] Correspondingly, in the structural dynamics differential equations: m corresponds to the mass of the mass block, k corresponds to the stiffness of the connecting spring, and c corresponds to the damping coefficient.

[0045] By setting appropriate parameters m, k, and c, the TMD can be synchronized with the vibration frequency of the structure to achieve the best vibration control effect.

[0046] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A mobile variable stiffness TMD cable vibration control system, characterized in that: The mobile variable stiffness TMD cable vibration control system is fitted around the outer periphery of the cable. The mobile variable stiffness TMD cable vibration control system includes a main body, two acceleration sensors (2), two power units (3), four self-locking devices (4), a variable stiffness TMD (5), and a control system integration device (6). The two power units (3) are located inside the main body and connected to the control system integration device (6). The two acceleration sensors (2) are located outside the main body and connected to the power units (3). The four self-locking devices (4) are located inside the main body and connected to the control system integration device (6). The main body is equipped with a variable stiffness TMD (5). The vibration mode of the cable is determined by the real-time data monitored by the acceleration sensor (2). Then, the position of the mobile variable stiffness TMD cable vibration control system is moved. The stiffness of the variable stiffness TMD (5) is adjusted in segments by the real-time vibration response amplitude. When the amplitude is greater than a threshold, the stiffness of the variable stiffness TMD (5) is automatically increased. After the stiffness is increased, the vibration response is monitored for a certain period of time to determine whether the stiffness of the variable stiffness TMD (5) needs to be further increased. When the amplitude is reduced to a threshold, the stiffness of the variable stiffness TMD (5) is stopped. Two accelerometers (2) are arranged in a direction perpendicular to the center line of the cable tooth (1), and the two accelerometers (2) point in directions perpendicular to each other. After monitoring the real-time data in the two directions, the orthogonal decomposition method is used to determine the vibration direction and amplitude, and the signal is transmitted to the control system integration device (6) for processing.

2. The mobile variable stiffness TMD cable vibration control system according to claim 1, characterized in that: When it is necessary to control a single half-wave, the mobile variable stiffness TMD cable vibration control system actively moves to the position of 1 / 2 length of the cable.

3. The mobile variable stiffness TMD cable vibration control system according to claim 1, characterized in that: When it is necessary to control the double half-wave, the mobile variable stiffness TMD cable vibration control system actively moves to the position of 1 / 4 or 3 / 4 of the cable length.

4. The mobile variable stiffness TMD cable vibration control system according to claim 1, characterized in that: When it is necessary to control the three half-waves, the mobile variable stiffness TMD cable vibration control system actively moves to a position of 1 / 6 or 5 / 6 of the cable length.

5. The mobile variable stiffness TMD cable vibration control system according to claim 1, characterized in that: The cable is provided with cable teeth (1), and the mobile variable stiffness TMD cable vibration control system is fitted onto the cable teeth (1).

6. The mobile variable stiffness TMD cable vibration control system according to claim 5, characterized in that: The main body, power unit (3) and self-locking device (4) are all made of aluminum alloy.

7. The mobile variable stiffness TMD cable vibration control system according to claim 5, characterized in that: The self-locking device (4) includes gears. The mobile variable stiffness TMD cable vibration control system moves up and down by the gears on the power unit (3) rolling and meshing with the cable teeth (1). The self-locking device (4) is fixed by the cable teeth (1).

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