An ultra-low frequency passive self-adaptive tuned vibration absorber based on string-mass system

Abstract

The present application relates to the technical field of vibration control, and specifically provides an ultra-low frequency passive self-adaptive tuning vibration absorber based on a string-mass system, comprising a mechanical sensing assembly, a mechanical driving assembly, a mechanical transmission assembly and a tuning vibration absorbing assembly arranged on a target structure; the mechanical sensing assembly and the mechanical driving assembly are arranged correspondingly, are used for sensing vibration of the target structure and can generate relative motion; the mechanical driving assembly is connected with the mechanical transmission assembly, and the mechanical driving assembly drives the mechanical transmission assembly to work based on the relative motion generated by the mechanical sensing assembly; the mechanical transmission assembly is connected with the tuning vibration absorbing assembly. The vibration absorber provided by the present application has a wide application range, compared with existing self-adaptive tuning vibration absorbers, has the characteristics of not needing external power supply driving, simple structure and being capable of realizing ultra-low frequency vibration control, and effectively controls wide-band or even multi-order modal vibration through a pure mechanical structure.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology, specifically to an ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system. Background Technology

[0002] Tuned vibration damping technology is one of the important means of vibration control in engineering structures. Traditional forms mainly include tuned mass dampers (TMDs) and tuned liquid dampers (TLDs). These devices typically have a narrow operating frequency band, are only effective for single-mode vibration, and are easily affected by factors such as design deviations, construction errors, material aging, structural damage, and load changes, which can lead to frequency detuning and a decrease in vibration reduction performance.

[0003] Adaptive tuned vibration absorbers are devices that can automatically adjust the dynamic characteristics of a structure-absorber system under different excitation frequencies. They not only improve the control effect of single-mode vibration but also have the potential for multi-mode vibration control. Existing implementation methods are mainly divided into active and semi-active types: the active type applies control forces related to the structural state by placing actuators between the absorber and the controlled structure to correct the structural dynamic characteristics and enhance system robustness; the semi-active type improves vibration reduction performance by adjusting the damping, stiffness, or equivalent mass of the absorber in real time through actuators. Although both methods are flexible in design and have significant control effects, they both rely on sensors, actuators, and external power supplies, resulting in high maintenance costs, limited system reliability, and the potential for stability issues with active control.

[0004] Furthermore, the demand for ultra-low frequency vibration control has become increasingly prominent in various fields in recent years. For example, as the span of bridge main beams continues to increase, the overall stiffness decreases, and the structural modal frequencies gradually shift towards the ultra-low frequency region. Traditional tuned vibration absorbers, while meeting tuning requirements, often struggle to ensure that the static elongation of the spring is sufficiently small to accommodate limited installation space.

[0005] In summary, there is an urgent need to provide an ultra-low frequency passive adaptive tuned vibration absorber based on a string-mass system to solve the technical problems existing in the prior art. Summary of the Invention

[0006] The purpose of this invention is to provide an ultra-low frequency passive adaptive tuned vibration absorber based on a string-mass system, in order to solve the technical problems existing in the prior art. The specific technical solution is as follows:

[0007] An ultra-low frequency passive adaptive tuned vibration absorber based on a string-mass system includes a mechanical sensing component, a mechanical drive component, a mechanical transmission component, and a tuned vibration absorption component disposed on the target structure.

[0008] The mechanical sensing component and the mechanical driving component are respectively arranged to sense the vibration of the target structure and generate relative motion.

[0009] The mechanical drive assembly is connected to the mechanical transmission assembly, and the mechanical drive assembly drives the mechanical transmission assembly to work based on the relative motion generated by the mechanical sensing assembly.

[0010] The mechanical transmission assembly is connected to the tuned vibration absorption assembly.

[0011] Furthermore, the mechanical sensing component includes a first mass block and a first spring, with the upper and lower sides of the first mass block respectively connected to the target structure via the first spring.

[0012] Furthermore, the mechanical drive assembly includes a bearing support, a Y-shaped vibration-sensing drive wheel, a ratchet, a pawl, and a drive shaft; the drive shaft is rotatably mounted on the bearing support; the Y-shaped vibration-sensing drive wheel is connected to the drive shaft via a one-way bearing; the ratchet is disposed on the side of the Y-shaped vibration-sensing drive wheel and fixedly connected to the drive shaft; the pawl is rotatably mounted on the side of the Y-shaped vibration-sensing drive wheel via a pivot and engages with the ratchet.

[0013] Furthermore, the Y-shaped vibration-sensing drive wheel includes a drive wheel body and a Y-shaped arm. The drive wheel body is rotatably connected to the transmission shaft, and the Y-shaped arm is correspondingly arranged with the first mass block.

[0014] Furthermore, the mechanical transmission assembly includes a first gear, a second gear, a reciprocating lead screw, a first slider, a second slider, a slide rail, and a third slider;

[0015] The first gear is fixedly connected to the drive shaft; the reciprocating screw is rotatably connected to the target structure; the second gear is fixedly connected to the reciprocating screw; and the first gear and the second gear are meshed together.

[0016] The first slider is provided in two sets, and the two sets of first sliders are symmetrically arranged at the left and right ends of the reciprocating screw and threadedly connected to the reciprocating screw;

[0017] The slide rail is fixedly mounted on the target structure, and the first slider is slidably connected to the slide rail via the second slider.

[0018] The third slider is fixedly mounted on the first slider.

[0019] Furthermore, the reciprocating lead screw has symmetrically arranged threaded grooves at both ends, and the first slider has a through hole for passing through the reciprocating lead screw, and the through hole has a thread that matches the threaded groove.

[0020] Furthermore, the tuned vibration absorption assembly includes a tensioned string, a second spring, a gear-rack inertial amplification mechanism, and a second mass block;

[0021] The second mass block is a central mass block with a frame structure. One end of the second spring is fixedly connected to the target structure, and the other end is fixedly connected to the frame of the second mass block.

[0022] The tensioning wires are respectively arranged on the left and right sides of the second mass block. One end of the tensioning wire is fixedly connected to the frame of the second mass block, and the other end is fixedly connected to the target structure.

[0023] The tension string passes through and is slidably connected to the third slider; the axial direction of the tension string is the same as the axial direction of the reciprocating lead screw.

[0024] The gear-rack inertia amplification mechanism is connected to the second mass block.

[0025] Furthermore, the tension string has a built-in pre-tension force; the effective length of the tension string participating in tuning is greater than twice the length of the second mass block.

[0026] Furthermore, the third slider includes a slider body and two pulleys. The two pulleys are symmetrically arranged inside the slider body and located on the side away from the connection end between the tension string and the target structure. The outer ring of the pulley is provided with a groove, and the grooves of the two pulleys cooperate to form a gap for the tension string to pass through.

[0027] Furthermore, the gear-rack inertia amplification mechanism includes a third gear, a rack, a flywheel, and a connecting rod;

[0028] The connecting rod passes through the center of the second mass block and is connected to the second mass block through a bearing;

[0029] The third gear is fixedly connected to the connecting rod, the rack is freely inserted through the holes in the upper and lower plates of the second mass block frame, and the two ends of the rack are respectively fixed to the upper and lower sides of the target structure. The third gear is meshed with the rack.

[0030] The flywheel is fixedly connected to the connecting rod.

[0031] The application of the technical solution of the present invention has the following beneficial effects:

[0032] (1) This invention provides an ultra-low frequency passive adaptive tuned vibration absorber based on a string-mass system, comprising a mechanical sensing component, a mechanical driving component, a mechanical transmission component, and a tuned vibration absorber component disposed on a target structure; the mechanical sensing component and the mechanical driving component are correspondingly disposed to sense the vibration of the target structure and generate relative motion; the mechanical driving component is connected to the mechanical transmission component, and the mechanical driving component drives the mechanical transmission component to work based on the relative motion generated by the mechanical sensing component; the mechanical transmission component is connected to the tuned vibration absorber component. The vibration absorber provided by this invention has a wide range of applications and, compared with existing adaptive tuned vibration absorbers, features such as no need for external power supply, simple structure, and ability to achieve ultra-low frequency vibration control, and achieves effective control of wide-frequency and even multi-mode vibration through a purely mechanical structure.

[0033] (2) The present invention uses mechanical sensing components to replace the sensors in the existing active / semi-active adaptive tuning vibration absorbers to realize vibration sensing; at the same time, mechanical drive components and mechanical transmission components are used to replace the actuators to realize the adjustment of the dynamic characteristics of the structure-vibration absorber system. This avoids the dependence on external power supply caused by sensors and actuators, and is more adaptable to the vibration control needs in complex environments than previous devices.

[0034] (3) In this invention, a gear-rack inertial amplification mechanism is introduced into the tuning vibration absorption assembly. This mechanism is attached to the second mass block and moves with its vibration. The gear-rack transmission drives the flywheel fixed to the connecting rod to rotate synchronously, generating an additional inertial effect, thereby effectively reducing the equivalent tuning frequency of the tuning vibration absorption assembly. Compared with the existing device, it is more conducive to the control of ultra-low frequency vibration.

[0035] (4) The present invention uses a string-mass system as the basic tuning mechanism for tuning vibration absorption. The system mainly utilizes the string tension component of the string body and the inertia of the second mass block to form resonance characteristics. The tuning frequency of the vibration absorber is closely related to the string tension and the effective length of the tensioned string participating in the tuning. The present invention changes the effective length of the tensioned string participating in the tuning by adjusting the fulcrum position of the tensioned string, thereby adjusting the tuning frequency of the vibration absorber. Compared with the existing device that achieves adaptive tuning by adjusting the string tension, the method of the present invention is simpler and can be adjusted by purely mechanical means, which has high feasibility.

[0036] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0037] 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:

[0038] Figure 1 This is a schematic diagram of the overall structure of the ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system in this invention;

[0039] Figure 2 This is a schematic diagram of an ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system installed on a target structure in an embodiment of the present invention;

[0040] Figure 3 This is a structural schematic diagram of a mechanical sensing component;

[0041] Figure 4 This is a structural schematic diagram of a mechanical drive assembly;

[0042] Figure 5 This is a structural schematic diagram of a mechanical transmission assembly;

[0043] Figure 6 This is a schematic diagram of the structure of the tuned vibration absorption assembly;

[0044] Figure 7 This is a schematic diagram illustrating the working principle of a mechanical sensing component;

[0045] Figure 8 This is a schematic diagram of the third slider;

[0046] Figure 9 These are acceleration response diagrams of the main girder of the bridge under three working conditions;

[0047] Figure 10 This is a graph showing the change in the effective length of the tensioned string participating in the tuning process under the third working condition;

[0048] Figure 11 This is a graph showing the change in the tuning frequency of the passive adaptive tuning vibration absorber under the third operating condition.

[0049] The components are as follows: 1. Target structure; 2. First mass block; 3. First spring; 4. Bearing support; 5. Y-shaped vibration-sensing drive wheel; 6. Ratchet; 7. Pawl; 8. Drive shaft; 9. First gear; 10. Second gear; 11. Reciprocating screw; 12. First slider; 13. Second slider; 14. Slide rail; 15. Third slider; 151. Slider body; 152. Pulley; 16. Tensioner string; 17. Second spring; 18. Third gear; 19. Rack; 20. Flywheel; 21. Second mass block; 22. Connecting rod. Detailed Implementation

[0050] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0052] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0053] Example:

[0054] See Figure 1 and Figure 2 This embodiment provides an ultra-low frequency passive adaptive tuned vibration absorber based on a string-mass system, including a mechanical sensing component, a mechanical drive component, a mechanical transmission component, and a tuned vibration absorber component disposed on a target structure 1; the mechanical sensing component and the mechanical drive component are correspondingly disposed to sense the vibration of the target structure 1 and generate relative motion; the mechanical drive component is connected to the mechanical transmission component, and the mechanical drive component drives the mechanical transmission component to work based on the relative motion generated by the mechanical sensing component; the mechanical transmission component is connected to the tuned vibration absorber component.

[0055] In this embodiment, the target structure 1 includes engineering structures such as long-span bridges, super high-rise buildings, and offshore wind turbines. This embodiment uses a long-span bridge as an example for illustration. The mechanical sensing component, mechanical drive component, mechanical transmission component, and tuned vibration absorption component are all installed inside the main beam of the bridge. It should be noted that the target structure 1 is not limited to the illustrated structure and can be extended to other vibration control application scenarios.

[0056] See Figure 2 and Figure 3 In this embodiment, preferably, the mechanical sensing component includes a first mass block 2 and a first spring 3, and the upper and lower sides of the first mass block 2 are respectively connected to the target structure 1 through the first spring 3.

[0057] Specifically, the mechanical sensing component is used to convert the acceleration of the target structure 1 into the displacement response of the first mass block 2, such as... Figure 7 The schematic diagram of the working principle of the mechanical sensing component shown is illustrated. According to the principles of dynamics, the equation of motion for the first mass block 2 is:

[0058] ;

[0059] in, The mass of the first mass block 2, The acceleration response of target structure 1, The relative acceleration response of the first mass block 2 relative to the target structure 1 is given. This represents the relative displacement response of the first mass block 2 relative to the target structure 1. The stiffness of the first spring 3, , The stiffness of the first spring 3 on the upper side of the first mass block 2. The stiffness of the first spring 3 on the lower side of the first mass block 2. Indicates time;

[0060] To quantify the conversion relationship of this mechanical sensing component, taking the relative displacement response amplitude of the first mass block 2 relative to the target structure 1 as an example, the following relationship is satisfied between it and the acceleration response amplitude of the target structure 1:

[0061] ;

[0062] in, Let be the amplitude of the relative displacement response of the first mass block 2 relative to the target structure 1. The acceleration response amplitude of target structure 1, For the power amplification factor:

[0063] ;

[0064] in, The frequency of the vibration acceleration of target structure 1 For the frequency of the mechanical sensing component:

[0065] ;

[0066] when hour, If the value is constant, then the relative displacement response amplitude of the first mass block 2 can quantitatively describe the acceleration response amplitude of the target structure 1:

[0067] ;

[0068] If strict requirements cannot be met due to engineering constraints During the design phase, the frequency range that the target structure 1 may exhibit can be determined. and Determine the minimum power amplification factor during use. and threshold As a relative displacement threshold that triggers the operation of the mechanical drive components, the relative displacement threshold determined in this way can ensure that the vibration absorber does not become detuned in actual use and has a certain degree of robustness.

[0069] See Figure 4 In this embodiment, preferably, the mechanical drive assembly includes a bearing support 4, a Y-shaped vibration-sensing drive wheel 5, a ratchet 6, a pawl 7, and a drive shaft 8; the drive shaft 8 is rotatably mounted on the bearing support 4; the Y-shaped vibration-sensing drive wheel 5 is connected to the drive shaft 8 via a one-way bearing; the ratchet 6 is disposed on the side of the Y-shaped vibration-sensing drive wheel 5 and fixedly connected to the drive shaft 8, and the ratchet 6 rotates synchronously with the drive shaft 8; the pawl 7 is rotatably mounted on the side of the Y-shaped vibration-sensing drive wheel 5 via a pivot and engages with the ratchet 6.

[0070] In this embodiment, the Y-shaped vibration-sensing drive wheel 5 includes a drive wheel body and a Y-shaped arm. The drive wheel body is rotatably connected to the transmission shaft 8, and the Y-shaped arm is correspondingly arranged with the first mass block 2. When the movement of the first mass block 2 reaches the relative displacement threshold, it can drive the Y-shaped vibration-sensing drive wheel 5 to rotate. The included angle between the two arms of the Y-shaped arm can be adjusted according to design requirements to achieve adjustment of the relative displacement threshold.

[0071] Specifically, the acceleration design threshold of the target structure 1 is converted into the relative displacement threshold of the first mass block 2 through the structural design of the mechanical sensing component. By designing the included angle between the two arms of the Y-shaped vibration driving wheel 5, the Y-shaped vibration driving wheel 5 can be driven to move when the first mass block 2 exceeds the relative displacement threshold. The Y-shaped vibration driving wheel 5 is connected to the transmission shaft 8 through a one-way bearing, and the ratchet 6 is fixedly connected to the transmission shaft 8. The pawl 7 restricts the one-way stepping movement of the ratchet 6, ensuring the one-way stepping rotation of the transmission shaft 8.

[0072] See Figure 5 In this embodiment, the mechanical transmission assembly includes a first gear 9, a second gear 10, a reciprocating lead screw 11, a first slider 12, a second slider 13, a slide rail 14, and a third slider 15; the first gear 9 is fixedly connected to the transmission shaft 8 and rotates synchronously with the transmission shaft 8; see also Figure 2 The two ends of the reciprocating lead screw 11 are rotatably connected to the left and right sides of the engineering structure through bearings. The second gear 10 is fixedly connected to the reciprocating lead screw 11. The first gear 9 and the second gear 10 are meshed together. In this embodiment, the number of gears is not limited to two. A gear set including multiple gears can also be used to achieve transmission.

[0073] In this embodiment, preferably, the first slider 12 is provided in two sets, and the two sets of first sliders 12 are symmetrically arranged at the left and right ends of the reciprocating screw 11 and threadedly connected to the reciprocating screw 11; specifically, the two ends of the reciprocating screw 11 are symmetrically provided with threaded grooves, and the first slider 12 is provided with a through hole for passing through the reciprocating screw 11, and the through hole is provided with a thread matching the threaded groove; the slide rail 14 is fixedly arranged on the target structure 1, and the length direction of the slide rail 14 is the same as the axial direction of the reciprocating screw 11, and the first slider 12 is slidably connected to the slide rail 14 through the second slider 13.

[0074] The rotation of the first gear 9 drives the rotation of the second gear 10, which in turn drives the reciprocating screw 11 to rotate, thereby causing the first slider 12 to move axially along the reciprocating screw 11.

[0075] In this embodiment, the third slider 15 is fixedly mounted on the first slider 12 and moves axially along the reciprocating screw 11 with the first slider 12.

[0076] See Figure 6 In this embodiment, the tuned vibration absorption assembly includes a tension string 16, a second spring 17, a gear-rack inertial amplification mechanism, and a second mass block 21. Preferably, the second mass block 21 is a central mass block with a frame structure. One end of the second spring 17 is fixedly connected to the target structure 1, and the other end is fixedly connected to the upper plate of the frame of the second mass block 21. The tension string 16 is arranged on the left and right sides of the second mass block 21. One end of the tension string 16 is fixedly connected to the frame of the second mass block 21, and the other end is fixedly connected to the target structure 1. The tension string 16 passes through the third slider 15 and is slidably connected to the third slider 15. The axial direction of the tension string 16 is the same as the axial direction of the reciprocating lead screw 11. See also... Figure 8 The third slider 15 includes a slider body 151 and two pulleys 152. The two pulleys 152 are symmetrically arranged inside the slider body 151 and are located on the side away from the connection end between the tension string 16 and the target structure 1. The outer ring of the pulley 152 is provided with a groove. The grooves of the two pulleys 152 cooperate to form a gap for the tension string 16 to pass through. Preferably, the radius of the groove is equal to the radius of the string. The third slider 15 constrains the lateral displacement of the tension string 16 at its contact position, thereby ensuring that the third slider 15 can move freely along the axial direction of the tension string 16 while limiting the lateral vibration of the tension string 16. In addition, by controlling the sliding position of the third slider 15, the effective length of the tension string 16 participating in the tuning can be adjusted, thereby realizing the adaptive adjustment of the tuning frequency.

[0077] In this embodiment, the transmission ratio between the drive shaft 8 and the reciprocating lead screw 11 is determined by the gear ratio of the first gear 9 and the second gear 10. By configuring different gear ratios, the distance of each step sliding of the third slider 15 can be adjusted; in addition, the distance of each step sliding of the third slider 15 can also be controlled by setting the thread lead of the reciprocating lead screw 11.

[0078] In this embodiment, the tension string 16 has a built-in pre-tension force; the effective length of the tension string 16 participating in tuning is greater than twice the length of the second mass block 21, so as to avoid detuning during the tuning process.

[0079] In this embodiment, see Figure 6 The gear-rack inertia amplification mechanism is connected to the second mass block 21. The gear-rack inertia amplification mechanism includes a third gear 18, a rack 19, a flywheel 20, and a connecting rod 22.

[0080] The connecting rod 22 passes through the center of the second mass block 21 and is connected to the second mass block 21 through a bearing; the third gear 18 is fixedly connected to the connecting rod 22; the rack 19 is freely inserted through the holes in the upper and lower plates of the frame of the second mass block 21, and the two ends of the rack 19 are respectively fixed to the upper and lower sides of the target structure 1; the third gear 18 is meshed with the rack 19; the flywheel 20 is fixedly connected to the connecting rod 22.

[0081] In this embodiment, the basic tuning mechanism of the tuning vibration absorption component is a string-mass system consisting of a tension string 16, a second spring 17, and a second mass block 21. When the target structure 1 vibrates, the second mass block 21 vibrates, causing the third gear 18 to move along the rack 19, which in turn drives the connecting rod 22 to rotate. The flywheel 20 rotates synchronously with the connecting rod 22 to provide inertia, thereby reducing the tuning frequency of the basic tuning mechanism and achieving a tuning vibration absorption effect in the ultra-low frequency range.

[0082] In this embodiment, the inertia coefficient provided by the gear-rack inertia amplification mechanism... for:

[0083] ;

[0084] in, The radius of flywheel 20, The radius of the third gear is 18. The mass of flywheel 20 is used to adjust the inertial coefficient by designing the radius ratio of flywheel 20 to gear 18 and the mass of flywheel 20, thereby achieving ultra-low frequency vibration control.

[0085] In this embodiment, the tuning frequency of the vibration absorber for:

[0086] ;

[0087] in, The stiffness of the second spring 17, For the tension of the 16-string tension, The effective length for the tension string 16 to participate in tuning. The mass of the second mass block 21 is used. In this embodiment, the effective length of the tension string 16 participating in tuning is changed by driving the movement of the third slider 15. This allows for the adjustment of the tuning frequency of the vibration absorption component, thereby achieving the adaptive tuning effect of the vibration absorber.

[0088] In practical applications, the vibration absorber of this invention is installed inside the target structure. When the target structure under test begins to vibrate, the first mass block 2 generates a relative displacement due to inertia. When the relative displacement of the first mass block 2 exceeds the relative displacement threshold, the Y-shaped vibration-sensing drive wheel 5 rotates under the drive of the first mass block 2, and drives the transmission shaft 8 to rotate under the cooperation of the ratchet 6 and the pawl 7. The transmission shaft 8 drives the reciprocating screw 11 to rotate through the first gear 9 and the second gear 10, thereby causing the first slider 12 to drive the third slider 15 to move axially along the reciprocating screw 11, thereby realizing the adjustment of the fulcrum position of the tension string 16, that is, realizing the adjustment of the effective length of the tension string 16 participating in the tuning.

[0089] Meanwhile, when the target structure under test begins to vibrate, the second mass block 21 vibrates, causing the third gear 18 to move along the rack 19, which in turn drives the connecting rod 22 to rotate. The flywheel 20 rotates synchronously with the connecting rod 22 to provide inertia, reduce the tuning frequency of the basic tuning mechanism, and thus achieve the tuning and vibration absorption effect in the ultra-low frequency range.

[0090] This invention adjusts the effective length of the tensioned string 16 in the tuning vibration absorption assembly through a purely mechanical structure to achieve stiffness variation in the tuning vibration absorber, thereby enabling adjustable tuning frequency of the vibration absorber. Furthermore, the vibration absorber provided by this invention can achieve frequency adaptive tuning without external power supply, and by introducing a gear-rack inertial amplification mechanism, the tuning frequency is effectively reduced, thereby enabling control of broadband and even multi-mode ultra-low frequency vibrations.

[0091] To verify the effectiveness of the vibration absorber proposed in this invention and the adjustability of the tuning frequency, an engineering case is provided to illustrate the vibration reduction effect and frequency adjustment of the vibration absorber.

[0092] The selected target structure is the main girder of a bridge, with a length of 595m, an equivalent mass of 7460 kg / m, a fourth-order mode frequency of 0.392, and a structural damping ratio of 0.0024. The vibration absorber parameters are set as follows: the stiffness of the second spring 17... Take 200,000 N / m as the tension of a 16mm long tension string. Taking a mass of 100,000 N, the ratio of the total mass of flywheel 20 and the second mass block 21 to the mass of the bridge is 0.005. The ratio of the inertia coefficient of the gear-rack inertia amplification mechanism to the mass of the bridge is 0.05. The total chord length of the tension string 16 is 4 m, and its effective length for tuning can be adjusted within the range of 0.4 m to 4 m. The external excitation is set as a simple harmonic excitation. N is applied at a point 1 / 8 of the total length of the bridge; the acceleration trigger threshold for the main beam is set to 0.01 m / s^2.

[0093] This experimental case set up three comparative conditions: the first condition was that the main bridge beam was not equipped with vibration absorbers; the second condition was that the main bridge beam was equipped with non-adaptive tuning vibration absorbers; and the third condition was that the main bridge beam was equipped with the passive adaptive tuning vibration absorber proposed in this invention. In the second condition, the effective length of the tension string of the vibration absorber participating in tuning was fixed at 0.4m. This value corresponds exactly to the initial effective length of the tension string of the vibration absorber participating in tuning in the third condition. Under this condition, the tuning frequency of the vibration absorber was 0.499Hz, which was used to simulate the tuning detuning caused by performance degradation of the bridge or vibration absorber after long-term use.

[0094] Calculations show that the acceleration response of the bridge main girder under the three working conditions is as follows: Figure 9 As shown, correspondingly, the effective length variation curve of the tensioned string 16 participating in the tuning process under the third working condition is as follows: Figure 10 As shown, the variation curve of the vibration absorber's tuning frequency under the third operating condition is as follows: Figure 11 As shown. By Figure 9 It can be seen that the acceleration response in the first working condition is greater than that in the second working condition, and the second working condition is greater than that in the third working condition, indicating that the vibration absorber of the present invention can effectively suppress the vibration of the target structure; at the same time, combined with Figure 10 and Figure 11 It can be seen that by adjusting the effective length of the tension string 16 participating in the tuning, the tuning frequency can be dynamically changed and approached the fourth mode frequency that the bridge needs to control, thereby achieving adaptive tuning, effectively improving the performance degradation and detuning problems caused by long-term use, and further achieving the goal of reducing vibration.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ultra-low frequency passive adaptive tuned vibration absorber based on a string-mass system, characterized in that, Includes a mechanical sensing component, a mechanical drive component, a mechanical transmission component, and a tuned vibration absorption component disposed on the target structure (1); The mechanical sensing component and the mechanical driving component are respectively set to sense the vibration of the target structure (1) and generate relative motion; The mechanical drive assembly is connected to the mechanical transmission assembly, and the mechanical drive assembly drives the mechanical transmission assembly to work based on the relative motion generated by the mechanical sensing assembly. The mechanical transmission assembly is connected to the tuned vibration absorption assembly; The mechanical sensing component includes a first mass block (2) and a first spring (3). The upper and lower sides of the first mass block (2) are connected to the target structure (1) through the first spring (3). The mechanical drive assembly includes a bearing support (4), a Y-shaped vibration-sensing drive wheel (5), a ratchet (6), a pawl (7), and a drive shaft (8); the drive shaft (8) is rotatably mounted on the bearing support (4); the Y-shaped vibration-sensing drive wheel (5) is connected to the drive shaft (8) via a one-way bearing; the ratchet (6) is disposed on the side of the Y-shaped vibration-sensing drive wheel (5) and fixedly connected to the drive shaft (8); the pawl (7) is pivotally mounted on the side of the Y-shaped vibration-sensing drive wheel (5) and meshes with the ratchet (6); The Y-shaped vibration-sensing drive wheel (5) includes a drive wheel body and a Y-shaped arm. The drive wheel body is rotatably connected to the transmission shaft (8), and the Y-shaped arm is correspondingly arranged with the first mass block (2). The tuned vibration absorption assembly includes a tension string (16) and a second mass block (21). The tension string (16) is arranged on the left and right sides of the second mass block (21). One end of the tension string (16) is fixedly connected to the frame of the second mass block (21), and the other end is fixedly connected to the target structure (1).

2. The ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system according to claim 1, characterized in that, The mechanical transmission assembly includes a first gear (9), a second gear (10), a reciprocating lead screw (11), a first slider (12), a second slider (13), a slide rail (14), and a third slider (15). The first gear (9) is fixedly connected to the transmission shaft (8); the reciprocating screw (11) is rotatably connected to the target structure (1); the second gear (10) is fixedly connected to the reciprocating screw (11); the first gear (9) and the second gear (10) are meshed together. The first slider (12) is provided in two sets. The two sets of first sliders (12) are symmetrically arranged at the left and right ends of the reciprocating screw (11) and threadedly connected to the reciprocating screw (11); The slide rail (14) is fixedly mounted on the target structure (1), and the first slider (12) is slidably connected to the slide rail (14) through the second slider (13); The third slider (15) is fixedly mounted on the first slider (12).

3. The ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system according to claim 2, characterized in that, The reciprocating lead screw (11) has symmetrical threaded grooves at both ends. The first slider (12) has a through hole for passing through the reciprocating lead screw (11). The through hole has a thread that matches the threaded groove.

4. The ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system according to claim 2, characterized in that, The tuned vibration absorption assembly also includes a second spring (17) and a gear-rack inertial amplification mechanism; The second mass block (21) is a central mass block with a frame structure. One end of the second spring (17) is fixedly connected to the target structure (1), and the other end is fixedly connected to the frame of the second mass block (21). The tension string (16) passes through the third slider (15) and is slidably connected to the third slider (15); the axial direction of the tension string (16) is the same as the axial direction of the reciprocating screw (11); The gear-rack inertial amplification mechanism is connected to the second mass block (21).

5. The ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system according to claim 4, characterized in that, The tension string (16) has a built-in pre-tension force; the effective length of the tension string (16) participating in the tuning is greater than twice the length of the second mass block (21).

6. The ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system according to claim 4, characterized in that, The third slider (15) includes a slider body (151) and pulleys (152). The two pulleys (152) are symmetrically arranged inside the slider body (151) and located on the side away from the connection end between the tension string (16) and the target structure (1). The outer ring of the pulley (152) is provided with a groove, and the grooves of the two pulleys (152) cooperate to form a gap for the tension string (16) to pass through.

7. The ultra-low frequency passive adaptive tuning vibration absorber based on a string-mass system according to claim 4, characterized in that, The gear-rack inertia amplification mechanism includes a third gear (18), a rack (19), a flywheel (20), and a connecting rod (22). The connecting rod (22) passes through the center of the second mass block (21) and is connected to the second mass block (21) through a bearing; The third gear (18) is fixedly connected to the connecting rod (22), the rack (19) is freely inserted through the upper and lower plate holes of the second mass block (21) frame, and the two ends of the rack (19) are respectively fixed to the upper and lower sides of the target structure (1), and the third gear (18) and the rack (19) are meshed together. The flywheel (20) is fixedly connected to the connecting rod (22).

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