A variable stiffness damping device and damping unit based on axial compression instability

Abstract

This invention discloses a variable stiffness vibration damping device and damping unit based on axial compression instability. The device consists of spring steel sheets with initial curvatures of multiple order simple harmonic functions, symmetrically arranged in a vertical plane. The mid-span of the spring steel sheets is connected by slide rails, and there are corresponding force transmission support structures. Under reciprocating axial compression, the spring steel sheets on both sides of the symmetrical plane undergo instability by transforming from symmetrical deformation to asymmetrical deformation mode, resulting in variable stiffness. Energy can be released or dissipated through the contact and rebound of the multi-order series and parallel steel sheets at different positions. The device of this invention has the advantages of large output, high stiffness, simple structure, rich variable stiffness behavior, and strong energy dissipation capacity, which is beneficial to the engineering application of energy dissipation and vibration reduction technology.

Description

Technical Field

[0001] This invention mainly relates to the field of structural vibration control, specifically to a variable stiffness damping device and damping unit based on axial compression instability. Background Technology

[0002] Structural vibration control under different excitation and operating conditions requires variable stiffness vibration control technology. Traditionally, structural variable stiffness can be achieved by active or semi-active and passive measures that require external energy input: traditional active or semi-active variable stiffness systems include magnetorheological systems, electromagnetic eddy current systems, air spring systems and hydraulic systems, etc.; however, they require external energy input and control systems.

[0003] Passive variable stiffness devices rely on the inherent nonlinear behavior of the device, such as preloaded springs, axially constrained curved beams, variable friction plates, or variable friction pendulums. However, the above systems are relatively complex in structure, have low load-bearing capacity, and can only achieve a limited range of nonlinear mechanical behaviors.

[0004] Therefore, researching simple and high-strength variable stiffness mechanisms and devices to achieve rich and adjustable nonlinear behavior is one of the key issues in the field of vibration control. Summary of the Invention

[0005] To address the above technical problems, this invention proposes a variable stiffness damping device and damping unit based on axial compression instability, which has the characteristics of simple structure, low cost, high output and stable performance, and has significant advantages over traditional technologies.

[0006] To achieve the above-mentioned technical objectives, the technical means adopted by the present invention are as follows:

[0007] A variable stiffness damping device based on axial compression instability, comprising:

[0008] At least one pair of spring steel plates with initial curvatures of multiple-order simple harmonic functions are symmetrically arranged in a vertical plane;

[0009] Force-transmitting load-bearing components fixed to both ends of the spring steel sheet are used to transmit vertical loads;

[0010] A fixed constraint mechanism connecting the spring steel sheet at the mid-span, the fixed constraint mechanism allowing the spring steel sheet to deform horizontally and constraining other degrees of freedom;

[0011] A latching mechanism that controls the locking or releasing of a fixed constraint mechanism;

[0012] The device achieves variable stiffness by the instability transition of the spring steel sheet from a symmetrical deformation mode to an asymmetrical deformation mode under axial compression load, and reduces vibration through strain energy release and dissipation.

[0013] Beneficial effects:

[0014] First, the device of the present invention uses symmetrically arranged spring steel sheets with initial curvature. By using the initial curvature of their multi-order trigonometric functions, the abrupt change in the central lateral deformation of the structure under axial compression can be artificially controlled, resulting in a designable variable stiffness behavior.

[0015] Secondly, the device reduces the ultimate strain of the spring steel sheet under the same axial deformation by using the initial curvature of a higher-order trigonometric function; thus enabling the device to exhibit geometric nonlinear phenomena under the influence of large deformations, such as pseudo-buckling, negative stiffness, and elastic energy dissipation, even at lower strain.

[0016] Third, the device uses a fixed constraint mechanism to allow the symmetrical spring steel sheets to continue to increase due to their collision constraint load after they have undergone pseudo-buckling or even negative stiffness due to axial compression. This avoids the deformation concentration caused by negative stiffness in the structure when used as a vibration isolation or energy dissipation device.

[0017] In one alternative embodiment, the spring steel sheet has a concave mid-span curvature, which causes quasi-buckling under axial compression due to geometric nonlinearity. Its buckling load, pre-buckling stiffness, and post-buckling strengthening / softening behavior are controlled by a multi-order curvature distribution.

[0018] Beneficial effects: The device can adjust the stiffness, output and energy consumption of the device according to the vibration control requirements by adjusting the geometric characteristics of the spring plates, cross-sectional structure and symmetrical spacing, etc., to achieve optimized vibration control.

[0019] In an alternative embodiment, after buckling of a single spring steel leaf, its mid-span lateral displacement is constrained by any of the following methods:

[0020] (a) Symmetrically arranged high-order spring steel sheets;

[0021] (b) Fixed constraint mechanism;

[0022] (c) the latching mechanism;

[0023] The device is re-strengthened after buckling and softening, and energy is dissipated through a loading-strengthening-unloading-softening cycle under cyclic loading.

[0024] In one alternative embodiment, the mid-span curvature of the spring steel sheet bulges outward. When the fixed constraint mechanism is released by the snap-fit ​​mechanism and the spring steel sheet slides freely, the dominant deformation mode of the spring steel sheet changes abruptly from a low order to a high order, releasing strain energy and generating a step increase in stiffness.

[0025] Beneficial effects: The device exhibits rich nonlinear mechanical characteristics, and has both excellent energy dissipation capacity and seismic isolation potential.

[0026] In one optional embodiment, the spring steel sheet is composed of multiple spring sheets of different lengths arranged in series and parallel in multiple levels, and the preset multi-level softening-strengthening-energy dissipation sequence is achieved through the interaction of a fixed constraint mechanism.

[0027] Beneficial effects: This device can achieve programmable and precise control of the device's mechanical performance through different configurations and arrangements of spring plates.

[0028] In one alternative embodiment, the latching mechanism limits the output of the displacement control device of the fixed constraint mechanism by mechanical locking, or triggers the deformation mode transition by releasing the fixed constraint mechanism.

[0029] Beneficial effects: The device can adjust the output force of the yielding section through the buckling device, which can meet the load-bearing requirements of different scenarios. At the same time, the release of the buckling mechanism can cause the output force of the device to jump suddenly, which is represented as a nearly vertical line segment on the force-displacement curve.

[0030] In an optional embodiment, the initial curvature of the spring steel sheet satisfies the formula:

[0031] ,

[0032] in,

[0033] ,

[0034] In the formula, To preset the total deflection of the curvature spring steel sheet, The position along the height direction of the spring steel sheet. For the first Deflection of order curvature, For the first The preset amplitude of the curvature. For the first Frequency coefficient of order curvature This is the total height of the spring steel sheet.

[0035] Beneficial effect: By setting a preset curvature for the spring steel sheet, the device can reduce the stress on the steel sheet when achieving the same deformation compared to a spring steel sheet without curvature.

[0036] In one optional embodiment, the load-bearing capacity of the device is increased by combining spring steel sheets with different preset curvatures in parallel, wherein the curvature coefficient is configured as follows:

[0037] Third spring steel sheet, ;

[0038] Fourth spring steel sheet: ;

[0039] Fifth spring steel sheet: ;

[0040] Sixth spring steel sheet: ;

[0041] In the formula, To preset the total deflection of the curvature spring steel sheet, The position along the height direction of the spring steel sheet. This is the total height of the spring steel sheet, which is taken as 100mm here.

[0042] Among them, the third spring steel sheet and the fifth spring steel sheet are connected in parallel on one side, and the fourth spring steel sheet and the sixth spring steel sheet are symmetrically connected in parallel, which induces directional horizontal displacement and collision energy dissipation through curvature difference.

[0043] Beneficial effects: By connecting spring steel sheets with different initial curvatures in parallel on one side, the mechanical performance of each spring sheet can be superimposed, thereby improving the overall output of the device.

[0044] The present invention further proposes a damping unit for a tuned mass damper, which employs the aforementioned variable stiffness damping device based on axial compression instability to absorb the relative motion energy between the mass block and the main structure. Attached Figure Description

[0045] Figure 1 is an overall perspective view of the spring steel sheet in the mid-span curvature concave state in the variable stiffness damping device based on axial compression instability of the present invention.

[0046] Figure 2 yes Figure 1 The main view;

[0047] Among them, 1-force transmission fixed support; 2-spring steel sheet with initial curvature; 3-fixed constraint mechanism;

[0048] Figure 3 This is an overall three-dimensional view of the spring steel sheet in the variable stiffness damping device based on axial compression instability of the present invention, under the state of outward convex curvature at mid-span.

[0049] Figure 4 yes Figure 3 The main view;

[0050] Figure 5 These are diagrams illustrating the different mechanical properties expected to be achieved by the variable stiffness damping device with snap-fit ​​mechanism of this invention.

[0051] Figure 6 This is a schematic diagram of a spring steel sheet with initial curvature according to the present invention;

[0052] Figure 7 This is a schematic diagram of the multi-level series and parallel connection of the present invention;

[0053] Figure 8 This is a schematic diagram of the variable stiffness damping device based on axial compression instability according to Embodiment 7 of the present invention;

[0054] Among them, 5-spring steel sheet fixing device;

[0055] Figure 9 This is an actual assembly photograph of the variable stiffness damping device based on axial compression instability according to Embodiment 7 of the present invention;

[0056] Figure 10 These are the universal testing machine test results of the variable stiffness damping device using the preset curvature combination 1 in Embodiment 7 of the present invention;

[0057] Figure 11 This is the actual assembly diagram and universal testing machine test results of the variable stiffness damping device using the preset curvature combination 2 in Embodiment 8 of the present invention.

[0058] Figure 12 is an overall perspective view of the tuned mass damper of the variable stiffness damping device based on axial compression instability in Embodiment 2 of the present invention.

[0059] Figure 13 yes Figure 12 The main view;

[0060] Figure 14 This is a diagram showing the force output of the yield section after the control device is adjusted by the spacing of the snap-fit ​​fixing constraint mechanism.

[0061] In the diagram: 4 - Buckling mechanism or limiting device;

[0062] Figure 15 It is the force-displacement curve characteristic of the device's output force jump when the latch is released;

[0063] Figure 16 This is a comparison graph of the force-displacement curve of the embodiment after buckling re-strengthening and that of the ordinary device without a strengthening process. Detailed Implementation

[0064] The present invention can be better understood from the following embodiments; the descriptions of the embodiments are for illustrative purposes only and should not and will not limit the invention as described in detail in the claims.

[0065] Example 1

[0066] A variable stiffness damping device based on axial compression instability, comprising:

[0067] At least one pair of spring steel plates with initial curvatures of multiple-order simple harmonic functions are symmetrically arranged in a vertical plane;

[0068] Force-transmitting load-bearing components fixed to both ends of the spring steel sheet are used to transmit vertical loads;

[0069] A fixed constraint mechanism connecting the spring steel sheet at the mid-span, the fixed constraint mechanism allowing the spring steel sheet to deform horizontally and constraining other degrees of freedom;

[0070] A latching mechanism that controls the locking or releasing of a fixed constraint mechanism;

[0071] The device achieves variable stiffness by the instability transition of the spring steel sheet from a symmetrical deformation mode to an asymmetrical deformation mode under axial compression load, and reduces vibration through strain energy release and dissipation.

[0072] The variable stiffness damping device based on axial compression instability of the present invention has the following advantages:

[0073] First, the device uses symmetrically arranged spring steel sheets with initial curvature. By using the initial curvature of its multi-order trigonometric functions, the abrupt change in the central lateral deformation of the structure under axial compression can be artificially controlled, resulting in designable variable stiffness behavior.

[0074] Secondly, the device reduces the ultimate strain of the spring steel sheet under the same axial deformation by using the initial curvature of a higher-order trigonometric function; thus enabling the device to exhibit geometric nonlinear phenomena under the influence of large deformations, such as pseudo-buckling, negative stiffness, and elastic energy dissipation, even at lower strain.

[0075] Third, the device uses a fixed constraint mechanism to allow the symmetrical spring steel sheets to continue to increase due to their collision constraint load after they have undergone pseudo-buckling or even negative stiffness due to axial compression. This avoids the deformation concentration caused by negative stiffness in the structure when used as a vibration isolation or energy dissipation device.

[0076] Example 2

[0077] like Figures 1-2 As shown, in one optional embodiment, the mid-span curvature of the spring steel sheet is concave, and under axial compression load, it undergoes quasi-buckling due to geometric nonlinearity. Its buckling load, pre-buckling stiffness, and post-buckling strengthening / softening behavior are controlled through a multi-order curvature distribution. This embodiment allows for optimized vibration control by adjusting the device's stiffness, output, and energy dissipation capacity based on the spring sheet's geometric characteristics, cross-sectional structure, and symmetrical spacing, according to vibration control requirements.

[0078] As a further preferred embodiment of the technical solution, after a single spring steel leaf buckles, its mid-span lateral displacement is constrained by any of the following methods:

[0079] (a) Symmetrically arranged high-order spring steel sheets;

[0080] (b) Fixed constraint mechanism;

[0081] (c) the latching mechanism;

[0082] The device is re-strengthened after buckling and softening, and energy is dissipated through a loading-strengthening-unloading-softening cycle under cyclic loading.

[0083] Example 3

[0084] like Figures 3-4As shown, the spring steel sheet has an outwardly convex mid-span curvature. When it slides freely after the locking mechanism releases the fixed constraint, the dominant deformation mode of the spring steel sheet abruptly changes from a low order to a high order, releasing strain energy and generating a step increase in stiffness. This embodiment exhibits rich nonlinear mechanical properties, possessing both excellent energy dissipation capacity and seismic isolation potential.

[0085] Example 4

[0086] like Figure 7 As shown, the spring steel sheet 2 is composed of multiple spring sheets of different lengths connected in series and parallel in multiple levels. Through the interaction of a fixed constraint mechanism, a preset multi-level softening-strengthening-energy dissipation sequence is achieved. This embodiment can achieve programmable precision control of the mechanical performance of the device through different configurations and arrangements of the spring sheets.

[0087] Example 5

[0088] like Figures 8-9 As shown, this invention relates to a variable stiffness damping device based on axial compression instability. The device consists of a force-transmitting fixed support 1, spring steel sheets 2 with initial curvature, a fixed constraint mechanism 3 that constrains the torsion of the spring sheets and allows horizontal deformation of the spring sheets, and a spring steel sheet fixing device 5. The spring steel sheets can be arranged symmetrically or in parallel, connected by the force-transmitting load-bearing structure to form an integral load-bearing structure for vertical load bearing. The spring sheets are connected at mid-span by guide rails. The mid-span of the spring sheets can freely deform horizontally with the fixed constraint mechanism, but other degrees of freedom are constrained. Deformation between the fixed constraint mechanisms can be constrained or released by the opposing deformation of the symmetrical spring sheets, the locking and releasing mechanisms, etc.

[0089] The preset curvature of the spring steel sheet can be determined by the following formula:

[0090] ,

[0091] in,

[0092] ,

[0093] Based on the preset curvature formula of the spring steel sheet, this embodiment adopts the following preset curvature combination:

[0094] Preset curvature combination 1:

[0095] First spring plate, ;

[0096] Second spring plate, .

[0097] In the formula, To preset the total deflection of the curvature spring steel sheet, The position along the height direction of the spring steel sheet. This is the total height of the spring steel sheet, which is taken as 100mm here.

[0098] As a preferred embodiment of the present invention, in order to facilitate the verification of the various performance and mechanical properties of the device, the spring steel sheet with initial curvature can also be made of 3D printed nylon material. The first spring sheet and the second spring sheet are symmetrically placed to form an axial compression instability unit. Due to the slight difference in the initial curvature of the first spring sheet and the second spring sheet, a directional horizontal movement will occur when the device is axially instable. By symmetrically placing the axial compression instability unit again, the collision constraint load continues to increase.

[0099] Example 6

[0100] like Figure 11 As shown, this example sets another set of initial curvature spring steel sheets. By combining different preset curvature spring steel sheets in parallel, the load-bearing capacity of the device is increased, and completely different mechanical performance can be obtained.

[0101] Preset curvature combination 2:

[0102] The third spring plate, ;

[0103] Fourth spring sheet: ;

[0104] Fifth spring sheet: ;

[0105] Sixth spring plate: ;

[0106] In the formula, To preset the total deflection of the curvature spring steel sheet, The position along the height direction of the spring steel sheet. This is the total height of the spring sheet, which is 100mm here.

[0107] To facilitate the verification of the various performance and mechanical properties of this device, the spring steel sheet with initial curvature can also be made of 3D printed nylon material. The spring sheet of the preset curvature combination 2 is configured such that the third spring sheet and the fifth spring sheet are connected in parallel on one side, and the fourth spring sheet and the sixth spring sheet are arranged symmetrically in parallel.

[0108] Example 7

[0109] like Figures 12-13 As shown, the variable stiffness damping device based on axial compression instability of this invention can, according to vibration control requirements, achieve the following output force by using spring steel sheets with preset multi-order curvature combinations: Figure 5 The quasi-zero stiffness state shown allows the device to significantly reduce its own dynamic stiffness without sacrificing its load-bearing capacity, thereby achieving effective isolation of low-frequency vibrations.

[0110] The load-bearing capacity of a single spring steel sheet is increased by increasing the cross-sectional thickness of the spring steel sheet. Furthermore, the load-bearing capacity of the entire device is multiplied by connecting more spring steel sheets with the same preset curvature and thickness in parallel on the same side to meet the load-bearing capacity requirements of building seismic isolation.

[0111] By reducing the symmetrical spacing of the spring steel plates, the output of the quasi-zero stiffness platform section can be significantly improved without changing the mechanical performance of the device in the elastic stage, thus meeting the requirements of high load-bearing capacity.

[0112] By adjusting the spacing between the fixed constraint mechanisms 3, the effective range of the quasi-zero stiffness platform section of the device is adjusted. The specific adjustment measures are as follows: the larger the spacing between the fixed constraint mechanisms 3, the larger the range of the quasi-zero stiffness platform section of the device, which helps the device to maintain a good vibration isolation effect when encountering large amplitude excitation, thereby improving its adaptability and stability under complex working conditions.

[0113] The spring sheet with initial curvature is made of spring steel. In this embodiment, the assembly device of Embodiment 1 is used to replace the damper in the tuned mass damper, which can be used to absorb and dissipate the energy generated by the relative motion between the mass block and the main structure, and further reduce the vibration of the structure.

[0114] Example 8

[0115] like Figures 14-15 As shown, the latching mechanism 4 restricts the output of the displacement control device of the fixed constraint mechanism 3 by mechanical locking, or triggers the deformation mode conversion by releasing the fixed constraint mechanism. In this embodiment, the output of the device after yielding can be adjusted by the latching device to meet the load-bearing requirements of different scenarios. At the same time, the release of the latching mechanism can cause the output of the device to jump suddenly, which is represented as a near-vertical line segment on the force-displacement curve.

[0116] like Figure 16 As shown, the present invention achieves a leap in load-bearing capacity by reinforcing the device after buckling and softening, while simultaneously enabling the loading and unloading curves under cyclic loads to encompass a larger area, thus achieving more efficient energy dissipation. Through this process, it achieves a stronger energy dissipation capacity than the control group without reinforcement.

Claims

1. A variable stiffness damping device based on axial compression instability, characterized in that, include: At least one pair of spring steel sheets (2) with initial curvature of multi-order simple harmonic functions are symmetrically arranged in the vertical plane; The load-bearing components (1) fixed at both ends of the spring steel sheet are used to transmit vertical loads; A fixed constraint mechanism (3) is connected to the middle of the spring steel sheet, which allows the spring steel sheet to deform horizontally and constrains other degrees of freedom; Control of the fixed constraint mechanism (3) and the latching mechanism (4) for locking or releasing; The device achieves variable stiffness by the instability transition of the spring steel sheet from a symmetrical deformation mode to an asymmetrical deformation mode under axial compression load, and reduces vibration through strain energy release and dissipation.

2. The variable stiffness damping device based on axial compression instability according to claim 1, characterized in that, The spring steel sheet (2) has a concave mid-span curvature. Under axial compression load, it undergoes a pseudo-buckling phenomenon due to geometric nonlinearity. Its buckling load, pre-buckling stiffness, and post-buckling strengthening / softening behavior are controlled by multi-order curvature distribution.

3. The variable stiffness damping device based on axial compression instability according to claim 2, characterized in that, After buckling, the mid-span lateral displacement of a single spring steel leaf (2) is constrained by any of the following methods: (a) Symmetrically arranged high-order spring steel sheets (2); (b) Fixed constraint mechanism (3); (c) The latching mechanism (4); The device is re-strengthened after buckling and softening, and energy is dissipated through loading-strengthening and unloading-softening cycles under cyclic loading.

4. The variable stiffness damping device based on axial compression instability according to claim 1, characterized in that, The spring steel sheet (2) has a convex mid-span curvature. When the fixed constraint mechanism (3) is released through the snap-fit ​​mechanism (4), the mid-span can freely deform horizontally with the fixed constraint mechanism. The dominant deformation mode of the spring steel sheet (2) changes abruptly from a low order to a high order, releasing strain energy and generating a step increase in stiffness.

5. The variable stiffness damping device based on axial compression instability according to claim 1, characterized in that, The spring steel sheet (2) is composed of multiple spring steel sheets of different lengths in series and parallel, and the preset multi-level softening-strengthening-energy dissipation sequence is realized through the interaction of the fixed constraint mechanism (3).

6. The variable stiffness damping device based on axial compression instability according to claim 1, characterized in that, The device achieves multi-directional vibration isolation through the vertical buckling behavior of the spring steel sheet (2) and the low lateral stiffness of the spring steel sheet (2) in the horizontal direction. When the long side of the spring steel sheet (2) is arranged vertically, it forms a multi-dimensional vibration isolation system with two horizontal directions and one vertical direction.

7. The variable stiffness damping device based on axial compression instability according to claim 1, characterized in that, The latching mechanism (4) restricts the displacement of the fixed constraint mechanism (3) by mechanical locking, or triggers the deformation mode conversion by releasing the fixed constraint mechanism (3).

8. The variable stiffness damping device based on axial compression instability according to claim 1, characterized in that, The initial curvature of the spring steel sheet (2) satisfies the formula: ， in, ， In the formula To preset the total deflection of the curvature spring steel sheet, The position along the height direction of the spring steel sheet. For the first Deflection of order curvature, For the first The preset amplitude of the order curvature, For the first Frequency coefficient of order curvature This is the total height of the spring steel sheet.

9. The variable stiffness damping device based on axial compression instability according to claim 8, characterized in that, The load-bearing capacity of the device is increased by combining spring steel sheets with different preset curvatures in parallel. The curvature coefficient is configured as follows: Third spring steel sheet, ; Fourth spring steel sheet: ; Fifth spring steel sheet: ; Sixth spring steel sheet: ; In the formula, To preset the total deflection of the curvature spring steel sheet, The position along the height direction of the spring steel sheet. This is the total height of the spring steel sheet; Among them, the third spring steel sheet and the fifth spring steel sheet are connected in parallel on one side, and the fourth spring sheet and the sixth spring sheet are symmetrically connected in parallel. The curvature difference induces directional horizontal displacement and collision energy dissipation.

10. A damping unit for a tuned mass damper, characterized in that, A variable stiffness damping device based on axial compression instability as described in any one of claims 1-9 is used to absorb the relative motion energy between the mass block and the main structure.

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