Variable stiffness damping device based on axial pressure instability and damping unit

Abstract

The invention discloses a variable stiffness damping device based on axial pressure instability and a damping unit, the device is symmetrically arranged on a vertical plane by spring steel sheets with multi-order harmonic function initial curvature, the midspan of the spring steel sheets is connected by a slide rail, and the spring steel sheets are provided with corresponding force transmission support structures. According to the device, under the action of reciprocating axial pressure, the spring steel sheets on the two sides of the symmetric plane are converted into an asymmetric deformation mode from symmetric deformation to be unstable, the variable stiffness phenomenon can be generated, and energy can be released or dissipated through contact and rebounding of the multi-order steel sheets connected in series and in parallel at different positions. The device has the advantages of being large in output force, high in rigidity, simple in structure, rich in variable rigidity behavior and high in energy dissipation capacity, and engineering application of the energy dissipation and vibration reduction technology is facilitated.

Description

Technical Field

[0001] The present invention mainly relates to the field of structural vibration control, and in particular to a variable stiffness shock absorbing device and a damping unit based on axial compression instability. Background Art

[0002] Controlling structural vibrations under different excitations and operating conditions requires variable stiffness vibration control technology. Traditionally, variable structural stiffness can be achieved through active, semi-active, or passive methods 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; however, these systems require external energy input and a control system.

[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 achieve relatively limited nonlinear mechanical behavior.

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

[0005] In response to the above technical problems, the present invention proposes a variable stiffness shock absorbing device and damping unit based on axial pressure instability, which has the characteristics of simple structure, low cost, high output and stable performance, and has obvious advantages over traditional technologies.

[0006] In order to achieve the above technical objectives, the technical means adopted by the present invention are:

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

[0008] At least one pair of spring steel sheets having initial curvatures of multi-order simple harmonic functions, symmetrically arranged in a vertical plane;

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

[0010] A fixed constraint mechanism connecting the spring steel sheets in the middle of the span, the fixed constraint mechanism allowing the spring steel sheets to deform horizontally and constrain other degrees of freedom;

[0011] A buckle mechanism that controls the locking or release of the fixed restraint mechanism;

[0012] The device achieves variable stiffness by converting the spring steel sheet from a symmetrical deformation mode to an asymmetrical deformation mode under axial compression load, and reduces vibration by releasing and dissipating strain energy.

[0013] Beneficial effects:

[0014] First, the device is arranged symmetrically by spring steel sheets with initial curvature, and the initial curvature of the multi-order trigonometric function can artificially control the sudden change of the central lateral deformation when the structure is subjected to axial compression, thereby generating a designed variable stiffness behavior.

[0015] Second, the device reduces the ultimate strain of the spring steel sheet under the same axial deformation through the initial curvature of the high-order trigonometric function, so that the device can generate geometric nonlinear phenomena such as pseudo-kinking, negative stiffness, and elastic energy dissipation under the influence of large deformation at a lower strain.

[0016] Third, the device can avoid deformation concentration caused by negative stiffness of the structure when used for vibration isolation or energy dissipation devices by fixing the restraint mechanism and allowing the symmetric spring steel sheet to continue to increase the impact of the restraint load after kinking and even negative stiffness due to axial compression.

[0017] In an alternative embodiment, the spring steel sheet has a concave curvature at the midspan, and the kinking phenomenon occurs due to geometric nonlinearity under axial compression load, and the buckling load, pre-buckling stiffness, and post-buckling stiffening / softening behavior are regulated by multi-order curvature distribution.

[0018] Beneficial effects: The device can regulate the stiffness, output, and energy dissipation capacity of the device according to the vibration control requirements through the geometric characteristics, cross-sectional structure, and symmetric spacing of the spring sheet, and realize optimized vibration control.

[0019] In an alternative embodiment, the lateral displacement of the single spring steel sheet after buckling is constrained in any of the following ways:

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

[0021] (b) a fixed restraint mechanism;

[0022] (c) the buckle mechanism;

[0023] so that the device is re-stiffened after buckling softening and dissipates energy through the loading stiffening-unloading softening cycle under reciprocating load.

[0024] In an alternative embodiment, the spring steel sheet has a convex curvature at the midspan, and when the fixed restraint mechanism is released by the buckle mechanism to allow the spring steel sheet to slide freely, the dominant deformation mode of the spring steel sheet suddenly changes from low-order to high-order, releasing strain energy and producing a stiffness step increase.

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

[0026] In an alternative embodiment, the spring steel sheet is composed of multiple spring sheets of different lengths in a series, parallel, and multi-level combination, and the fixed restraint mechanism interacts to achieve a preset multi-level softening-stiffening-energy dissipation sequence.

[0027] Beneficial effect: The device can achieve programmable precise control of the mechanical performance of the device through different configurations and arrangements of spring sheets.

[0028] In an alternative embodiment, the buckle mechanism limits the displacement of the fixed constraint mechanism to control the output of the device by mechanical locking, or triggers the transformation of the deformation mode by releasing the fixed constraint mechanism.

[0029] Beneficial effect: The device can control the output size of the post-yield segment through the buckle device, which can meet the bearing requirements of different scenarios. At the same time, the release of the buckle mechanism can make the device output jump, which appears as a nearly vertical line segment on the force-displacement curve.

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

[0031] ,

[0032] wherein,

[0033] ,

[0034] In the formula, is the total deflection of the preset curvature spring sheet, is the position along the height direction of the spring sheet, is the deflection of the order curvature, is the preset amplitude of the order curvature, is the frequency coefficient of the order curvature, is the total height of the spring sheet.

[0035] Beneficial effect: By setting the preset curvature of the spring sheet, the device can make the stress of the spring sheet smaller than that of the spring sheet without curvature when reaching the same deformation.

[0036] In an alternative embodiment, different preset curvature spring sheets are combined in parallel to increase the bearing capacity of the device, and the curvature coefficient configuration is:

[0037] The third spring sheet, ;

[0038] The fourth spring sheet: ;

[0039] The fifth spring sheet: ;

[0040] The sixth spring sheet: ;

[0041] In the formula, total deflection of the preset curvature spring steel sheet, position along the height direction of the spring steel sheet, total height of the spring steel sheet, here 100mm.

[0042] The third spring steel sheet and the fifth spring steel sheet are parallel on one side, the fourth spring steel sheet and the sixth spring steel sheet are symmetrically and parallel arranged, and the directional horizontal displacement and collision energy dissipation are induced by the curvature difference.

[0043] Beneficial effects: the device can superimpose the mechanical performance of each spring sheet by parallelizing the spring sheets with different initial curvatures on one side, and improve the overall output of the device.

[0044] The application further provides a damping unit of a tuned mass damper, which adopts the variable stiffness damping device based on axial compression instability and is used for absorbing the relative motion energy between a mass block and a main structure. DETAILED DESCRIPTION

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

[0046] Figure 2 is the front view of Figure 1 ;

[0047] Wherein, 1 is a force transmission fixed support; 2 is a spring steel sheet with an initial curvature; 3 is a fixed constraint mechanism.

[0048] Figure 3 is an overall perspective view of the spring steel sheet in the convex state of the mid-span curvature of the variable stiffness damping device based on axial compression instability of the application;

[0049] Figure 4 is the front view of Figure 3 ;

[0050] Figure 5 is a different mechanical performance diagram that the variable stiffness damping device with buckles of the application is expected to achieve;

[0051] Figure 6 is a schematic diagram of the spring steel sheet with an initial curvature of the application;

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

[0053] Figure 8 is a schematic diagram of the variable stiffness damping device based on axial compression instability of the embodiment 7 of the application;

[0054] Wherein, 5 is a spring steel sheet fixing device.

[0055] Figure 9 is the actual assembly photo of the variable stiffness damping device based on buckling instability of the embodiment 7 of the present application;

[0056] Figure 10 is the universal testing machine test result of the variable stiffness damping device using preset curvature combination 1 of the embodiment 7 of the present application;

[0057] Figure 11 is the actual assembly photo and universal testing machine test result of the variable stiffness damping device using preset curvature combination 2 of the embodiment 8 of the present application;

[0058] Fig. 12 is a whole perspective view of the tuned mass damper of the variable stiffness damping device based on buckling instability of the embodiment 2 of the present application;

[0059] Figure 13 is the front view of Figure 12 ;

[0060] Figure 14 is the diagram of the buckle control fixed constraint mechanism spacing to realize the output of the device after the yield section;

[0061] In the figure: 4-buckle or limiting device;

[0062] Figure 15 is the force displacement curve feature of the device output jump when the buckle is released;

[0063] Figure 16 is the comparison diagram of the force displacement curve of the embodiment after buckling and re-strengthening and the ordinary device without the strengthening process. DETAILED DESCRIPTION

[0064] The present application can be better understood according to the following embodiments; the content described in the embodiments is only used to illustrate the present application, and should not and will not limit the present application described in detail in the claims.

[0065] Embodiment 1

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

[0067] At least one pair of spring steel sheets with multiple order harmonic function initial curvature, symmetrically arranged in the vertical plane;

[0068] Force transmission bearing members fixed at both ends of the spring steel sheet, for transmitting vertical load;

[0069] A fixed constraint mechanism connected in the middle of the spring steel sheet, the fixed constraint mechanism allows the spring steel sheet to deform horizontally and restricts other degrees of freedom;

[0070] A buckle mechanism for controlling the locking or releasing of the fixed constraint mechanism;

[0071] The device realizes variable stiffness by the instability conversion of the spring steel sheet from the symmetric deformation mode to the asymmetric deformation mode under the axial compression load, and realizes shock absorption through strain energy release and dissipation.

[0072] The variable stiffness shock absorption device based on axial compression instability has the following advantages:

[0073] First, the device is symmetrically arranged by the spring steel sheet with initial curvature, and the sudden change of the central lateral deformation can be artificially controlled when the structure is subjected to axial compression, thereby generating a designed variable stiffness behavior through the initial curvature of the multi-order trigonometric function.

[0074] Second, the device reduces the ultimate strain of the spring steel sheet under the same axial deformation through the initial curvature of the high-order trigonometric function, so that the device can generate geometric nonlinear phenomena such as pseudo buckling, negative stiffness, elastic energy dissipation and the like under the influence of large deformation at a lower strain.

[0075] Third, the device can continue to increase the impact constraint load after the symmetric spring steel sheet generates pseudo buckling or even negative stiffness due to axial compression through the fixed constraint mechanism, thereby avoiding deformation concentration of the structure due to negative stiffness when used for vibration isolation or energy dissipation devices.

[0076] Example 2

[0077] As shown in Figures 1-2 In an alternative embodiment, the spring steel sheet has a concave curvature in the middle span, and the buckling load, pre-buckling stiffness and post-buckling stiffening / softening behavior are adjusted by the multi-order curvature distribution. The device can adjust the stiffness, output and energy dissipation capacity of the device according to the vibration control requirements by adjusting the geometric characteristics, cross-sectional structure, symmetric spacing and other aspects of the spring sheet, so as to realize optimized vibration control.

[0078] As a further preferred embodiment of the above technical solution, the lateral displacement of the spring steel sheet in the middle span after buckling is constrained in any of the following ways:

[0079] (a) symmetrically arranged high-order spring steel sheet;

[0080] (b) fixed constraint mechanism;

[0081] (c) the buckle mechanism;

[0082] so that the device is re-stiffened after buckling softening and dissipates energy through the loading stiffening-unloading softening cycle under the reciprocating load.

[0083] Example 3

[0084] As shown in Figures 3-4As shown, the spring steel sheet has an outwardly convex mid-span curvature. When the retaining mechanism is released by the snap mechanism and the spring steel sheet slides freely, the dominant deformation mode of the spring steel sheet suddenly changes from a low-order to a high-order mode, releasing strain energy and generating a step-change increase in stiffness. This embodiment exhibits rich nonlinear mechanical properties, combining excellent energy dissipation capacity with seismic isolation potential.

[0085] Example 4

[0086] like Figure 7 As shown, the spring steel sheet 2 is composed of multiple spring sheets of varying lengths, connected in series and parallel, in multiple stages. Through the interaction of fixed restraint mechanisms, a pre-set multi-stage softening-strengthening-energy dissipation sequence is achieved. This embodiment allows programmable and precise control of the device's mechanical performance through the varying configuration and arrangement of the spring sheets.

[0087] Example 5

[0088] like Figures 8-9 As shown, the present invention utilizes a variable-stiffness shock-absorbing device for axial compression instability. The device comprises a force-transmitting fixed support 1, a spring steel sheet 2 with an initial curvature, a fixed constraint mechanism 3 that constrains the spring sheet's torsion and allows for horizontal deformation, and a spring steel sheet fixture 5. The spring steel sheets can be arranged symmetrically or in parallel, connected by a force-transmitting load-bearing structure to form a unit capable of bearing vertical loads. The spring sheets are connected by guide rails at their mid-spans, allowing for free horizontal deformation in response to the fixed constraint mechanism, but their other degrees of freedom are constrained. Deformation between the fixed constraint mechanisms can be constrained or released by mechanisms such as the opposing deformation of the symmetrical spring sheets and the locking and release of the snap mechanism.

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

[0090] ,

[0091] in,

[0092] ,

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

[0094] Preset curvature combination 1:

[0095] First spring leaf, ;

[0096] The second spring leaf, .

[0097] Where, is the total deflection of the spring steel sheet with preset curvature, is the position along the height direction of the spring steel sheet, It is the total height of the spring steel sheet, which is 100mm here.

[0098] As a preferred embodiment of the present application, in order to facilitate the verification of the 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 initial curvature of the first spring sheet and the second spring sheet, a directional horizontal movement will be generated when the device is in axial compression instability, and by symmetrically placing the axial compression instability unit again, the impact constraint load continues to increase.

[0099] Example 6

[0100] As Figure 11 shown, another set of initial curvature spring steel sheets is provided in this example, which increases the carrying capacity of the device by combining different pre-set curvature spring steel sheets in parallel, and can obtain completely different mechanical performance.

[0101] Pre-set curvature combination 2:

[0102] The third spring sheet, ;

[0103] The fourth spring sheet: ;

[0104] The fifth spring sheet: ;

[0105] The sixth spring sheet: ;

[0106] In the formula, is the total deflection of the pre-set curvature spring steel sheet, is the position along the height direction of the spring steel sheet, is the total height of the spring sheet, which is taken as 100mm here.

[0107] In order to facilitate the verification of the performance and mechanical properties of the device, the spring steel sheet with initial curvature can also be made of 3d printed nylon material, and the spring sheet of the pre-set curvature combination 2 is arranged in parallel on one side of the third spring sheet and the fifth spring sheet, and the fourth spring sheet and the sixth spring sheet are symmetrically arranged in parallel.

[0108] Example 7

[0109] As Figures 12-13 shown, the variable stiffness shock-absorbing device based on axial compression instability of the present application can achieve the quasi-zero stiffness state as Figure 5 shown by pre-setting the spring steel sheet with multiple-order curvature combination according to the vibration control requirement, so that the device significantly reduces its dynamic stiffness without sacrificing its carrying capacity, thereby realizing effective isolation of low-frequency vibration;

[0110] By increasing the cross-sectional thickness of the spring steel sheet, the carrying capacity of a single spring steel sheet is increased, and by connecting more spring steel sheets with the same preset curvature and thickness in parallel on the same side, the carrying capacity of the device as a whole is multiplied to meet the carrying capacity requirements of building seismic mitigation.

[0111] By reducing the symmetric spacing of the spring steel sheets, the output of the quasi-zero stiffness platform segment can be significantly improved without changing the mechanical performance of the elastic stage, meeting the demand for high carrying capacity.

[0112] By adjusting the spacing between the fixed constraint mechanisms 3, the action interval of the quasi-zero stiffness platform segment of the device is regulated. The larger the spacing between the fixed constraint mechanisms 3, the larger the interval of the quasi-zero stiffness platform segment of the device, which helps the device to maintain 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 assembled device of embodiment 1 is used instead of 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, further reducing the vibration of the structure.

[0114] Embodiment 8

[0115] As shown in Figures 14-15 The buckle mechanism 4 limits the displacement of the fixed constraint mechanism 3 to regulate the output of the device, or triggers the deformation modal conversion by releasing the fixed constraint mechanism. The device of this embodiment can regulate the output size of the post-yield segment through the buckle device, and can meet the carrying capacity requirements of different scenes. At the same time, the release of the buckle mechanism can make the device output jump, which appears as a nearly vertical line segment on the force-displacement curve.

[0116] As shown in Figure 16 The device is re-strengthened after softening, which realizes the carrying capacity transition and at the same time realizes the loading and unloading curve surrounding more area under reciprocating load, that is, more effective energy dissipation. Through this process, the device has stronger energy dissipation capacity than the control group without strengthening process.

Claims

1. A variable stiffness vibration isolation device based on axial buckling instability, characterized by, Comprise: at least one pair of spring steel plates (2) with multi-order harmonic function initial curvature, symmetrically arranged in the vertical plane; force-carrying members (1) fixed at both ends of the spring steel plate for transmitting vertical load; fixed constraint mechanism (3) connected in the span of the spring steel plate, which allows the spring steel plate to deform horizontally and restricts other degrees of freedom; buckle mechanism (4) for controlling the locking or releasing of the fixed constraint mechanism (3); wherein the device realizes variable stiffness through the instability conversion of the spring steel plate from symmetric deformation mode to asymmetric deformation mode under axial compression load, and reduces vibration through strain energy release and dissipation.

2. The variable stiffness vibration reduction device based on axial compression instability according to claim 1, wherein the curvature of the spring steel plate (2) is concave in the span, and the spring steel plate (2) exhibits pseudo-buckling phenomenon due to geometric nonlinearity under axial compression load, and the buckling load, pre-buckling stiffness and post-buckling stiffening / softening behavior are regulated by multi-order curvature distribution.

3. The variable stiffness vibration reduction device based on axial compression instability according to claim 2, wherein the lateral displacement of the spring steel plate (2) in the span after buckling is constrained in any of the following ways: (a) symmetrically arranged high-order spring steel plates (2); (b) fixed constraint mechanism (3); (c) the buckle mechanism (4); so that the device is re-stiffened after buckling softening and dissipates energy through loading stiffening and unloading softening cycles under reciprocating load.

4. The variable stiffness vibration reduction device based on axial compression instability according to claim 1, wherein the curvature of the spring steel plate (2) is convex in the span, and the fixed constraint mechanism (3) is released by the buckle mechanism (4), and the spring steel plate (2) can freely deform horizontally when the fixed constraint mechanism is free to deform horizontally, and the dominant deformation mode of the spring steel plate (2) changes from low order to high order, releasing strain energy and producing a step increase in stiffness.

5. The variable stiffness vibration reduction device based on axial compression instability according to claim 1, wherein the spring steel plate (2) is composed of multiple spring steel plates of different lengths in series and parallel, and the interaction of the fixed constraint mechanism (3) realizes the preset multi-stage softening-stiffening-energy dissipation sequence.

6. The variable stiffness vibration reduction device based on axial compression instability according to claim 1, wherein the device realizes multi-directional vibration isolation through the buckling behavior of the spring steel plate (2) in the vertical direction and the low lateral stiffness of the spring steel plate (2) in the horizontal direction, and when the long side of the spring steel plate (2) is arranged vertically, a multi-dimensional vibration isolation system with two horizontal and one vertical directions is formed.

7. The variable stiffness vibration reduction device based on axial compression instability according to claim 1, wherein the buckle mechanism (4) limits 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 vibration reduction device based on axial compression instability according to claim 1, wherein the initial curvature of the spring steel plate (2) satisfies the formula: wherein, 9. The variable stiffness vibration reduction device based on axial compression instability according to claim 8, wherein the carrying capacity of the device is increased by parallel combination of spring steel plates with different preset curvatures, and the curvature coefficient is configured as: ​ ​ ​ ​ ​ ， ​ ， wherein is the total deflection of the preset curvature spring steel sheet, is the position in the height direction of the spring steel sheet, is the deflection of the order curvature, is the preset amplitude of the order curvature, is the frequency coefficient of the order curvature, is the total height of the spring steel sheet. ​ ​ third spring sheet, ; Fourth spring steel sheet: ; Fifth spring steel sheet: ; sixth spring sheet: ; wherein is the total deflection of the preset curvature spring steel sheet, is the position in the height direction of the spring steel sheet, is the total height of the spring steel sheet; Among them, the third spring steel sheet and the fifth spring steel sheet are parallel on one side, and the fourth spring sheet and the sixth spring sheet are symmetrically and parallel arranged, and the directional horizontal displacement and the collision energy dissipation are induced by the curvature difference.

10. A damper unit of a tuned mass damper, characterized by The variable stiffness damping device based on axial instability is used to absorb the relative motion energy between the mass block and the main structure.

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