Plate-rod combined negative stiffness damper

Abstract

The application discloses a plate-rod combined negative stiffness damper, which comprises a damping object, a linear supporting spring, a linear damping, a sliding groove, a plate spring, a connecting rod, a rigid cantilever and a smooth hinge; one end of the damping object is elastically connected with a side wall through the linear supporting spring and the linear damping, and the other end is fixedly connected with the rigid cantilever; the damping object is horizontally slid in the horizontally placed sliding groove through a pulley; two end surfaces of the plate spring are fixed with the side wall, and the center position of the plate spring is an arch height position; the plate spring is symmetrically distributed in the horizontal direction about the rigid cantilever in a relative arch height position mode; the left and right sides of the center position of the plate spring are symmetrically provided with the horizontal connecting rods; one end of the connecting rod is smoothly hinged with the plate spring, and the other end is smoothly hinged with the rigid cantilever. The damper can control the vibration in the horizontal direction, and has the advantages of simple structure, light mass, easy manufacturing, low price, reliable work and strong bearing capacity.

Description

Technical Field

[0001] This invention belongs to the field of structural vibration reduction technology, and relates to a vibration damper, specifically a plate-rod combined negative stiffness vibration damper. Background Technology

[0002] Vibration is widespread in industrial sectors such as automotive, shipbuilding, aerospace, and ultra-precision machinery, and it typically has a significant negative impact on engineering systems. Minor issues can cause malfunctions, affecting production efficiency and product quality, while serious issues can lead to safety accidents and personal injury. Therefore, finding suitable vibration suppression methods to reduce or even eliminate the adverse effects of vibration in engineering projects, thereby ensuring the normal operation of structures, is usually a primary task in engineering practice.

[0003] Currently, passive vibration control technology has been extensively researched and developed, and has been widely applied in fields such as civil engineering and mechanical engineering. However, most traditional vibration dampers utilize linear systems, and due to the mutual constraints between load-bearing capacity and operating frequency band, they often fail to achieve ideal vibration reduction results, and in some cases, vibration amplification may even occur. To overcome the shortcomings of traditional linear passive vibration reduction technology, researchers often design and introduce nonlinear negative stiffness devices to improve the vibration reduction performance of the system.

[0004] Existing negative stiffness devices include: (1) oblique spring structures (or oblique spring-linkage structures) based on geometric nonlinearity; (2) buckling beam structures based on elastic body deformation; and (3) electromagnetic structures based on the interaction between different magnetic poles. Among them, the oblique spring structure has the advantages of clear principle and simple structure, and has become a common simplified equivalent form in the design of vibration reduction systems in practical engineering. However, its stability is poor, and buckling problems are very easy to occur during installation and use. The buckling beam device has good stability, but its effective range is severely limited by the beam thickness, making it unsuitable for practical engineering. Electromagnetic devices rely heavily on external energy and are expensive. Figure 1 The diagram shows a helical spring structure with negative stiffness (or similar). Figure 2 The inclined spring-link structure shown exhibits poor stability during vibration, and its vibration damping performance is severely affected by installation and manufacturing errors. Furthermore, vibration control is primarily focused on the vertical direction, with relatively few designs addressing horizontal vibration control, especially for resisting horizontal seismic excitation. This limits the widespread adoption of negative stiffness vibration dampers in broader and more diverse engineering applications.

[0005] In summary, existing vibration damping devices based on negative stiffness suffer from poor stability, which is the main obstacle preventing the development of mature negative stiffness vibration damping systems to date.

[0006] In addition, large helical springs face multiple challenges in practical engineering applications. First, they are difficult to process, requiring precise and complex manufacturing processes; second, their cost is relatively high, increasing the overall project investment; and third, installation and maintenance are also relatively difficult, requiring professional technicians and personnel to ensure their normal operation. Summary of the Invention

[0007] To effectively overcome the stability and cost problems of traditional helical spring negative stiffness devices, this invention provides a plate-rod combined negative stiffness vibration damper. This damper can control vibrations in the horizontal direction and possesses numerous advantages such as simple structure, light weight, easy manufacturing, low cost, reliable operation, and high load-bearing capacity, ensuring its stability and durability under various working conditions. The combined design of the plate spring and connecting rod not only enhances the structural stability of the damper but also makes it perform excellently in controlling horizontal vibrations. This innovative design not only helps improve the vibration resistance of building and mechanical structures but also significantly reduces the complexity and cost of maintenance and management.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A plate-and-rod combined negative stiffness vibration damper includes a damping object, a linear support spring, a linear damper, a groove, and a negative stiffness structure, wherein:

[0010] The negative stiffness structure includes a leaf spring, a connecting rod, a rigid cantilever, and a smooth hinge.

[0011] One end of the vibration damping object is elastically connected to the side wall via a linear support spring and a linear damper, while the other end of the vibration damping object is fixedly connected to a rigid cantilever.

[0012] The vibration damping object slides horizontally in a horizontally placed groove via pulleys;

[0013] The two end faces of the leaf spring are fixed together with the side wall, and the center position of the leaf spring is the arch height position;

[0014] The number of leaf springs is two, and the two leaf springs are symmetrically distributed about the rigid cantilever in a horizontal orthogonal direction with their arch heights opposite each other.

[0015] The leaf spring has parallel connecting rods symmetrically installed on both sides of its center position.

[0016] One end of the connecting rod is smoothly hinged to the leaf spring via a smooth hinge, and the other end of the connecting rod is smoothly hinged to the rigid cantilever via a smooth hinge.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) Compared with the inclined spring structure, the negative stiffness structure of the present invention uses a leaf spring. Compared with the helical spring, the leaf spring has many advantages such as simple structure, light weight, easy manufacturing, low price, reliable operation and strong load-bearing capacity.

[0019] (2) Compared with the inclined spring linkage structure, the present invention adopts a multi-bar connection form that is symmetrical about the center line on each side, which has better stability than the single-bar connection form on each side;

[0020] (3) Compared with the vertical vibration reduction structure, the main focus of the present invention is the horizontal direction, which can not only weaken the influence of horizontal harmonic excitation, but also be applicable in the case of horizontal seismic excitation.

[0021] (4) Compared with a damper with fixed parameters, the negative stiffness characteristic of the present invention can be adjusted at will. The adjustment method is related to the structural parameters of the leaf spring (such as length, width, arch height, curvature, etc.). The arch height can be adjusted by adjusting rod. Therefore, the damping performance of the present invention can be adjusted according to different excitations, making it more flexible. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a inclined spring structure;

[0023] Figure 2 This is a schematic diagram of a model of a diagonal spring-connecting rod assembly structure;

[0024] Figure 3 This is a front view of the plate-rod combined negative stiffness vibration damper of the present invention;

[0025] Figure 4 This is a top view of the plate-rod combined negative stiffness vibration damper of the present invention;

[0026] Figure 5 This is a schematic diagram of the structure of the leaf spring of the present invention;

[0027] Figure 6 This is an assembly flowchart of the negative stiffness structure of the present invention;

[0028] Figure 7 This is a schematic diagram illustrating the vibration reduction effect in the embodiment;

[0029] Figure 8 This is a schematic diagram of the application of this invention in high-rise buildings;

[0030] Among them: 1-Vibration damping object, 2-Linear support spring, 3-Linear damping, 4-Slide groove, 5-Negative stiffness structure, 6-Adjusting rod, 5.1-Leaf spring, 5.2-Connecting rod, 5.3-Rigid cantilever, 5.4-Smooth hinge, 6.1-Long rod, 6.2-Short rod. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0032] This invention provides a plate-and-rod combined negative stiffness vibration damper, such as... Figure 3 , Figure 4 and Figure 5 As shown, the vibration damper includes a vibration damping object 1, a linear support spring 2, a linear damper 3, a slide 4, a negative stiffness structure 5, and an adjusting rod 6, wherein the negative stiffness structure includes a leaf spring 5.1, a connecting rod 5.2, a rigid cantilever 5.3, and a smooth hinge 5.4.

[0033] To suppress the horizontal vibration of the damping object 1, it can be simplified as a single-degree-of-freedom mass moving horizontally. The damping object 1 is elastically connected to the side wall via a linear support spring 2 and a linear damper 3, and contacts the horizontally placed slide 4 using pulleys. In this way, the dynamic response and mechanical behavior of the damping object 1 can be strictly controlled and predicted, thereby achieving vibration suppression in the horizontal direction.

[0034] The negative stiffness structure 5 provides negative stiffness force, and its main working element is a leaf spring 5.1. During operation, the two end faces of the leaf spring 5.1 are fixed to the side wall, and the distance between the two fixed ends is less than the length of the leaf spring 5.1. Therefore, the leaf spring 5.1 is compressed into a certain shape (approximately parabolic or semi-elliptical, etc.). The leaf spring 5.1 can also be pre-manufactured into this shape, with its center position being the arch height position. Parallel connecting rods 5.2 are symmetrically installed on both sides of the center position of the leaf spring 5.1. The multi-rod connection on each side has stronger stability than the single-rod connection on each side. The length of connecting rod 5.2 should be greater than the length from the arch height of leaf spring 5.1 to the centerline of rigid cantilever 5.3, so that the arch height of leaf spring 5.1 receives a certain initial compression. Leaf spring 5.1 is smoothly hinged to one end of connecting rod 5.2 via smooth hinge 5.4, and the other end of connecting rod 5.2 is smoothly hinged to rigid cantilever 5.3 via smooth hinge 5.4. Rigid cantilever 5.3 is fixed to the vibration damping object 1. Since the vibration of vibration damping object 1 and rigid cantilever 5.3 is the same, the mass of rigid cantilever 5.3 can be integrated into the mass of vibration damping object 1.

[0035] During assembly, the initial compression restoring force generated by the leaf spring 5.1 restricts the installation of the connecting rod 5.2. The connecting rod 5.2 causes the arch height of the leaf spring 5.1 to retract inward, resulting in a decrease in the distance between the arch height and the end face of the leaf spring. If this process is reversed and the end face position is actively adjusted to be closer to the arch height, the same effect will still be produced. The following describes the assembly process of leaf spring 5.1 and connecting rod 5.2: (1) Place the two leaf springs 5.1 horizontally with their arch height positions opposite each other, and install connecting rod 5.2 and rigid cantilever 5.3; (2) Install adjusting rods 6 at the end faces of different leaf springs 5.1 respectively. The adjusting rod 6 consists of a long rod 6.1 and two short rods 6.2. The long rod 6.1 and the short rods 6.2 are perpendicular to each other. The end face of leaf spring 5.1 is stuck at the vertical position of the long and short rods, and the long rod 6.1 is parallel to the connecting rod 5.2 and the short rods 6.2 are parallel to the rigid cantilever 5.3 as much as possible; (3) The short rods 6.2 are all retracted towards the direction of the rigid cantilever, which drives the end face of leaf spring 5.1 to approach the arch height position; (4) After achieving the expected effect, fix leaf spring 5.1 to the side wall and remove adjusting rod 6.

[0036] Because the force and displacement of the leaf spring 5.1 exhibit nonlinear characteristics, and due to the influence of geometric nonlinearity, the overall motion of this invention will differ from that of a traditional negative stiffness damper. Therefore, this invention needs to be analyzed, including the following steps:

[0037] (1) Define parameters:

[0038] The mass of the vibration damping object and the rigid cantilever is m, the stiffness of the linear elastic support is k, the linear damping coefficient is c, the initial arch height of the leaf spring is w0, the length of the connecting rod is L, the distance between the connecting rods is L1, the relative displacement between the vibration damping object and the foundation is x(t), and the horizontal excitation is y(t). Here, y(t) can represent not only harmonic excitation but also random excitation under seismic action.

[0039] (2) Static analysis of the negative stiffness structure:

[0040] The relationship between the elastic force and the amount of deformation at the center of the leaf spring is as follows:

[0041] F = AX 3 +BX 2 +CX 2

[0042] Where A, B, and C are all functions of the spring span L0, width b, arch height w0, and elastic modulus E. Explicit expressions need to be obtained by fitting a large amount of experimental or simulation data.

[0043] Then, both connecting rods can be considered as equivalent to connecting rods acting at the center of the leaf spring, and their lengths are:

[0044] L eq =L±ΔL

[0045] Where ΔL is a function of the link distance L1, and L is the length of the link. The explicit expression needs to be obtained by fitting a large amount of experimental or simulation data. When the link is to the right of the center position, it is "+", and when the link is to the left of the center position, it is "-".

[0046] Under the action of relative displacement x, the expression for the elastic force of the four connecting rods on both sides in the vibration direction is:

[0047]

[0048] Where: L eq It is the equivalent length of the link towards the center position.

[0049] Then, by performing a Taylor expansion of the above elastic force and truncating it three times, we can obtain:

[0050] F NS =k1x+k3x 3

[0051] in:

[0052]

[0053]

[0054] (3) Dynamic analysis of the plate-rod combined negative stiffness vibration damper:

[0055] According to Newton's second law, the kinematic equation of the plate-rod combined negative stiffness vibration damper is:

[0056]

[0057] By solving the kinematic equations, the amplitude-frequency characteristics, displacement transmissibility, displacement response, and mode shape of the system can be obtained.

[0058] The linear stiffness of the plate-and-rod combined negative stiffness vibration damper is k+k1. Since k1 is a negative number, the linear stiffness decreases, the natural frequency decreases, and the deviation between the excitation frequency and the system's natural frequency increases. If the excitation frequency falls within the frequency range where the displacement transmissibility is less than 1, the amplitude of structural vibration will decrease, thereby achieving the purpose of vibration reduction.

[0059] Example:

[0060] Considering m = 5 kg, k = 1000 N / m, c = 14.14 Ns / m, k1 = -830.4 N / m, and k3 = 171760 N / m 3The excitation is a simple harmonic excitation with an acceleration amplitude of 4 m / s². 2 The resulting system displacement transmissibility with and without negative stiffness is as follows: Figure 7 As shown, for a linear system without negative stiffness, the displacement transmissibility is less than 0 when the excitation frequency is higher than 3.18 Hz. For a nonlinear system with negative stiffness (i.e., the present invention), the displacement transmissibility is less than 0 when the excitation frequency is higher than 1.84 Hz. Furthermore, at high frequencies, the displacement transmissibility of the structure with negative stiffness is also lower than that of the structure without negative stiffness. Therefore, the negative stiffness device lowers the initial vibration isolation frequency of the structure, resulting in a wider vibration isolation bandwidth, a smaller displacement transmissibility, and a better vibration reduction effect.

[0061] Furthermore, the plate-and-rod combined negative stiffness vibration damper of the present invention can be applied not only to vibration control of single-degree-of-freedom systems, but also to multi-degree-of-freedom systems, such as in the field of high-rise buildings. A schematic diagram of its application in high-rise buildings is shown below. Figure 8 As shown.

[0062] Furthermore, y(t) can represent not only harmonic excitation but also stochastic excitation under seismic action.

Claims

1. A plate-rod combined negative stiffness vibration damper, characterized in that... The vibration damper includes a damping element, a linear support spring, a linear damper, a groove, and a negative stiffness structure, wherein: The negative stiffness structure includes a leaf spring, a connecting rod, and a rigid cantilever. One end of the vibration damping object is elastically connected to the side wall via a linear support spring and a linear damper, while the other end of the vibration damping object is fixedly connected to a rigid cantilever. The vibration damping object slides horizontally in a horizontally placed groove via pulleys; The two end faces of the leaf spring are fixed together with the side wall, and the center position of the leaf spring is the arch height position; The number of leaf springs is two, and the two leaf springs are symmetrically distributed about the rigid cantilever in a horizontal orthogonal direction with their arch heights opposite each other. The leaf spring has parallel connecting rods symmetrically installed on both sides of its center position. One end of the connecting rod is hinged to a leaf spring, and the other end of the connecting rod is hinged to a rigid cantilever. The assembly process of the negative stiffness structure is as follows: (1) The leaf springs are placed horizontally with their arch height positions opposite each other, and the connecting rods and rigid cantilever are installed; (2) Adjusting rods are installed at the end faces of different leaf springs respectively. The adjusting rod consists of a long rod and two short rods. The long rod and the short rod are perpendicular to each other. The end face of the leaf spring is stuck at the vertical position of the long and short rods, and the long rod is kept as parallel as possible to the connecting rod and the short rod is kept parallel to the rigid cantilever; (3) The two short rods are retracted towards the rigid cantilever, which drives the end face of the leaf spring to approach the arch height position; (4) After the expected effect is achieved, the leaf springs are fixed to the side wall and the adjusting rods are removed.

2. The plate-rod combined negative stiffness vibration damper according to claim 1, characterized in that... The leaf spring has a certain initial shape, which can be pre-manufactured or pre-compressed.

3. The plate-rod combined negative stiffness vibration damper according to claim 1, characterized in that... The plate-and-rod combined negative stiffness vibration damper is suitable for both harmonic excitation and random excitation under seismic loading.

4. The application of the plate-rod combined negative stiffness vibration damper according to any one of claims 1-3 in the horizontal vibration control of a single degree of freedom system.

5. The application of the plate-rod combined negative stiffness vibration damper according to any one of claims 1-3 in the horizontal vibration control of a multi-degree-of-freedom system.

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