A novel quasi-zero stiffness vibration isolator and design method

Abstract

The application relates to a novel quasi-zero stiffness vibration isolator and a design method, and belongs to the technical field of vibration isolators. The novel quasi-zero stiffness vibration isolator comprises a bottom flange seat, a top mounting flange vertically arranged above the bottom flange seat, an intermediate flange arranged between the top mounting flange and the bottom flange seat, a plurality of support columns connecting the intermediate flange and the bottom flange seat, a plurality of Euler beams connecting the intermediate flange and the top mounting flange, a limiting sleeve arranged in the middle of the bottom flange seat, a compression spring assembly arranged in the limiting sleeve, and a top block arranged at the top of the compression spring assembly and connected with the top mounting flange. Beneficial effects: the quasi-zero stiffness vibration isolator can obviously reduce the vibration amplitude and vibration decay time of an antenna and a feed source in a low frequency band under the condition of meeting the self mass and volume constraints, and effectively blocks the vibration caused by flexible accessories in a spaceborne radar.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vibration isolators, and particularly relates to a novel quasi-zero stiffness vibration isolator and a design method. BACKGROUND

[0002] With the development of spaceflight and aerospace technology and new material technology, instruments and equipment carried by spacecraft are increasingly precise and lightweight. However, due to the vacuum and undamped characteristics of the space environment, low-frequency micro-vibration caused by the driving mechanism of the spacecraft cannot be eliminated or significantly reduced in time. Such micro-vibration can seriously affect the normal operation of the precise instruments on the spacecraft. Therefore, it is very important and urgent to isolate the micro-vibration of the spaceborne precise equipment.

[0003] Currently, the mainstream vibration isolation technology is divided into passive vibration isolation and active-passive combined vibration isolation. The active-passive vibration isolation has the disadvantages of high cost, poor stability, and the like, and is not suitable for the space environment. Although the passive vibration isolation has the advantages of high maturity, simple structure, and low cost, it also has the disadvantage of poor low-frequency vibration isolation effect. In recent years, the passive vibration isolator based on the quasi-zero stiffness principle can make up for the above-mentioned shortcomings and achieve good low-frequency vibration suppression.

[0004] The quasi-zero stiffness principle is to connect the positive stiffness and the negative stiffness in parallel, thereby having high static stiffness and low dynamic stiffness, i.e., the "high static and low dynamic" characteristics. The high static stiffness can ensure that the vibration isolator has a certain load capacity, and the low dynamic stiffness can achieve effective low-frequency vibration isolation.

[0005] Currently, the negative stiffness in the quasi-zero stiffness is mainly realized by the Euler compression rod buckling, the inverted pendulum, the variable damper, and the electromagnet. The inverted pendulum cannot produce large negative stiffness due to the strength limitation of the pendulum rod, the variable damper cannot actively output the control force, and thus can only achieve half-range negative stiffness. The electromagnet has serious nonlinearity and may cause electromagnetic interference to the precise instruments. Therefore, the technology of realizing the negative stiffness by the Euler compression rod buckling is almost not adjustable after design and standardization, but compared with the other technologies, it is still the most suitable for the vibration isolation of the spaceborne equipment in the space environment. SUMMARY

[0006] The present application provides a novel quasi-zero stiffness vibration isolator to solve the above-mentioned technical problems. The quasi-zero stiffness vibration isolator can significantly reduce the vibration amplitude and the vibration decay time of the antenna and the feed source in the low-frequency band and effectively block the vibration caused by the flexible accessories in the spaceborne radar under the condition of meeting the mass and volume constraints.

[0007] The technical scheme for solving the above technical problems is as follows: a novel quasi-zero stiffness vibration isolator, comprising a bottom flange base, a top mounting flange vertically arranged above the bottom flange base, an intermediate flange arranged between the top mounting flange and the bottom flange base, a plurality of support columns connecting the intermediate flange and the bottom flange base, a plurality of Euler beams connecting the intermediate flange and the top mounting flange, a limiting sleeve arranged at the middle of the bottom flange base, and a compression spring assembly arranged in the limiting sleeve, wherein the top of the compression spring assembly is provided with a top block connected with the top mounting flange.

[0008] Beneficial effects: the quasi-zero stiffness vibration isolator can significantly reduce the vibration amplitude and vibration decay time of the antenna and the feed source in the low frequency band while meeting the constraints of its own mass and volume, and effectively blocks the vibration caused by the flexible accessories in the spaceborne radar.

[0009] On the basis of the above technical scheme, the application can also be improved as follows.

[0010] Preferably, the compression spring assembly comprises a compression sleeve and a spring, the compression sleeve is embedded in the limiting sleeve, the spring is sleeved on the compression sleeve, and the top end of the spring abuts against the top block.

[0011] Preferably, a plurality of support columns are arranged in a ring shape on the bottom flange base.

[0012] Preferably, a plurality of Euler beams are arranged in a ring shape on the intermediate flange.

[0013] Preferably, the Euler beams are connected with the intermediate flange through bolts.

[0014] The second object of the application is to provide a design method of the novel quasi-zero stiffness vibration isolator, comprising the following steps:

[0015] S1, determining the known quantities of the mass m of the object to be isolated, the dimensionless dynamic stiffness of the vibration isolator the micro-vibration stroke Δx, the original length l0 of the linear spring, the Young's modulus E of the material of the Euler beam, the angle θ0 between the axis at the initial position of the Euler beam and the horizontal plane, the maximum distance D between the support columns, and the height H of the vibration isolator;

[0016] S2, establishing a theoretical formula according to the known quantities in step S1 and the designed geometric parameters of the quasi-zero stiffness vibration isolator, the formula being as follows:

[0017]

[0018] mg=nES sinθ0(1-sinθ0) (2)

[0019] Where n is the number of Euler beams; α is the length factor, ranging from 0.5 to 2; S is the cross-sectional area of ​​the Euler beam; l is the length of the Euler beam; k l The stiffness of the linear spring;

[0020] S3, the known quantity m from step S1, The theoretical formulas for Δx, l0, E, θ0, and step S2 are then used, along with the GlobalSearch optimization function in MATLAB, to optimize the unknown physical quantities n, S, l, and k. l Optimize as follows:

[0021] Optimization variables: n, S, l, k l

[0022] Objective function: min(nlS)

[0023] Constraints:

[0024] S4. Determine the number and size of Euler beams based on n, S, and l obtained in step S3; based on k... l By selecting the appropriate compression spring assembly, a new type of quasi-zero stiffness vibration isolator was obtained. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 Flowchart for optimizing the design of vibration isolators;

[0027] Figure 2 This is a schematic diagram of the overall structure of the vibration isolator;

[0028] Figure 3 A schematic diagram showing the installation of the flange, support column, and limit sleeve on the bottom surface;

[0029] Figure 4 A schematic diagram of a rubber spring and compression sleeve structure;

[0030] Figure 5 This is a schematic diagram of the intermediate flange installation.

[0031] Figure 6 A schematic diagram showing the installation of the top cap on a rubber spring;

[0032] Figure 7 Schematic diagram of the installation of flanges on the top surface of the Euler beam;

[0033] Figure 8 Figure for performance comparison of two stiffness isolators in examples.

[0034] In the drawings, the components represented by each reference numeral are listed as follows:

[0035] 1, bottom flange seat; 2, top mounting flange; 3, middle flange; 4, support column; 5, Euler beam; 6, limiting sleeve; 7, top block; 8, compression sleeve; 9, spring; 10, bolt. DETAILED DESCRIPTION

[0036] The principles and features of the present application are described below, and the examples are only used to explain the present application, not to limit the scope of the present application.

[0037] A new quasi-zero stiffness isolator, comprising: a bottom flange seat 1, a top mounting flange 2 vertically above the bottom flange seat 1, a middle flange 3 between the top mounting flange 2 and the bottom flange seat 1, the middle flange 3 and the bottom flange seat 1 connected by a plurality of support columns 4, the plurality of support columns 4 fixedly arranged circumferentially on the bottom flange seat 1, and the top of the support column 4 fixed on the middle flange 3 by a nut. The middle flange 3 and the top mounting flange 2 are connected by a plurality of Euler beams 5, the plurality of Euler beams 5 are arranged circumferentially on the middle flange 3, the Euler beams 5 and the middle flange 3 are connected by a bolt 10, the middle of the bottom flange seat 1 is provided with a limiting sleeve 6, the limiting sleeve 6 is provided with a compression spring assembly, and the top of the compression spring assembly is provided with a top block 7 connected with the top mounting flange 2.

[0038] Preferably, the compression spring assembly comprises a compression sleeve 8 and a rubber spring 9, the compression sleeve 8 is embedded and installed in the limiting sleeve 6, the rubber spring 9 is sleeved on the compression sleeve 8, and the top end of the rubber spring 9 abuts against the top block 7.

[0039] A design method of a new quasi-zero stiffness isolator, comprising the following steps:

[0040] S1, determining the known quantities of the mass m of the object to be isolated, the dimensionless dynamic stiffness of the isolator the micro-vibration stroke Δx, the original length l0 of the linear spring, the Young's modulus E of the Euler beam material, the angle θ0 between the axis at the initial position of the Euler beam and the horizontal plane, the maximum distance D between the support columns, and the height H of the isolator;

[0041] S2, establishing a theoretical formula according to the known quantities of step S1 and the geometric parameters of the designed quasi-zero stiffness isolator, the formula is as follows:

[0042]

[0043] mg = nES sin θ0(1 - sin θ0) (2)

[0044] Where n is the number of Euler beams; α is the length factor, taking the value of 0.5-2; S is the cross-sectional area of the Euler beam; l is the length of the Euler beam; k l is the stiffness of the linear spring;

[0045] S3, the known quantity m, Δx, l0, E, θ0 and the theoretical formula of step S2, and then using the GlobalSearch optimization function in MATLAB to optimize the unknown physical quantities n, S, l, k l . The specific optimization format is:

[0046] Optimization variables: n, S, l, k l

[0047] Objective function: min(nlS)

[0048] Constraints:

[0049] S4, determine the number and size of the Euler beam according to n, S, l obtained in step S3; select the compression spring assembly according to k l , and get a new quasi-zero stiffness vibration isolator.

[0050] Example 1

[0051] According to the above design method, a new quasi-zero stiffness vibration isolator is designed. According to the known quantity input: m = 500 kg, Δx = 0.1 m, l0 = 0.2 m, the material of the Euler beam is polypropylene (Young's modulus E = 0.896 GPa), θ0 = 5°, D = 0.8 m, H = 0.4 m, and then using the optimization method of step S3 can get the linear spring k l = 4900 N / m, n = 4, l = 0.3888 m, S = 17.184 mm 2 . Under the same excitation in the low frequency band of 0-10HZ, compared with the traditional vibration isolator with only linear spring, the vibration amplitude of the quasi-zero stiffness vibration isolator designed according to the above physical and geometric parameters is greatly reduced, and the specific vibration isolation performance is shown in Figure 8 .

[0052] The above example demonstrates that a new quasi-zero stiffness vibration isolator can be designed by following the steps of the patent, which has very significant vibration isolation function in the low frequency band.

[0053] The above merely preferred embodiments of the present application and are not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A design method of a novel quasi-zero stiffness vibration isolator, the vibration isolator comprising a bottom flange base (1), a top mounting flange (2 vertically above the bottom flange base (1), an intermediate flange (3) between the top mounting flange (2) and the bottom flange base (1), the intermediate flange (3) connected with the bottom flange base (1) through a plurality of support columns (4), the intermediate flange (3) connected with the top mounting flange (2) through a plurality of Euler beams (5), a limiting sleeve (6) arranged in the middle of the bottom flange base (1), a compression spring assembly arranged in the limiting sleeve (6), a top block (7) arranged at the top of the compression spring assembly and connected with the top mounting flange (2); characterized in that, The design method comprises the following steps: S1, determining a known quantity, the mass of the isolated object m, the dimensionless dynamic stiffness of the isolator micro-vibration stroke Δx, linear spring original length l0, Young's modulus E of the Euler beam material, the angle θ0 between the axis at the initial position of the Euler beam and the horizontal plane, the maximum distance D between the support columns, and the height H of the isolator; S2, establishing a theoretical formula according to the known quantity and the designed quasi-zero stiffness vibration isolator geometric parameters of step S1, the formula being as follows: mg = nESsinθ0 (1-sinθ0) (2) wherein n is the number of Euler beams; a is a length factor, having a value of 0.5 to 2; S is the cross-sectional area of the Euler beam; l is the length of the Euler beam; k l is the stiffness of the linear spring; S3, the known amount m of step S1, Δx, l0, E, θ0 and the theoretical formula of step S2, and then use the GlobalSearch optimization function in MATLAB to find the unknown physical quantities n, S, l, k l Optimization, the specific optimization format is: Optimization variables: n, S, l, k l Objective function: min (nlS) Constraints: S4, determine the number and size of Euler beams according to n, S, and l obtained in step S3; according to k l The compression spring assembly is selected to obtain a new type of quasi-zero stiffness vibration isolator.

2. The design method of a novel quasi-zero stiffness vibration isolator according to claim 1, characterized in that, The compression spring assembly comprises a compression sleeve (8) embedded in the limiting sleeve (6) and a spring (9) sleeved on the compression sleeve (8), and a top end of the spring (9) abuts against the top block (7).

3. The design method of a novel quasi-zero stiffness vibration isolator according to claim 1, characterized in that, A plurality of the support columns (4) are arranged in a ring shape on the bottom flange base (1).

4. The design method of a novel quasi-zero stiffness vibration isolator according to claim 1, characterized in that, A plurality of the Euler beams (5) are arranged in a ring shape on the middle flange (3).

5. The design method of a novel quasi-zero stiffness vibration isolator according to claim 1, characterized in that, The Euler beam (5) is connected with the middle flange (3) through a bolt (10).

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