A negative stiffness parallel structure for reducing the stiffness variation of a negative stiffness spring

Abstract

This method provides a parallel structure for reducing the stiffness variation of negative stiffness springs. It is used for hybrid connections of negative stiffness springs to adjust negative stiffness characteristics. Its characteristic is the use of two or more structures with different stiffness characteristics, interconnected to compensate for each other, achieving lower stiffness fluctuations over a wider range of motion. This method uses two or more elastic elements of different stiffness types connected in parallel, utilizing the complementary gradient differences in stiffness to reduce stiffness fluctuations in the working section of the negative stiffness system and improve its performance. The negative stiffness structure designed using this method can effectively reduce the gradient of negative stiffness variation with stroke, obtaining a high-precision negative stiffness system, and ultimately a quasi-zero stiffness system with a lower system frequency.

Description

Technical Field

[0001] This application belongs to the field of low-frequency vibration isolation technology and relates to a micro-vibration quasi-zero stiffness vibration isolator, specifically a negative stiffness parallel structure that reduces the change in the stiffness of a negative stiffness spring. Background Technology

[0002] Vibration has always been an unavoidable adverse factor in machining, manufacturing, and precision instrument measurement and control. It not only generates noise but also reduces production accuracy and can even shorten product lifespan. In precision and ultra-precision machining and measurement and control, the hazards of low-frequency and ultra-low-frequency vibrations are particularly prominent.

[0003] Currently, negative stiffness springs used as core components for micro-vibration isolation employ horizontally placed pre-compressed springs. The negative stiffness is achieved by utilizing the vertical component of the restoring force vector of this horizontal spring. Therefore, the main drawbacks of this type of traditional negative stiffness structure for micro-vibration isolation include the following:

[0004] 1. Traditional negative stiffness structures generally exhibit parabolic working characteristics. Negative stiffness structures are single structures, and the negative stiffness characteristic curve has not undergone further compensation and optimization, resulting in a large gradient in the change of negative stiffness with stroke.

[0005] 2. The stiffness gradient of traditional negative stiffness structures varies significantly with the motion stroke, making it difficult to match with the linear stiffness characteristics of vertical springs. When linear negative stiffness is achieved by adjusting parameters, the negative stiffness loses its adjustability.

[0006] 3. The adaptation range between negative stiffness and vertical positive stiffness is small, the matching accuracy between positive and negative stiffness is poor, the quasi-zero working range is small, and the large residual stiffness makes it difficult to further reduce the system frequency.

[0007] 4. The negative stiffness that varies with the motion stroke makes the equilibrium point of the parallel positive and negative stiffness system sensitive to position, making it difficult to adjust the parallel positive and negative stiffness system and causing the negative stiffness structure to repeatedly jump to the two extreme points.

[0008] 5. To achieve lower stiffness fluctuations, current negative stiffness technology mainly involves adjusting a single negative stiffness structural parameter to significantly increase spring compression and structural length. This is difficult to implement in engineering, and it is even difficult to achieve ultra-low stiffness over a large stroke range. This limits the performance and application of current structural low-frequency micro-vibration isolators.

[0009] However, common negative stiffness structures still have some problems, especially the strong nonlinearity of the negative stiffness value, which changes significantly with the displacement stroke of the negative stiffness structure, making it difficult to maintain stability throughout the entire working displacement range. Once the working displacement range is large, the negative stiffness value may even decrease sharply. This causes the entire structure to be unable to maintain stable properties during operation, and also limits the application of such negative stiffness structures in more situations. Summary of the Invention

[0010] The purpose of this application is to overcome the shortcomings of the prior art and provide a method for reducing the stiffness variation of a negative stiffness spring.

[0011] The technical problem solved by this invention is achieved through the following technical solution:

[0012] A parallel negative stiffness structure for reducing the stiffness variation of a negative stiffness spring is used as a core element for micro-vibration isolation. The core element for micro-vibration isolation includes a positive stiffness structure and a main negative stiffness structure. The characteristic feature is that it also includes two or more negative stiffness elastic elements. The negative stiffness elastic elements include different parabolic concave and convex stiffness gradient properties. The negative stiffness elastic element with concave stiffness gradient property is connected in parallel with the negative stiffness elastic element with convex stiffness gradient property.

[0013] Furthermore, the negative stiffness elastic element with concave stiffness gradient properties is connected in parallel at both ends with the negative stiffness elastic element with convex stiffness gradient properties.

[0014] Furthermore, the negative stiffness elastic element with concave stiffness gradient properties and the negative stiffness elastic element with convex stiffness gradient properties respectively place their head or tail end at a point of action of another negative stiffness structure.

[0015] Furthermore, the negative stiffness elastic element with concave stiffness gradient properties is a spring and a rotating compression rod negative stiffness structure, which includes springs connected in series. With long pole ,spring The tail end and the long rod The head end is connected to the long rod. The tail end is connected to a vibrating block.

[0016] Furthermore, the negative stiffness elastic element with convex stiffness gradient properties is a spring and a triangular negative stiffness structure of long and short rods, which includes long rods connected end to end in sequence. ,spring and short rod long pole and short rod The tail end connection point is connected to the vibrating block.

[0017] Moreover, the spring The first end is connected to the spring The tail end.

[0018] Furthermore, the vibrating block is also connected to a linear spring with vertical positive stiffness. .

[0019] The advantages and positive effects of this application are:

[0020] 1. This method is applied to the design of structural negative stiffness elastic elements. The proposed method of using a composite of different stiffness gradient characteristics can achieve smaller stiffness fluctuations in structural negative stiffness elements.

[0021] 2. This method is mainly applied to structural negative stiffness components. These negative stiffness structures are primarily used in high-precision, small-amplitude, or micro-vibration applications. Due to the continuity mechanism of their structural negative stiffness, they exhibit good linearity, are sensitive to minute vibrations, and do not introduce damping. However, due to the limitations of the mechanical continuity structure, the adjustment of the negative stiffness's angle of application and compression is somewhat restricted.

[0022] 3. This method is characterized by the parallel connection or series-parallel hybrid connection of two or more negative stiffness structures to adjust the working characteristics of negative stiffness, including stiffness in the equilibrium point region, stiffness fluctuation characteristics, and constant stiffness working range. Attached Figure Description

[0023] Figure 1 This is an example of a quasi-zero stiffness structure with negative stiffness in parallel.

[0024] Figure 2 It is the combined negative stiffness characteristic curve of two negative stiffness modules in parallel.

[0025] (a) Example of a negative stiffness system with a stroke stiffness change of ±5mm;

[0026] (b) Example of a negative stiffness system with a stroke stiffness variation of ±10mm;

[0027] (c) Example of a negative stiffness system with a stroke stiffness variation of ±20mm;

[0028] (d) Example of a negative stiffness system with a stroke stiffness change of ±40mm. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention. The terms "lateral" and "longitudinal" mentioned in these embodiments are used to describe the relative positions of the structures and do not limit the installation direction of the structures.

[0030] Design principles:

[0031] Research has revealed that most negative stiffness structures exhibit a parabolic stiffness gradient within their working stroke. Different stiffness structures possess different stiffness gradient properties, and some negative stiffness structures even exhibit differences in the concave and convex directions of their parabolic curves as structural parameters change. Therefore, they can be connected in parallel for complementarity. The parallel connection of negative stiffness structures is not limited to connecting the two ends of different negative stiffness mechanisms in parallel.

[0032] The second and third negative stiffness structures can utilize the action points on the main negative stiffness structure to achieve the adjustment design of negative stiffness performance, so that the negative stiffness elastic elements with concave stiffness gradient properties and the negative stiffness elastic elements with convex stiffness gradient properties are connected in parallel with the local structure of the main negative stiffness structure.

[0033] A method for reducing stiffness variation in negative stiffness springs involves using two or more elastic elements of different stiffness in parallel, utilizing the complementary gradient differences in stiffness to reduce stiffness fluctuations in the working section of the negative stiffness system and improve the performance of the negative stiffness system.

[0034] However, to make the method clear, a negative stiffness parallel structure based on the above method is proposed. By utilizing the above principle, the negative stiffness parallel mechanism can obtain better stiffness characteristics, effectively reduce the gradient of negative stiffness with stroke, obtain a high-precision negative stiffness system, and thus obtain a quasi-zero stiffness system with a lower system frequency.

[0035] This method is not limited to specific negative stiffness parallel structures.

[0036] Example 1

[0037] The schematic diagram of the negative stiffness parallel structure in this embodiment is shown below. Figure 1 As shown, it includes:

[0038] 1) By spring and long pole A negative stiffness structure consisting of a spring and a rotating pressure bar;

[0039] 2) By spring Long pole and short rod A triangular negative stiffness structure consisting of springs and long and short rods;

[0040] 3) By linear spring The resulting vertical positive stiffness;

[0041] After considering the stiffness of the aforementioned negative stiffness spring and negative stiffness spring precompression and , pole length and The adjustment,

[0042] For example: = = =100N / mm, : : : =4:2:1:1, When = 30mm,

[0043] The overall stiffness characteristics of a negative stiffness structure can be made to resemble... Figure 2 As shown, extremely low negative stiffness characteristics are obtained over a large stroke, effectively reducing the gradient of negative stiffness variation with stroke, and obtaining a high-precision negative stiffness system.

[0044] Stiffness variation within ±5mm is less than ,

[0045] The stiffness variation is less than 0.0005 N / mm within a range of ±10 mm.

[0046] The stiffness variation is less than 0.05 N / mm within a range of ±20 mm.

[0047] The interconnection between elastic elements and structures is not limited to the structures mentioned above.

[0048] Although embodiments and drawings of this application have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of this application and the appended claims. Therefore, the scope of this application is not limited to the content disclosed in the embodiments and drawings.

Claims

1. A negative stiffness parallel structure for reducing the stiffness variation of a negative stiffness spring, used as a core component for micro-vibration isolation, characterized in that: It includes a negative stiffness elastic element with a convex stiffness gradient property, a negative stiffness elastic element with a concave stiffness gradient property, a vibrating block, and a linear spring with vertical positive stiffness. The negative stiffness elastic element with a concave stiffness gradient property and the negative stiffness elastic element with a convex stiffness gradient property are connected in parallel. The negative stiffness elastic element with concave stiffness gradient properties is a spring and a rotating compression rod negative stiffness structure, including springs connected in series. With long pole ,spring The tail end and the long rod The head end is connected to the long rod. The tail end is connected to a vibrating block; The negative stiffness elastic element with convex stiffness gradient properties is a triangular negative stiffness structure consisting of a spring and long and short rods, including long rods connected end to end in sequence. ,spring and short rod long pole and short rod The tail end connection point is connected to the vibrating block; The vibrating block is also connected to a linear spring with vertical positive stiffness. .

2. The negative stiffness parallel structure for reducing the stiffness variation of a negative stiffness spring according to claim 1, characterized in that: The negative stiffness elastic element with concave stiffness gradient property is connected in parallel at both ends with the negative stiffness elastic element with convex stiffness gradient property.

3. The negative stiffness parallel structure for reducing the stiffness variation of a negative stiffness spring according to claim 1, characterized in that: The negative stiffness elastic element with concave stiffness gradient property and the negative stiffness elastic element with convex stiffness gradient property respectively set their head or tail end at a point of action of another negative stiffness structure.

4. The negative stiffness parallel structure for reducing the stiffness variation of a negative stiffness spring according to claim 1, characterized in that: The spring The first end is connected to the spring The tail end.

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