A nonlinear metamaterial vibration isolator with quasi-zero stiffness

Abstract

The present invention discloses a nonlinear metamaterial vibration isolator with quasi-zero stiffness, which belongs to the technical field of metamaterials and vibration reduction and noise reduction. The vibration isolator is composed of structural parts and vibration isolation components. The vibration isolation components play the role of vibration isolation and buffering. A polymer material with a certain load-bearing capacity is used. The interior of the vibration isolation component has a metamaterial structure formed by periodic arrangement of metamaterial unit cells. The geometric shape of the metamaterial unit cell is similar to a half hexagon. The metamaterial structure is obtained by periodic arrays of metamaterial unit cells in the vertical and horizontal directions. The structural parts are made of metal materials, and the structural parts and the vibration isolation components are connected in a composite manner of mechanical locking and bonding. The present invention can realize the quasi-zero stiffness nonlinear characteristics of the vibration isolator, greatly reduce the natural frequency of the vibration isolator while ensuring the stability of the system, and effectively improve the vibration isolation effect.

Description

Technical Field

[0001] The invention belongs to the technical field of metamaterials and vibration and noise reduction, and in particular relates to a nonlinear metamaterial vibration isolator with quasi-zero stiffness. Background Art

[0002] With the development of industry, mechanical equipment has gradually become larger, faster, and more complex, and vibration and noise problems have become increasingly prominent. As the most important platform for the struggle for sea power, ships have increasingly higher requirements for underwater acoustic stealth performance, and mechanical vibration and noise are one of the main noise sources when ships are sailing in stealth. Using vibration isolators to isolate vibration transmission has become a practical method of vibration reduction and noise reduction. From the vibration isolation principle, it can be seen that the smaller the stiffness of the vibration isolation component, the better the vibration isolation effect. However, for the most widely used rubber vibration isolators, the smaller the stiffness, the worse the lateral stability, and the vibration isolation effect often has to be sacrificed in order to ensure the stability of the system. Quasi-zero stiffness vibration isolation technology is a new type of vibration isolation technology. It achieves quasi-zero stiffness by connecting positive and negative stiffness in parallel. At present, many researchers have designed and manufactured a variety of quasi-zero stiffness vibration isolation mechanisms based on various positive and negative stiffness parallel structures, and have achieved excellent vibration isolation effects. However, there are many disadvantages in the current quasi-zero stiffness mechanism. The mechanism needs to assemble many parts and auxiliary devices, and the structure is complex. In addition, according to the published literature, the quasi-zero stiffness mechanism can only achieve vibration isolation in a single direction, and the stability in directions other than the main vibration direction is poor, which makes it difficult to realize engineering applications. Therefore, it is necessary to further explore new, simple and reliable quasi-zero stiffness vibration isolation components to meet the engineering application requirements of large-load low-frequency vibration isolation of weapons and equipment.

[0003] Metamaterial design method is a disruptive technology that has emerged in the past decade. Metamaterials have extraordinary physical properties that natural materials do not have. Through orderly structural design at the key physical scale of the material, it breaks through the limitations of certain apparent natural laws, thereby obtaining extraordinary material functions that exceed the ordinary properties inherent in nature. Using metamaterial structural design technology to achieve quasi-zero stiffness nonlinear characteristics is a new idea proposed in recent years. Since the three-dimensional stiffness of metamaterials is designable, while ensuring the lateral stiffness, extremely low stiffness can be achieved in the main vibration direction, greatly improving the vibration isolation performance. Compared with quasi-zero stiffness mechanisms, quasi-zero stiffness metamaterial isolators have the characteristics of simple structure, reliable engineering applicability and strong. Summary of the invention

[0004] In view of this, the present invention provides a nonlinear metamaterial isolator with quasi-zero stiffness, which can realize the quasi-zero stiffness nonlinear characteristics of the isolator, greatly reduce the natural frequency of the isolator while ensuring the stability of the system, and effectively improve the vibration isolation effect.

[0005] A nonlinear metamaterial vibration isolator with quasi-zero stiffness, the vibration isolator is composed of a structural member and a vibration isolation component, the vibration isolation component plays a vibration isolation and buffering role, and adopts a polymer material with a certain load-bearing capacity. The vibration isolation component has a metamaterial structure formed by periodically arranging metamaterial cells, the geometric shape of the metamaterial cell is similar to a half hexagon, and the metamaterial structure is obtained by periodically arranging the metamaterial cells in the vertical and horizontal directions; the structural member is made of metal material, and the structural member and the vibration isolation component are connected by a composite method of mechanical locking and bonding.

[0006] Furthermore, the structural configuration of the metamaterial unit cell in the vibration isolation component is a two-dimensional structure stretched in the third direction. The geometric configuration consists of a vertical arm, a flexible hinge, an oblique arm and a tensile connecting rod. The geometric configuration has six constraint parameters: the angle θ between the oblique arm and the horizontal direction, the wall thickness t of the oblique arm, and the vertical arm. l , vertical arm wall thickness t h , radius R at the flexible hinge r , the fillet radius R at the intersection of the inclined arm and the tensile connecting rod f and the depth D of the metamaterial unit cell.

[0007] Furthermore, the compression modulus of the base material of the vibration isolation component is 15-400 MPa, the metamaterial unit cell is geometrically symmetrical along the horizontal direction, the length L of the oblique arm thereof is in the range of 2-100 mm, the angle θ between the oblique arm and the horizontal direction is in the range of 1-15°, and the wall thickness t of the oblique arm is l The value range of is 1.5~20mm, and the radius R of the flexible hinge between the two oblique arms of the metamaterial unit cell is r The radius of the inscribed circle at the connection between the oblique arm and the vertical arm is 1.5 to 30 mm. f is 1.5 to 30 mm, the wall thickness of the vertical arm is t h The range is 1.5 to 25 mm, the penetration depth D of the inner contour of the unit cell ranges from 20 to 400 mm; the number of layers m of the metamaterial vibration isolation component ranges from ≥1 layer, and the number of columns of the metamaterial vibration isolation component ranges from ≥1 column.

[0008] Furthermore, the structural member includes an upper end cover, a metal frame and a lower base plate, and the structural member plays the role of bearing, transmitting force and fixing the vibration isolator.

[0009] Furthermore, the metamaterial unit cell is periodically extended in the vertical and horizontal directions. In the vertical direction, in order to ensure the continuity of the multi-layer metamaterial unit cell and the processability of the cavity, the unit cells are arranged periodically and tilted upward in the vertical direction, and the unit cell structure can be arranged in an infinite number of rows in the horizontal direction.

[0010] Furthermore, the composite bonding connection is achieved by implanting a metal frame into the vibration isolation component, opening threaded holes on the frame, applying adhesive to the mating surfaces of the vibration isolation component and the metal structural component, and then fastening with bolts to form a three-layer plywood structure of "metal structural component / adhesive / vibration isolation component" to achieve the connection between the structural component and the vibration isolation component.

[0011] Furthermore, the metamaterial unit cell structure of the vibration isolation component is processed by CNC micro-milling or diamond wire cutting; the structural component material is selected from high-strength steel material, which is processed and formed by casting and welding methods to connect the vibration isolation component.

[0012] Furthermore, the flexible hinge is located at the connection between the oblique arms and the vertical arms of all unit cells, and its thickness is smaller than that of the oblique arms, which plays a role in reducing stress and assisting in adjusting the nonlinearity.

[0013] Beneficial effects:

[0014] 1. The present invention breaks the dependence on the vibration isolation substrate in the design process of traditional vibration isolators, simplifies the design of new vibration isolators, effectively shortens the development cycle of vibration isolation products, and broadens the selection range of the substrate of vibration isolation materials.

[0015] 2. The present invention realizes quasi-zero stiffness nonlinear mechanical properties through metamaterial technology, reaches extremely low stiffness near the rated load, significantly improves low-frequency vibration isolation performance, and provides a new way to reduce vibration and noise of ships.

[0016] 3. The invention has high lateral stability. It overcomes the contradiction that the traditional vibration isolator cannot simultaneously meet the requirements of low-frequency vibration isolation and the stability of the vibration isolation system, ensures the low-frequency vibration isolation effect while improving the lateral stability, and can realize the engineering promotion and application of low-frequency vibration isolation technology.

[0017] 4. The invention has strong applicability. Compared with the traditional quasi-zero stiffness mechanism, the metamaterial vibration isolation component with quasi-zero stiffness has a simple processing technology, a seamless structure, and no additional auxiliary connecting components are required. The positive stiffness and negative stiffness in the structure can be generated by the metamaterial itself, and the structure is reliable and simple, which is convenient for engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the nonlinear metamaterial isolator of the present invention;

[0019] Figure 2 It is a cross-sectional view of a basic unit cell of the metamaterial vibration isolation component of the present invention;

[0020] Figure 3 A 3D diagram of a basic unit cell of the metamaterial vibration isolation component of the present invention;

[0021] Figure 4 It is the metamaterial vibration isolation component part of the present invention;

[0022] Figure 5 It is the metamaterial vibration isolation component of the metamaterial vibration isolator prototype of the present invention;

[0023] Figure 6 A prototype of the metamaterial vibration isolator of the present invention;

[0024] Figure 7 It is the static load displacement curve of the metamaterial isolator prototype of the present invention.

[0025] Among them: 1-upper end cover, 2-metamaterial vibration isolation component, 3-metal frame, 4-lower base plate, 5-vertical arm, 6-flexible hinge, 7-oblique arm, 8-tensile connecting rod. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0027] As attached Figure 1 As shown, the present invention provides a nonlinear metamaterial vibration isolator with quasi-zero stiffness, wherein the nonlinear metamaterial vibration isolator is composed of a vibration isolation component and a structural component, such as Figure 1 As shown, (2) is a metamaterial vibration isolation component; the structural components include: (1) an upper end cover, an implant frame 3 and a lower base plate 4. The metamaterial vibration isolation component plays a role in vibration isolation and buffering; the structural component plays a role in bearing, transmitting force and fixing the vibration isolator.

[0028] According to the above scheme, the substrate of the metamaterial vibration isolation component (1) is any polymer material, composite material or metal material suitable for vibration isolation. Figure 1 As shown, the structural configuration of the vibration isolation component microstructure is a two-dimensional structure stretched in the third direction. The main structure of the geometric configuration is composed of a vertical arm 5, a flexible hinge 6, an inclined arm 7 and a tensile connecting rod 8, and the basic unit cell configuration is as follows Figure 2 and Figure 3 As shown, there are six main parameters constraining the angle θ, the thickness of the inclined beam t l , vertical beam wall thickness t h , radius R at the flexible hinge r , fillet radius R f , the number of parallel rows m and the number of parallel columns n, the depth D of the metamaterial unit cell.

[0029] Metamaterial vibration isolation components are made of Figure 2 and Figure 3 The basic unit cell configuration is extended periodically in the vertical and horizontal directions. In the vertical direction, in order to ensure the continuity of multi-layer unit cells and the processability of the cavity, the unit cells are arranged periodically in an inclined upward direction. The unit cell structure can be arranged in an infinite number of rows in the horizontal direction. Figure 4 Examples of the two metamaterial structures formed.

[0030] In this embodiment, the vibration isolation substrate is selected as a rubber material, the compression modulus of the substrate is 100 MPa, and the design target of the vibration isolator is a rated load of 200 kg. At the rated load, the stiffness is quasi-zero. The unit cell structure parameters optimized by the metamaterial design method are as follows: the length L of the oblique arm is 14.8 mm, the angle θ between the oblique arm and the horizontal direction is 7.5°, and the wall thickness t of the oblique arm is 14.8 mm. l The value is 3.0mm, and the wall thickness of the vertical arm is t h The radius of the inscribed circle at the connection between the two groups of oblique arms of the unit cell of the vibration isolation component is 3.5 mm. r The value is 2.1mm, and the radius R of the inscribed circle at the connection between the oblique arm and the vertical arm of the vibration isolation component is f The value is 3.0 mm, the penetration depth D of the contour within the unit cell is in the range of 80 mm, the number of layers m of the metamaterial structure formed by the above unit cell is 2 layers, and the number of columns n is 2 columns.

[0031] The structural diagram of the vibration isolation component is as follows: Figure 5 As shown, the upper and lower end surfaces are provided with positioning anti-shear grooves to facilitate positioning during assembly and prevent the interface from peeling off due to shearing. Secondly, the mating surface is provided with a circular groove for bolt connection to increase the compression force area when the bolt is tightened and relieve local stress concentration. The vibration isolation component is provided with a metal skeleton implantation groove perpendicular to the penetration direction of the single cell hole, which is used to implant the metal skeleton to provide a mechanical locking connection between the vibration isolation component of the metamaterial vibration isolator and the structural component. The role of the metal implantation skeleton is to provide a metal threaded connection hole on the one hand, and to increase the force area of ​​the mechanical connection interface of the bolt on the other hand, reduce the interface stress concentration, and prevent local tearing of the vibration isolation component.

[0032] The vibration isolation components and structural components are connected by mechanical locking and bonding to form a vibration isolator prototype. Figure 6 As shown, the static mechanical curve of the vibration isolator product designed and manufactured according to the above embodiment is as follows Figure 7 As shown in the figure, the rated load is 200kg. At the rated load, the stiffness of the nonlinear metamaterial isolator is 0N / mm, the static stiffness in the non-load-bearing direction in the X direction is 875N / mm, and the static stiffness in the Y direction is 1510N / mm. The static stiffness in the non-load-bearing direction is much greater than that in the main load-bearing direction, which makes up for the shortcomings of traditional rubber isolators and is conducive to improving the anti-skid, anti-pitch and anti-roll capabilities of the vibration isolation system.

[0033] The design of the vibration isolator includes the following steps:

[0034] (1) Based on the design requirements, obtain inputs such as the static load, interface size, vibration characteristics of the vibration source, the vibration isolation effect to be achieved, mechanical environment and climate environment, and preliminarily define the material selection range of the metamaterial vibration isolation component and other auxiliary mechanisms;

[0035] (2) According to the design input obtained in step (1), a finite element model of the metamaterial vibration isolation component is established, and the six dimensional parameters of the metamaterial vibration isolation component are optimized to obtain the required mechanical nonlinear characteristics as the optimization goal, and the geometric dimensions of the metamaterial vibration isolation component are determined.

[0036] (3) According to the geometric parameters of the material and metamaterial vibration isolation components determined in step (2) and in combination with the interface dimensions described in step (1), the specific form, size and connection method of the nonlinear metamaterial vibration isolator vibration isolation components and mechanical structure components are designed.

[0037] (4) Based on the specific form and size of each component of the vibration isolator determined in step (3), a suitable processing technology is selected according to the determined material to process a prototype for mechanical property testing.

[0038] (5) Perform mechanical property tests on the prototype formed in step (4), and compare the test results with the design requirements determined in step (1). If the requirements are not met, repeat steps (1) to (5) until the design requirements are met, thereby forming a final design solution.

[0039] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A nonlinear metamaterial isolator with quasi-zero stiffness, characterized in that: The vibration isolator is composed of a structural member and a vibration isolation component. The vibration isolation component has a vibration isolation and buffering effect and adopts a polymer material with a certain load-bearing capacity. The base material of the vibration isolation component is a rubber material. The interior of the vibration isolation component has a metamaterial structure formed by periodically arranging metamaterial unit cells. The geometric shape of the metamaterial unit cell is similar to half a hexagon. The metamaterial unit cell is formed by hollowing out half of a similar hexagonal structure. The metamaterial structure is obtained by periodically arranging metamaterial unit cells in the vertical and horizontal directions. The structural member is made of metal material, and the structural member and the vibration isolation component are connected by a composite method of mechanical locking and bonding; The structural configuration of the metamaterial unit cell in the vibration isolation component is a two-dimensional structure stretched in the third direction. The geometric shape consists of a vertical arm, a flexible hinge, an oblique arm and a tensile connecting rod. The geometric shape has six constraint parameters: the angle between the oblique arm and the horizontal direction. θ , inclined arm wall thickness t l , vertical arm wall thickness t h , the radius at the flexible hinge R r , fillet radius at the intersection of the oblique arm and the tensile connecting rod R f and the depth of the metamaterial unit cell D .

2. The nonlinear metamaterial isolator with quasi-zero stiffness according to claim 1, characterized in that: The compression modulus of the base material of the vibration isolation component is 15-400 MPa, the metamaterial unit cell is geometrically symmetrical along the horizontal direction, and the length of its oblique arm is L The value range of is 2-100 mm, the value range of the angle θ between the inclined arm and the horizontal direction is 1-15°, and the wall thickness of the inclined arm is t l The value range of is 1.5~20mm, and the radius of the flexible hinge between the two oblique arms of the metamaterial unit cell is R r 1.5~30mm, the radius of the inscribed circle at the connection between the oblique arm and the vertical arm R f The wall thickness of the vertical arm is 1.5 to 30 mm. t h The penetration depth of the single cell profile is in the range of 1.5 to 25 mm. D The value range of is 20~400 mm; the number of layers m of the metamaterial vibration isolation component ranges from ≥1 layer, and the number of columns of the metamaterial vibration isolation component ranges from ≥1 column.

3. The nonlinear metamaterial isolator with quasi-zero stiffness according to claim 2, characterized in that: The structural member comprises an upper end cover, a metal frame and a lower bottom plate, and the structural member plays the role of bearing, transmitting force and fixing the vibration isolator.

4. The nonlinear metamaterial isolator with quasi-zero stiffness according to claim 3, characterized in that: The metamaterial unit cell is extended periodically in the vertical and horizontal directions. In the vertical direction, in order to ensure the continuity of the multi-layer metamaterial unit cell and the processability of the cavity, the unit cell is arranged periodically in an inclined upward direction. The unit cell structure can be arranged in an infinite number of rows in the horizontal direction.

5. The nonlinear metamaterial isolator with quasi-zero stiffness according to claim 4, characterized in that: The composite bonding connection is achieved by implanting a metal frame into the vibration isolation component, opening threaded holes on the frame, applying adhesive to the mating surfaces of the vibration isolation component and the metal structural component, and then fastening with bolts to form a three-layer plywood structure of "metal structural component / adhesive / vibration isolation component" to achieve the connection between the structural component and the vibration isolation component.

6. The nonlinear metamaterial isolator with quasi-zero stiffness according to claim 5, characterized in that: The metamaterial unit cell structure of the vibration isolation component is processed by CNC micro-milling or diamond wire slow-feed cutting; the structural component material is high-strength steel material, which is processed and formed by casting and welding methods to connect the vibration isolation component.

7. The nonlinear metamaterial isolator with quasi-zero stiffness according to claim 6, characterized in that: The flexible hinge is located at the connection between the oblique arms and the vertical arms of all unit cells, and its thickness is smaller than the thickness of the oblique arms.

Images