Elastic curved beam amplified unit cell and metamaterial with negative stiffness characteristics

Abstract

The present invention relates to an elastic curved beam amplification and synergistic unit cell and metamaterial with negative inertia and stiffness characteristics. The unit cell comprises a positive-negative stiffness unit and a frame. The frame comprises an inner shell and an outer shell. The inner shell is slidably connected within the outer shell. The positive-negative stiffness unit comprises a slider and an elastic curved beam. The slider slides into the inner shell, and the extended end of the slider is fixedly connected to the outer shell via an elastic beam. The inner shell is fixedly connected to the outer shell via an elastic beam at the other end where the slider extends. The elastic curved beam is fixedly connected to the inner shell, and a protrusion is fixedly connected to the slider, which slides in contact with the elastic curved beam. Compared with the prior art, the present invention can achieve synergistic control of structural vibration under low-frequency multi-dimensional excitation.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering and relates to an elastic curved beam amplification and synergistic unit cell and a metamaterial with inertia capacity negative stiffness characteristics. Background Art

[0002] Metamaterials are new artificial composite periodic materials based on artificially structured unit cells, capable of achieving mechanical properties unattainable by traditional natural materials. The sensitivity of metamaterial periodic structures to dynamic loads offers the potential for vibration and noise control. Traditional local resonance metamaterials incorporate local resonance units encased in flexible materials within their unit cell structures, creating a band gap that blocks elastic wave propagation. This opens the door to achieving low-frequency band gaps and constructing metamaterials for earthquake engineering. However, existing local resonance metamaterials generally struggle to achieve low-frequency band gaps. This is particularly true for seismic wave modulation, where achieving a low-frequency band gap often requires increasing the mass of the resonance unit and reducing its internal stiffness, limiting the application of this technology within complex engineering constraints. Furthermore, while local resonance metamaterials are more suitable for vibration reduction in the extremely low frequency range compared to Bragg-type metamaterials, they lack the ability to effectively attenuate elastic waves within the resonance band gap. Therefore, the development of new metamaterial units with low-frequency band gaps and high attenuation coefficients is urgently needed.

[0003] Patent CN114658782A discloses a bidirectional buffering energy-absorbing metamaterial with enhanced performance, including a multicellular metamaterial structure formed by a plurality of unit cells arranged periodically; the unit cell is composed of a cross-curved beam, a bidirectional ring, a spiral rod, a rectangular frame and a connecting rod; the rectangular frame is composed of straight beams, and the cross-curved beam is composed of two curved beams crossed, two groups of cross-curved beams are installed in two opposite surfaces of the frame, the ends of the cross-curved beams are fixedly connected to the rectangular frame, the two groups of cross-curved beams are parallel to each other, the upper and lower end faces of the bidirectional rings in the unit cell are respectively fixedly connected to the middle of the two groups of cross-curved beams by spiral rods, different unit cells are connected to the intersection of the cross-curved beams in the vertical direction by straight rods, and are connected horizontally by sharing the rectangular frame. Multiple unit cells are arranged periodically to form a multicellular metamaterial structure. Although this patent enhances the energy absorption capacity of the metamaterial by superimposing cross-curved beams, on the one hand, the deformation of the cross-curved beams in this patent is consistent with the external displacement and does not have internal vibration freedom, which weakens its energy absorption effect under small deformation conditions. On the other hand, the metamaterial in this patent lacks enhanced energy dissipation units, making it difficult to quickly dissipate the absorbed energy, limiting its energy dissipation and vibration reduction capabilities.

[0004] Patent CN115596799A discloses a modular multistable metamaterial structure with adjustable mechanical properties, comprising a unit cell with adjustable mechanical properties, a long horizontal connecting rod, and a short vertical connecting rod. The unit cells, long horizontal connecting rods, and short vertical connecting rods can be assembled as needed to form a modular multistable metamaterial structure with any number of rows and columns. Although this patent uses a variable-shape curved beam design to adjust the mechanical behavior of the unit cells and achieves a multistable metamaterial structure through assembly, the unit cells lack the capabilities of mass amplification and superdamping, making it difficult for the constructed metamaterial system to achieve a low-frequency band gap. Furthermore, the attenuation of elastic waves within the resonant band gap is insufficient. Summary of the Invention

[0005] The purpose of the present invention is to overcome at least one of the defects of the above-mentioned prior art and to provide an elastic curved beam amplification and enhancement type unit cell and metamaterial with negative stiffness characteristics of inertia. The present invention can achieve enhanced control of structural vibration under low-frequency multi-dimensional excitation.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide an elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics, the unit cell includes a positive stiffness-negative stiffness unit and a frame.

[0008] The frame includes an inner shell and an outer shell, wherein the inner shell is arranged in a sliding connection with the outer shell, and the outer shell provides the load-bearing capacity for the unit cell.

[0009] The positive stiffness-negative stiffness unit includes a slider and an elastic curved beam. The slider slides into the inner shell. The protruding end of the slider is fixedly connected to the outer shell through the elastic beam. The other end of the inner shell where the slider protrudes is fixedly connected to the outer shell through the elastic beam.

[0010] An elastic curved beam is fixedly connected to the inner shell, and a protrusion is fixedly connected to the slider, and the protrusion slides in contact with the elastic curved beam. When the protrusion and the elastic curved beam just come into contact, it is set as the initial state of the unit cell. When the protrusion contacts the arc vertex on the central axis of the elastic curved beam, it is set as the equilibrium point of the elastic curved beam.

[0011] When an external load acts on the protrusion of the slider through the elastic beam, the elastic curved beam first exhibits a positive stiffness characteristic. After the protrusion of the slider crosses the equilibrium point of the elastic curved beam, the elastic curved beam exhibits a negative stiffness characteristic.

[0012] The elastic beam connecting the outer shell and the internal components on both sides has a function similar to a tuned spring, which amplifies the displacement of the slider through resonance tuning, thereby amplifying the deformation of the negative stiffness / inertia unit.

[0013] As a preferred technical solution, the elastic curved beam is expressed in the form of a cosine function as follows:

[0014]

[0015] Where A is the height of the elastic curved beam, K is the shape factor of the elastic curved beam, and its value range is (0,1], D is the span of the elastic curved beam, and M is the offset value of the elastic curved beam.

[0016] Furthermore, the contact surface between the elastic curved beam and the protrusion is set as a variable friction coefficient surface, which is conducive to realizing the super damping mechanism of the unit cell and enhancing the attenuation of the elastic wave peak in the band gap.

[0017] Furthermore, the friction coefficient of the surface of the elastic curved beam is symmetrically distributed along the central axis of the elastic curved beam, and decreases linearly from the central axis to both sides. The distribution design of the friction coefficient achieves a balance between the displacement stroke of the slider and the friction energy consumption, that is, the artificial design achieves damping performance that cannot be achieved by traditional natural materials.

[0018] As a preferred technical solution, the friction coefficient of the surface of the elastic curved beam depends on the type and composition of the surface coating, with a maximum value of 0.5-1.0 and a minimum value of 0.1-0.2.

[0019] As a preferred technical solution, the span range of the elastic curved beam depends on the motion range within which the slider maintains contact with the elastic curved beam, which is related to the design of the unit cell.

[0020] Furthermore, the positive stiffness-negative stiffness unit also includes a connecting plate, the protruding end of the slider is fixedly connected to the connecting plate, and the connecting plate is fixedly connected to the elastic beam on the other side of the slider. The slider moves horizontally along the slot of the inner shell, and the protrusion contacts the elastic curved beam during the movement.

[0021] Furthermore, the elastic beams are provided in plurality, one of which is arranged on the central axis of the unit cell, and the others are symmetrically arranged on both sides of the central axis;

[0022] The elastic beams symmetrically arranged on both sides of the central axis are configured as elastic curved beams. The distance between the connection end of the elastic curved beam close to the inner shell and the central axis is smaller than the distance between the connection end with the outer shell and the central axis. The purpose of the bending design of the elastic curved beam is to enable the elastic curved beam to have deformation ability, so that it can achieve compression deformation, tensile deformation and reset during the force process.

[0023] Furthermore, the unit cell further includes a lever rotation inertia unit, which includes a support plate, a rotating shaft, and a mass block. The support plate is fixedly connected to the inner shell, and a rotating shaft is hingedly provided on the support plate. One side of the rotating shaft is fixedly connected to the slider via a beam, and the other side is fixedly connected to the mass block via a beam. The rotating shaft and the mass block only undergo in-plane rotational motion.

[0024] When the slider pushes the beam-rotating shaft-beam, the mass block on the other side will rotate, thus achieving the inertia effect.

[0025] Furthermore, one side of the rotating shaft is fixedly connected to the slider via a short beam, and the other side is fixedly connected to the mass block via a long beam;

[0026] At the same time, the length of the beam on the slider side is smaller than the length of the beam on the mass block side, achieving a lever mass amplification effect. The length ratio of the long beam to the short beam is significant in adjusting the inertia coefficient of the unit cell.

[0027] Furthermore, the short beams and long beams are provided in plurality, one of which is arranged on the central axis of the unit cell, and the others are symmetrically arranged on both sides of the central axis;

[0028] The short beams and long beams symmetrically arranged on both sides of the central axis are respectively set as short curved beams and long curved beams. The distance between the connection end of the short curved beam and the slider and the central axis is smaller than the distance between the connection end with the rotating shaft and the central axis. The distance between the connection end of the long curved beam and the rotating shaft and the central axis is smaller than the distance between the connection end with the mass block and the central axis. The purpose of the bending design of the short curved beams and the long curved beams is to make the short curved beams and the long curved beams have deformation ability, so that they can achieve compression deformation, tensile deformation and reset during the force process.

[0029] As a preferred technical solution, the shape of the mass block is selected from any one of a sphere, a cuboid, and a cube, without any special requirements.

[0030] Furthermore, the side walls of the inner shell and the outer shell are connected to assist movement via a ball sliding connection.

[0031] One of the technical solutions of the present invention is to provide a method for amplifying and enhancing the performance of an elastic curved beam having negative stiffness characteristics of inertia capacity. The method uses the unit cell to perform amplification and enhancement, comprising the following steps:

[0032] When the unit cell starts working, the external excitation is transmitted to the connecting plate through the outer shell and the elastic beam. The connecting plate drives the slider inward relative to the inner shell to cause horizontal displacement.

[0033] The protrusion of the slider compresses the elastic curved beam to cause elastic deformation, and the elastic curved beam provides a reaction force to resist the horizontal movement of the slider, that is, to produce a positive stiffness effect;

[0034] When the protrusion of the slider crosses the center axis of the elastic curved beam, the elastic curved beam provides a horizontal inward force, thereby prompting the slider to further move horizontally inward relative to the inner shell, that is, a negative stiffness effect is generated;

[0035] At the same time, the variable friction coefficient of the elastic curved beam surface makes the unit cell have super damping characteristics;

[0036] The horizontal movement of the slider drives the short beam to undergo elastic deformation, and the short beam drives the rotating shaft to rotate, further causing the long beam to undergo elastic deformation movement;

[0037] Based on the elastic deformation characteristics of the beam, the rotation of the long beam will drive the mass block at the end to rotate along the central axis of the unit cell;

[0038] Based on the length ratio between the short beam and the long beam, the rotational motion of the mass block has a lever deformation amplification effect;

[0039] This results in an inertia mass enhancement effect based on the mass block rotation and beam lever amplification effect;

[0040] When the connecting plate moves outward relative to the inner shell, the unit cell realizes the same working mode and has the ability to dissipate energy in a reciprocating manner.

[0041] One of the technical solutions of the present invention is to provide a metamaterial comprising a plurality of the aforementioned unit cells connected in series or in parallel, wherein the elastic beams are used for local resonance tuning to amplify the deformation of the negative stiffness / inertia unit, and in conjunction with the positive stiffness-negative stiffness unit and the lever rotation inertia unit, a super-damping mechanism of the unit cell is achieved by designing the friction coefficient on the positive stiffness-negative stiffness unit, effectively improving the peak control effect of a finite unit cell sequence on short-term impact effects, and having a regular shell that facilitates various combinations and applications.

[0042] When external excitation is input, each unit cell works in sequence, which can provide a better broadband vibration reduction effect.

[0043] As an optimal technical solution, the unit cell is simplified into a model of nonlinear inertial force, nonlinear elastic force and nonlinear damping force. Based on the model, series and parallel designs are carried out to calculate and realize specific negative stiffness values, inertia coefficients and damping coefficients under different configurations.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The metamaterial unit cell proposed in the present invention realizes the fusion of multiple mechanisms of elastic curved beam amplification type inertial mass efficiency, positive stiffness-negative stiffness adaptation and friction type super damping, which solves the problems of the current single form of metamaterial unit cell, narrow metamaterial band gap, high central frequency band, and insufficient elastic wave attenuation in the band gap. The present invention realizes the effects of ultra-wideband low-frequency band gap, variable friction type super damping vibration reduction (compared with the damping efficiency enhancement of local resonance type metamaterial) and nonlinear inertial energy absorption, which can realize the efficiency control of structural vibration under low-frequency, wide-band and multi-dimensional excitation, and improve the robustness of metamaterial vibration reduction to wide-band excitation and design parameter changes.

[0046] (2) The elastic curved beam amplified unit cell with inertia negative stiffness characteristics proposed in the present invention can be built into a frame periodic structure with high static bearing capacity. Based on the nonlinear inertia-negative stiffness resonance unit and the variable friction super damping, a low-frequency broadband band gap is provided, which solves the contradiction between the static bearing capacity and the isolation capability of the existing seismic isolation technology. The proposed metamaterial unit cell has the advantages of small size, easy production, and easy combination. It can be produced by preparation processes such as 3D printing, and has the advantages of low production cost and high production efficiency compared with traditional production processes.

[0047] (3) The metamaterial unit cell proposed in the present invention has a standardized design and a regular appearance. It can be connected in series, in parallel and in other combinations, thereby providing a specific negative stiffness value, inertia coefficient and damping coefficient to meet the different needs of seismic isolation in engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the side cross-sectional structure of the initial state of the elastic curved beam amplified synergistic unit cell with inertia negative stiffness characteristics in an embodiment of the present invention;

[0049] Figure 2 Schematic diagram of the top cross-sectional structure of the initial state of the elastic curved beam amplified synergistic unit cell with negative stiffness characteristics of inertia capacity according to an embodiment of the present invention;

[0050] Figure 3 Schematic diagram of the friction coefficient distribution on the surface of the elastic curved beam in an embodiment of the present invention;

[0051] Figure 4 Schematic diagram of the side cross-sectional structure of the initial state of the metamaterial in an embodiment of the present invention.

[0052] Description of the marks in the figure:

[0053] 1—connecting plate, 2—slider, 3—elastic curved beam, 4—short beam, 5—long beam, 6—support plate, 7—rotating shaft, 8—mass block, 9—inner shell, 10—elastic beam, 11—outer shell, 12—ball, 13—protrusion. DETAILED DESCRIPTION

[0054] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0055] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like, used to describe common objects, merely refer to different instances of the same object and are not intended to imply that the objects described must be in a given order, whether temporally, spatially, sequentially, or in any other manner.

[0056] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0057] Example:

[0058] An elastic curved beam amplified and enhanced unit cell with negative stiffness characteristics, such as Figure 1 and Figure 2 As shown, it includes positive stiffness-negative stiffness elements and frames,

[0059] The frame includes an inner shell 9 and an outer shell 11. The inner shell 9 is arranged in a sliding connection with the outer shell 11. The outer shell 11 can provide the load-bearing capacity for the unit cell.

[0060] The positive stiffness-negative stiffness unit includes a slider 2 and an elastic curved beam 3. The slider 2 slides into the inner shell 9. The protruding end of the slider 2 is fixedly connected to the outer shell 11 through the elastic beam 10. The other end of the inner shell 9 where the slider 2 protrudes is fixedly connected to the outer shell 11 through the elastic beam 10.

[0061] An elastic curved beam 3 is fixedly connected to the inner shell 9, and a protrusion 13 is fixedly connected to the slider 2. The protrusion 13 slides in contact with the elastic curved beam 3. When the protrusion 13 and the elastic curved beam 3 just come into contact, it is set as the initial state of the unit cell. When the protrusion 13 contacts the arc vertex on the central axis of the elastic curved beam 3, it is set as the equilibrium point of the elastic curved beam 3.

[0062] When an external load acts on the protrusion 13 of the slider 2 through the elastic beam 10, the elastic curved beam 3 first exhibits a positive stiffness characteristic. After the protrusion 13 of the slider 2 crosses the equilibrium point of the elastic curved beam 3, the elastic curved beam 3 exhibits a negative stiffness characteristic.

[0063] The elastic beam 10 connecting the housing 11 and the internal components on both sides has a function similar to a tuning spring, which can amplify the displacement of the slider 2 through resonance tuning, thereby amplifying the deformation of the negative stiffness / inertia unit;

[0064] The positive-negative stiffness unit further includes a connecting plate 1, to which the extending end of the slider 2 is fixedly connected. The connecting plate 1 is fixedly connected to an elastic beam 10 on the other side of the slider 2. The slider 2 can move horizontally along the slot of the inner shell 9, and during movement, the protrusion 13 contacts the elastic curved beam 3.

[0065] There are five elastic beams 10, one of which is arranged on the central axis of the unit cell, and four are orthogonally symmetrically arranged on both sides of the central axis;

[0066] Four elastic beams 10 symmetrically arranged on both sides of the central axis are configured as elastic curved beams. The distance between the connection end of the elastic curved beam close to the inner shell 9 and the central axis is smaller than the distance between the connection end with the outer shell 11 and the central axis. The purpose of the bending design of the elastic curved beam is to enable the elastic curved beam to have deformation ability, so that it can achieve compression deformation, tension deformation and reset during the force process;

[0067] The unit cell also includes a lever rotation inertia unit, which includes a support plate 6, a rotating shaft 7, and a mass block 8. The support plate 6 is fixedly connected to the inner shell 9. The rotating shaft 7 is hingedly provided on the support plate 6. One side of the rotating shaft 7 is fixedly connected to the slider 2 through a beam, and the other side is fixedly connected to the mass block 8 through a beam. The rotating shaft 7 and the mass block 8 can only undergo in-plane rotational motion.

[0068] When the slider 2 pushes the beam-rotating shaft 7-beam, the mass block 8 on the other side will rotate, thus achieving the inertia effect;

[0069] One side of the rotating shaft 7 is fixedly connected to the slider 2 via the short beam 4, and the other side is fixedly connected to the mass block 8 via the long beam 5;

[0070] At the same time, the length of the beam on the slider 2 side is smaller than the length of the beam on the mass block 8 side, which can achieve the lever mass amplification effect;

[0071] In this embodiment, the length ratio of the long beam 5 to the short beam 4 is 2. The significance of the length ratio is to adjust the inertia coefficient of the unit cell;

[0072] There are five short beams 4 and five long beams 5 respectively, one of which is arranged on the central axis of the unit cell, and four are orthogonally symmetrically arranged on both sides of the central axis;

[0073] The four short beams 4 and long beams 5 symmetrically arranged on both sides of the central axis are respectively set as short curved beams and long curved beams. The distance between the connection end of the short curved beam and the slider 2 and the central axis is smaller than the distance between the connection end with the rotating shaft 7 and the central axis. The distance between the connection end of the long curved beam and the rotating shaft 7 and the central axis is smaller than the distance between the connection end with the mass block 8 and the central axis. The purpose of the bending design of the short curved beam and the long curved beam is to make the short curved beam and the long curved beam have deformation ability, so that they can achieve compression deformation, tension deformation and reset during the force process.

[0074] The shape of the mass block 8 is a sphere (or other optional shapes such as a cuboid or a cube, without special requirements);

[0075] The inner shell 9 and the side walls of the outer shell 11 are connected by a sliding ball 12 to assist the movement;

[0076] The form of the elastic curved beam 3 is expressed by the cosine function as follows:

[0077]

[0078] Wherein, A is the height of the elastic curved beam 3, K is the shape factor of the elastic curved beam 3, and its value range is (0,1], D is the span of the elastic curved beam 3, and M is the offset value of the elastic curved beam 3;

[0079] In this embodiment, A is 100 mm, K is 0.4, D is 400 mm, and M is 0 mm;

[0080] like Figure 3 As shown, the contact surface between the elastic curved beam 3 and the protrusion 13 is set as a variable friction coefficient surface, which is conducive to realizing the super damping mechanism of the unit cell and enhancing the attenuation of the elastic wave peak in the band gap;

[0081] The friction coefficient on the surface of the elastic curved beam 3 is symmetrically distributed along the central axis of the elastic curved beam 3 and decreases linearly from the central axis to both sides. The distribution design of the friction coefficient can achieve a balance between the displacement stroke of the slider 2 and the friction energy consumption. In other words, the artificial design achieves damping performance that cannot be achieved by traditional natural materials.

[0082] The friction coefficient of the surface of the elastic curved beam 3 depends on the type and composition of the surface coating, with a maximum value ranging from 0.5 to 1.0 and a minimum value ranging from 0.1 to 0.2;

[0083] The span range of the elastic curved beam 3 depends on the range of motion of the slider 2 to maintain contact with the elastic curved beam 3, which is related to the design of the unit cell;

[0084] In this embodiment, the friction coefficient of the surface at the center axis of the elastic curved beam 3 is 0.6, and the friction coefficient of the farthest surfaces on both sides 200 mm away from the center axis is 0.15.

[0085] In this embodiment, the material of the plate, slider 2, beam, shaft 7 and shell is thermoplastic polyurethane elastomer, the material of the mass block 8 is thermoplastic polyurethane elastomer wrapped steel, and the material of the ball 12 is steel.

[0086] A method for amplifying and enhancing the performance of an elastic curved beam with negative stiffness characteristics of inertia is proposed, which uses the above-mentioned unit cell to amplify and enhance the performance. The specific steps are as follows:

[0087] When the unit cell starts working, the external excitation is transmitted to the connecting plate 1 through the outer shell 11 and the elastic beam 10. The connecting plate 1 moves to the left relative to the inner shell 9 and drives the slider 2 to move horizontally.

[0088] The protrusion 13 of the slider 2 compresses the elastic curved beam 3 to cause elastic deformation, and the elastic curved beam 3 provides a reaction force to resist the horizontal movement of the slider 2, that is, to produce a positive stiffness effect;

[0089] When the protrusion 13 of the slider 2 crosses the central axis of the elastic curved beam 3, the elastic curved beam 3 provides a horizontal leftward force, thereby prompting the slider 2 to further move horizontally to the left relative to the inner shell 9, that is, a negative stiffness effect is generated;

[0090] At the same time, the variable friction coefficient on the surface of the elastic curved beam 3 makes the unit cell have super damping characteristics;

[0091] The horizontal movement of the slider 2 drives the short beam 4 to undergo elastic deformation, and the short beam 4 drives the rotating shaft 7 to rotate, further causing the long beam 5 to undergo elastic deformation movement;

[0092] Based on the elastic deformation characteristics of the beam, the rotation of the long beam 5 will drive the mass block 8 at the end to rotate along the central axis of the unit cell;

[0093] Based on the length ratio between the short beam 4 and the long beam 5, the rotational motion of the mass 8 has a lever deformation amplification effect;

[0094] This results in an inertial mass enhancement effect based on the rotation of the mass block 8 and the beam lever amplification effect;

[0095] When the connecting plate 1 moves rightward relative to the inner shell 9, the unit cell can realize the same working mode and has the ability of reciprocating energy consumption.

[0096] A metamaterial, such as Figure 4As shown, it includes a plurality of the above-mentioned unit cells connected in series or in parallel. In this embodiment, three unit cells are preferably connected in series. The elastic beam 10 is used for local resonance tuning to amplify the deformation of the negative stiffness / inertia unit. In combination with the positive stiffness-negative stiffness unit and the lever rotation inertia unit, the super-damping mechanism of the unit cell is realized by designing the friction coefficient on the positive stiffness-negative stiffness unit. This can effectively improve the peak control effect of the finite unit cell sequence on short-term impact. The regular shell 11 facilitates various combinations and applications.

[0097] When external excitation is input, each unit cell works in sequence, which can provide a better broadband vibration reduction effect;

[0098] The unit cell is simplified into a model of nonlinear inertial force, nonlinear elastic force and nonlinear damping force. Based on the model, series and parallel designs are carried out to calculate and realize specific negative stiffness values, inertia coefficients and damping coefficients under different configurations.

[0099] The present invention provides a standardized design of a metamaterial cell that combines negative stiffness enhancement, leverage amplification enhancement, and inertia capacity enhancement mechanisms, thereby realizing the mutual integration of multiple mechanisms. The negative stiffness enhancement mechanism and the leverage amplification mechanism can improve the energy consumption capacity of the metamaterial cell, and the inertia capacity enhancement mechanism can provide an excellent broadband shock absorption effect, achieving a nonlinear shock absorption effect under a variety of enhancement mechanisms, and can realize vibration control of structures under multi-level coupled excitation. In addition, the metamaterial cell of the present invention has the advantages of small size, easy production, and easy combination. Through mutual combination, specific negative stiffness values, inertia coefficients, and damping coefficients can be achieved to meet the different needs of seismic isolation in engineering projects.

[0100] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. An elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics, characterized in that: The unit cell consists of positive stiffness-negative stiffness elements and a frame. The frame comprises an inner shell (9) and an outer shell (11), wherein the inner shell (9) is arranged in a sliding connection with the outer shell (11). The positive stiffness-negative stiffness unit comprises a slider (2) and an elastic curved beam (3), wherein the slider (2) slides and extends into the inner shell (9), the extended end of the slider (2) is fixedly connected to the outer shell (11) via the elastic beam (10), and the inner shell (9) is fixedly connected to the outer shell (11) via the elastic beam (10) at the other end of the slider (2). An elastic curved beam (3) is fixedly connected to the inner shell (9), and a protrusion (13) is fixedly connected to the slider (2), wherein the protrusion (13) is in sliding contact with the elastic curved beam (3); The unit cell further comprises a lever rotation inertia unit, which comprises a support plate (6), a rotating shaft (7) and a mass block (8). The support plate (6) is fixedly connected to the inner shell (9), and a rotating shaft (7) is hingedly provided on the support plate (6). One side of the rotating shaft (7) is fixedly connected to the slider (2) through a beam, and the other side of the rotating shaft (7) is fixedly connected to the mass block (8) through a beam.

2. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 1 is characterized in that: The contact surface between the elastic curved beam (3) and the protrusion (13) is configured as a variable friction coefficient surface.

3. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 2, characterized in that: The friction coefficient of the surface of the elastic curved beam (3) is symmetrically distributed along the central axis of the elastic curved beam (3), and decreases linearly from the central axis to both sides.

4. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 1, characterized in that: The positive stiffness-negative stiffness unit further comprises a connecting plate (1), the protruding end of the slider (2) is fixedly connected to the connecting plate (1), and the connecting plate (1) is fixedly connected to the elastic beam (10) on the other side of the slider (2).

5. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 1, characterized in that: The elastic beams (10) are provided in plurality, one of which is arranged on the central axis of the unit cell, and the others are symmetrically arranged on both sides of the central axis; The elastic beams (10) symmetrically arranged on both sides of the central axis are configured as elastic curved beams, and the distance between the connection end of the elastic curved beam close to the inner shell (9) and the central axis is smaller than the distance between the connection end of the elastic curved beam close to the outer shell (11) and the central axis.

6. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 1, characterized in that: One side of the rotating shaft (7) is fixedly connected to the slider (2) via a short beam (4), and the other side is fixedly connected to the mass block (8) via a long beam (5).

7. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 6, characterized in that: The short beams (4) and the long beams (5) are respectively provided with a plurality of them, one of which is arranged on the central axis of the unit cell, and the others are symmetrically arranged on both sides of the central axis; The short beam (4) and the long beam (5) symmetrically arranged on both sides of the central axis are respectively configured as a short curved beam and a long curved beam, wherein the distance between the connecting end of the short curved beam and the slider (2) and the central axis is smaller than the distance between the connecting end of the short curved beam and the rotating shaft (7) and the central axis, and the distance between the connecting end of the long curved beam and the rotating shaft (7) and the central axis is smaller than the distance between the connecting end of the long curved beam and the rotating shaft (7) and the central axis.

8. The elastic curved beam amplification and synergistic unit cell with inertia negative stiffness characteristics according to claim 1, characterized in that: The side walls of the inner shell (9) and the outer shell (11) are slidably connected via balls (12).

9. A metamaterial, characterized in that The metamaterial comprises a plurality of unit cells according to any one of claims 1 to 8 connected in series or in parallel.

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