A quasi-zero stiffness vibration dual-control device based on metamaterials

Abstract

A quasi-zero stiffness vibration double-control device based on metamaterial relates to the technical field of isolation and vibration control. The device comprises a vertical vibration isolation structure, a horizontal isolation layer, an intermediate plate and upper and lower connecting plates, and the vertical vibration isolation structure is connected to the top surface of the horizontal isolation layer. The innovation lies in that the vertical isolation layer is composed of a plurality of horizontally arranged quasi-zero stiffness metamaterial cells, each quasi-zero stiffness metamaterial cell contains a buckle mechanism and a wave beam mechanism, the negative stiffness generated by the buckle mechanism in the movement process and the positive stiffness generated by the wave beam mechanism in the loading process are mutually offset, forming a quasi-zero stiffness mechanism. The quasi-zero stiffness metamaterial cell of the present application can change the initial stiffness by adjusting the bolt pretightening force, thereby changing the vertical bearing capacity to adapt to different engineering requirements, and solves the problem of low-frequency isolation failure of traditional isolation devices, and is especially suitable for the dual protection requirements of earthquake and vibration of track transportation upper cover buildings.

Description

Technical Field

[0001] This invention relates to the field of vibration isolation and vibration control technology, specifically a quasi-zero stiffness vibration dual control device based on metamaterials. Background Technology

[0002] Seismic isolation technology is an effective means of achieving structural seismic resilience. Traditional horizontal seismic isolation technology (such as a building seismic isolation rubber bearing disclosed in CN119507572A) can effectively isolate horizontal seismic forces, but its large vertical stiffness makes it less effective at isolating vertical vibrations. Traditional seismic isolation technology is mainly designed to isolate horizontal earthquakes and cannot isolate vertical vibrations from sources such as rail transit. Therefore, developing seismic isolation devices that combine horizontal isolation and vertical vibration control has become a major research hotspot. Currently, linear spring structures are mainly used for vibration reduction in engineering applications (such as a vibration control device for indoor high-voltage electrical equipment disclosed in CN119009738A and a compact three-dimensional friction pendulum seismic isolation bearing disclosed in CN112780093A). This structure is easy to apply but is severely affected by the load mass and spring stiffness.

[0003] Metamaterials are unconventional materials with unique structural forms, distinct from natural and traditional man-made materials. Among them, quasi-zero stiffness metamaterials, through the design of special structural forms, exhibit nonlinear stiffness properties, which have the advantages of limiting the increase of structural reaction forces and avoiding the structure's natural frequencies. Thus, by changing material parameters or optimizing structural design, the load-bearing capacity and quasi-zero stiffness range of vibration isolation units can be improved. They possess both load-bearing capacity and effectively reduce structural frequencies, thereby achieving low-frequency vibration isolation.

[0004] Technical solutions for achieving quasi-zero stiffness typically involve connecting components with both positive and negative stiffness characteristics in parallel, so that their stiffnesses are superimposed to obtain quasi-zero stiffness. Thanks to advancements in structural optimization and additive manufacturing technologies, quasi-zero stiffness characteristics and low-frequency vibration reduction effects can be achieved using metamaterial-integrated structural design methods. However, most quasi-zero stiffness solutions are only applicable to constant loads (e.g., a nonlinear metamaterial vibration isolator with quasi-zero stiffness disclosed in CN112049885A, and a quasi-zero stiffness vibration reduction device based on tensioned integral structure disclosed in CN119289036A). Once the load changes, the system will deviate from its ideal static equilibrium position; essentially, it is a positive stiffness linear vibration isolation system, and the low-frequency vibration isolation effect will be greatly reduced. Summary of the Invention

[0005] The present invention aims to construct a metamaterial-based quasi-zero stiffness vibration dual control device suitable for different load ranges, thereby reducing the vibration of rail transit and improving the seismic resistance of buildings, achieving the goal of structural vibration dual control, and solving the problems existing in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A quasi-zero stiffness vibration control device based on metamaterials includes an upper connecting plate, a vertical vibration isolation layer, a middle connecting plate, a horizontal vibration isolation layer, and a lower connecting plate. The lower end of the upper connecting plate is connected to the vertical vibration isolation layer. The internal structure of the vertical vibration isolation layer includes several quasi-zero stiffness metamaterial cells. Each quasi-zero stiffness metamaterial cell includes a snap-fit ​​mechanism and a wave beam mechanism. The wave beam mechanism consists of a wave beam, long bolts, a pressure plate, and a nut. The wave beam has a periodic corrugated cross-section and is composed of four sinusoidal wave structures with the same height and included angle arranged vertically. The upper and lower ends of the wave beam are connected by long bolts, and the pressure plate is fixed to the outside of the wave beam by nuts. The snap-fit ​​mechanism consists of a nut, a snap-fit ​​beam, short bolts, and a snap-fit ​​plate. The snap-fit ​​beam has symmetrically distributed isosceles trapezoidal protrusions with equal spacing on both sides, and the snap-fit ​​plate has grooved teeth that mesh with it. The upper end of the snap-on beam is fixedly connected to the upper connecting plate, and the lower end of the snap-on plate is fixedly connected to the middle plate. The snap-on beam is fixed in the middle of the inner sides of the two snap-on plates by short bolts and nuts, and protrudes one tooth pitch above the groove of the snap-on plate, forming a staggered state to achieve sandwich-style assembly. The snap-on mechanism is located in the central area of ​​the vertical vibration isolation layer, and the corrugated beam mechanism is arranged around the snap-on mechanism, forming a nested structure of "outer ring positive stiffness - inner core negative stiffness". Among them, the corrugated beam mechanism is mainly used to bear the pressure above, providing positive stiffness for the vertical vibration isolation layer; the snap-on mechanism is used to bear the pressure above, providing negative stiffness for the vertical vibration isolation layer. Traditional vibration isolation devices are limited by positive stiffness characteristics, and the system's natural frequency cannot break through the lower limit of material stiffness. By introducing the negative stiffness (k2) of the snap-on mechanism, it is superimposed with the positive stiffness (k1) of the corrugated beam to form an equivalent stiffness:

[0008]

[0009] When k1≈|k2|, the system enters a quasi-zero stiffness state, and the natural frequency approaches zero, thus enabling the vertical isolation layer to isolate low-frequency vibrations. The initial stiffness of the vertical isolation layer can be changed by adjusting the bolt preload, thereby altering its vertical bearing capacity. The horizontal isolation layer consists of laminated rubber bearings or friction pendulum bearings. Through the combination of horizontal and vertical isolation, the goal of dual control of structural vibration is achieved.

[0010] As a further explanation of the present invention: the vertical vibration isolation layer is composed of multiple quasi-zero stiffness metamaterial cells arranged in a ring or rectangle.

[0011] As a further explanation of the present invention: since the overall height of the quasi-zero stiffness vibration dual control device based on metamaterials is higher than the mounting base, the snap-fit ​​mechanism and the wave beam mechanism in the quasi-zero stiffness metamaterial cell are both in a compressed state after installation.

[0012] As a further explanation of the present invention: When the center of the vertical vibration isolation layer is compressed vertically, the locking mechanism begins to move downwards. The protrusions of the locking beam gradually approach the protrusions in the locking plate, and the locking beam and locking plate press against each other. The locking plate tends to resist the movement of the locking beam. At this time, the force-displacement curve of the locking mechanism will exhibit positive stiffness behavior. When the protrusions in the locking beam leave the protrusions in the locking plate, it is in an unstable state. At this time, the locking plate will not hinder the structural movement, but will instead promote the downward movement of the locking beam. In this state, the force-displacement curve of the locking mechanism will exhibit negative stiffness behavior.

[0013] As a further explanation of the present invention: when the center of the vertical vibration isolation layer is compressed in the vertical direction, the wave beam mechanism begins to move downward. After being compressed, the wave beam will produce lateral deformation, and the whole exhibits positive stiffness behavior. The positive stiffness wave beam mechanism and the negative stiffness snapping mechanism work together. The negative stiffness generated by the snapping mechanism can offset the positive stiffness generated by the wave beam mechanism in the static equilibrium position, so that the vertical stiffness of the vertical vibration isolation layer in the static equilibrium state tends to zero, thereby exhibiting a quasi-zero stiffness vibration isolation mechanism.

[0014] As a further explanation of the present invention: by changing the torque applied to the nut, the preload on the long bolt is changed. The preload is transmitted to both sides of the corrugated beam via the pressure plate, making it easier / more difficult for the corrugated beam to deform, thereby changing the initial stiffness of the corrugated beam mechanism. Similarly, by changing the preload of the short bolt on the buckle plate, the downward movement of the buckle beam is made easier / more difficult, thereby changing the initial stiffness of the buckle beam mechanism. At this time, the initial stiffness of the overall vertical vibration isolation layer changes, thereby changing its load-bearing capacity.

[0015] As a further explanation of the present invention: the structural parameters of the corrugated beam are related to the positive stiffness of the vertical vibration isolation layer; the structural parameters of the snap-on beam and snap-on plate are related to the negative stiffness of the vertical vibration isolation layer; and the preload of the long bolt and the short bolt are related to the vertical bearing capacity of the vertical vibration isolation layer.

[0016] As a further explanation of the present invention: the upper connecting plate, the quasi-zero stiffness metamaterial cell and the intermediate plate can be assembled together by bolting, welding or gluing.

[0017] As a further explanation of the present invention: bolt holes are pre-drilled on the surfaces of the upper connecting plate, the lower connecting plate, and the intermediate plate. The intermediate plate can be connected to the horizontal vibration isolation layer, and the lower connecting plate can be connected to the mounting base surface via bolts.

[0018] Further explanation of the present invention: The material of the quasi-zero stiffness vibration dual control device based on metamaterials can be rubber, plastic, resin and metal.

[0019] The advantages of the technical solution of the present invention over the prior art are:

[0020] 1. This invention achieves near-zero stiffness performance through metamaterial technology. By combining the snap-fit ​​mechanism and the corrugated beam mechanism, the vertical vibration isolation layer exhibits zero stiffness characteristics within the rated load range. The horizontal vibration isolation layer and the vertical vibration isolation layer are decoupled in series, which fully utilizes the vibration isolation / vibration control capability of the vibration-damping dual-control support.

[0021] 2. This invention addresses the limitation that most existing quasi-zero stiffness technologies can only achieve quasi-zero stiffness under a single load. By changing the preload of the long and short bolts, the bearing capacity of the vertical vibration isolation layer can be adjusted, thereby enabling the device to achieve quasi-zero stiffness characteristics and low-frequency vibration isolation under different load conditions. Furthermore, the bolts and pressure plates after applying preload can further prevent out-of-plane buckling of the vertical vibration isolation layer.

[0022] 3. The present invention can be modularly assembled, and the size of the device can be adjusted according to construction needs, increasing the applicability of the present invention. Furthermore, the functions of each component of the present invention are clearly defined, which facilitates mass production and engineering application. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a quasi-zero stiffness vibration dual-control device based on metamaterials according to the present invention.

[0024] Figure 2 This is a front view of the structure of a quasi-zero stiffness vibration dual-control device based on metamaterials according to the present invention.

[0025] Figure 3 This is a schematic diagram of the quasi-zero stiffness metamaterial cell structure described in this invention;

[0026] Figure 4 This is a schematic diagram of the corrugated beam mechanism described in this invention;

[0027] Figure 5 This is a schematic diagram of the corrugated beam structure described in this invention;

[0028] Figure 6 This is a schematic diagram of the buckling mechanism structure described in this invention;

[0029] Figure 7 This is a schematic diagram illustrating the mechanism by which the snap-fit ​​mechanism structure of the present invention generates negative stiffness.

[0030] Figure 8 The force-displacement curves of the quasi-zero stiffness metamaterial cell, snap-fit ​​mechanism structure, and corrugated beam mechanism described in this invention are shown below.

[0031] Figure 9 This is a force-displacement curve of the quasi-zero stiffness metamaterial cell element described in this invention under different bolt preloads.

[0032] The attached diagram lists the components represented by each number as follows:

[0033] 1. Upper connecting plate, 2. Vertical vibration isolation layer, 3. Middle plate, 4. Horizontal vibration isolation layer, 5. Lower connecting plate, 6. Quasi-zero stiffness metamaterial cell, (6.1) Corrugated beam, (6.2) Long bolt, (6.3) Pressure plate, (6.4) Nut, (6.5) Clip beam, (6.6) Short bolt, (6.7) Clip plate. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation thereof.

[0035] Please see Figure 1-2 A technical solution is provided: a quasi-zero stiffness vibration dual-control device based on metamaterials, comprising an upper connecting plate 1, a vertical vibration isolation layer 2, a middle plate 3, a horizontal vibration isolation layer 4, and a lower connecting plate 5; the lower end of the upper connecting plate 1 is fixedly connected to the vertical vibration isolation layer 2, and bolt holes are pre-drilled on the surfaces of the upper connecting plate, the lower connecting plate, and the middle plate. The middle plate is connected to the horizontal vibration isolation layer, and the lower connecting plate is connected to the mounting base surface by bolts.

[0036] Specifically, such as Figure 1 As shown, the vertical vibration isolation layer 2 is formed by N horizontally arranged structures of quasi-zero stiffness metamaterial cells 6 along the x and y directions, where N is a positive integer; in this embodiment, N=2.

[0037] Specifically, such as Figure 3 As shown, each quasi-zero stiffness metamaterial cell 6 consists of a snap-fit ​​mechanism and a corrugated beam mechanism, wherein the corrugated beam mechanism consists of a corrugated beam 6.1, a long bolt 6.2, a pressure plate 6.3, and a nut 6.4. Figure 4 As shown, the upper and lower ends of the corrugated beam are connected by long bolts 6.2, and the pressure plate 6.3 is fixed to the outside of the corrugated beam by nuts 6.4. Figure 6 As shown, the buckling mechanism consists of a nut 6.4, a buckling beam 6.5, a short bolt 6.6, and a buckling plate 6.7. The buckling plate 6.7 is fixed to both sides of the buckling beam 6.5 by the short bolt 6.6 and the nut 6.4.

[0038] Specifically, the corrugated beam 6.1, the snap-fit ​​beam 6.5, and the snap-fit ​​plate 6.7 are integrally formed by casting or additive manufacturing. In this embodiment, the corrugated beam 6.1 is made of rubber or engineering plastics such as PA, while the snap-fit ​​beam 6.5 and the snap-fit ​​plate 6.7 are made of metal.

[0039] Specifically, such as Figure 4-5As shown, in this embodiment, the corrugated beam 6.1 has a periodic corrugated cross-section, which is composed of four sinusoidal waveform structures with the same height and included angle arranged in the vertical direction. In the actual design of the corrugated beam mechanism, the design parameters of the corrugated beam 6.1 include the distance L1 between beams, the overall height H1 of the beam, the beam width d1, the beam thickness t1, the height H2 of the arc structure, and the angle θ1 between the arc structure and the water direction. The corrugated beam 6.1 is the main load-bearing component of the vertical vibration isolation layer 2, and it always provides positive stiffness during compression.

[0040] Specifically, such as Figure 6 As shown, the protruding tooth shape parameters of the snap-on plate are the same as those of the snap-on beam. In the actual design of the snap-on beam mechanism, the design parameters of snap-on beam 6.5 include beam thickness t2, protruding tooth height H3, protruding tooth platform height H4, and the angle θ2 between the protruding tooth inclined surface and the horizontal direction. The snap-on beam mechanism provides negative stiffness for the vertical vibration isolation layer 2. Therefore, by adjusting the design parameters in the snap-on beam mechanism, the equipment load can be adjusted to the plateau region of the quasi-zero stiffness metamaterial force-displacement curve. In this range, the stiffness of the vertical vibration isolation layer 2 approaches zero, thereby widening its low-frequency vibration isolation range.

[0041] Specifically, such as Figure 7 As shown, the latching mechanism begins to move downwards (segment 0-A). The protrusions of the latching beam gradually approach the protrusions in the latching plate, causing the latching beam and latching plate to press against each other. The latching plate tends to resist the movement of the latching beam. At this time, the force-displacement curve of the latching mechanism exhibits positive stiffness behavior. When the protrusions in the latching beam leave the protrusions in the latching plate (segment AB), the mechanism is in an unstable state. In this state, the latching plate does not hinder the structural movement but instead promotes the downward movement of the latching beam. Under these conditions, the force-displacement curve of the latching mechanism exhibits negative stiffness behavior.

[0042] Specifically, in this embodiment, the corrugated beam 6.1 has an L1 of 174 mm, a height H1 of 10.8 mm, a width d1 of 12 mm, a thickness t1 of 45 mm, an arc-shaped structure height H2 of 3.6 mm, and an angle θ1 between the arc-shaped structure and the water direction of 60°; the snap-fit ​​beam 6.5 has a beam thickness t2 of 75 mm, a tooth height H3 of 3.5 mm, a tooth platform height H4 of 1.2 mm, and an angle θ2 between the tooth inclined surface and the horizontal direction of 45°. For example... Figure 8 As shown, during the motion, the wave-beam mechanism always provides positive stiffness, while the snap-on beam mechanism first provides positive stiffness and then generates a negative stiffness range. The generated negative stiffness can offset the positive stiffness generated by the wave-beam mechanism in this range, thereby causing the metamaterial cell to exhibit a quasi-zero stiffness plateau region.

[0043] Specifically, in this embodiment, the corrugated beam mechanism and the upper connecting plate are bonded together using DELI-7174 fast-curing adhesive. In the snap-on beam mechanism, the upper end of the snap-on beam is welded to the upper connecting plate, and the lower end of the snap-on plate is welded to the middle plate.

[0044] Specifically, such as Figure 9 As shown, the bolt preload is positively correlated with the initial stiffness and load-bearing capacity of the quasi-zero stiffness metamaterial cell, with F3>F1>F2. By changing the bolt preload, the initial stiffness of the quasi-zero stiffness metamaterial cell can be further altered, thereby changing the load-bearing capacity of the vertical vibration isolation layer 2 to adapt to various engineering requirements and increase the applicability of the invention.

[0045] Specifically, the laminated rubber layer, as an important component of this seismic isolation bearing, employs an alternating layering design of rubber layers and stiffening steel plates. This design not only ensures the bearing's load-bearing capacity and stability but also endows it with good deformation capacity and resilience. The rubber layer possesses excellent elasticity and damping performance, effectively absorbing and dispersing seismic energy, while the stiffening steel plates enhance the bearing's rigidity and stability, making it less prone to deformation or damage under seismic loads.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents. The shape of the quasi-zero stiffness metamaterial vibration isolation device is not limited to the form presented herein, and other similar types of limiting devices also fall within the scope of this invention.

Claims

1. A quasi-zero stiffness vibration dual-control device based on metamaterials, comprising an upper connecting plate (1), a vertical vibration isolation layer (2), a middle plate (3), a horizontal vibration isolation layer (4), and a lower connecting plate (5); the lower end of the upper connecting plate (1) is fixedly connected to the vertical vibration isolation layer (2), and the internal structure of the vertical vibration isolation layer (2) comprises a plurality of uniformly distributed quasi-zero stiffness metamaterial cells (6), characterized in that: Each quasi-zero stiffness metamaterial cell (6) includes a snap-fit ​​mechanism and a corrugated beam mechanism. The corrugated beam mechanism is arranged outside the snap-fit ​​mechanism. The corrugated beam mechanism includes a corrugated beam (6.1), a long bolt (6.2), a pressure plate (6.3), and a nut (6.4). The upper and lower ends of the corrugated beam are connected by the long bolt (6.2). The pressure plate (6.3) is fixed to the outside of the corrugated beam by the nut (6.4). The upper and lower ends of the corrugated beam (6.1) are fixedly connected to the upper connecting plate (1) and the intermediate plate (3), respectively. When the corrugated beam mechanism is loaded, the corrugated beam (6.1) undergoes lateral deformation, and its vertical height decreases. The snap-fit ​​mechanism includes the nut (6.4). The fastening mechanism comprises a buckle beam (6.5), a short bolt (6.6), and a buckle plate (6.7). The buckle plate (6.7) is fixed to both sides of the buckle beam (6.5) by the short bolt (6.6) and the nut (6.4). The buckle beam (6.5) and the buckle plate (6.7) are toothed. The upper end of the buckle beam (6.5) is fixedly connected to the upper connecting plate (1), and the lower end of the buckle plate (6.7) is fixedly connected to the middle plate (3). The buckle beam (6.5) is arranged in the middle of the inner side of the two buckle plates (6.7) and is higher than the buckle plate (6.7) by one tooth. When the buckling mechanism is loaded, the buckle beam (6.5) presses the inner side of the buckle plate (6.7) and moves vertically. The snap-fit ​​mechanism is located in the central area of ​​the vertical isolation layer, and the corrugated beam mechanism is arranged around the snap-fit ​​mechanism, forming a nested structure of "outer ring positive stiffness - inner core negative stiffness". The corrugated beam mechanism is used to bear the pressure from above and provide positive stiffness for the vertical isolation layer; the snap-fit ​​mechanism is used to bear the pressure from above and provide negative stiffness for the vertical isolation layer. The snap-fit ​​mechanism and the corrugated beam mechanism in the quasi-zero stiffness metamaterial cell (6) are in a compressed state at any time after installation; the structural parameters of the corrugated beam (6.1) are related to the positive stiffness of the vertical vibration isolation layer (2); the structural parameters of the snap-fit ​​beam (6.5) and the snap-fit ​​plate (6.7) are related to the negative stiffness of the vertical vibration isolation layer (2); the preload of the long bolt (6.2) and the short bolt (6.6) is related to the vertical bearing capacity of the vertical vibration isolation layer (2).

2. The quasi-zero stiffness vibration dual-control device based on metamaterials according to claim 1, characterized in that, The internal structure includes N quasi-zero stiffness metamaterial cells (6), which are uniformly distributed in a rectangle or along the circumference and can be periodically extended in the vertical and horizontal directions. N is a positive integer and N≥2.

3. The quasi-zero stiffness vibration dual-control device based on metamaterials according to claim 1, characterized in that, The upper connecting plate (1) and the lower connecting plate (5) have pre-drilled bolt holes, welding interfaces or anchor bolt holes on their surfaces; the components are fixedly connected by adhesive, welding, bolts or anchor bolts.

4. The quasi-zero stiffness vibration dual-control device based on metamaterials according to claim 1, characterized in that, The horizontal isolation layer (4) is a laminated rubber bearing or a friction pendulum structure, installed above or below the vertical isolation layer (2).

5. The quasi-zero stiffness vibration dual-control device based on metamaterials according to claim 1, characterized in that, The device is made of rubber, plastic, resin or metal.

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