Semi-active anti-impact shock isolator based on negative stiffness beam

Abstract

The invention discloses a semi-active anti-impact shock isolator based on a negative stiffness beam and belongs to the technical field of shock isolation, and the semi-active anti-impact shock isolator based on the negative stiffness beam is jointly composed of a rubber shock isolation layer, a rubber limiting layer, a negative stiffness interlayer beam and an MRE shock isolation layer. According to the invention, effective shock isolation and impact resistance can be carried out on a building structure under impact loads such as sudden collision or explosion; compared with a traditional rubber vibration isolator, the negative stiffness characteristic of the hyperbolic beam and the characteristic that the rigidity of the MRE vibration isolation layer is controllable are utilized, the hyperbolic beam and the MRE vibration isolation layer are connected in parallel, constant impact resistance can be obtained within a certain range, and a building main body structure can be better protected under impact loads such as collision and explosion; and impact energy can be further dissipated under the action of rapid impact.

Description

Technical Field

[0001] The invention mainly relates to the technical field of vibration reduction and seismic isolation of civil engineering building structures, and in particular to a semi-active anti-impact seismic isolator based on a negative stiffness beam. Background Art

[0002] Base isolation is the most widely used structural vibration control technology. It is widely used not only in civil buildings and engineering, but also in many important infrastructures and nuclear power fields. For traditional passive isolation technology to achieve low-frequency isolation, the natural frequency of the structure must be reduced.

[0003] Negative stiffness theory was first applied to the field of vibration control of mechanical equipment and precision instruments, and most of the research was done on vibration isolation. Combining negative stiffness with positive stiffness can achieve lower initial stiffness, thereby achieving ultra-low frequency isolation. Traditional isolation design can extend the natural vibration period of the structure and has good isolation performance, but when the building structure encounters sudden impact loads such as collisions and explosions, it often causes large deformation or even collapse. Traditional isolation cannot cope with impact loads well.

[0004] In recent years, smart materials have been increasingly used in seismic isolation technology. Magnetorheological Elastomer (MRE) is an excellent smart material with technical characteristics such as controllability, reversibility, and rapid response. Compared with magnetorheological fluids (MRF), the solid state of MRE makes it more stable. Shear thickening gel (STG) is an excellent viscoelastic material that overcomes the defects of shear thickening fluids, such as instability, easy sedimentation, and difficult packaging, while retaining the excellent mechanical properties of STG. With the increase of strain rate, STG changes from a liquid-like state to a solid-like state. During the phase transition, it absorbs a lot of energy, increases stiffness, and has good impact resistance.

[0005] The "composite structure magnetorheological elastomer isolator" disclosed in the Chinese patent (application number: 201710182094.2) combines the characteristics of controllable shear modulus and controllable compression modulus of the elastomer, making full use of the controllable stiffness of the elastomer and having a certain strength of bearing capacity, but its energy dissipation capacity is poor. The "shear mode magnetorheological elastomer variable frequency isolator" disclosed in the Chinese patent (application number: 201510044266.0) can achieve multi-frequency vibration isolation under multi-frequency states through the movement of the elastomer, but it cannot resist impact loads. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the present invention proposes a semi-active impact-resistant isolator based on a negative stiffness beam, which overcomes the problem of narrow isolation frequency band and poor adaptability of traditional rubber isolators. Compared with the existing intelligent isolators, the present invention adds a negative stiffness device, utilizes the negative stiffness characteristics and is connected in parallel with the rubber isolation layer, further extending the natural vibration period of the structure, so that the isolator has a wider isolation frequency, and adopts a multi-stage parallel arrangement, so that the isolator can ensure a larger output under rare earthquakes, and realize isolation and vibration reduction under various earthquake conditions such as small displacement and large displacement. At the same time, an MRE isolation layer is arranged to enable the isolator to provide controllable impact resistance and dissipate impact energy under impact load conditions.

[0007] The technical solution of the present invention is as follows:

[0008] A semi-active anti-shock isolator based on a negative stiffness beam comprises an upper cover plate, an intermediate cover plate, a lower cover plate, a rubber isolation layer, a rubber limiting layer, a negative stiffness sandwich beam and an MRE isolation layer;

[0009] The rubber isolation layer is arranged between the upper cover plate and the middle cover plate, the rubber limiting layer, the negative stiffness sandwich beam and the MRE isolation layer are arranged between the middle cover plate and the lower cover plate, the negative stiffness sandwich beam is arranged on both sides of the MRE isolation layer, and the rubber limiting layer is distributed around the negative stiffness sandwich beam.

[0010] The rubber seismic isolation layer comprises an upper sealing plate, a lower sealing plate, a first sandwich steel plate and a first sandwich rubber, wherein the first sandwich steel plate and the first sandwich rubber are alternately arranged between the upper sealing plate and the lower sealing plate;

[0011] The rubber limiting layer comprises an upper connecting plate, a lower limiting plate, an upper limiting plate, a lower connecting plate, a second interlayer rubber and a second interlayer steel plate, wherein the second interlayer rubber and the second interlayer steel plate are alternately arranged between the upper connecting plate and the lower limiting plate, and between the upper limiting plate and the lower connecting plate;

[0012] The negative stiffness sandwich beam comprises a connecting plate, a connecting block, an upper partition beam, an intermediate sandwich and a lower partition beam, the intermediate sandwich is arranged on the upper partition beam and the lower partition beam, and the connecting plate and the connecting block are arranged on both sides for fixed support.

[0013] The MRE seismic isolation layer includes a left cover plate, a right cover plate, an MRE, a third interlayer steel plate, a positioning column and an excitation coil. The MRE and the third interlayer steel plate are alternately arranged between the left cover plate and the right cover plate, the positioning column is arranged between the left cover plate and the right cover plate, and the excitation coil is arranged around the positioning column.

[0014] In the above technical solution, the upper sealing plate, the lower sealing plate, the first sandwich steel plate and the first sandwich rubber are formed into a whole by vulcanization.

[0015] In the above technical solution, the upper connecting plate, the second interlayer rubber, the second interlayer steel plate, the lower limiting plate, the upper limiting plate and the lower connecting plate are formed into a whole by vulcanization.

[0016] In the above technical solution, the number of the rubber limiting layers is preferably 6.

[0017] In the above technical solution, the upper partition beam and the lower partition beam have a certain curvature and are formed by pre-pressing, and the middle interlayer is shear thickening putty.

[0018] In the above technical solution, the left cover plate, MRE, the third sandwich steel plate and the right cover plate are formed into a whole through vulcanization.

[0019] In the above technical solution, bolt holes are reserved on the upper cover plate and the lower cover plate.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. In view of the problem that existing rubber isolators are unable to cope with impact loads, the present invention adds a negative stiffness beam and an MRE isolation layer, which are connected in parallel with the rubber limiting layer as the impact-resistant layer of the isolator, so that the isolator has better impact isolation performance. The negative stiffness sandwich beam and the MRE isolation layer can dissipate impact energy under impact loads.

[0022] 2. In view of the weak impact resistance of existing intelligent seismic isolators, the curvature of the upper and lower beams is formed by pre-pressing, and the middle layer is shear thickening clay. At the same time, the stiffness of the MRE seismic isolation layer is adjustable, which can provide constant impact resistance and has a higher impact isolation rate.

[0023] 3. In view of the defect of the existing rubber isolators that the isolation frequency is single and the adaptability is not strong, the present invention adopts a multi-layer parallel design so that the isolators can meet the general isolation requirements and also cope with sudden impact loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 It is a cross-sectional view (AA) of the negative stiffness seismic isolation and impact resistance layer of the seismic isolator of the present invention;

[0026] Figure 3 It is a schematic diagram of the negative stiffness sandwich beam of the present invention.

[0027] In the figure: 1 is an upper cover plate, 2 is an upper sealing plate, 3 is a first sandwich rubber, 4 is a first sandwich steel plate, 5 is a lower sealing plate, 6 is an intermediate cover plate, 7 is an upper connecting plate, 8 is a second sandwich rubber, 9 is a second sandwich steel plate, 10 is a lower limit plate; 11 is an upper limit plate, 12 is a lower connecting plate, 13 is a lower cover plate, 14 is a connecting plate, 15 is a connecting block, 16 is an upper partition beam, 17 is an intermediate interlayer, 18 is a lower partition beam, 19 is a left cover plate, 20 is an MRE, 21 is a third sandwich steel plate, 22 is a right cover plate, 23 is a bolt, 24 is a polytetrafluoroethylene sheet, 25 is a bolt hole, 26 is a positioning column, and 27 is an excitation coil. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. However, the following embodiments are limited to explaining the present invention, and the protection scope of the present invention should include the entire contents of the claims, and through the description of the following embodiments, those skilled in the art can fully implement the entire contents of the claims of the present invention.

[0029] Example

[0030] A semi-active anti-shock isolator based on a negative stiffness beam, comprising an upper cover plate 1, an upper sealing plate 2, a first sandwich rubber 3, a first sandwich steel plate 4, a lower sealing plate 5, an intermediate cover plate 6, an upper connecting plate 7, a second sandwich rubber 8, a second sandwich steel plate 9, a lower limit plate 10, an upper limit plate 11, a lower connecting plate 12, a lower cover plate 13, a connecting plate 14, a connecting block 15, an upper partition beam 16, an intermediate interlayer 17, a lower partition beam 18, a left cover plate 19, an MRE 20, a third sandwich steel plate 21, a right cover plate 22, bolts 23, a polytetrafluoroethylene sheet 24, a bolt hole 25, a positioning column 26, and an excitation coil 27. The overall structure diagram is shown in Figure 1 .

[0031] The upper cover plate 1 and the upper sealing plate 2 are bolted together, the lower sealing plate 5 and the middle cover plate 6 are bolted together, and the upper sealing plate 2, the lower sealing plate 5, the first interlayer steel plate 4, and the first interlayer rubber 3 are vulcanized to form an integral rubber seismic isolation layer, which serves as a stiffness supplement to ensure the output of the seismic isolator.

[0032] The upper connecting plate 7 and the middle cover plate 6 are bolted together, the upper connecting plate 7, the second interlayer rubber 8, the second interlayer steel plate 9, the lower limit plate 10, the upper limit plate 11, and the lower connecting plate 12 are formed as a whole by vulcanization, the lower connecting plate 12 and the lower cover plate 13 are bolted together, the upper connecting plate 7, the second interlayer rubber 8, the second interlayer steel plate 9, the lower limit plate 10, the upper limit plate 11, the lower connecting plate 12, and the upper cover plate 6 form 6 independent rubber bearings arranged around the center, these rubber bearings are the rubber limiting layers of the seismic isolator, which ensure the output of the seismic isolator under the large displacement vibration condition caused by rare earthquakes, avoid the seismic isolation layer from being damaged due to excessive displacement, and enable the seismic isolator to perform seismic isolation and vibration reduction under various conditions such as small displacement and large displacement.

[0033] The connecting plate 14 on the left is bolted to the middle cover plate 6, the ends of the upper partition beam 16 and the lower partition beam 18 are connected by welding, the connecting plate 14 on the right is bolted to the lower cover plate 13, and the connecting block 15 and the connecting plate 14 are connected as a whole by welding. The connecting plate 14, the connecting block 15, the upper partition beam 16, the middle interlayer 17, and the lower partition beam 18 constitute the negative stiffness interlayer beam of the seismic isolator. The schematic diagram of the negative stiffness interlayer beam is shown in Figure 2 The curvature of the upper partition beam 16 and the lower partition beam 18 is formed by pre-pressing, the middle interlayer 17 is shear thickening mortar, and the staggered negative stiffness beams are the negative stiffness devices of the seismic isolator, providing negative stiffness. The shear thickening mortar changes from a liquid-like state to a solid-like state under impact conditions, absorbs a lot of energy during the phase transition process, and the stiffness is also increased, which has good impact resistance.

[0034] The left cover plate 19, MRE20, the third sandwich steel plate 21, and the right cover plate 22 are formed into a whole by vulcanization. The positioning column 26 is connected to the left cover plate 19 by bolts. The excitation coil 27 is wound around the outer ring of the positioning column 26. The left cover plate 19, MRE20, the third sandwich steel plate 21, the right cover plate 22, the positioning column 26, and the excitation coil 27 constitute the MRE seismic isolation layer of the seismic isolator. Under the action of the magnetic field, the stiffness of the MRE can be changed. This layer has a controllable positive stiffness and is connected in parallel with the negative stiffness device, so that the seismic isolator has a lower initial stiffness, further reducing the natural frequency of the structure. The negative stiffness sandwich beam and the MRE seismic isolation layer constitute the negative stiffness seismic isolation and impact resistance layer of the seismic isolator of the present invention, so that the seismic isolator has better seismic isolation and impact resistance. The schematic diagram of this layer is shown in Figure 2 .

[0035] Certain bolt holes 25 are reserved on the upper cover plate 1 and the lower cover plate 13 to facilitate connection with external structures.

[0036] Working principle: A semi-active anti-impact seismic isolator based on a negative stiffness beam of the present invention includes four working layers: a rubber isolation layer, a rubber limiting layer, a negative stiffness sandwich beam and an MRE isolation layer. The upper partition beam 16, the middle sandwich layer 17, the lower partition beam 18 and the connecting plate 14 constitute the negative stiffness sandwich beam of the seismic isolator. The curvature of the upper partition beam 16 and the lower partition beam 18 are formed by pre-pressing. The middle sandwich layer 17 is a shear thickening clay. The staggered negative stiffness beams are the negative stiffness devices of the seismic isolator, providing negative stiffness. The shear thickening clay changes from a liquid-like state to a solid-like state under impact conditions. It absorbs a large amount of energy during the phase transition process, and its stiffness is also improved, which has good impact resistance. The left cover plate 19, MRE 20, the third sandwich steel plate 21, and the right cover plate 22 are formed into a whole by vulcanization. The positioning column 26 is connected to the left cover plate 19 by bolts. The excitation coil 27 is wound around the outer ring of the positioning column 26. The left cover plate 19, MRE 20, the third sandwich steel plate 21, the right cover plate 22, the positioning column 26, and the excitation coil 27 constitute the MRE isolation layer of the seismic isolator. Under the action of the magnetic field, the stiffness of the MRE can be changed. This layer has a controllable positive stiffness and is connected in parallel with the negative stiffness device, so that the seismic isolator has a lower initial stiffness, further reducing the natural frequency of the structure. The negative stiffness sandwich beam and the MRE isolation The seismic layer constitutes the negative stiffness seismic isolation and impact resistance layer of the seismic isolator of the present invention, so that the seismic isolator has better seismic isolation and impact resistance, broadens the seismic isolation frequency of the seismic isolator, and is suitable for the vibration conditions of small amplitude or small displacement caused by earthquakes or wind vibrations; the upper connecting plate 7, the second interlayer rubber 8, the second interlayer steel plate 9, the lower limit plate 10, the upper limit plate 11, the lower connecting plate 12, and the upper cover plate 13 constitute 6 independent rubber bearings arranged around the center. These rubber bearings are the rubber limit layers of the seismic isolator, which prevent the seismic isolation layer from being damaged due to excessive displacement, so that the seismic isolator can be isolated and vibration-reduced under various working conditions such as small displacement and large displacement. When impact loads such as collisions or explosions occur, as the last limit of the seismic isolator, a layer of impact energy is dissipated to ensure that the displacement of the seismic isolation layer is within the safety limit.

[0037] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A semi-active shock isolator based on a negative stiffness beam, characterized in that: It includes an upper cover plate, a middle cover plate, a lower cover plate, a rubber isolation layer, a rubber limiting layer, a negative stiffness sandwich beam and an MRE isolation layer; The rubber isolation layer is arranged between the upper cover plate and the middle cover plate, the rubber limiting layer, the negative stiffness sandwich beam and the MRE isolation layer are arranged between the middle cover plate and the lower cover plate, the negative stiffness sandwich beam is arranged on both sides of the MRE isolation layer, and the rubber limiting layer is distributed around the negative stiffness sandwich beam.

2. The semi-active shock isolator based on a negative stiffness beam according to claim 1, characterized in that: The rubber seismic isolation layer comprises an upper sealing plate, a lower sealing plate, a first sandwich steel plate and a first sandwich rubber, wherein the first sandwich steel plate and the first sandwich rubber are alternately arranged between the upper sealing plate and the lower sealing plate.

3. The semi-active anti-shock isolator based on a negative stiffness beam according to claim 1, characterized in that: The rubber limiting layer includes an upper connecting plate, a lower limiting plate, an upper limiting plate, a lower connecting plate, a second interlayer rubber and a second interlayer steel plate, wherein the second interlayer rubber and the second interlayer steel plate are alternately arranged between the upper connecting plate and the lower limiting plate, and between the upper limiting plate and the lower connecting plate.

4. The semi-active anti-shock isolator based on a negative stiffness beam according to claim 1, characterized in that: The negative stiffness sandwich beam comprises a connecting plate, a connecting block, an upper partition beam, an intermediate sandwich and a lower partition beam, the intermediate sandwich is arranged on the upper partition beam and the lower partition beam, and the connecting plate and the connecting block are arranged on both sides for fixed support.

5. The semi-active shock isolator based on negative stiffness beam according to claim 1, characterized in that: The MRE seismic isolation layer includes a left cover plate, a right cover plate, an MRE, a third interlayer steel plate, a positioning column and an excitation coil. The MRE and the third interlayer steel plate are alternately arranged between the left cover plate and the right cover plate, the positioning column is arranged between the left cover plate and the right cover plate, and the excitation coil is arranged around the positioning column.

6. The semi-active shock isolator based on a negative stiffness beam according to claim 2, characterized in that: The upper sealing plate, the lower sealing plate, the first sandwich steel plate and the first sandwich rubber are formed into a whole by vulcanization.

7. The semi-active shock isolator based on a negative stiffness beam according to claim 3, characterized in that: The upper connecting plate, the second interlayer rubber, the second interlayer steel plate, the lower limiting plate, the upper limiting plate and the lower connecting plate are formed into a whole by vulcanization.

8. The semi-active anti-shock isolator based on a negative stiffness beam according to claim 4, characterized in that: The upper partition beam and the lower partition beam have curvature and are formed by pre-pressing, and the middle interlayer is shear thickening putty.

9. The semi-active anti-shock isolator based on a negative stiffness beam according to claim 5, characterized in that: The left cover plate, MRE, the third sandwich steel plate and the right cover plate are formed into a whole through vulcanization.

10. The semi-active shock isolator based on negative stiffness beam according to claim 1, characterized in that: Bolt holes are reserved on the upper cover plate and the lower cover plate.

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