A quasi-zero stiffness-inertia amplified periodic structure

Abstract

The present invention relates to a quasi-zero stiffness-inertia amplification type periodic structure, which includes a base plate (2) and a plurality of resonant units; the resonant unit includes an outer sleeve (1), a rotating inner cylinder (3), a ball screw (4), a rotating nut (5), a flywheel (6), a vertical spring (7), a horizontally pre-compressed spring (8) and a support member (9); the resonant unit is connected to the base plate (2) through the outer sleeve (1); the support member (9) fixedly supports the ball screw (4) to move in the vertical direction, a vertical spring (7) is installed at the bottom, and horizontally pre-compressed springs (8) are installed around. Compared with the prior art, under the action of vibration, the equivalent dynamic stiffness of the present invention is reduced, and the flywheel rotates to amplify the inertia generated by its physical mass, realizing the shielding and blocking of elastic waves in the ultra-low frequency band range, and having the advantages of high reliability and strong robustness, and can be applied to the fields of noise reduction and vibration reduction of engineering structures such as houses, bridges and rail transit.

Description

Technical Field

[0001] The present invention belongs to the technical field of noise and vibration reduction of engineering structures, and relates to a quasi-zero stiffness-inertia amplified periodic structure. Background Art

[0002] The concept of artificial periodic structures comes from phononic crystals, which are structures with periodic distributions of elastic constants and densities. The interconnected materials are the matrix, and the non-connected materials or structures are called scatterers. When elastic waves propagate in a periodic structure, they are affected by the internal structure and are blocked from propagating within a certain frequency range (bandgap), while they can propagate without loss in other frequency ranges (passbands). The generation mechanism of the bandgap is divided into Bragg scattering type and local resonance type. Among them, the Bragg scattering type bandgap frequency is related to the unit distribution distance (lattice constant). When the wavelength of the incident wave is close to the lattice constant, it is strongly scattered by the structure. The local resonance type forms a bandgap through the resonance of a single scatterer. The bandgap frequency range is only related to the natural vibration frequency of the scatterer and the relative mass ratio to the matrix. The starting frequency of the bandgap is consistent with the natural vibration frequency, and the larger the relative mass ratio to the matrix, the larger the bandgap frequency range.

[0003] Engineering structures such as houses, bridges, and rail transit are often affected by vibrations generated by earthquakes, wind vibrations, and wheel-rail interactions during rail transit operation. The main frequencies of the elastic waves generated by these external excitations are in the range of 0 - 100 Hz, and the corresponding wavelengths are very large. Periodic structures need to match larger-sized units to achieve Bragg scattering bandgaps, while local resonance bandgaps are not affected by periodicity and are better applicable to vibration reduction and isolation of engineering structures. However, traditional linear resonance units are limited by the stiffness of the connecting spring and the mass ratio, and cannot simultaneously take into account the bearing capacity and wide-frequency vibration reduction bandgap. Therefore, it is of great engineering practical significance to develop resonant units of local resonance type periodic structures with low-frequency and wide-frequency bandgap characteristics.

[0004] Patent CN214168591U discloses a wide-frequency passive vibration isolator and rail system, including an inertia amplification component and a rotary viscous damper. The inertia amplification component includes a fixed support, a ball screw, and a flywheel. The bottom of the fixed support is connected to one end of the ball screw. A ball nut is threadedly connected to the ball screw. The rotary viscous damper includes an outer tube and an inner tube. The inner tube is arranged inside the outer tube, and a viscous material is filled between the inner tube and the outer tube. A bearing is arranged in the mounting hole. One end of the ball nut passes through the mounting hole and is connected to the inner tube inside the outer tube. However, this patent is limited by the axial displacement of the rotating screw, the inertia amplification effect caused by the rotation of the flywheel is limited, and there is a risk of leakage of the viscous liquid, affecting the stability of the damping system. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of narrow vibration damping frequency band and limited load-bearing capacity of the existing devices, and to provide a quasi-zero stiffness-inertia amplification type periodic structure with excellent vibration damping performance in the low-frequency range, which is used for vibration damping of engineering structures such as houses, bridges and rail transit.

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

[0007] A quasi-zero stiffness-inertia amplification type periodic structure, which includes a base plate and a plurality of resonant units arranged periodically;

[0008] The resonant unit includes an outer sleeve, and a rotating inner cylinder, a ball screw, a rotating nut, a flywheel, a vertical spring, a horizontally pre-compressed spring and a support member arranged inside the outer sleeve;

[0009] The resonant unit is integrally connected to the base plate through the outer sleeve by welding or bolts;

[0010] The ball screw is arranged at the axis of the outer sleeve. A through hole is opened at the top of the outer sleeve. The ball screw passes through the through hole and is connected to the top of the outer sleeve through the rotating inner cylinder. The rotating inner cylinder is integrally connected to the rotating nut and the flywheel arranged in sequence from bottom to top by welding and rotates together to form a rotating body;

[0011] An unpenetrated cavity is opened above the support member to fixedly support the ball screw to move in the vertical direction. A vertical spring is installed at the bottom, and a plurality of horizontally pre-compressed springs are installed around. The other end of the vertical spring is connected to the bottom of the outer sleeve, and the other end of the horizontally pre-compressed spring is connected to the side wall of the outer sleeve.

[0012] Further, a plurality of resonant units are distributed in a periodic matrix in the transverse and longitudinal directions of the base plate, and two adjacent resonant units are independent of each other.

[0013] Further, n resonant units are equidistantly arranged in the transverse direction of the periodic structure, and m resonant units are equidistantly arranged in the longitudinal direction. The distribution of the periodic structure is of the n×m type.

[0014] Further, the value range of the number n of the resonant units arranged in the transverse direction of the periodic structure is n≥3, and the value range of the number m of the resonant units arranged in the longitudinal direction of the periodic structure is m≥3.

[0015] Further, the ball screw matches the thread groove of the rotating nut, and the rotation angle of the rotating nut will be converted according to the lead of the corresponding specification with the axial linear movement of the ball screw.

[0016] Further, a rotation assisting mechanism is provided at the contact between the rotating inner cylinder and the top through hole of the outer sleeve and at the contact between the rotating inner cylinder and the cavity above the support member to reduce the rotational resistance between them.

[0017] Further, the support member is a square thin-walled structure, and four horizontal pre-compressed springs are installed around it.

[0018] Further, an upper limit plate and a lower limit plate are also provided inside the outer sleeve. When the support member moves axially in the vertical direction between the upper limit plate and the lower limit plate, the originally pre-compressed horizontal springs provide a thrust in the vertical direction. When working together with the vertical springs, the equivalent vertical stiffness is reduced, amplifying the axial movement of the ball screw. At the same time, the rotating body composed of the rotating nut, the rotating inner cylinder, and the flywheel rotates. The upper limit plate and the lower limit plate limit the displacement of the support member from being too large, resulting in a weakening of the stiffness reduction effect.

[0019] Further, buffer materials are attached to the upper limit plate and the lower limit plate. The buffer materials are selected from one or more of rubber, foam plastics, or pearl cotton to reduce the device loss caused by the collision with the support member.

[0020] Further, both the vertical spring and the horizontal pre-compressed spring are linear springs, and the material is high carbon steel.

[0021] When an elastic wave is input to one side of the periodic structure, the vibration of the base plate causes the resonance of the resonant unit. At this time, the support member will deviate from the horizontal equilibrium position, and the horizontal pre-compressed spring will tilt and provide a thrust along the moving direction of the support member. The direction of the thrust is the same as the compression / tension direction of the vertical spring, reducing the restoring force of the spring group in the vertical direction and weakening the equivalent vertical stiffness. At this time, the ball screw supported by the support member quickly moves linearly in the axial direction, and the rotating body formed by the rotating inner cylinder and the flywheel rotates under the rotation of the rotating nut. The inertia generated by the moment of inertia of the flywheel is much greater than the inertia generated by its own physical mass, realizing equivalent inertia amplification, increasing the equivalent mass ratio of the resonant unit, and broadening the frequency range of the elastic wave bandgap shielded by the periodic structure. When the support member moves to a certain distance, the vertical thrust component provided by the horizontal pre-compressed spring will weaken. Therefore, the upper limit plate and the lower limit plate are provided to prevent the support member from having too large a displacement. When the input frequency range is consistent with the frequency range of the elastic wave bandgap shielded by the designed periodic structure, the vibration of the periodic structure is mainly the self-vibration of the distributed resonant units, and the vibration on the base plate is very small, achieving the vibration reduction effect.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) In the present invention, a conversion between axial linear motion and horizontal rotation is achieved by using a ball screw, a rotating nut, and a flywheel. When the flywheel rotates, the inertial effect generated by its moment of inertia is much greater than the inertial effect generated by its physical mass, realizing the gain of the mass of the resonant unit during motion, that is, increasing the equivalent mass ratio of the scatterer to the matrix in the periodic structure, and effectively improving the bandgap frequency range of the periodic structure for shielding and blocking elastic waves.

[0024] (2) In the present invention, by adopting a quasi-zero stiffness spring mechanism, high static stiffness and low dynamic stiffness are achieved, while taking into account the requirements of low-frequency vibration reduction of the resonant unit of the periodic structure and the static vertical bearing capacity of the structure. On the other hand, when the resonant unit resonates, the low dynamic stiffness will amplify the linear motion of the ball screw in the axial direction, and further amplify the rotation of the flywheel through the rotating nut to achieve inertial amplification.

[0025] (3) In the present invention, by adopting a limit plate device, the excessive axial movement of the support member is restricted, which may cause the vertical force of the horizontal pre-compressed spring in the quasi-zero stiffness spring mechanism to be too small, thereby affecting the reduction effect of the dynamic stiffness. The buffer material used in the limit plate can avoid the loss of the device during collision.

[0026] (4) The structure of the present invention is simple, has a small mass compared with the traditional periodic structure, can form a wider bandgap in the low-frequency range of 0 - 100 Hz, effectively suppress the propagation of low-frequency elastic waves or sound waves, and at the same time, the materials are cheap and reliable, the manufacturing and assembly are simple, and it is convenient for standardized production, with stronger applicability and economy. Description of the Drawings

[0027] Figure 1 is a schematic diagram of the quasi-zero stiffness - inertial amplification type periodic structure in the embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of the resonant unit in the embodiment of the present invention;

[0029] Figure 3 is the front view of the resonant unit in the embodiment of the present invention;

[0030] Figure 4 is the A - A sectional view of the resonant unit in the embodiment of the present invention;

[0031] Figure 5 is the B - B sectional view of the resonant unit in the embodiment of the present invention.

[0032] Description of the reference numerals in the drawings:

[0033] 1 - outer sleeve, 2 - base plate, 3 - rotating inner cylinder, 4 - ball screw, 5 - rotating nut, 6 - flywheel, 7 - vertical spring, 8 - horizontal pre-compressed spring, 9 - support member, 10 - upper limit plate, 11 - lower limit plate. Detailed Embodiments

[0034] The present invention will be described in detail below in conjunction with specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0035] Unless otherwise specified, the devices used in the following embodiments are all conventional devices in the art; unless otherwise specified, the materials used are all commercially available products or prepared by conventional methods in the art. Those not described in detail in the following embodiments can be achieved by conventional experimental means in the art.

[0036] Embodiment:

[0037] A quasi-zero stiffness-inertia amplification type periodic structure, as Figure 1 shown. The periodic structure includes a base plate 2 and resonant units arranged in a periodic manner. The resonant units are connected to the base plate 2 as a whole through an outer sleeve 1 by welding or bolt connection. In this embodiment, welding is preferably used. n resonant units and m resonant units are respectively arranged in the transverse direction and the longitudinal direction of the periodic structure, where n≥3 and m≥3. In this embodiment, 12×10 is preferably used, and adjacent two resonant units are independent of each other.

[0038] The said resonant unit, as Figures 2 to 5As shown in the figure, it includes an outer sleeve 1, a rotating inner cylinder 3, a ball screw 4, a rotating nut 5, a flywheel 6, a vertical spring 7, a horizontally pre-compressed spring 8, a support member 9, an upper limit plate 10 and a lower limit plate 11. The ball screw 4 is arranged at the axis of the outer sleeve 1. A through hole is opened at the top of the outer sleeve 1. The ball screw 4 passes through the through hole and is connected to the top of the outer sleeve 1 through the rotating inner cylinder 3. The rotating inner cylinder 3 is welded and connected as a whole with the rotating nut 5 and the flywheel 6 arranged in sequence from bottom to top, and they rotate together to form a rotating body. The ball screw 4 matches the spiral groove of the rotating nut 5, and the rotation angle of the rotating nut 5 will be converted according to the lead of the corresponding specification with the axial linear movement of the ball screw 4; a rotation assisting mechanism is arranged at the contact between the rotating inner cylinder 3 and the through hole at the top of the outer sleeve 1 and at the contact between the rotating inner cylinder 3 and the cavity above the support member 9 to reduce the rotation resistance between them; the support member 9 is a square thin-wall structure, with a non-through cavity opened above, the bottom is fixedly connected to support the vertical movement of the ball screw 4, a vertical spring 7 is installed at the bottom, and a plurality of horizontally pre-compressed springs 8 are installed around, preferably four in this embodiment. The other end of the vertical spring 7 is connected to the bottom of the outer sleeve 1, and the other end of the horizontally pre-compressed spring 8 is connected to the side wall of the outer sleeve 1. When the support member 9 moves axially in the vertical direction between the upper limit plate 10 and the lower limit plate 11, the originally pre-compressed horizontal spring 8 provides a thrust in the vertical direction. When working together with the vertical spring 7, the equivalent vertical stiffness is reduced, amplifying the axial movement of the ball screw 4. At the same time, the rotating body composed of the rotating nut 5, the rotating inner cylinder 3 and the flywheel 6 rotates. The upper limit plate 10 and the lower limit plate 11 limit the displacement of the support member 9 from being too large, resulting in the weakening of the stiffness reduction effect. The materials of the vertical spring 7 and the horizontally pre-compressed spring 8 are both linear springs, and the material is high-carbon steel; a buffer material is added to the upper limit plate 10 and the lower limit plate 11. The buffer material is one or more of rubber, foam plastic or pearl cotton, preferably rubber in this embodiment, to reduce the device loss caused by the collision with the support member 9 and at the same time increase the energy dissipated during the collision.

[0039] When elastic waves are input to one side of the periodic structure, the vibration of the base plate 2 causes the resonance of the resonant units. At this time, the support member 9 will deviate from the horizontal equilibrium position, and the horizontally pre-compressed spring 8 will tilt and provide a thrust force along the moving direction of the support member 9. The direction of the thrust force is consistent with the compression / tension direction of the vertical spring 7, reducing the restoring force of the spring group in the vertical direction and weakening the equivalent vertical stiffness. At this time, the ball screw 4 supported by the support member 9 quickly moves linearly in the axial direction, and the rotating body formed by the rotating inner cylinder 3 and the flywheel 6 rotates under the rotation of the rotating nut 5. The inertial effect generated by the moment of inertia of the flywheel 6 is much greater than the inertia generated by its own physical mass, realizing equivalent inertial amplification, increasing the equivalent mass ratio of the resonant unit, and broadening the frequency range of the elastic wave bandgap shielded by the periodic structure. When the support member 9 moves to a certain distance, the vertical thrust component that the horizontally pre-compressed spring 8 can provide will weaken. Therefore, the upper limit plate 10 and the lower limit plate 11 are provided to prevent the support member 9 from having excessive displacement. When the input frequency range is consistent with the elastic wave bandgap frequency range of the designed periodic structure, the vibration of the periodic structure is mainly the self-vibration of the distributed resonant units, and the vibration on the base plate 2 is very small, achieving the vibration reduction effect.

[0040] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A quasi-zero stiffness-inertia amplified periodic structure, characterized in that, The periodic structure includes a base plate (2) and a plurality of resonant units arranged periodically. The resonant unit includes an outer sleeve (1), and a rotating inner cylinder (3), a ball screw (4), a rotating nut (5), a flywheel (6), a vertical spring (7), a horizontally pre-compressed spring (8) and a support member (9) arranged inside the outer sleeve (1). The outer sleeve (1) is connected to the base plate (2). The ball screw (4) is arranged at the axis of the outer sleeve (1). A through hole is opened at the top of the outer sleeve (1). The ball screw (4) passes through the through hole and is connected to the top of the outer sleeve (1) through the rotating inner cylinder (3). The rotating inner cylinder (3) is respectively connected to the rotating nut (5) and the flywheel (6) arranged successively from bottom to top. An unpenetrated cavity is opened above the support member (9) to fixedly support the ball screw (4) to move in the vertical direction. A vertical spring (7) is installed at the bottom, and a plurality of horizontally pre-compressed springs (8) are installed around. The other end of the vertical spring (7) is connected to the bottom of the outer sleeve (1), and the other end of the horizontally pre-compressed spring (8) is connected to the side wall of the outer sleeve (1).

2. The quasi-zero stiffness-inertia amplified periodic structure according to claim 1, wherein A plurality of resonant units are distributed in a periodic matrix along the transverse and longitudinal directions of the base plate (2), and two adjacent resonant units are independent of each other.

3. A quasi-zero stiffness-inertia amplified periodic structure according to claim 2, characterized in that, n resonant units are arranged at equal intervals in the transverse direction of the periodic structure, and m resonant units are arranged at equal intervals in the longitudinal direction.

4. A quasi-zero stiffness-inertia amplified periodic structure according to claim 3, characterized in that, The value range of the number n of resonant units arranged in the transverse direction of the periodic structure is n≥3, and the value range of the number m of resonant units arranged in the longitudinal direction of the periodic structure is m≥3.

5. A quasi-zero stiffness-inertia amplified periodic structure according to claim 1, characterized in that, The ball screw (4) matches the thread groove of the rotating nut (5).

6. A quasi-zero stiffness-inertia amplified periodic structure according to claim 1, characterized in that, A rotation assisting mechanism is provided at the contact between the rotating inner cylinder (3) and the through hole at the top of the outer sleeve (1) and at the contact between the rotating inner cylinder (3) and the cavity above the support member (9).

7. A quasi-zero stiffness-inertia amplified periodic structure according to claim 1, characterized in that, The support member (9) is of a square thin-wall structure, and four horizontally pre-compressed springs (8) are installed around.

8. A quasi-zero stiffness-inertia amplified periodic structure according to claim 1, characterized in that, An upper limit plate (10) and a lower limit plate (11) are further arranged inside the outer sleeve (1), and the support member (9) moves between the upper limit plate (10) and the lower limit plate (11).

9. A quasi-zero stiffness-inertia amplified periodic structure according to claim 8, characterized in that, Buffer materials are attached to the upper limit plate (10) and the lower limit plate (11), and the buffer materials are selected from one or more of rubber, foam plastic or pearl cotton.

10. A quasi-zero stiffness-inertia amplified periodic structure according to claim 1, characterized in that, Both the vertical spring (7) and the horizontally pre-compressed spring (8) are linear springs, and the material is high carbon steel.

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