Semi-active pendulum type tuned mass damper and frequency adjusting method thereof

Abstract

The invention relates to the technical field of civil structure vibration control, in particular to a semi-active pendulum type tuned mass damper and a frequency adjusting method thereof. The invention provides a semi-active swing type tuned mass damper which comprises a swing rod, a mass block, a permanent magnet, a magnetic conductive component, a coil and a current controller, the current controller is electrically connected with the coil, and the coil is wound on the magnetic conductive component; the mass block is connected with the permanent magnet and is arranged in a suspended mode through the swing rod, and the swing rod can swing. Variable-frequency tuning is carried out based on electromagnetic attraction / repulsive force, the magnitude and direction of current can be adjusted through the current controller during use, the mass block can change the equivalent gravitational acceleration under the action of mutual attraction or repulsive of the magnetic conductive component and the permanent magnet, and the purposes of frequency tuning and vibration control are achieved through the resonance effect.

Description

Technical Field

[0001] The invention relates to the technical field of civil structure vibration control, in particular to a semi-active pendulum-type tuned mass damper and a frequency adjustment method thereof. Background Art

[0002] Tuned Mass Damper (TMD) is used to be installed on the controlled building structure. It uses the resonance principle to absorb and transfer the vibration energy of the controlled structure to the control device, thereby reducing the wind vibration and seismic response of the building structure. Calculation analysis and practice have proved that the natural frequency of the tuned mass damper is close to the natural frequency of the controlled structure, which is a prerequisite for ensuring that the vibration energy of the controlled structure is transferred to the tuned mass damper; otherwise, the vibration reduction effect is poor and may even aggravate the vibration of the controlled structure. If the frequency of the TMD cannot be changed, the control effect is poor for loads with strong randomness such as earthquakes and wind, which affects the stability of the controlled structure. Therefore, in engineering applications, the tuned mass damper needs to have a frequency adjustment device to achieve the best vibration reduction effect.

[0003] Existing pendulum TMDs all use the method of adjusting the pendulum length to adjust the frequency, but it is difficult to adjust the pendulum length for certain control frequencies of the controlled structure, which limits its application. For example, at 1-2Hz, the pendulum length is only about 0.1m-0.2m, making it difficult to make and adjust the accuracy; and when the pendulum length is small, the same amplitude of structural vibration may cause a larger swing amplitude, so that the pendulum TMD is in a frequency nonlinear stage, which will also cause a decrease in the shock absorption effect. Summary of the invention

[0004] The purpose of the present invention is to provide a semi-active pendulum tuned mass damper and a frequency adjustment method thereof in view of the fact that the frequency is adjusted by adjusting the pendulum length in the prior art pendulum tuned mass damper, which has the problem of great adjustment difficulty and poor application effect when the pendulum length is small.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a semi-active pendulum tuned mass damper, comprising a pendulum rod, a mass block, a permanent magnet, a magnetic conductive component, a coil and a current controller, wherein the current controller is electrically connected to the coil, and the coil is wound around the magnetic conductive component; the mass block is connected to the permanent magnet, and the mass block is suspended by the pendulum rod, and the pendulum rod can swing.

[0007] When in use, the damper is fixed to the controlled structure, and the pendulum is set vertically so that the permanent magnet and the magnetic conductive component are placed close to each other. By turning on the current controller, the current flows through the coil on the magnetic conductive component to generate an electromagnetic field. When the controlled structure vibrates, the mass block is affected by the controlled structure and swings. At this time, the current size and direction can be adjusted by the current controller so that the mass block is electromagnetically attracted or repelled by the magnetic conductive component under the action of the attached permanent magnet, thereby changing the equivalent gravitational acceleration, and then using the resonance effect to achieve the purpose of tuning the frequency and controlling the vibration. The above-mentioned semi-active pendulum tuned mass damper has a simple structure, convenient current control, and its mass block swing frequency is less affected by the structure itself, and the vibration reduction effect is stable. Compared with the method of adjusting the pendulum length, it has better application effect and applicability.

[0008] As a preferred solution of the present invention, the magnetic conductive component is in the shape of a rod.

[0009] As a preferred solution of the present invention, at least two of the rocker arms are connected to the mass block, the mass block and the rocker arms are hingedly connected, and at least two of the rocker arms are arranged in the same plane to achieve unidirectional swing.

[0010] As a preferred solution of the present invention, the rocker arm is hingedly connected to the controlled structure.

[0011] As a preferred solution of the present invention, the swing rod is hingedly connected to the mass block and has good swing adaptability.

[0012] As a preferred solution of the present invention, the swing rod is arranged vertically.

[0013] In a second aspect, the present invention provides a frequency regulation method for a semi-active pendulum tuned mass damper, which uses the above-mentioned semi-active pendulum tuned mass damper to control the frequency of the mass block swing by adjusting the current size and direction of the current controller.

[0014] As a preferred solution of the present invention, according to the control frequency f of the mass block swing, the current magnitude and direction are obtained based on the following relationship:

[0015]

[0016] Where g is the acceleration due to gravity, F M is the electromagnetic attraction or repulsion, m is the mass of the mass block, l is the initial distance, I is the current, N is the number of coil turns, μ0 is the vacuum permeability, S δ is the cross-sectional area at the end face of the magnetic pole, and δ is the air gap length.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] By using the semi-active pendulum tuned mass damper provided by the present invention for vibration reduction setting, the current size and direction can be adjusted by a current controller to control the frequency of the mass block swinging. The structure is simple, the current control is convenient, and the swing frequency of the mass block is less affected by the structure itself. The vibration reduction effect is stable, and the application effect and applicability are better than the method of adjusting the pendulum length. It can cope with random loads such as wind and earthquake, and can be widely used in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a usage state diagram of a semi-active pendulum tuned mass damper in Example 1.

[0020] Icon: 1- pendulum; 2- mass block; 3- magnetic component; 4- coil; 5- current controller; 6- controlled structure. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] Example 1

[0024] This embodiment provides a semi-active pendulum tuned mass damper, such as Figure 1 As shown, it includes a pendulum 1, a mass block 2, a permanent magnet, a magnetic conductive component 3, a coil 4 and a current controller 5. The current controller 5 is electrically connected to the coil 4, and the coil 4 is wound on the magnetic conductive component 3; the mass block 2 is connected to the permanent magnet, and the mass block 2 is suspended by the pendulum 1, and the pendulum 1 can swing.

[0025] Specifically, the magnetic member 3 is in the shape of a rod, and the coil 4 is wound multiple times along its length. The magnetic member 3 is made of magnetic material, such as iron, cadmium, cobalt, etc. Both ends of the coil 4 are connected to the positive and negative poles of the current controller 5 respectively.

[0026] Two pendulum rods 1 are connected to the mass block 2. The pendulum rods 1 are rigid components. One end of the mass block 2 and the pendulum rod 1 are hingedly connected to better adapt to the swing. The other end of the pendulum rod 1 is hingedly connected to the controlled structure 6. The two pendulum rods 1 are arranged in parallel to achieve unidirectional swing. The mass block 2 has a long length and can be a plate or a rod. The mass block 2 is arranged in parallel just above the magnetic conductive member 3. A permanent magnet is additionally arranged below the mass block 2 to act on the magnetic conductive member 3. The material of the permanent magnet can be rare earth permanent magnet material, samarium cobalt, nickel cadmium cobalt, ferrite permanent magnet material, etc. The permanent magnet and the magnetic conductive member 3 are arranged at intervals. The permanent magnet and the magnetic conductive member 3 are both cylindrical structures. The permanent magnet and the magnetic conductive member 3 are coaxially arranged, and any polarity end (N pole or S pole) of the permanent magnet is arranged toward the magnetic conductive member 3.

[0027] When in use, the damper is fixed to the controlled structure 6, and the pendulum 1 is arranged vertically so that the permanent magnet and the magnetic conductive member 3 are placed close to each other. Due to the tuning effect, when the controlled structure 6 vibrates, the damper is driven to move, thereby causing the mass block 2 to swing. During the swinging process of the mass block 2, the current controller 5 is turned on. When the current flows through the coil 4 wound on the magnetic conductive member 3, an electromagnetic field is generated above. The mass block 2 will change the equivalent gravitational acceleration under the action of the mutual attraction or repulsion between the magnetic conductive member 3 and the permanent magnet, thereby tuning the frequency and controlling the vibration. By using the damper for tuning, the current size and direction can be adjusted through the current controller 5 to control the swinging frequency of the mass block 2.

[0028] The semi-active pendulum tuned mass damper has a simple structure, and the swing frequency of its mass block 2 is affected by the magnitude and direction of the current, and the current is easy to control, so the vibration reduction effect is stable, and the application effect and applicability are better. Compared with the prior art that adjusts the frequency by adjusting the pendulum length, the frequency adjustment using the semi-active pendulum tuned mass damper is less affected by the structure itself.

[0029] The semi-active pendulum tuned mass damper in this embodiment is a type of tuned mass damper. It is frequency-variable based on electromagnetic attraction / repulsion. It not only has the advantages of a passive tuned mass damper, but also can control the change of current size and direction in real time. It can adjust the frequency of the mass damper well, so as to cope with random loads such as wind and earthquake. Therefore, it can be widely used in engineering practice.

[0030] Example 2

[0031] Based on Example 1, this embodiment provides a frequency adjustment method for a semi-active pendulum tuned mass damper, which uses the above-mentioned semi-active pendulum tuned mass damper to control the frequency of the mass block swing by adjusting the current size and direction of the current controller.

[0032] Specifically, this embodiment performs frequency adjustment of the pendulum tuned mass damper based on electromagnetic attraction / repulsion, and the theoretical basis of its vibration control is:

[0033] ① Calculation of electromagnetic attraction / repulsion:

[0034] ②Use Lagrange's theorem to establish the equation of motion:

[0035] Where i is the degree of freedom, i = 1, 2;

[0036]

[0037] Q=±F M Lsinθ;

[0038] Since the main force is a conservative force, its potential energy is expressed in generalized coordinates:

[0039] V = mgL(1-cosθ);

[0040] ③Then the equation of motion is solved as:

[0041] After simplification:

[0042] ④Further, consider the frequency of electromagnetic attraction / repulsion pendulum:

[0043] Without electromagnetic:

[0044] In the case of electromagnetism, the above Lagrange theorem is derived and transformed to obtain:

[0045] Where, I-current, δ-air gap length, S δ - cross-sectional area at the end face of the magnetic pole, μ0-vacuum magnetic permeability, N-number of coil turns, T-kinetic energy, V-potential energy, Q-generalized force, q-generalized coordinates, - generalized speed, - generalized momentum, m-mass of the mass block, l-initial distance between the permanent magnet and the magnetic conductive member, θ-initial rotation angle, g is the gravitational acceleration, F M It is the electromagnetic attraction or repulsion.

[0046] In view of the problems existing in the existing pendulum tuned mass damper, the present invention proposes a variable-frequency semi-active pendulum tuned mass damper based on electromagnetic attraction / repulsion, carries out relevant theoretical derivation, establishes the motion equation of the damper system, and establishes the relationship between the damper frequency f and the external current I, so that the damper's own frequency can be controlled by utilizing the current magnitude and direction, thereby achieving the effect of structural vibration reduction and vibration control, and has a tuning effect that the passive pendulum tuned mass damper does not have.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A semi-active pendulum tuned mass damper, characterized in that: The invention comprises a pendulum (1), a mass block (2), a permanent magnet, a magnetic conductive component (3), a coil (4) and a current controller (5), wherein the current controller (5) is electrically connected to the coil (4), and the coil (4) is wound around the magnetic conductive component (3); the mass block (2) is connected to the permanent magnet, the mass block (2) is suspended by the pendulum (1), and the pendulum (1) is capable of swinging.

2. A semi-active pendulum tuned mass damper according to claim 1, characterized in that: The magnetic conductive component (3) is in the shape of a rod.

3. A semi-active pendulum tuned mass damper according to claim 1, characterized in that: The mass block (2) is connected to two of the rocker rods (1); the mass block (2) and the rocker rods (1) are hingedly connected; and the two rocker rods (1) are arranged in parallel.

4. A semi-active pendulum tuned mass damper according to claim 1, characterized in that: The swing rod (1) is hingedly connected to the controlled structure (6).

5. A semi-active pendulum tuned mass damper according to any one of claims 1 to 4, characterized in that: The rocker arm (1) is hingedly connected to the mass block (2).

6. A semi-active pendulum tuned mass damper according to any one of claims 1 to 4, characterized in that: The swing rod (1) is arranged vertically.

7. A frequency adjustment method for a semi-active pendulum tuned mass damper, characterized in that: A semi-active pendulum tuned mass damper as claimed in any one of claims 1 to 6 is used to control the frequency of the swing of the mass block (2) by adjusting the current magnitude and direction of the current controller (5).

8. The frequency adjustment method according to claim 7, characterized in that: According to the control frequency f of the swing of the mass block (2), the magnitude and direction of the current are calculated based on the following relationship: Where g is the acceleration due to gravity, F M is the electromagnetic attraction or repulsion, m is the mass of the mass block (2), l is the initial distance, I is the current, N is the number of coil turns, μ0 is the vacuum magnetic permeability, S δ is the cross-sectional area at the end face of the magnetic pole, and δ is the air gap length.

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