A semi-active pendulum tuned mass damper and a frequency adjusting method thereof

Abstract

The present application relates to the technical field of civil structure vibration control, and particularly relates to a semi-active pendulum tuned mass damper and a frequency adjusting method thereof. The present application provides a semi-active pendulum tuned mass damper, which comprises a pendulum rod, a mass block, a permanent magnet, a magnetic conducting member, a coil and a current controller. The current controller is electrically connected with the coil, and the coil is wound on the magnetic conducting member. The mass block is connected with the permanent magnet and is suspended by the pendulum rod. The pendulum rod can swing. The present application can adjust the frequency based on electromagnetic attraction / repulsion. When in use, the current controller can adjust the current size and direction, so that the mass block can change the equivalent gravity acceleration under the mutual attraction or repulsion of the magnetic conducting member and the permanent magnet. The resonance effect is utilized to achieve the tuning frequency and control the vibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of civil structure vibration control, and particularly relates to a semi-active pendulum type tuned mass damper and a frequency adjusting method thereof. BACKGROUND

[0002] A tuned mass damper (TMD) is used to be installed on a controlled building structure, and vibration energy of the controlled structure is absorbed and transferred to the control device by resonance principle, so as to reduce wind vibration and seismic response of the building structure. It is proved by calculation analysis and practice that the inherent frequency of the TMD is close to the inherent frequency of the controlled structure, which is a prerequisite for ensuring that the vibration energy of the controlled structure is transferred to the TMD; otherwise, the vibration reduction effect is poor, and the vibration of the controlled structure may even be intensified. If the frequency of the TMD cannot be changed, the control effect is poor for random loads such as earthquakes and winds, which affects the stability of the controlled structure. Therefore, in engineering applications, the TMD needs to have a frequency adjusting device to achieve the optimal vibration reduction effect.

[0003] The existing pendulum type TMD adjusts the frequency by adjusting the length of the pendulum, but it is difficult to adjust the length of the pendulum for some control frequencies of the controlled structure, which limits the application. For example, when the frequency is 1-2 Hz, the length of the pendulum is only about 0.1 m-0.2 m, and it is difficult to adjust the length with high precision. Moreover, when the length of the pendulum is small, the same amplitude of structure vibration may cause a large pendulum amplitude, so that the pendulum type TMD is in a frequency nonlinear stage, which also causes the vibration reduction effect to decrease. SUMMARY

[0004] The present application aims at the problem that the existing pendulum type TMD adjusts the frequency by adjusting the length of the pendulum, and it is difficult to adjust the length of the pendulum when the length is small, and the application effect is poor, and provides a semi-active pendulum type TMD and a frequency adjusting method thereof.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] In a first aspect, the present application provides a semi-active pendulum type TMD, which comprises a pendulum rod, a mass block, a permanent magnet, a magnetic guide member, a coil and a current controller. The current controller is electrically connected with the coil, and the coil is wound on the magnetic guide member. The mass block is connected with the permanent magnet, and the mass block is suspended by the pendulum rod. The pendulum rod can swing.

[0007] In use, the damper is fixed to the controlled structure, and the swing rod is vertically arranged, so that the permanent magnet and the magnetic conducting member are close to each other, and the electromagnetic field is generated by turning on the current controller to make the current flow through the coil on the magnetic conducting member; when the controlled structure vibrates, the mass block swings under the influence of the controlled structure, at this time, the current size and direction can be adjusted by the current controller, so that the mass block is subjected to the electromagnetic attraction or repulsion of the magnetic conducting member under the action of the additional permanent magnet, thereby changing the equivalent gravitational acceleration, and then the resonance effect is used to achieve the purpose of tuning frequency and controlling vibration. The semi-active pendulum tuned mass damper has the advantages of simple structure, convenient current control, small influence of the mass block swing frequency on the structure itself, stable damping effect, and better application effect and applicability compared with the method of adjusting the swing length.

[0008] As a preferred scheme of the present application, the magnetic conducting member is in the shape of a rod.

[0009] As a preferred scheme of the present application, the mass block is connected with at least two swing rods, and the mass block and the swing rods are hingedly connected, and the at least two swing rods are arranged in the same plane to realize one-way swing.

[0010] As a preferred scheme of the present application, the swing rod is hingedly connected with the controlled structure.

[0011] As a preferred scheme of the present application, the swing rod is hingedly connected with the mass block, and the swing adaptability is good.

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

[0013] In the second aspect, the present application provides a frequency adjusting method of a semi-active pendulum tuned mass damper, which adopts the semi-active pendulum tuned mass damper, and controls the swing frequency of the mass block by adjusting the current size and direction of the current controller.

[0014] As a preferred scheme of the present application, the current size and direction are calculated based on the following relationship according to the control frequency f of the mass block swing:

[0015]

[0016] In the formula, g is the gravitational acceleration, 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 turns of the coil, μ0 is the vacuum permeability, S δ is the cross-sectional area at the pole end face, and δ is the air gap length.

[0017] In summary, due to the adoption of the above technical scheme, the present application has the following advantages:

[0018] The semi-active pendulum type tuned mass damper provided by the application can adjust the current size and direction through the current controller, control the frequency of the mass block swing, has simple structure, convenient current control, and small influence of the mass block swing frequency on the structure itself, stable damping effect, better application effect and applicability compared with the application effect and applicability of the length adjustment mode, can cope with random loads such as wind and earthquake, and can be widely applied to engineering practice. BRIEF DESCRIPTION OF DRAWINGS

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

[0020] Figure legend: 1-pendulum rod; 2-mass block; 3-magnetic guide member; 4-coil; 5-current controller; 6-structure to be controlled. DETAILED DESCRIPTION

[0021] The application will be described in detail below with reference to the drawings.

[0022] In order to make the purpose, technical scheme and advantages of the application clearer and more apparent, the application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0023] Example 1

[0024] This embodiment provides a semi-active pendulum type tuned mass damper, as shown in Figure 1 , including a pendulum rod 1, a mass block 2, a permanent magnet, a magnetic guide member 3, a coil 4 and a current controller 5, the current controller 5 is electrically connected with the coil 4, and the coil 4 is wound on the magnetic guide member 3; the mass block 2 is connected with the permanent magnet, and the mass block 2 is suspended by the pendulum rod 1, and the pendulum rod 1 can swing.

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

[0026] The mass 2 is connected with two pendulums 1, the pendulum 1 is a rigid member, the mass 2 and one end of the pendulum 1 are hingedly connected to better adapt to the swing, the other end of the pendulum 1 is hingedly connected with the controlled structure 6, the two pendulums 1 are arranged in parallel to realize one-way swing. The mass 2 has a relatively long length, which can be a plate member or a rod member, etc., and is arranged in parallel above the magnetic conducting member 3. A permanent magnet is additionally arranged below the mass 2 to act with the magnetic conducting member 3, and the material of the permanent magnet can be a rare earth permanent magnet material, samarium-cobalt, nickel-cadmium-cobalt, ferrite permanent magnet material, etc. The permanent magnet and the magnetic conducting member 3 are arranged in a spaced manner, and both the permanent magnet and the magnetic conducting member 3 adopt a cylindrical structure, and the permanent magnet and the magnetic conducting member 3 are coaxially arranged, and any polarity end (N pole or S pole) of the permanent magnet is arranged to face the magnetic conducting member 3.

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

[0028] The above semi-active pendulum type tuned mass damper has a simple structure, the swing frequency of the mass 2 is affected by the current size and direction, and the current control is convenient, so the damping effect is stable, and the application effect and applicability are better. Compared with the prior art which adjusts the frequency by adjusting the length of the pendulum, the frequency adjustment by using the above semi-active pendulum type tuned mass damper is less affected by the structure itself.

[0029] The semi-active pendulum type tuned mass damper in the embodiment is a kind of tuned mass damper, which can be set to variable frequency based on electromagnetic attraction / repulsion, has the advantages of passive tuned mass damper, and can change the current size, direction, etc. in real time, can well adjust the frequency of the mass damper, so as to cope with random loads such as wind and earthquake, and therefore can be widely applied to engineering practice.

[0030] Embodiment 2

[0031] Based on embodiment 1, a frequency adjustment method of a semi-active pendulum type tuned mass damper is provided, which uses the above semi-active pendulum type tuned mass damper to control the frequency of the swing of the mass by adjusting the current size and direction of the current control device.

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

[0033] ① Calculation of electromagnetic attraction / repulsion:

[0034] ② Use Lagrange theorem to establish motion equation:

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

[0036]

[0037] Q = ± F M Lsinθ;

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

[0039] V = mgL(1-cosθ);

[0040] ③ Thus, the motion equation is:

[0041] After simplification:

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

[0043] Without electromagnetic:

[0044] In the presence of electromagnetic, the transformation is derived from the above Lagrange theorem:

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

[0046] The present application aims at the problems existing in the prior art pendulum tuned mass damper, and proposes a variable frequency semi-active pendulum tuned mass damper based on electromagnetic attraction / repulsion, and carries out relevant theoretical derivation, establishes a motion equation of the damper system, and establishes a relationship between the frequency f of the damper and the applied current I, so that the frequency of the damper itself can be controlled by using the size and direction of the current, so as to achieve the effect of structural vibration reduction and control, and the damper has the tuning effect which the passive pendulum tuned mass damper does not have.

[0047] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A semi-active pendulum tuned mass damper characterized by, It comprises a swing rod (1), a mass block (2), a permanent magnet, a magnetic conducting member (3), a coil (4) and a current controller (5), the current controller (5) is electrically connected with the coil (4), the coil (4) is wound on the magnetic conducting member (3); the mass block (2) is connected with the permanent magnet, the mass block (2) is suspended by the swing rod (1), the swing rod (1) can swing; The magnetic conducting member (3) is in the shape of a rod and is coaxially arranged with the permanent magnet, any polarity end of the permanent magnet is arranged towards the magnetic conducting member (3); The current controller (5) is used for adjusting the current size and direction to change the equivalent gravity acceleration of the mass block (2) so as to adjust the swing frequency thereof.

2. A semi-active pendulum tuned mass damper according to claim 1, wherein Two swing rods (1) are connected on the mass block (2), the mass block (2) and the swing rod (1) are hingedly connected, and the two swing rods (1) are arranged in parallel.

3. A semi-active pendulum tuned mass damper according to claim 1, wherein The swing rod (1) is hingedly connected with a controlled structure (6).

4. A semi-active pendulum tuned mass damper according to any one of claims 1-3, characterized in that, The swing rod (1) is hingedly connected with the mass block (2).

5. A semi-active pendulum tuned mass damper according to any one of claims 1-3, characterized in that, The swing rod (1) is vertically arranged.

6. A frequency adjustment method of a semi-active pendulum tuned mass damper, characterized by, A semi-active swing type tuned mass damper is adopted, the frequency of the mass block (2) swing is controlled by adjusting the current size and direction of the current controller (5).

7. The frequency adjustment method of claim 6, wherein, According to the control frequency of the mass (2) swing f The current size and direction are calculated based on the following relationship: ； ； wherein g is the gravitational acceleration, F M is the electromagnetic attractive or repulsive force, is the mass of the mass (2), is the initial distance, is the electric current, is the number of turns of the coil, is the vacuum permeability, is the cross-sectional area at the pole face, is the air gap length.

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