阅读说明：本技术 一种利用扣件刚度失谐实现低频减振的系统和方法 (System and method for realizing low-frequency vibration reduction by utilizing fastener rigidity detuning ) 是由 刘文武 史海欧 罗信伟 贺利工 吴嘉 冯青松 王仲林 杨舟 刘堂辉 吴梦 孙菁 于 2020-05-15 设计创作，主要内容包括：本发明涉一种利用扣件刚度失谐实现低频减振的系统和方法,所述系统包括：钢轨以及在钢轨设置的多个扣件,其特征在于：扣件的刚度满足失谐要求。采用本申请的方案操作简单,扣件刚度失谐的设置只需通过人为拧松扣件或者更换小刚度扣件即可；只需要在扣件刚度失谐位置的钢轨安装阻尼层等其它能够耗散能量的材料,不需要再轨道结构全段安装,节省了成本的同时,也有效地实现了控制低频振动的效果。(The invention relates to a system and a method for realizing low-frequency vibration reduction by utilizing fastener rigidity detuning, wherein the system comprises: rail and at a plurality of fasteners of rail setting, its characterized in that: the stiffness of the fastener meets the detuning requirement. The scheme of the application is simple to operate, and the rigidity of the fastener is detuned only by manually loosening the fastener or replacing the small-rigidity fastener; the steel rail at the position of the rigidity detuning of the fastener is only required to be provided with other materials capable of dissipating energy, such as a damping layer and the like, and the whole section of the rail structure is not required to be installed, so that the cost is saved, and the effect of controlling the low-frequency vibration is effectively realized.)

1. A system for achieving low frequency damping with fastener stiffness detuning, the system comprising: rail and at a plurality of fasteners of rail setting, its characterized in that: the stiffness of the fastener meets the detuning requirement.

2. The system of claim 1 for achieving low frequency damping using fastener stiffness detuning, wherein: the rigidity detuning requirement is that the steel rail defect state frequency and the fastener rigidity detuning degree meet the following relation: -17.326 × Δ k +130.803

Wherein f represents a defect state frequency; Δ k represents fastener detuning, i.e., fastener release.

3. The system for achieving low frequency vibration damping using fastener stiffness detuning of claim 2, wherein: the rigidity detuning degree is realized by adjusting the rigidity of the fastener at any fastener of the steel rail.

4. The system for achieving low frequency vibration damping using fastener stiffness detuning of claim 2, wherein: the rigidity of the fastener is adjusted to be changed into a corresponding small-rigidity fastener or manually loosened by using a torque wrench.

5. The system for achieving low frequency vibration damping using fastener stiffness detuning of claim 2, wherein: the steel rail at the rigidity detuning position is provided with a vibration energy dissipation structure.

6. A method for realizing low-frequency vibration reduction by utilizing rigidity detuning of a fastener is characterized by comprising the following steps of: the method is implemented by the system of any one of claims 1-5, the method comprising:

determining the defect state frequency of the steel rail;

determining the approximate range of the stiffness detuning degree of the fastener according to the frequency of the defect state;

and adjusting the rigidity of the fastener at any fastener of the steel rail according to the determined range of the detuning degree of the rigidity of the fastener.

7. The method for achieving low frequency vibration damping using fastener stiffness detuning as claimed in claim 6, wherein: the defect state frequency of the steel rail and the rigidity detuning degree of the fastener satisfy the following relation: -17.326 × Δ k +130.803

Wherein f represents a defect state frequency; Δ k represents fastener detuning.

8. The method of claim 7 for achieving low frequency vibration damping using fastener stiffness detuning, wherein: the rigidity of the pair of fasteners is adjusted to replace the corresponding small-rigidity fastener or manually loosen by using a torque wrench.

Technical Field

The invention belongs to the technical field of rail transit, and particularly relates to a system and a method for realizing low-frequency vibration reduction by utilizing fastener rigidity detuning.

Background

Along with the great improvement of the speed and the operation density of modern railways, more and more railway lines are designed to be complicated and inevitably pass through residential areas and urban areas, when a high-speed railway passes through the residential areas and the urban areas, the vibration of a track structure causes serious noise pollution due to the radiation of sound waves, adverse effects are caused on the working and living health of residents nearby along the line, the normal use of buildings nearby, precise instruments and the like, and the railway system becomes the most representative environmental problem. Therefore, it is important to control the environmental vibration caused by the train running.

Researches have proved that the periodic ballastless track structure has band gap characteristics, vibration waves within the band gap frequency range cannot be transmitted along the longitudinal direction of the steel rail, most vibration energy is transmitted to the lower part of the foundation, and the vibration band gap frequency of the ballastless track structure is mainly within the range of 0-200Hz, which causes the problem of low-frequency environment vibration.

Disclosure of Invention

The invention aims to provide a steel rail vibration absorption system and a steel rail vibration absorption method for solving the problems. Specifically, the present application provides a system for achieving low frequency damping with fastener stiffness detuning, the system comprising: rail and at a plurality of fasteners of rail setting, its characterized in that: the stiffness of the fastener meets the detuning requirement.

Further, it is characterized in that: the rigidity detuning requirement is that the steel rail defect state frequency and the fastener rigidity detuning degree meet the following relation: -17.326 × Δ k +130.803

Wherein f represents a defect state frequency; Δ k represents fastener detuning, i.e., fastener release.

Further, it is characterized in that: the rigidity detuning degree is realized by adjusting the rigidity of the fastener at any fastener of the steel rail.

Further, it is characterized in that: the rigidity of the fastener is adjusted to be changed into a corresponding small-rigidity fastener or manually loosened by using a torque wrench.

Further, it is characterized in that: the steel rail at the rigidity detuning position is provided with a vibration energy dissipation structure.

The application also provides a method for realizing low-frequency vibration reduction by utilizing fastener rigidity detuning, which is characterized in that: the method is implemented by the system of any one of the above, and the method comprises the following steps:

determining the defect state frequency of the steel rail;

determining the approximate range of the stiffness detuning degree of the fastener according to the frequency of the defect state;

and adjusting the rigidity of the fastener at any fastener of the steel rail according to the determined range of the detuning degree of the rigidity of the fastener.

Further, it is characterized in that: the defect state frequency of the steel rail and the rigidity detuning degree of the fastener satisfy the following relation:

f＝-17.326×Δk+130.803

wherein f represents a defect state frequency; Δ k represents fastener detuning.

Further, it is characterized in that: the rigidity of the pair of fasteners is adjusted to replace the corresponding small-rigidity fastener or manually loosen by using a torque wrench.

The method is simple to operate, and the rigidity of the fastener is detuned only by manually loosening the fastener or replacing the small-rigidity fastener; the steel rail at the position of the rigidity detuning of the fastener is only required to be provided with other materials capable of dissipating energy, such as a damping layer and the like, and the whole section of the rail structure is not required to be installed, so that the cost is saved, and the effect of controlling the low-frequency vibration is effectively realized.

Drawings

FIG. 1 is a graph showing the effect of fastener loosening on dispersion characteristics, wherein A is the fastener not loosened and the right side is a partial left-side enlarged view; b is the loosening condition of the fastener, and the right side in the figure is a partial enlarged view of the left side;

FIG. 2 is a graph showing the effect of fastener release on transmission characteristics, where A is the fastener not released; b is the condition that the fastener is not loosened;

FIG. 3 is a graph showing the displacement response of the rail structure when the fastener is unfastened, wherein A is the unfastened condition of the fastener; b represents the loosening condition of the fastener;

FIG. 4 is a graph of power flow distribution of the track structure in a fastener-disengaged condition;

FIG. 5 is an analysis diagram of a defect state versus mode shape; wherein A is a defect state frequency corresponding mode diagram; b is a partial enlarged view;

FIG. 6 is a plot of fastener stiffness detuning versus defect state frequency;

fig. 7 is a schematic diagram of the system of the present application.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

The basic principle of the invention is as follows:

the periodicity of the ballastless track structure is mainly embodied in the periodic support at the lower part, so that when a fastener is loosened on the track structure, the periodicity of the ballastless track structure is influenced, similar to the point defect of a one-dimensional phononic crystal, and the vibration wave energy localization characteristic is further embodied, and based on the characteristic, the invention provides a method for realizing low-frequency vibration reduction by utilizing fastener rigidity detuning: the rigidity of the fastener is manually induced to be detuned, so that vibration energy is concentrated at the detuned position, and then the energy is dissipated by adding damping materials and the like, and the purpose of vibration reduction is achieved. The feasibility of this method is further analyzed below.

The periodicity of the ballastless track structure is mainly embodied in the periodic support at the lower part, so when the fastener of the track structure is loosened, the periodicity of the ballastless track structure is influenced, similar to the point defect of a one-dimensional phononic crystal, and the vibration wave energy localization characteristic is further embodied, so that the control of the environmental vibration is possible: the rigidity of the fastener is manually induced to be detuned, so that vibration energy is concentrated at the detuned position, and then the energy is dissipated by adding damping materials and the like, and the purpose of vibration reduction is achieved. The feasibility of this method is further analyzed below.

In actual engineering, for an integral track bed track, a track bed is formed by integrally pouring concrete, the rigidity of a lower structure is high, and the influence of the lower structures such as track slabs and the like is not considered, so that the lower part is assumed to be a rigid foundation, the periodic ballastless track structure is simplified into an infinite-length single-layer elastic point supporting beam model, a steel rail is simplified into a Timoshenko beam model, and a fastener is simplified into a supporting spring. According to elementary beam theory, a plane wave expansion method is utilized to expand a free vibration balance equation of the steel rail beam into:

in the formula, M₁(G₃-G₁)、M₂(G₃-G₁)、M₃(G₃-G₁)、M₄(G₃-G₁)、k_v(G₃-G₁) The Fourier coefficient respectively represents the product of the density and the cross section area of the steel rail, the Fourier coefficient of the product of the shape coefficient, the shear modulus and the cross section area of the steel rail, the Fourier coefficient of the product of the density and the inertia moment of the cross section of the steel rail, the Fourier coefficient of the product of the elastic modulus and the inertia moment of the cross section of the steel rail and the Fourier coefficient of the vertical rigidity of the fastener; u shape_k(G₁) Fourier coefficient representing vertical displacement of the steel rail beam; theta_k(G₁) Expressing the Fourier coefficient of the steel rail section corner; g₁、G₃Representing the reciprocal lattice vector space.

The formula (1) is essentially an infinite order complex matrix eigenvalue problem, and the vertical vibration dispersion curve of the periodic ballastless track structure can be obtained by solving the eigenvalue equation.

It should be noted that for a perfect periodic track structure with no loosening of the fastener, k_v(G₃-G₁) Can be expressed as:

wherein n represents the number of cells (each cross rail is a cell, namely a section of rail between adjacent fasteners), x_rThe position of the fastener spring is shown, namely the mid-span position of the rail unit cell with the rail under support, and the following conditions are satisfied:

for a detuning ballastless track structure with a loosened fastener, if the elastic support at the lower part of the jth steel rail unit cell is lost, the formula (3) can be written as follows:

fig. 1 shows a vertical vibration dispersion curve of a ballastless track structure under a condition that a fastener is not loosened/loosened.

In the analysis of frequency dispersion characteristics, the rigidity of a standard fastener is 25kN/mm which is a common value of a ballastless track structure in China, and detuning is introduced through the fastener at a certain position where the fastener is completely loosened. As can be seen from fig. 1A, the periodic ballastless track structure has an obvious bandgap characteristic (left part in fig. 1A), and it can be found by comparing 1A and 1B that after detuning is introduced, the original bandgap position does not change greatly, and at the same time, a flat band (corresponding to B2 in fig. 1B) is generated in the band gap range, and the frequency is not 111.54Hz, which is the defect state described in the phononic crystal theory. The effect of fastener stiffness detuning on vibration transmission characteristics is further analyzed below.

FIG. 2 shows the vibration transmission characteristic curve corresponding to the stiffness detuning/no-detuning of the fastener, and in the analysis, the stiffness detuning degree of the fastener is consistent with that in the frequency dispersion analysis, and the loosening degree is still complete.

It can be seen from figure 2 that the rail vibration transmission characteristic curve produces a distinct vibration attenuation region (shaded in figure 2) over the frequency range of 0-500Hz, consistent with the band gap frequency range represented by the 0-500Hz grey shading in figure 1. Meanwhile, as can be seen by comparing fig. 2A and 2B, when the fastener stiffness is detuned in the track structure, a vibration peak (point C2 in fig. 2B) occurs in the vibration attenuation region in the vibration transmission characteristic curve, and the corresponding frequency is 111.54Hz, which is also consistent with the frequency corresponding to the flat band B2 in fig. 1B.

The influence of the fastener loosening on the frequency dispersion characteristic and the transmission characteristic of the periodic ballastless track structure is analyzed, and the defect state of the track structure caused by the fastener loosening is proved. The vibration localization characteristics due to the defect state characteristics are further analyzed below from both vibration response and energy flow.

Fig. 3 shows a acceleration response distribution diagram in a finite-length ballastless track structure corresponding to a defect-state frequency of 111.54Hz under the action of unit harmonic load.

As is apparent from fig. 3A, when the fastener is not loosened, the defect state frequency 111.54Hz is in the band gap frequency range, the vibration wave cannot be transmitted along the longitudinal direction of the steel rail, and the vibration wave is basically attenuated to 0 when being transmitted to the 8 th steel rail cell position; in contrast, in fig. 3B, the rail structure is in a defect state due to the loose of the fastener, the vibration wave can be transmitted along the longitudinal direction of the rail, and a significant vibration amplification phenomenon is generated at the loose position of the fastener, which proves the vibration localization characteristic under the effect of the defect state characteristic. The flow of energy is further analyzed below.

As can be seen from FIG. 4, when the fastener of the track structure is loosened, the frequency of the generated defect state is a pass band, the vibration source can input power flow into the track structure greatly, and about ninety-eight percent of the power flow input into the track structure under the excitation of the frequency of the defect state of 111.54Hz is concentrated at the position of the fastener loosening, so that the vibration energy concentration at the position of the fastener loosening is caused, and the vibration localization characteristic of the position of the fastener loosening caused by the characteristic of the defect state is further proved.

The analysis of the dynamic response and the energy transfer characteristics proves that when the track structure is in a defect state caused by the loosening of the fastener, the elastic wave with the frequency of the defect state is limited at the detuning position, so that energy concentration is caused, and the correctness of the method is further proved, namely the vibration wave energy of a certain frequency band can be concentrated at the detuning position by artificially setting the rigidity detuning of the fastener, and then the concentrated energy is dissipated by adding a damping layer or a steel rail vibration absorber, so that the vibration reduction function is realized.

However, as can be seen from the foregoing analysis, only one defect state is generated when the fastener is loosened at a certain position of the track structure, but only one frequency is corresponding to the defect state, and the application value of vibration damping for controlling only one frequency is not high, which requires improvement on the method proposed at the beginning: through introducing fastener rigidity detune in a plurality of positions of periodic track structure, through the fastener pine degree of adjusting detune department for track structure produces a plurality of defect state frequencies, and then covers certain frequency channel, finally realizes the damping of certain frequency channel. The feasibility of this method was further analyzed below:

TABLE 1 analysis of the frequency of the defect state corresponding to the number of steel rail cells

FIG. 5 shows the rail mode for a defect state frequency of 111.54Hz when a single fastener is fully disengaged, wherein FIG. 5A is a partial enlargement of FIG. 5B. It can be found that the defect state is substantially a local vibration mode of the rail structure after the fastener is loosened, and in the local vibration mode, the steel rail cells loosened by the fastener and the two adjacent left and right cells are main participants of the deformation of the steel rail, and the deformation of the steel rail cells continuously extending towards two sides is gradually reduced along with the increase of the distance, so that the frequency of the defect state is finally converged to a fixed frequency value and cannot be changed along with the length all the time. To verify the convergence of the defect state frequency, we calculated the defect state frequency corresponding to different cell numbers under the condition of complete release of the fastener, as shown in table 1. As is apparent from Table 1, as the number of rail cells constituting the super cell gradually increases, the frequency of defect states generated when a single fastener is completely released gradually converges to 111.54 Hz. The defect states can be generated at a plurality of frequency positions only by introducing the rigidity of the fasteners with different detuning degrees at different positions of the track structure and only by meeting the requirement that the interval between two adjacent detuning positions is at least 3 steel rail unit cell lengths (namely 3 times of the distance between the fasteners), the defect state frequencies generated at the detuning positions are not influenced with each other, a small-range frequency band defect state frequency set is further formed, then concentrated energy is dissipated only by adopting additional damping or a vibration absorber at the detuning positions of the rigidity of the fasteners, and the vibration reduction effect is further realized.

FIG. 6 is a plot of fastener stiffness detuning, which is referred to herein as the degree of fastener release, in percent, versus frequency of defect states. Research shows that when the rigidity of the detuning fastener is higher than that of the standard fastener, the defect state characteristic generated in the track structure is not obvious, and only when the rigidity of the detuning fastener is lower than that of the standard fastener, the obvious defect state characteristic can be generated in the track structure. As can be seen from fig. 6, the defect-state frequency and the fastener stiffness detuning degree are in negative correlation, and polynomial fitting is performed, it can be seen that the defect-state frequency and the fastener stiffness detuning degree can be approximately fitted into a straight line, the correlation coefficient is 0.988, and the relationship between the two is:

f＝-17.326×Δk+130.803 (5)

wherein f represents a defect state frequency; Δ k represents fastener detuning, i.e., fastener release.

Therefore, the required stiffness detuning degree of the fastener can be calculated by using the formula (2) according to the requirement of the actual engineering vibration attenuation frequency band, and then the corresponding arrangement is carried out.

The following description will be made in conjunction with the accompanying drawings, wherein the system for implementing low-frequency damping by utilizing fastener stiffness detuning is based on the above principle, and comprises: rail and at a plurality of fasteners of rail setting, its characterized in that: the stiffness of the fastener meets the detuning requirement.

In one scheme, the stiffness detuning requirement is that the steel rail defect state frequency and the fastener stiffness detuning degree satisfy the following relation: -17.326 × Δ k +130.803

Wherein f represents a defect state frequency; Δ k represents fastener detuning, i.e., fastener release.

In one aspect, the stiffness detuning is achieved by adjusting the stiffness of the fastener at any fastener of the track structure.

Preferably, the rigidity of the fastener is adjusted to replace a corresponding low-rigidity fastener or manually loosened by using a torque wrench.

In one aspect, the rail at the stiffness detuned position is provided with a vibration energy dissipating structure. Preferably, the vibration energy dissipation structure is a damping layer, preferably made of rubber material, attached to two sides of the steel rail. In another aspect, the vibration energy dissipating structure is a dynamic vibration absorber that can be installed at a mid-span location of the rail between two adjacent fasteners. Preferably, the dynamic vibration absorber is in the form of a rubber-metal block (having a certain mass).

The application also provides a method for realizing low-frequency vibration reduction by utilizing fastener spacing detuning, which comprises the following steps:

(1) determining track structure frequency and determining approximate range of fastener stiffness detuning degree

The vibration frequency ranges required to be controlled in different engineering environments are not consistent, the low-frequency vibration frequency band required to be controlled is determined in advance according to the actual engineering condition, and the approximate range of the stiffness detuning degree of the fastener is determined through a relation formula (5) of the defect state frequency and the stiffness detuning degree of the fastener;

(2) according to the determined range of the stiffness detuning degree of the fastener, the stiffness of the fastener is adjusted at any fastener of the track structure

And adjusting the rigidity of the fastener at any fastener of the track structure according to the determined range of the detuning degree of the rigidity of the fastener. For the adjustment of the rigidity of the fastener, the corresponding small-rigidity fastener can be directly replaced, or a torque wrench can be used for artificial loosening, and then strain gauge tests are integrated to set the rigidity of the fastener, or the rigidity detuning degree of the fastener refers to the loosening degree of the fastener, in percentage, and the bolt tightening torque of the rail structure fastener is usually 120N · m, so that the rigidity change of the fastener can be roughly defined by the torque through the torque wrench directly. Such as: the required loosening degree of the fastener is calculated to be 20%, the tightening torque of the fastener bolt is 120 N.m, so that the torque of the loosened fastener bolt is about 96 N.m, the torque of the torque wrench is set to be 96 N.m, and then the fastener bolt is manually loosened by using the torque wrench. Because the actual track is approximately infinitely long, the stiffness of the track can be adjusted at any fastener position, and it should be noted that two adjacent fastener stiffness detuned positions should be at least three standard fastener pitch distances apart;

(3) after the rigidity of the fastener is correctly set to be detuned, other materials capable of dissipating energy such as a damping layer or a vibration absorber are installed on the steel rail at the rigidity detuned position of the fastener, and the like: if the damping layer is installed, the damping layer is attached to two sides of the steel rail by adopting a simple rubber material; if the dynamic vibration absorber is installed, the dynamic vibration absorber can be installed at the midspan position of the steel rail between two adjacent fasteners, and a rubber-metal block (with certain mass) form can also be used for replacing a complex dynamic vibration absorber.