CN113106788A - Floating track bed vibration reduction method and device based on multilayer composite damping - Google Patents
Floating track bed vibration reduction method and device based on multilayer composite damping Download PDFInfo
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- CN113106788A CN113106788A CN202110255694.3A CN202110255694A CN113106788A CN 113106788 A CN113106788 A CN 113106788A CN 202110255694 A CN202110255694 A CN 202110255694A CN 113106788 A CN113106788 A CN 113106788A
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B1/00—Ballastway; Other means for supporting the sleepers or the track; Drainage of the ballastway
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B19/00—Protection of permanent way against development of dust or against the effect of wind, sun, frost, or corrosion; Means to reduce development of noise
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Abstract
The invention relates to the field of rail transit, and discloses a floating track bed vibration reduction method and a vibration reduction device based on multilayer composite damping, wherein the vibration reduction method comprises the following steps: s10, determining a vibration transmission path according to the vibration generation source; s20, establishing a dynamic model based on the floating track bed based on the vibration transmission path; s30, carrying out vibration analysis on the floating track bed structure based on the dynamic model, and establishing a finite element mathematical model based on a finite element method and the floating track bed structure; s40, based on the finite element mathematical model, counting the interlayer displacement to obtain the best vibration reduction effect, and determining the thickness of the damping composite layer, the ratio of the thickness of the damping composite layer to the thickness of the restraint layer, the combined parameters of the damping composite layer and the number of the restraint layers.
Description
Technical Field
The invention relates to the field of rail transit, in particular to a floating track bed vibration reduction method and a vibration reduction device based on multilayer composite damping.
Background
At present, with the call of national low-carbon travel, subway travel becomes an indispensable selection mode for citizens, more and more cities plan to build or increase subway lines of cities, and the design of subway station ports of each station is usually close to residential quarter positions as much as possible in consideration of convenience of citizens in travel. When the subway train runs, the train is excited by a series of excitation from wheel tracks and the like to generate vibration, including impact of the weight load of the train on the rails. Finally, the vibration passes through the track system in an energy mode, passes through the track foundation and the soil layer, and is transmitted to surrounding buildings, so that noise is further generated, and normal life of people is influenced. As an important urban rail transit system, a subway is responsible for most of passenger flow in the city, and once a rail structure is vibrated for a long time to cause fatigue damage, the traveling of millions of people is influenced, and traffic paralysis is caused in severe cases.
The structure of present floating track bed is comparatively simple, generally only uses vibration isolation spring to carry out the damping, and the damping effect is relatively weak.
Disclosure of Invention
Therefore, a floating track bed vibration reduction method and a vibration reduction device based on multilayer composite damping are needed to be provided, and a vibration reduction scheme is optimized to improve the vibration reduction effect of the floating track bed.
In order to achieve the aim, the invention provides a floating track bed vibration reduction method based on multilayer composite damping, which is applied to a floating track bed of rail transit, wherein the floating track bed comprises at least two layers of constraint layers, at least one layer of damping composite layer is arranged between every two adjacent constraint layers, and the elastic modulus of the constraint layers is greater than that of the damping composite layers;
the vibration reduction method comprises the following steps:
s10, determining a vibration transmission path from the vibration generating source to the floating track bed to a roadbed connected with the floating track bed to a tunnel foundation where the roadbed is installed according to the vibration generating source;
s20, establishing a dynamic model based on the floating track bed based on the vibration transmission path;
s30, carrying out vibration analysis on the floating track bed structure based on the dynamic model, and establishing a finite element mathematical model based on a finite element method and the floating track bed structure;
and S40, counting the interlayer displacement condition to obtain the best vibration reduction effect based on the finite element mathematical model, and determining the combined parameters of the thickness of the damping composite layer, the ratio of the thickness of the damping composite layer to the thickness of the constraining layer, the damping composite layer and the number of the constraining layers.
Further, the vibration generation source includes the following:
(1) the self-weight load of the train impacts a rail arranged on the floating track bed;
(2) at the same time, different interaction forces are generated between each wheel of the train and the rail;
(3) periodically exciting the eccentricity of each wheel of the train;
(4) the rails mounted on the floating track bed are excited due to the unevenness.
Further, the finite element method comprises a classical lamination theory, a first-order shear deformation theory, a high-order shear deformation theory, a laminated plate shell theory, a composite unit method and an integral division unit method.
A floating track bed vibration damper based on multilayer composite damping comprises a floating track bed, a roadbed and a vibration isolator, wherein the vibration isolator is fixed on the roadbed, a floating gap is formed between the floating track bed and the roadbed, and the vibration isolator supports the floating track bed; the floating track bed comprises at least two layers of constrained layers, at least one damping composite layer is arranged between every two adjacent constrained layers, the elastic modulus of the constrained layers is larger than that of the damping composite layer, the damping composite layer comprises a plurality of mutually fixed damping layers, and the combination of the thickness of the damping composite layer, the thickness ratio of the damping composite layer to the constrained layers, the damping composite layer and the number of the constrained layers is determined by the vibration damping method.
Further, the thickness of the damping layer is 1-50mm, and the ratio of the thickness of the damping composite layer to the thickness of the constraining layer is 0.01-15.
Further, the floating track bed comprises five constraint layers, a damping composite layer is arranged between every two adjacent constraint layers, the thickness of the damping composite layer is 30mm, and the ratio of the thickness of the damping composite layer to the thickness of the constraint layers is 4.
Further, the damping composite bed contains a plurality of layers of damping layers, and the material of each layer of damping layer is selected from fiber reinforcement type resin, dura mater fiber, polyester staple fiber, glass silk staple fiber, polyurethane or blend alone, the blend is the blend of one or more elastomers in pitch and SBS, APP, EVA, CPE, include metal fiber fabric in the damping layer, non-metal fiber fabric, polymer fiber fabric or filler material, filler material is one or more in talcum powder, rubber powder, saw-dust, core, mica sheet, graphite flake, plastics, metal powder, the composite film. The restraint layer is made of epoxy resin or cement.
Furthermore, a plurality of damping mounting grooves are formed in at least one layer of the constraint layer, and particle dampers are fixed in the damping mounting grooves.
Furthermore, a plurality of damping mounting grooves are distributed on the constraint layers in an array mode, and the damping mounting grooves between every two adjacent constraint layers are arranged in a staggered mode or in an aligned mode.
Further, the particle damper comprises an upper end cover, a damper shell, damping particles and a lower end cover, wherein the inner hollow part of the damper shell is provided with a filling cavity, the damping particles are filled into the filling cavity, the damper shell is arranged in a damping mounting groove, and the upper end cover and the lower end cover are respectively fixed at the upper port and the lower port of the damping mounting groove.
The technical scheme has the following beneficial effects:
1. the method can quickly determine the floating track bed structure with the damping composite layer and the constraint layer, and when the floating track bed structure determined by the method is vibrated, the displacement deformation value of the floating track bed is small, the vibration reduction effect is good, and the stability and the safety of the whole traffic system are favorably improved
2. In the vibration damping device, because the elastic modulus of the constraint layer is greater than that of the damping composite layer, when the vibration damping device is subjected to bending vibration, the tensile deformation of the constraint layer is smaller than that of the damping layer, so that the stretching and the compression of the damping layer are hindered, the shear strain and the shear stress are generated in the damping composite layer, and the effect of dissipating the vibration energy is achieved by utilizing the shear effect of the damping layer.
Drawings
Fig. 1 is a flow chart of the vibration damping method described in embodiment 1.
Fig. 2 is a schematic view of the excitation source to a railway system.
Figure 3 is a form of connection of the railway system to the surrounding building.
Fig. 4 is a front view (ZX plane) of a dynamic model of a train-track-floating track bed-roadbed based vibration system.
Fig. 5 is a front view (ZY-plane) of a dynamic model of a vibration system based on train-track-floating track bed-roadbed.
FIG. 6 is a structure of a constraining layer and a damping composite layer.
FIG. 7 is a finite element model of a multilayer composite damping floating track bed vibration damping structure based on hexahedral elements.
FIG. 8 is a graph of displacement deformation values of a floating track bed based on multi-layer composite damping as a function of damping composite layer thickness.
FIG. 9 is a graph of the displacement deformation value of a floating track bed based on multi-layer composite damping as a function of the ratio of the thickness of the damping composite layer to the thickness of the constraining layer.
FIG. 10 is a graph showing the variation of the displacement deformation value of the floating track bed based on the multi-layer composite damping according to the ratio of the thickness of the damping composite layer to the thickness of the constraining layer, the combination of the damping composite layer and the number of the constraining layers.
Fig. 11 is a floating track bed damping device based on multilayer composite damping as described in example 2.
FIG. 12 is a floating track bed vibration damping device based on multi-layer composite damping as described in example 3.
FIG. 13 is a floating track bed vibration damping device based on multi-layer composite damping as described in example 4.
FIG. 14 is a floating track bed vibration damping device based on multi-layer composite damping as described in example 5.
FIG. 15 is a floating track bed vibration damping device based on multi-layer composite damping as described in example 6.
FIG. 16 shows a structure of a particle damper according to example 6.
FIG. 17 is a floating track bed vibration damping device based on multi-layer composite damping as described in example 7.
Description of reference numerals:
1. a floating track bed; 11. a constraining layer; 12. a damping composite layer; 121. a damping layer; 13. a damping mounting groove;
2. a rail; 3. a train; 4. a roadbed; 5. a vibration isolator; 6. a fastener;
7. a particle damper; 71. damping particles; 72. an upper end cover; 73. a damper housing; 74. a lower end cover;
Detailed Description
To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.
Example 1
Referring to fig. 1 to 10, in this embodiment, a floating track bed vibration damping method based on multilayer composite damping is provided, and is applied to a floating track bed 1 of rail transit, where the floating track bed 1 includes at least two constraining layers 11, at least one damping composite layer 12 is disposed between two adjacent constraining layers 11, and an elastic modulus of the constraining layer 11 is greater than an elastic modulus of the damping composite layer 12;
the vibration reduction method comprises the following steps:
s10, according to the vibration generating source, determining the vibration transmission path from the vibration generating source to the floating track bed 1 to the roadbed 4 connected with the floating track bed 1 to the tunnel foundation where the roadbed 4 is installed; the vibration generating sources include the following: 1, the dead weight load of a train 3 impacts a rail 2 installed on the floating track bed 1; 2, different interaction forces between each wheel of the train 3 and the rail 2 at the same moment; 3 eccentric periodic excitation of each wheel of the train 3; 4 excitation of the rail 2 installed on the floating track bed 1 due to the irregularity; as shown in fig. 2, the vibration generating source is the impact on the rail 2 during the running of the train 3, the vibration input end is the connecting position of the floating track bed 1 and the fastener 6, and the railway system comprises the fastener 6, the vibration isolator 5, the floating track bed 1, the rail 2 and the train 3. As shown in fig. 3, in the form of vibration generation source transmitted to the floating track bed 1, to the roadbed 4, to the surrounding building, in the form of the train 3 from the front and rear of the train to the rails 2, to the clip 6 parts, to the floating track bed 1, to the vibration isolators 5, to the entire railway system and the roadbed 4, to the tunnel foundation, to the surrounding building. The specific form is that the excitation vibration source is transmitted to the whole railway system from the contact surface of the train 3 wheel and the rail 2, transmitted to the roadbed 4 and then transmitted to the surrounding buildings in the form of waves, and the noise is directly radiated to the surrounding buildings.
S20, establishing a dynamic model based on the floating track bed 1 based on the vibration transmission path;
as shown in fig. 4 and 5, a dynamic model of the floating track bed 1 is established for the vibration system of the train 3-track-floating track bed 1-roadbed 4 based on a dynamic analysis method. A rectangular coordinate system is established for the mass center of the train 3, the transverse direction of the train 3 is taken as the X direction, the longitudinal direction is taken as the Z direction, and the length direction is taken as the Y direction. In the ZY plane direction, the rail 2 is positioned on the fastener 6 part, the fastener 6 part is regarded as an elastic supporting point, namely a linear damping unit, the arrangement mode of the fastener 6 part is determined according to the actual distance between the Y direction and the X direction, the fastener 6 part is positioned on the floating track bed 1 and can be regarded as a rigid short beam solid unit, and the longitudinal rigidity and the damping are mainly provided; the vibration isolators 5 located below the floating track bed 1 are connected with the roadbed 4 and the floating track bed 1, the three-way rigidity of the vibration isolators 5 is mainly provided by springs and can be linearly deformed, the damping is provided by viscous damping, the number of the vibration isolators 5 is also determined by specific intervals, the roadbed 4 is regarded as rigid by the combination of the uniformly distributed linear springs and the damping. In the present embodiment, mainly, the vibration generation source generated by the contact of the wheels with the rail 2 during the running of the train 3 is considered, which includes the excitation of x (t), y (t), and z (t). Certain rigidity and damping are contained between the train 3 carriage and the bogie, so that the problem of vibration transmitted to the train from an excitation vibration source is solved.
In fig. 4 and 5, M1 is the mass of the train, M2 is the mass of the bogie, M3 is the mass of the rail, M4 is the mass of the clip component, M5 is the mass of the floating track bed, M6 is the mass of the vibration isolator, M7 is the mass of the wheel, H1 is the vertical distance between the train and bogie centroids, d4 is the height of the clip component, d5 is the longitudinal height of the floating track bed, H2 is the floating gap between the floating track bed and the subgrade, L1 is the lateral spacing of the rail, L2 is the lateral spacing of the clip component, and L3 is the lateral spacing of the vibration isolator mounting groove.
S30, carrying out vibration analysis on the floating track bed structure based on the dynamic model, and establishing a finite element mathematical model based on a finite element method and the floating track bed structure; the finite element method comprises a classical lamination theory, a first-order shear deformation theory, a high-order shear deformation theory, a laminated plate shell theory, a composite unit method and an integral division unit method
Viscous damping is added to a single degree of freedom system, and comprises the following components:
in the formula, FdA damping coefficient representing viscous damping, c a damping coefficient representing viscous damping,
indicating the speed.
In the present embodiment, the damping composite layer 12 generates internal friction due to the deformation of the material under stress, so as to bring stress strain, and a hysteresis curve is formed after a phase is generated between the force and the deformation.
For simple harmonic motion, the damping force generated by viscous damping can be expressed as
In the formula, ω is frequency; psi is the phase; a is the amplitude.
From the hysteresis curve, in viscous damping, the energy lost per cycle is proportional to the stiffness of the material and proportional to the square of the displacement amplitude, i.e., the ratio of the energy loss to the maximum potential energy.
ΔE＝πβkA2
Wherein Δ E is the loss energy; beta is a damping constant; k is the structural equivalent spring coefficient; a is the amplitude.
In one loading cycle, the area of the hysteresis curve is the energy loss, so:
the two equations representing energy loss are equal, the equivalent viscous damping coefficient is expressed as:
based on the actual stress condition of the floating track bed 1, the floating track bed 1 is a member such as a plate and a beam, and the floating track bed 1 can be regarded as a multi-degree-of-freedom system in a railway system, so that infinite resonance points exist. Multiple resonances can be generated without the structure being destroyed. The damping treatment adopts a layered structure design, the size of the damping is expressed by a loss factor, and the damping can be known according to a hysteresis curve.
In the formula, eta is a loss factor; k is the stiffness of the system; and c is the equivalent damping coefficient of the system.
As can be seen from the formula of the loss factor, in a certain situation, the loss factor may have a linear relationship with the excitation frequency, but the viscous damping is not necessarily satisfied, so the viscous damping is expressed by a certain frequency domain time period, that is:
since the vibration isolator mounting groove is smaller than the overall dimension of the floating track bed, as shown in fig. 6, the structure of the constrained layer and the damping composite layer is shown, where d6 is the thickness of the composite damping layer 12, i.e. the Z-direction height, d7 is the thickness of the constrained layer 11, and then the composite material loss factor of the floating track bed 1 structure based on one composite damping layer 12 and one constrained layer 11 is:
in the formula eta2Is the equivalent loss factor of the composite damping; e2The equivalent elastic modulus of the composite damping; e1Is the modulus of elasticity of the constraining layer; d6Is the thickness of the composite damper 12; d7Is the thickness of the constraining layer 1.
In the frequency domain range, a dynamic equation is established for the multi-degree-of-freedom system, namely:
-mω2+[iωc(ω)+k]X(iω)＝F(iω)
based on the generalized coordination theory, the damping composite layer 12 of the floating track bed 1 is partially discretized into a plurality of unit bodies, so that the generalized potential energy general function of the whole system of the floating track bed based on the composite damping can be obtained, and the generalized potential energy general function is as follows:
the potential energy of the discrete unit k is
The additional energy around the discrete unit k due to the uncoordinated displacement is expressed as
As shown in fig. 7, based on Timoshenko theory and finite element method, 8-node units are established for the floating track bed 1 in a hexahedral unit manner, each node of each hexahedral unit contains 3 degrees of freedom of planar movement and 2n degrees of freedom of rotation, where the length of the unit is L, the thickness is t, the deflection is ω, the rotation angle is Φ, the shear strain is γ, and then the degree of freedom of the k unit is:
qk＝[q1,q2,q3,q4,q5,q6]T
the degree of freedom of node m of unit k is:
according to the generalized coordination theory, the strain, curvature and shear strain in the layer are obtained for each layer, namely:
according to the elastic mechanics, the internal stress of each layer is as follows:
σm＝Dm·εm
in the formula, DmAnd
is a material parameter matrix.
The above formula can be generalized to the multilayer composite damping floating track bed 1, and this embodiment is not to be considered as much as possible.
S40, based on the finite element mathematical model, counting the interlayer displacement condition to obtain the best vibration reduction effect, and determining the thickness of the damping composite layer 12, the ratio of the thickness of the damping composite layer 12 to the thickness of the constrained layer 11, and the layer number combination parameters of the damping composite layer 12 and the constrained layer 11;
the floating track bed 1 of the present embodiment is composed of a constrained layer 11 and a damping composite layer 12, and the number of the layers is several.
The damping layer 121 is made of a viscoelastic material, i.e., a rubber or plastic high polymer, and the original structural member of the floating track bed 1 is selected as the constraint layer 11, and is also an elastic layer made of cement. When the train 3 passes over the rails 2, the train 3 applies a certain harmonic excitation to the floating track bed 1 through the rails 2, thereby causing vibration, so that the whole floating track bed 1 is subjected to tension-compression deformation. The elastic modulus of the constraint layer 11 at the lower end is larger, and the displacement deformation of the constraint layer is smaller than that of the damping composite layer 12 at the upper end, so that an acting force in the opposite direction is generated on the damping composite layer 12, the stretching, compression and displacement deformation of the damping composite layer 12 are influenced, the shear stress strain is generated in the damping composite layer 12, finally, the vibration energy is dissipated through the shear stress strain of the damping composite layer 12, and the purpose of vibration reduction is achieved.
Under different parameters, the constrained layers 11 with different thicknesses are added above the damping composite layer 12 for comparison, the constrained layers 11 with the thicknesses of no constrained layer 11, 5mm, 10mm, 15mm and 20mm are set, at the moment, the shear deformation can be generated above the composite damping under the action of the constrained layer 11 and the constrained layer 11, and the best damping effect can be obtained by comparing the displacement deformation of the damping composite layer 12 under different parameters.
1. One parameter of the thickness of the damping composite layer 12, the ratio of the thickness of the damping composite layer 12 to the thickness of the constrained layer 11, and the combination of the number of the layers of the damping composite layer 12 and the constrained layer 11 is selected as a first research parameter, in the embodiment, the thickness of the damping composite layer 12 is used as the first research parameter, the thickness range is set to be 1mm-50mm, the ratio of the thickness of the damping composite layer 12 to the thickness of the constrained layer 11, the combination of the thickness of the damping composite layer 12 and the number of the layers of the constrained layer 11 are ensured to be the same, corresponding parameter values are input in finite element software, the first research parameter is used as a variable, and the displacement deformation of the floating track bed 1 is calculated and compared to obtain the. Use of
2. On the basis of the above steps, the remaining two parameters are the second study parameters, the ratio of the thickness of the damping composite layer 12 to the thickness of the constraining layer 11 is selected as the second study parameter in the embodiment, and the parameter selection range is 0 to 15, then the damping composite layer 12 and the constraining layer 11 are combined into the third study parameter, the optimal value of the first study parameter is input, the parameter value of the third study parameter is ensured to be the same, the second study parameter is used as a variable, the parameter value of the study parameter is input into finite element software, and is set to be 0 to 15, and the optimal parameters are determined by calculating and comparing the respective ratios of the thicknesses of the damping composite layer 12 and the constraining layer 11.
2. After the optimal values of the first research parameter and the second research parameter are obtained, the rest composite damping parameters are used as third research parameters, the third research parameters are used as research variables, the optimal values of the first research parameter and the second research parameter are input, the third research parameters are used as variables, the parameter values of the research parameters are input in finite element software, the first layer of constraint layer 11, the second layer of damping composite layer 12+ the first layer of constraint layer 11, the first layer of damping composite layer 12+ the second layer of constraint layer 11, the second layer of damping composite layer 12+ the third layer of constraint layer 11, the third layer of damping composite layer 12+ the fourth layer of constraint layer 11 and the fourth layer of damping composite layer 12+ the fifth layer of constraint layer 11 are set, and displacement deformation under the condition that different damping composite layers 12 and constraint layers 11 are added is calculated and compared respectively to determine the optimal parameters of the research.
As shown in fig. 9-11, in this embodiment, the optimal value of the thickness of the damping composite layer 12 is 30mm, the optimal value of the ratio of the thickness of the damping composite layer 12 to the thickness of the constraining layer 11 is 4, and the optimal value of the combination of the number of layers of the damping composite layer 12 and the constraining layer 11 is 4 damping composite layers 12+5 constraining layers 11.
It should be noted that, the determining processes of the thickness of the damping composite layer 12, the ratio of the thickness of the damping composite layer 12 to the thickness of the constraining layer 11, and the number of layers of the damping composite layer 12 and the constraining layer 11 are independent from each other and do not interfere with each other, and besides, in this embodiment, any one of the ratio of the thickness of the damping composite layer 12 to the thickness of the constraining layer 11, the number of layers of the damping composite layer 12 and the constraining layer 11, and the thickness of the damping composite layer 12 may be used as a first research parameter, and then the remaining two parameters are determined based on the determined parameters.
For example, the same number of damping composite layers 12 and constraining layers 11 and the same thickness of the damping composite layers 12 are input in the finite element software, the displacement deformation conditions of the floating track bed 1 under different ratios of the thicknesses of the damping composite layers 12 and the constraining layers 11 are observed and counted, and the parameter value with the minimum displacement deformation is taken as the optimal value.
Then, the optimal value of the ratio of the thickness of the damping composite layer 12 to the thickness of the constrained layer 11 and the same value of the thickness parameter of the damping composite layer 12 are input in the finite element software, the displacement deformation condition of the floating track bed 1 under different combinations of the layers of the damping composite layer 12 and the constrained layer 11 is observed and counted, and the value of the parameter with the minimum displacement deformation is taken as the optimal value.
Then, the optimal value of the ratio of the thickness of the damping composite layer 12 to the thickness of the constraint layer 11 and the optimal combination of the number of the damping composite layer 12 and the number of the constraint layer 11 are obtained on the basis of the steps, corresponding parameters are input into finite element software, the displacement deformation conditions of the floating track bed 1 under different thicknesses of the damping composite layer 12 are observed and counted, and the parameter value with the minimum displacement deformation is used as the optimal value.
And finally, setting the floating track bed 1 according to the ratio of the thickness of the damping composite layer 12 to the thickness of the constraint layer 11, the combination of the number of the damping composite layers 12 and the number of the constraint layers 11 and the thickness of the damping composite layer 12 determined in the steps, and then installing the set floating track bed 1 based on the composite damping in a railway system, so that the floating track bed 1 adopting the composite damping has the maximum damping effect, and the damping effect of the floating track bed 1 can be further improved.
On the basis, in order to verify the actual vibration damping effect of the multilayer damping composite layer 12, in this embodiment, a frequency sweep test may be performed on the floating track bed 1 on which the composite damping is installed, and the vibration damping effect of the floating track bed 1 is determined by comparing the total effective value of the acceleration of the floating track bed 1 before and after the composite damping is adopted, which is not discussed in detail in this embodiment.
The invention changes the structure and material composition of the floating track bed 1, applies the composite damping on the floating track bed 1, when the vibration generating source generates vibration, so that when the whole floating track bed 1 vibrates and even deforms, the inside of the damping composite layer 12 generates tension-compression deformation or shear deformation, and under the action of shear stress strain, the vibration energy of the whole structure is dissipated, thereby improving the structural damping of the railway system, further reducing the vibration amplitude of the railway system on the basis of the vibration isolator 5, and further improving the dynamic characteristic of the whole railway system.
Example 2
As shown in fig. 11, the embodiment provides a floating track bed vibration damper based on multilayer composite damping, which includes a floating track bed 1, a roadbed 4 and vibration isolators 5, wherein the vibration isolators 5 are fixed on the roadbed 4, a floating gap is formed between the floating track bed 1 and the roadbed, and the vibration isolators 5 support the floating track bed 1; the floating track bed 1 is provided with a plurality of fasteners 6 arranged at intervals, the fasteners 6 are used for fastening and fixing the rail 2, and the train 3 moves along the rail 2.
The floating track bed 1 comprises two layers of damping composite layers 12 and three layers of constraint layers 11 which are alternately stacked, the outermost two layers of constraint layers 11 clamp and fix the damping composite layers 12, the middle constraint layers 11 play a supporting role, and the damping composite layers 12 comprise three layers of damping layers 121.
The floating track bed 1 adopts a built-in steel spring vibration isolator 5, comprising: the road bed board has the following overall dimensions: the length of the standard plate is 25m, the width is 3.2m, the thickness is 300mm-400mm, 0.34m is taken, the height of a floating gap is 30mm, and the main component of the restraint layer 11 is concrete; the vibration isolator 5 comprises a spiral steel spring, viscous damping, an outer sleeve, a leveling steel plate and a locking system. The twice of the longitudinal distance of the fasteners 6 is a span, the longitudinal distance of the common vibration isolators 5 is three forms of one-time span, two-time span and three-time span, the distance of the vibration isolators 5 of the embodiment adopts one-time span, the longitudinal distance of the fasteners 6 on the floating track bed 1 is 0.625m, namely, the longitudinal distance of the steel springs is 1.25m of the distance of the two-time fasteners 6, and 20 steel spring vibration isolators 5 are arranged on one side of the floating track bed 1. The transverse spacing of the steel spring vibration isolator 5 is 1860mm, the transverse spacing of the lower gasket of the fastener 6 is 1513mm, and the diameter of the bottom of the steel spring vibration isolator 5 is 350 mm.
Example 3
As shown in fig. 12, this embodiment provides a floating track bed vibration damping device based on multi-layer composite damping, which is different from embodiment 2 in that there are three spaced constraining layers 11, and two mutually superposed damping composite layers 12 are provided between each two constraining layers 11, and the top and bottom constraining layers 11 are not shown in the figure.
Example 4
As shown in fig. 13, this embodiment provides a floating track bed vibration damping device based on multilayer composite damping, which is different from embodiment 2 in that there are 5 constraining layers 11 arranged at intervals, there is a damping composite layer 12 stacked between every two constraining layers 11, and each damping composite layer 12 includes three damping layers 121. The vibration damping calculation results of the examples 1 and 4, the first constraining layer, the first composite damping layer, the second constraining layer, the third composite damping layer and the fourth constraining layer are shown in fig. 10.
Example 5
As shown in fig. 14, this embodiment provides a floating track bed vibration damping device based on multilayer composite damping, which is different from embodiment 1 in that a plurality of damping mounting grooves 13 are arranged on three layers of constraining layers 11 in an array, and the damping mounting grooves 13 on the three layers of constraining layers 11 are aligned up and down.
In another embodiment, the damping installation grooves 13 on the adjacent constraint layers 11 are arranged in a staggered manner.
The particle damper 7 is fixed in the damping mounting groove 13. The particle damper 7 is filled with damping particles 71.
The particle damper 7 is made of rigid materials, and the outer surface of the damper shell is connected with the damping mounting groove 13 in a threaded connection mode, a key connection mode, a pin connection mode, a welding mode, a bonding mode, an interference connection mode, a riveting molding surface connection mode or a cement pouring connection mode.
The damping particles 71 are spherical or polyhedral in shape; the diameter range of the spherical damping particles 71 is 0.1mm-100mm, the side length range of the polyhedral damping particles 71 is 0.1mm-100mm, the damping particles 71 are one or more of alloy particles, glass particles, oxide ceramic particles, carbide ceramic particles and glass ceramic particles, and the alloy particles are made of one or more of iron-based alloy, aluminum-based alloy, tungsten-based alloy, nano-based alloy, magnesium-based alloy, potassium-based alloy, copper-based alloy, calcium-based alloy, scandium-based alloy, titanium-based alloy, vanadium-based alloy, nickel-based alloy, cobalt-based alloy, manganese-based alloy, lead-based alloy and chromium-based alloy.
Example 6
As shown in fig. 15 to 16, the present embodiment provides a floating track bed vibration damping device based on multilayer composite damping, which is different from embodiment 4 in that the floating track bed 1 of the present embodiment has only two layers of constraining layers 11, a damping composite layer 12 is provided between the two layers of constraining layers 11, and damping mounting grooves 13 on the two layers of constraining layers 11 are aligned with each other.
The particle damper 7 comprises a damper shell 73, a damper upper end cover 72, a damper lower end cover 74 and a plurality of particle dampers, wherein the damper shell 73, the damper upper end cover 74 and the damper lower end cover 74 are made of stainless steel in the embodiment, and the particle damper 7 is integrally a cylindrical frame body. A cavity with a certain volume is arranged in the damper, and particle damping is arranged in the damper cavity. The upper end cover 74 and the lower end cover 74 of the particle damper 7 are respectively provided with four threaded holes, and the damper housing 73 is fixedly connected with the damping mounting groove 13 through the four threaded holes of the upper end cover 74 and the lower end cover 74 of the particle damper 7 by bolts.
Example 7
As shown in fig. 17, this embodiment provides a floating track bed vibration damping device based on multilayer composite damping, which is different from embodiment 4 in that only the middle one of three constraining layers 11 has damping mounting grooves 13, and the damping mounting grooves 13 of the middle constraining layer 11 are distributed in an array.
In the invention, because the elastic modulus of the constraint layer 11 is greater than that of the damping composite layer 12, when bending vibration is applied, the tensile deformation of the constraint layer 11 is less than that of the damping layer 121, so as to hinder the stretching and compression of the damping layer 121, thereby generating shear strain and shear stress in the damping composite layer 12, and achieving the effect of dissipating vibration energy by using the shear effect of the damping layer 121, meanwhile, the particle damper 7 on the constraint layer 11 can effectively reduce the vibration transmitted from the constraint layer 11 to the damping composite layer 12, and the damping particles 71 in the particle damper 7 and the shear effect of the damping layer 121 play a synergistic role to jointly reduce the vibration on the floating track bed 1.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal that comprises the element. Further, herein, "greater than," "less than," "more than," and the like are understood to exclude the present numbers; the terms "above", "below", "within" and the like are to be understood as including the number.
Although the embodiments have been described, once the basic inventive concept is obtained, other variations and modifications of these embodiments can be made by those skilled in the art, so that the above embodiments are only examples of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes using the contents of the present specification and drawings, or any other related technical fields, which are directly or indirectly applied thereto, are included in the scope of the present invention.
Claims (10)
1. A vibration reduction method of a floating track bed based on multilayer composite damping is characterized in that the vibration reduction method is applied to the floating track bed of rail transit, the floating track bed comprises at least two layers of constraint layers, at least one layer of damping composite layer is arranged between every two adjacent constraint layers, and the elastic modulus of the constraint layers is greater than that of the damping composite layers;
the vibration reduction method comprises the following steps:
s10, determining a vibration transmission path from the vibration generating source to the floating track bed to a roadbed connected with the floating track bed to a tunnel foundation where the roadbed is installed according to the vibration generating source;
s20, establishing a dynamic model based on the floating track bed based on the vibration transmission path;
s30, carrying out vibration analysis on the floating track bed structure based on the dynamic model, and establishing a finite element mathematical model based on a finite element method and the floating track bed structure;
and S40, counting the interlayer displacement condition to obtain the best vibration reduction effect based on the finite element mathematical model, and determining the combined parameters of the thickness of the damping composite layer, the ratio of the thickness of the damping composite layer to the thickness of the constraining layer, the damping composite layer and the number of the constraining layers.
2. The floating track bed damping method of claim 1, wherein said vibration generating sources include the following:
(1) the self-weight load of the train impacts a rail arranged on the floating track bed;
(2) at the same time, different interaction forces are generated between each wheel of the train and the rail;
(3) periodically exciting the eccentricity of each wheel of the train;
(4) the rails mounted on the floating track bed are excited due to the unevenness.
3. The floating track bed damping method of claim 1 wherein the finite element method comprises classical lamination theory, first order shear deformation theory and higher order shear deformation theory, laminate shell theory, composite element method and integral split element method.
4. The floating track bed vibration damper based on the multilayer composite damping is characterized by comprising a floating track bed, a roadbed and a vibration isolator, wherein the vibration isolator is fixed on the roadbed, a floating gap is formed between the floating track bed and the roadbed, and the vibration isolator supports the floating track bed; the floating track bed comprises at least two layers of constrained layers, at least one damping composite layer is arranged between every two adjacent constrained layers, the elastic modulus of the constrained layers is larger than that of the damping composite layer, the damping composite layer comprises a plurality of mutually fixed damping layers, and the combination of the thickness of the damping composite layer, the ratio of the thickness of the damping composite layer to the thickness of the constrained layers, the damping composite layer and the number of the constrained layers is determined by adopting the vibration damping method of any one of claims 1 to 3.
5. The floating track bed damping method of claim 4, wherein; the thickness of the damping layer is 1-50mm, and the ratio of the thickness of the damping composite layer to the thickness of the restraint layer is 0.01-15.
6. The floating track bed vibration damper of claim 5 wherein said floating track bed includes five constraining layers with a damping composite layer between each two adjacent constraining layers, said damping composite layer having a thickness of 30mm and a ratio of the thickness of the damping composite layer to the thickness of the constraining layer of 4.
7. The floating track bed vibration damper of claim 4 wherein said damping composite layer comprises several damping layers, each damping layer is made of fiber reinforced resin, Dula fiber, polyester staple fiber, fiberglass staple fiber, polyurethane or blend, said blend is made of asphalt and one or more elastomers selected from SBS, APP, EVA and CPE, said damping layer comprises metal fiber fabric, non-metal fiber fabric, polymer fiber fabric or filling material, said filling material is one or more of talcum powder, rubber powder, wood dust, core material, mica sheet, graphite sheet, plastic, metal powder and composite film, said restraint layer is made of epoxy resin or cement.
8. The floating track bed vibration damping device of claim 4 wherein at least one of said constraining layers has a plurality of damping mount slots formed therein, said damping mount slots having particle dampers secured therein.
9. The floating track bed vibration damping device of claim 4 wherein a plurality of said damping mounting slots are arranged in an array on a confinement layer, and the damping mounting slots between two adjacent confinement layers are offset or aligned.
10. The floating track bed vibration damper according to claim 4, wherein the particle damper comprises an upper end cover, a damper shell, damping particles and a lower end cover, the damper shell is hollow inside to form a filling cavity, the damping particles are filled into the filling cavity, the damper shell is installed in the damping installation groove, and the upper end cover and the lower end cover are respectively fixed at the upper port and the lower port of the damping installation groove.
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