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The development of subway underground line and track E of elevated line
Jan 30, 2018

The development of subway underground line and track e of elevated line.

Article fasteners according to subway bomb technology application and development trend, in the domestic application of mature two article no bolt e play as the foundation, USES the finite element analysis method, a kind of design can be also used in subway engineering of underground lines and overhead lines Φ article 16 no bolt e little resistance to play.

The results show that not only can the type of equipment of the subway project be reduced, but the material consumption and the maximum stress level of the strip are lower than that of the existing products.

At present, it has been tested and tested with 5 million fatigue tests.

In the rail fastener system, the bullet bar is one of the most critical parts, and is the most vulnerable part of the fastener, which will endanger the safety of driving once it fails.

1. Main types and application characteristics of bullet bars in subway.

There are two main types of bullet bars used in the domestic subway system: there are bolt bars and no bolt bars.

Have bolt play article mainly bahn Ⅰ, Ⅱ play a small resistance and the bridge of play, etc., are all omega type;

No bolt play article mainly bahn Ⅲ article play and the subway D Ⅰ play etc, are all derived from the second generation of Pandrol e article.

The buckle pressure can be adjusted by bolt torque, but the parts are more, the installation and maintenance work is large, and the bolt looseness can lead to uneven buckle pressure.

There are less parts of bolt type e cartridge fastener, less pressure and less maintenance.

In the current design, the same subway laid if there are both underground and overhead lines, are generally less in the underground line using simple maintenance without bolt elastic fasteners, elevated line bolts have little resistance to play, play and fastener types are not unified.

Table 1 main technical specifications of domestic bullet bars.

Play a

Buckle pressure P /kN

Play cheng/mm

The diameter of/mm

The quality of /( m /kg)

Article type play

11.0

13.0

20

0.83

DⅠPlay a

8.2

10.5

18

0.64

A small resistance

Omega.

Play a


4.0

10.5

13

0.66

Article Pandrol company without bolt e play contains button diameter Φ 12 ~ 20 Φ, pressure 2 ~ 14 kN the full range of products, but the domestic several play (see table 1) in the article, article no bolt play button minimum pressure is 8.2 kN, does not apply to elevated line of seamless, can only be used in the ground wire, ground wire.

In order to achieve the unification of the strip and the fastener type of the underground line and the high line, to minimize the type of the rail equipment, recently the method of reducing the bullet path has been successfully tried in some projects.

Although the lower buckle pressure is realized, the dependence on the manufacturing accuracy of the fastener is increased, and the material performance of the strip is not fully utilized.

Therefore, it is necessary to study and design a new type of small resistance non-bolt bullet train for subway construction in China, which can be used for high line or underground line.

1. The development idea of general non-bolt bullet bars.

Main research route is based on the application of mature play article, make sure to play the type and material, and then puts forward button parameters such as stress, elastic range and the residual deformation, based on the prototype play article, finite element model is established, based on the maximum stress levels, fatigue strength and the elastic energy optimization analysis, determine the diameter of the article play geometry size and design.

2.1 determine the type and material of the cartridge.

Pandrol no bolt bullet has 3 generations of products (see figure 2): the first generation of PR bullets, the material performance is not well used, and now it is basically eliminated, and it has been deleted from the product list of Pandrol's official website;

The second generation e - type cartridges are widely adopted at home and abroad.

The third generation Fast is better, but the patent protection period is long, and the accessory structure is complicated, and there is no mature application in China.

According to the above situation, combined with the characteristics of the development of domestic subway couplers, this research is based on the shape of e type elastic strip, and the material also adopts the mature 60Si2Mn hot rolled spring steel.

2.2 propose main technical parameters.

2.2.1 buckle pressure P.

Existing elevated line with small resistance omega play button of the pressure P = 4 kn, the value has been a large number of engineering practical operation test for many years, can not only meet the stability and safety of track structure, and the beam rail forces don't become the controlling factors of bridge design.

Considering the article without bolt play after using for a long time there is a certain attenuation characteristics, so the small button article without bolt elastic pressure resistance should be appropriately increase, P = 5 kn is relatively appropriate, about the seamless line longitudinal force basic don't control the design of bridge structure.

The conventional wisdom holds that the greater the buckle pressure, the more it can maintain the stability of the line.

But in fact, the underground line under the condition of temperature difference and deformation of tunnel structure is much more superior than elevated line, so the clasp pressure P = 5 kn used in underground line no security problems, and relatively small original buckle under pressure can also reduce fastener track plate elastic losses, are more favorable for vibration noise reduction, and can prolong the service life of rail pad under.

2.2.2 play cheng

No bolt bullet can be controlled within 10~14mm range.

The spring is too small, and the pressure is easily affected by the parts processing and assembly error of the fastener.

It is too large to increase the material consumption and cost of the strip and fastener.

2.2.3 residual deformation and buckle pressure loss.

The spring steel is elastoplastic material, and if the maximum stress level exceeds the yield strength in the installation and operation condition, the residual deformation will be generated and the corresponding buckle pressure will also be lost.

The residual deformation can be theoretically analyzed according to the spring steel.

2.3 establish a finite element analysis model.

This design adopts the large general ANSYS finite element analysis software.

ANSYS has the ability of finite element analysis and can perform simple linear static analysis and complex nonlinear dynamic analysis.

For e play a complex space curve structure characteristics, using ANSYS in the 3 d finite beam element Beam188 to establish the entity model, and can be briefly analysis model of unit stress, the problem such as rotational degree of freedom.

Taking D bullet as an example, a finite element model of ANSYS was established using Beam188 unit, as shown in figure 3.

The projectile section is divided into 16 pieces, and the model is built along the axial direction with 1mm as the unit length, and the whole projectile is divided into 364 units.

2.4 strength and elastic energy index check.

2.4.1 Max composite stress.

According to the characteristics of the structure and the material, the fourth strength theory (distortion energy theory) is used to evaluate the stress level of the elastic strip.

To improve the reliability of new article play design, avoid failure risk occurred during use, the composite stress level of evaluation to play a fourth strength maximum stress sigma xd4, Max is less than or lower than the existing mature article, appropriate D elastic bar and 60 si2mn spring steel yield strength (1200 mpa), the smallest of the three values for the principle.

2.4.2 fatigue strength.

The fatigue strength is also one of the design considerations.

Referring to the reference [2],

Fatigue failure distortion can be used to evaluate the fatigue strength of elastic bars, and the stress state of the elastic bar should satisfy the following relational expression.

Sigma xd4, m ax-2, xd4, m < sigma N.


Sigma, xd4, m ax-sigma, xd4, m< sigma N.


In the formula: the ultimate strength of the spring steel;

The fatigue strength of spring steel;

Xd4, m -- the average of the stress of the fourth strength theory.

In use process, play a reciprocating load amplitude change is small, the eigenvalue rho material 0.8, so as long as the maximum combined stress levels meet the requirements, the theory of fatigue strength is checked to pass commonly, so the fatigue strength is actually puts forward strict requirements on manufacturing process and precision.

2.4.3 elastic energy of unit mass.

Because the play of the design parameters is more, in meet the design requirements of stress, elastic range, maximum combined stress, fatigue strength and residual deformation under the premise of spring bar after assembly under the same stress level can be used as a storage unit mass of W evaluation index of play the design rationality, economy, namely

In the formula: P -- -buckle pressure, kN;

-- -- -- -- -- -- --

M -- -- bullet quality, kg;

- maximum composite stress after assembly, MPa.

Because the evaluation of W needs to satisfy a series of parameters, the design conditions of the projectile are different and W is different, so it is only used as the auxiliary evaluation index in the design.

2.5 determine the diameter and dimension of the cartridge.

E play article mainly includes the control dimension shown in figure 4 Φ, e1 ~ e11, R1, R3, etc., different size to play all affect the performance of article, and the relationship between each other is very complex.

To do this, type design with Ⅲ article play and D Ⅰ play appearance size calculation, on the basis of the analysis of each size optimization may again.

, based on the article type Ⅲ play and 1 D Ⅰ elastic finite element analysis

In finite element analysis, in order to ensure the reliability of the calculation results, the first article of mature application type Ⅲ play and D Ⅰ play a confirmatory calculation, and then change the diameter of the two play article Φ, get different diameter Φ buckle pressure, maximum stress, etc, are shown in table 2.

Table 2 different diameter Ⅲ play a and D Ⅰ article elastic finite element analysis results

Play a

type


The diameter ofΦ/mm

The quality ofm/kg

Play cheng/mm

Buckle pressureP/kN

Maximum stressσxd4max /M Pa

The residual deformations/mm

Pressure lossP /kN

Elastic energyW

Ⅲ型弹条

14

0.40

13.0

2.82

990

0

0

0.091

16

0.53

13.0

4.80

1130

≈0

≈0

0.104

18

0.67

13.0

7.67

1270

0.46

0.27

0.117

20

0.83

13.0

11.66

1410

5.0

0.45

0.130

DⅠPlay a

14

0.39

10.5

3.09

952

0

0

0.088

16

0.51

10.5

5.07

1080

≈0

≈0

0.098

18

0.64

10.5

8.26

1220

0.39

0.31

0.111

20

0.79

10.5

12.56

1360

0.42

0.50

0.123

(1) Φ article 20 Ⅲ type play in play when the 13 mm, maximum stress more than 60 si2mn spring steel yield strength, because of spring steel yield hardening characteristics, play a still can be normal use, but if the maximum stress in manufacturing defect, increases the possibility of failure in use process, and use for a long time will produce certain performance attenuation;

D Ⅰ play in play when the 10.5 mm, maximum stress in line with yield strength.

FIG. 5 shows the surface stress distribution of two elastic bars.


(1) the smaller the diameter of the projectile is, the smaller the maximum stress value is, and the safer the elastic band is, while the elastic energy decreases with the decrease of the diameter.

(2) the Φ 16 mm or less, play the stress level is less than the yield strength, article elastic deformation can be thought of in a completely elastic state, play of the residual deformation and pressure loss can be ignored.

1. The design features of general non-bolted e-type cartridges.

Seen from table 2, article in Ⅲ type and D Ⅰ play to separate bullet cheng, rated diameter button Φ 16 pressure respectively 4. 80, 5.07 kN, and play a consistent design requirements, type Ⅲ play at this time of the elastic energy index slightly better, but the maximum stress value is bigger, material consumption is bigger also, so the elastic design using D Ⅰ play of controlling the dimensions, consider and subway system widely used D article Ⅰ play interchangeability.

Play a part of the details of the new design size optimization adjustment, main technical parameters: pressure P = 5.1 kN, play delta = 10.5 mm, cheng Φ = 16 m in diameter, the individual quality of 0.51 kg.

Compared with the original D article Ⅰ play, Φ article 16 play has the following characteristics.

Button (1) pressure both satisfies the requirement of trajectory stability, and forces become the bridge design control of beam and rail, and can be used in underground lines and overhead lines at the same time, the article so as to realize the full play and types of fasteners, minimize rail equipment types, to reduce the cost of rail system and operation and maintenance cost have positive significance.

(2) the maximum stress level was slightly lower than the spring steel yield strength, and compared to the original D Ⅰ play a 11% reduction, to overcome play a long-term use of residual deformation and pressure loss, improve the stability and reliability.

(3) the material usage than the special original D Ⅰ play, small resistance omega play were 20%, 20%, and the economy better.

5. Trial test and application prospect.

In early 2008, the new design of general article without bolt e play (Φ 16) has completed the trial production (see figure 6), and through the test of 5 million fatigue test.

The next step will be the design of the fastener according to the comprehensive technical requirements of the metro fastener system.

It can be applied in engineering after the inspection and relevant examination of the coupler assembly test.

Using this design Φ article 16 general e play without bolt fasteners, can have better performance and economical efficiency, fasteners in domestic subway plays its advantages for the construction of a new round of high tide.

In addition, 60 si2mn Φ 16 hot-rolled spring steel in the domestic use is not much, but each year, a batch of export supply batch delivery guaranteed.

reference

[1] Yang jie, mi. Materials and design: analysis, prediction and prevention of material failure in engineering materials [M]. Beijing: mechanical industry press, 1990.

[2] xiao junheng. Optimization design and research of bullet fastener [D]. Beijing: ministry of railways science research institute, 1994.

Article [3] Zhao Rukang. Play Ⅱ type fastener design study [R]. Beijing: science institute of the ministry of railways, 1995.

[4] luo xiaoyong. Research and application of type elastic buckle pressure [J]. Railway standard design, 2002(6).

[5] wu jianzhong, li tenmillion, li xiangjiu. Research and design of rail transit rail fasteners in urban rail [J]. Urban fast rail transportation, 2005,18 (3).