Scholarly article on topic 'Analysis of the Effect of Heavy Duty Freight Cars Loaded Overweight Goods on the Track Structure'

Analysis of the Effect of Heavy Duty Freight Cars Loaded Overweight Goods on the Track Structure Academic research paper on "Civil engineering"

CC BY-NC-ND
0
0
Share paper
OECD Field of science
Keywords
{"heavy duty freight car" / "track structure" / "finite element analysis" / "overweight goods" / "railway safety transportation"}

Abstract of research paper on Civil engineering, author of scientific article — Xiao-hong Li, Yan-hui Han, Yu-ling Tan

Abstract Overweight goods are kind of special goods and must be loaded on the heavy duty freight cars when transported by railway. However, this sort of car is not taken consideration when the track structure is designed. In order to have knowledge regarding the action of the heavy duty freight cars on the track structure and correctly organize the transportation of the overweight goods, the strength of track was studied with the action of the heavy duty freight cars according to the basic theory of static mechanical calculation. Taking the D2 car as an example of heavy duty freight cars and selecting the traditional track of railway, the finite element calculation model of track was established. With the software ANSYS, the forces and deformations of track structure were calculated under several parameters and conditions of different load position, spring rigidity coefficient and rail type. Then, the D32, D38 type of heavy duty freight cars and several common locomotives were selected and the forces and deformations with these loads were calculated and compared. The results show that the static extrema of forces and deformations of track structure have different laws under different parameters and conditions. The heavy duty freight cars loaded overweight goods generally make the track structure engender greater forces and deformations than those common locomotives do, and the D2 car is of all the most adverse to the track. This indicates that heavy duty freight cars probably bring the bad effect to the lines. Therefore, when transporting overweight goods loaded on the heavy duty freight cars, adaptable measures and correct transport scheme are to be taken to decrease the damage to the lines.

Academic research paper on topic "Analysis of the Effect of Heavy Duty Freight Cars Loaded Overweight Goods on the Track Structure"

Available online at www.sciencedirect.com

ScienceDirect

Procedia - Social and Behavioral Sciences 138 (2014) 45 - 53

The 9th International Conference on Traffic & Transportation Studies (ICTTS'2014)

Analysis of the Effect of Heavy Duty Freight Cars Loaded Overweight Goods on the Track Structure

Xiao-hong Lia*, Yan-hui Hana, Yu-ling Tanb

a School of Traffic and Transportation, Beijing Jiaotong University, No.3 Shangyuancun, Haidian District, Beijing 100044, P.R. China b School of Civil Engineering, Beijing Jiaotong University, No.3 Shangyuancun, Haidian District, Beijing 100044, P.R. China

Abstract

Overweight goods are kind of special goods and must be loaded on the heavy duty freight cars when transported by railway. However, this sort of car is not taken consideration when the track structure is designed. In order to have knowledge regarding the action of the heavy duty freight cars on the track structure and correctly organize the transportation of the overweight goods, the strength of track was studied with the action of the heavy duty freight cars according to the basic theory of static mechanical calculation. Taking the D2 car as an example of heavy duty freight cars and selecting the traditional track of railway, the finite element calculation model of track was established. With the software ANSYS, the forces and deformations of track structure were calculated under several parameters and conditions of different load position, spring rigidity coefficient and rail type. Then, the D32, D38 type of heavy duty freight cars and several common locomotives were selected and the forces and deformations with these loads were calculated and compared. The results show that the static extrema of forces and deformations of track structure have different laws under different parameters and conditions. The heavy duty freight cars loaded overweight goods generally make the track structure engender greater forces and deformations than those common locomotives do, and the D2 car is of all the most adverse to the track. This indicates that heavy duty freight cars probably bring the bad effect to the lines. Therefore, when transporting overweight goods loaded on the heavy duty freight cars, adaptable measures and correct transport scheme are to be taken to decrease the damage to the lines.

© 2014 ElsevierLtd.This is anopenaccess article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of Beijing Jiaotong University(BJU), Systems Engineering Society of China (SESC).

Keywords: heavy duty freight car; track structure; finite element analysis; overweight goods; railway safety transportation

* Corresponding author. Tel.: +86-(0)10-5168-8354. E-mail address: xhli1@bjtu.edu.cn.

1877-0428 © 2014 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of Beijing Jiaotong University(BJU), Systems Engineering Society of China (SESC). doi:10.1016/j.sbspro.2014.07.180

1. Introduction

With the development of railway transportation toward high speed, heavy-haul, mass traffic volume and high density, as basic infrastructure of railway, the track is bearing greater and greater burden which has increased the workload of maintaining. On the other hand, more and more special goods such as some large equipment of electric power industry, mechanical industry and chemical industry are being transported by railway, and many of them are overweight goods (Ministry of Railway, 2007). However, the existing design of track structure of railway takes no consideration to the action of the heavy duty freight cars (Fan, 2003; Zhong, 2005); and also, when the overweight goods loaded on the heavy duty freight cars are transported, relative departments often pay more attention to their effects to bridges (Schulz, 1995; Daniel, 1996; Zhang, 2000; Batisse, 2004; Zhong, 2005), how they act and what effect will produce to the track haven't been adequately taken into account. It's known that the effect upon the track with those heavy duty freight cars loading overweight goods is related to the safety of railway transportation. Thus, exploring the general law of acting to decrease the bad effect to the track and then give the support reason to correctly organize the transportation of the overweight goods have been the important part of the transportation of overweight goods. Based on this, the paper studied the strength of track by establishing the finite element model to calculate the forces and deformations of track structure respectively under the load of the heavy duty freight cars and common locomotives, and then found the difference between them and gave some ways to solve the problem.

2. Limited fundamental premise

This paper will analyze the carrying capacity of the track structure through the static calculation to the strength of the track. Before that, a fundamental premise is limited as follows.

• First, the traditional ballasted track is selected for study. For this kind of track, the rails in branch lines are usually in lower grade and more serious abrasion. They often become the main restraining factor when passing the overweight goods trains. The paper mainly selects the rail and analyzes its forces and deformation.

• Second, this paper only analyzes the vertical force acting to the track. The action forces are very complex and own a characteristic of strong randomicity and repeatability. They are generally divided into vertical force perpendicular to the track plane, transverse level force perpendicular to the track axial direction and the longitudinal level force parallel to the track axial direction (Lian, 2009). Being the main force of all, the vertical force is analyzed in this paper.

• Third, when making the static calculation to the track, the rail is regarded as an infinite long beam supported on elastic base. The beam model supported by elastic dot is selected as the static calculation model to the vertical force of the track structure. The strength of the track is calculated by matrix method, or finite element method (Xing, 1994; Gao, 2004), and also the infinite long railway track is substituted by the finite long beam supported by elastic dot.

3. The finite element model of track under the load of heavy duty freight car with overweight goods

3.1. The selection of some parameters (1) The load

This paper selects the full loaded D2 car as the heavy duty freight car with overweight goods, and considers that being the load acting on the track to calculate the finite element model. Fig. 1 shows the structure of the D2 car.

Fig. 1. Structure diagram of the D2 car

(2) The type of rail

The type of rail is divided by the approximately weight of kilograms per meter. Nowadays, the main types include 50, 60, 70 kg/m. They are adopted in different conditions. The rail with higher weight is set on those important lines with heavier axle load, greater traffic volume and higher speed, while the rail with lower weight on those subsidiary lines. The rigidity of the rail has a direct impact on the total rigidity of the track. The smaller the total rigidity of the track is, the greater the flexibility of the rail acted by the load of the trains becomes. Three types of rail are chosen when establishing the finite element model.

(3) The spring rigidity coefficient

The spring units are used to simulate the flexibility under the track. The two values of 3x107 N/m and 7x107 N/m are chosen as the spring rigidity coefficients according to the part of track fascicule in the Manual of Technology of Railway Maintenance (Ministry of Railway, 1993).

3.2. The finite element model of the track and the calculation results

The beam-spring units are used to simulate in the model. The rail is simulated by the beam and the elasticity under the track by the spring units. Through changing the type of the rail and the rigidity coefficient of the spring units, the forces and deformation of the track structure are analyzed under the acting of the heavy duty freight car with overweight goods.

The model of typical track is established which bearing wheel force of the D2 type heavy duty freight car with the 1400-1500-1400 mm fixed wheelbase as Fig. 2. The concentrate load layout on track structure and the beam-elements and spring-elements serial number are showed as the Fig 3 and Fig. 4.

Fig. 2. Typical track model composed of beam-elements Fig. 3. Concentrate load layout on track structure

and spring-elements

— [i. -I

VlilUiUUiUUiy

Fig. 4. Beam-elements and spring-elements serial number Fig. 5. Rail deformation drawing

According to the finite element model established, and calculating with the ANSYS software, the results are obtained of the finite element simulating rail deformation, shear force and bending moment. See the Fig. 5~ Fig. 7.

11 Jj^}^......... ' JÜMWi...... n

Fig. 6. Rail shear force drawing

Fig. 7. Rail bending moment drawing

3.3. Analysis of the forces and deformation of the track structure under the acting of heavy duty freight car with overweight goods

Based on the finite element model, the forces and deformation of the track structure are calculated separately with the different load acting position, different spring rigidity coefficient and different rail type. The following gives a deeper analysis to the calculation results.

(1) Analysis on rail forces and deformation with different load acting position

In order to find the most disadvantage load acting dot to the beam unit, a mechanical calculation is made based on the different acting position of the first wheel load of D2 car. The data are gotten as Table 1.

It can be seen from Table 1 that the deformation has no too much relation to the position of the first acting dots, but the maximum shear force and maximum bending moment all arrive to the largest values as the first acting dot is 0.3m from the spring unit (or being in the middle of two sleepers). With this result, the latter models consider all calculations with the first acting dot being in the middle of two sleepers.

(2) Analysis on rail forces and deformation with different spring rigidity coefficients

In order to analyze the effect of the spring rigidity coefficient to the track structure, a mechanical calculation is made with the two different rigidity of 3x107 N/m and 7x107 N/m. The data are gotten as Table 2.

Table 2 shows that the spring rigidity coefficients simulating the elasticity under the track have some influence to the acting of the track. When the spring rigidity coefficient is 7x107 N/m, each of the maximum deformation, maximum shear force and maximum bending moment is smaller than those when the coefficient is 3x107 N/m. However, the maximum sleeper force has the opposite situation, that is, it has a greater value when the coefficient is 7x107 N/m.

Table 1. Comparison on rail maximum deformation and kinds of forces with D2 load being in different position

Position of The maximum The maximum The minimum The maximum The minimum The maximum

the first rail deformation rail shear force rail shear force rail bending rail bending sleeper force

acting dot (m) (N) (N) moment (N-m) moment (N-m) (N)

On the spring unit 0.001735 73374 -73583 18917 -9451 51551

0.1m from the spring unit 0.001735 73583 -73374 18917 -9451 51551

0.2m from the spring unit 0.001735 72381 -75912 20140 -10186 51840

0.3m from the spring unit 0.001732 78058 -75626 20494 -10170 51742

Notes: 1. The spring rigidity coefficient is 3x107 N/m, and the type of rail is 60 kg/m;

2. The sign values of the bending moment in table are the same as the calculation results of the ANSYS, "+" shows tensioned in the upper and the "-" in the lower, which are contrary to the design rule; The sign values of the shear force are in accord with the design rule. The latter tables also obey this regulation.

Table 2. Comparison on rail maximum deformation and kinds of forces with different spring rigidity coefficients under D2 load (the rail is of 60kg/m type)_

Spring rigidity coefficient (N/m) The maximum rail deformation (m) The maximum rail shear force (N) The minimum rail shear force (N) The maximum rail bending moment (N-m) The minimum rail bending moment (N-m) The maximum sleeper force (N)

3*107 0.001732 78058 -75626 20494 -10170 51742

7*107 0.000769 76744 -76079 18142 -9303 53484

(3) Analysis on rail forces and deformation with different type of rail

Since different types of rail exist on the lines operating heavy duty freight cars, in order to know whether those cars have different action to the track, a finite element calculation is made to three types of rail of 50kg/m, 60kg/m and 70kg/m. Then, the forces and deformations of the three types of rail are acquired with the different spring rigidity coefficients. Below are the results as Table 3 and Table 4.

Table 3. Comparison on rail maximum deformation and kinds of forces with different rail types under D2 load (the spring rigidity coefficient is 3* 107 N/m)

Type of rail (kg/m) The maximum rail deformation (m) The maximum rail shear force (N) The minimum rail shear force (N) The maximum rail bending moment (N-m) The minimum rail bending moment (N-m) The maximum sleeper force (N)

50 0.00176 77174 -75812 19143 -9781 52491

60 0.001732 78058 -75626 20494 -10170 51742

75 0.001715 78854 -75532 21594 -10279 51315

Table 4. Comparison on rail maximum deformation and kinds of forces with different rail types under D2 load (the spring rigidity coefficient is 7*10 N/m)

Type of rail (kg/m) The maximum rail deformation (m) The maximum rail shear force (N) The minimum rail shear force (N) The maximum rail bending moment (N-m) The minimum rail bending moment (N-m) The maximum sleeper force (N)

50 0.00082 76785 -76655 17080 -8630 55382

60 0.000769 76744 -76079 18124 -9303 53484

75 0.000756 77089 -75843 18986 -9718 52611

4. Comparison and analysis to the action of track between the heavy duty freight cars loaded overweight goods and common locomotives

4.1. Basic load data

Making a comparison of the different action to the track with the locomotives is a good way to have a deeper knowledge about the effect of the cars loaded overweight goods to the track. Therefore, common locomotives are chosen to make the finite element calculations. The common locomotives include common electric power locomotives and diesel locomotives running on the lines nowadays such as shaoshan, dongfeng and hexiehao. Besides, other two heavy duty freight cars D32 and D38 are chosen to be compared. Their load data are showed in Table 5.

Table 5. The load data of heavy duty freight cars and common electric power locomotives and diesel locomotives

Type of cars and locomotives Axle load (t) Number of axles (N) Distance between bogie centers (mm) Wheelbase (mm)

D2 23.6 16 5800 1400-1500-1400

D32 22.75 24 3250 1750

D38 18.94 32 5800 1400x3

SS1 23 6 10400 2300

SS3 23 6 11500 2000-2300

SS4G 23 2*4 8200 3000

SS7 23 6 7100 2880

SS7E 21 6 11570 2150

SS8 22 4 9000 2900

DF4 23 6 12000 1800

DF7D 22 6 9980 1800

DF10F 20 6 8600 1800

DF11D 22.5 6 12000 2000

HXD3 23/25 6 14700 2250-2000

CRH5 17/16 32 19000 2700

4.2 .Comparison on static extrema based on the calculations

By calculating the finite element model, the static extrema of heavy duty freight cars and common locomotives are received with different parameters. Taking the condition of 3x107 N/m spring rigidity coefficient and 60kg/m type of rail as an example, an analysis is given in the below. The calculation data are disposed and form Table 6.

According to the same method, each table with other sorts of parameters can be gotten, and the data in tables are showed in diagrams as Fig. 8(1) ~ Fig. 8(6). For the following diagrams, the first figure of horizontal-axis expresses a shortening of spring rigidity coefficient and the second type of rail. For example, (3,50) expresses that the parameter is of 3x107 N/m spring rigidity coefficient and 50 kg/m type of rail; The vertical-axis expresses different values of forces and deformation, and the "other loc." expresses the common locomotives except HXD3.

The following results can be deduced from Fig 8 (1) ~ Fig 8 (6):

(1) The maximum rail deformations under the action of D2 car, except for one instance, which are a bit smaller than HXD3 type locomotive when the spring rigidity coefficient is 7x107 N/m and the type of rail is 50 kg/m, are larger than that of common locomotives in all other situations.

(2) The maximum rail shear forces under the action of D2 car (include D32) are smaller than the HXD3 type locomotive, and except for two instances, which are smaller than the SS7 type locomotive when the spring rigidity coefficient is 7x107 N/m, the type of rail is 50 kg/m and 60 kg/m, are larger than that of common locomotives in all

other situations.

(3) The minimum rail shear forces (or the maximum rail minus shear forces ) under the action of D2 car (include D32) are all larger than that of common locomotives.

(4) The maximum rail bending moments under the action of D2 car (include D32, D38 ) are all smaller than that of common locomotives.

(5) The minimum rail bending moments (or the maximum minus bending moments) under the action of D2 car (include D32) are smaller than the HXD3 type locomotive, and except for two instances, which are smaller than the SS7 type locomotive when the spring rigidity coefficient is 3x107 N/m, the type of rail is 60 kg/m and 75 kg/m, are larger than that of common locomotives in all other situations.

(6) The maximum sleeper forces under the action of D2 car, except for one instance, which are a bit smaller than the HXD3 type locomotive when the spring rigidity coefficient is 7x107 N/m and the type of rail is 50 kg/m, are larger than that of common locomotives in all other situations.

From above, it can be seen that, in most cases, when the D2 car is on the track, the forces and deformation of the track are larger than that of the common locomotives.

Table 6. Comparison on static extrema of heavy duty freight cars loaded overweight goods and common locomotives

Type of cars and locomotives The maximum rail deformation (m) The maximum rail shear force (N) The minimum rail shear force (N) The maximum rail bending moment (N-m) The minimum rail bending moment (N-m) The maximum sleeper force (N)

D2 0.001732 78058 -75626 20494 -10170 51742

D32 0.001526 75359 -72684 20800 -10526 45512

D38 0.001434 62411 -60965 16286 -8944 42600

Common locomotives 0.001436 72650 -72650 24609 -10661 40791

(except HXD3)

HXD3 0.00144 83085 -72178 25035 -11588 42934

Notes: 1. The common locomotives in the table include shaoshan, dongfeng and etc. type locomotive as listed in table 5; 2. The data come from the condition of 3x107 N/m spring rigidity coefficient and 60kg/m type of rail.

(3,50) (3,60' (3,75) (7,50) (7,60) (7,75)

Fig. 8. (1) Comparison on rail maximum deformation

(3,50) 0,60) (3,75) <7,50) (7,60) (7,75)

— 02

—032

—other lo'

Fig. 8. (2) Comparison on rail maximum shear force

Fig. 8. (3) Comparison on rail minimum shear force Fig. 8. (4) Comparison on rail maximum bending moment

Fig. 8. (5) Comparison on rail minimum bending moment

(3,50) (3,60) (3,75) (7,50) (7,60) (7,75)

Fig. 8. (6) Comparison on maximum sleeper force

5. Conclusions

The paper has made calculations of the action of D2, D32 and D38 car on the track, and then made a comparison with that of the common locomotives. The results show that they have some laws: the heavy duty freight cars generally make the forces and deformations of the track larger than that of the common locomotives, and the D2 car is the worst of all on the track. This indicates that the heavy duty freight cars loaded overweight goods perhaps bring some bad effect on the lines when they pass them.

There are two ways to solve this problem which can be done by vehicle design department and transportation department. One is to improve the structure of the heavy duty freight car, and the other is to make a reasonable transport scheme. In present, the latter is also the most practical way due to the cars' prevalent use. Specifically, when making a transport scheme, some effective measures such as selecting a suitable heavy duty freight car, decreasing the loading, planning correct loading ways and choosing better transport line, will reduce the destroy to the lines, or at least can have a relatively smaller load acting on the track.

References

Bellingham, WA, United States. Society of Photo-Optical Instrumentation Engineers, 2458, 209-217.

Fan, H., Gao, L., & Xu, X. D. (2003). Simulative Calculation of the Track Strength Under the Train loaded with Overweight Freight. Railway Construction, 5, 38-39.

Gao, Y. J., & Zhai, W. M. (2004). Finite Element Analysis of Track Structure Strength. Journal of Traffic and Transportation Engineering, 4, 36-39.

Leighty, C. A., Laman, J. A., & Gittings, G. L. (2004). Heavy axle study: impact of higher rail car weight limits on short-line railroad bridge structures. Civil Engineering and Environmental Systems, 21, 91-104.

Li, C. H. (2005). The Track. Chengdu: Southwest Jiaotong University Press. Lian, S. L. (2009). Track Engineering. Beijing: China Communications Press.

Schulz, J. L., & Commander, B. C. (1995, June). Efficient field testing for load rating railroad bridges. In Nondestructive Evaluation of Aging Infrastructure (pp. 209-217). International Society for Optics and Photonics.

The Ministry of Railway of the People's Republic of China. (1993). Manual of Technology of Railway Maintenance (track). Beijing: China Railway Publishing House.

The Ministry of Railway of the People's Republic of China. (2007). Rules on Transport of Out-of-Gauge and Overweight Goods on Railways. Beijing: China Railway Publishing House.

Tobias, D. H., Foutch, D. A., & Choros, J. (1996). Loading spectra for railway bridges under current operating conditions. Journal of Bridge Engineering, 1, 127-134.

Xing, S. Z. (1994). Matrix Solution of Strength Calculation of Railway Track Structure. Beijing: China Railway Publishing House.

Zhang, J. G. (2000). Crucial Effect on the Railway Safety Transportation with the Analysis of Bridge Experiment. Railway Standard Design, 20, 16-18.

Zhong, C. Z. (2005). Detection Countermeasure to the Marred Railway Bridge Passing the Heavy Duty Freight Cars. Railway Standard Design, 10, 80-81.