Fatigue analysis of rail joint using finite element method

IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
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Volume: 02 Issue: 01 | Jan-2013, Available @ http://www.ijret.org 80
FATIGUE ANALYSIS OF RAIL JOINT USING FINITE ELEMENT METHOD
Sunil Patel1
, Veerendra Kumar2
, Raji Nareliya3
1
Assistant Professor, Golobal Group of Institutions, 2
Professor, Government Engineering College, 3
Assistant Professor,
Hitkarni College of Engineering, Jabalpur, M.P. – India,
sunieel_24@yahoo.com, prof.veerendra.kumar@gmail.com, raji_nareliya@yahoo.co.in
Abstract
Fatigue life estimates can be used to guide the selection of inspection intervals for rail joint bars in service. A three-dimensional finite
element model for rail joint bars is developed and dynamic load is applied to estimate the fatigue life of the joint bars. Different
components of the rail joint bars are being created separately and assemble in Autodesk Inventor. The model consists of assembly of
the rail, joint bars, bolts, nuts, washers, and wheel. A three-dimensional finite element analysis of rail joint bars is carried out in
ANSYS after importing from Autodesk Inventor. The static and dynamic loads are being applied to estimate fatigue life and endurance
strength at the section. The material properties of the rail and wheel are assumed to be same. The material properties of the wheel
and rail are considered to be bilinear kinematic hardening in ANSYS. All the material properties and boundary conditions are being
applied strictly as per the guidelines made available by the Indian Railways in their manual.
Key Words: Rail Joint, Modeling, Finite Element Method
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1. INTRODUCTION
A rail joint is the weakest link in the track. There is a break in
the continuity of the rail in horizontal as well as in vertical
plane at this location because of the expansion gap and Im
perfection in the rail heads at joint. The fitting at the joint
become loose, causing heavy wear and tear to the track
materials. It is normally felt that a rail joint requires about
30% extra maintenance than the plain track.
A modern steel rail has a flat bottom and its cross section is
derived from an I -profile. The upper flanges of the I-profile
have been converted to form the railhead. In India, one
commonly used rail profile is the UIC60 rail, where 60 refer to
the mass of the rail in kg per meter. The rails provide
continuous and level surface for movement of trains. The rails
provide a pathway which is smooth and has very less friction.
The friction between steel wheel and steel rail is about 1/5thof
the friction between the pneumatic tire and metal led road. The
rails serve as a lateral guide for the running of wheels. The
rails bear the stresses developed due to vertical loads
transmitted to it through axles and wheels of rolling stock as
well as due to braking forces and thermal stresses. The rails
carry out the function of transmitting the load to a large area
of formulation through sleeper’s ballast. The rails also act as
electrical conductors for signaling system.
In a railway track with concrete sleepers protect the sleeper
from wear and impact damage, and they provide electrical
insulation of the rails. From a track dynamics point of view,
the rail pads play an important role. They influence the overall
track stiffness. When the track is loaded by the train, a soft rail
pad permits a larger deflection of the rails and axle from the
train is distributed over more sleepers. Also, soft rail pads
isolate high-frequency vibrations. They suppress the
transmission of high-frequency vibrations down into the
ballast. A stiff rail pad, on the other hand, gives a more direct
transmission of the axle load, including the high-frequency
load variation down to the sleepers below the sleepers below
the wheels. The sleepers provide support of the rails and
preserve gauge, level and alignment of the track. The sleepers
transmit vertical, lateral, and longitudinal forces from the rail
down to the ballast bed. They should also provide electrical
insulation between the two rails. The ballast layer supports the
track (the rails and the sleepers) against vertical and lateral
forces from the trains. It is tightly compacted or tamped
around the sleepers to keep the track precisely leveled and
aligned. From a physical point of view, the ballast materials
and their interactions are complex. Constitutive laws of ballast
materials are under development. The main functions of
ballast are :
 To transfer and distribute the load from sleepers to a
larger area of formation
 To provide elasticity and resilience to track for
getting proper riding comfort
 To provide necessary resistance to track for
longitudinal and lateral stability
 To provide effective drainage to track
 To provide effective means of maintaining evenness
and alignment of the track

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Fig.1 A typical 4 bolt insulated rail joint
The function of the fishplate is to hold the two rails together
both in the horizontal and vertical planes. The fish plates are
manufactured from a special type of steel having composition
of Carbon, Manganese, Silicon, Sulphur and Phosphorous 0.30
to 0.42%, Not more than 0.8%, Not more than 0.15%, Not
more than 0.06 % respectively. The fish plates are so designed
that the fishing angles at the top and bottom surface coincide
with those of the rail section so as to have a perfect contact
with the rail. Elastic elements (springs) are components which
return to their original dimensions when forces causing them
to deflect are removed. Elastic elements used to: Equalize the
vertical wheels (unloading of any wheel is dangerous because
it causes a reduction/loss of guidance forces).Stabilize the
motion of vehicles on track (self-excited lateral oscillations
i.e., hunting of wheel sets is dangerous).Reduce the dynamic
forces and accelerations due to track irregularities.
2. FINITE ELEMENT ESTIMATIONS OF
STRESSES IN JOINT BAR
Rail joint is a critical component of rail infrastructure
component of rail infrastructure. Rail joints are widely used in
the rail network. It consists of two joint bars. The bolts, nuts
and washers are used to tightly fastening the assembly.
The assembly of model is done in modeling package of
Autodesk Inventor Software. Autodesk inventor is 3D
mechanical design software for creating 3-D digital prototypes
used in the design, visualization and simulation of products.
Cross section of standard Rail joint bar is shown in Fig.-2. The
standard rail sections and the standard rail length prescribed
on Indian Railways are used.
Fig.2 Standard Rail Joint
The model of assembly is being created in Autodesk Inventor
after creating different components of the rail/wheel assembly
separately. The model consists of assembly of the rail, joint
bars, bolts, nuts, washers, and wheel.
A three dimensional finite element analysis of a rail/wheel
contact is carried out on the rail joint section of track in
ANSYS after importing from Autodesk Inventor. Fig.-3 shows
model when wheel is on straight track. The static and dynamic
loads are being applied to estimate stresses at the section.UIC
60 kg rail is used for analysis. The rail’s length is a little more
than the distance of two sleepers.
Fig.3 Autodesk generated assembly of wheel over rail joint
Once model is imported in ANSYS material properties were
defined. All the material data is taken with reference to Indian
Railways.

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3. MATERIAL PROPERTIES
 Ultimate tensile strength : 880 MPa
 Tensile yield strength : 540 MPa
 Compressive yield strength : 540 MPa
 Endurance limit : 413 MPa
 Elastic support : 8.632 x 10-4 N/mm3
 Maximum Axle load : 159358.0625 N
4. BOUNDARY CONDITIONS
All the material properties and boundary conditions are being
applied strictly as per the guidelines made available by the
Indian Railways in their manual. The wheel runs at constant
speed of 120 km/hr. UIC 60 rail is used for analysis. The
initial temperature of wheel and rail is taken as 220C for
analysis in ANSYS. The diameter of wheel is 915 mm. The
axle load is 159.36 KN. Friction coefficient is 0.15. The
material’s density is 7800 kg/m3. Material properties of the
rail and wheel are assumed to be same. The material properties
of the wheel and rail are considered to be bilinear kinematic
hardening in ANSYS. Fig.4 shows boundary conditions and
load conditions on rail joint bar.
Fig.4 Boundary and load condition
5. RESULTS AND DISCUSSIONS
In this research, results obtained and observations made for
the fatigue analysis of rail joint bars are analyzing following
parameters :
 Fatigue factor of safety at a specified design life
 Fatigue life
 Von-Mises stresses
 Fatigue damage at a specified design life
 Stress biaxiality
Factor of safety in Rail joint bars with wheel is shown in
Fig.5, the value of safety factor amounted to be 0.46295.
Safety Factor from the lateral direction with wheel is shown in
Fig.-6., the critical section is shown by red portion. Life in rail
wheel joint bars with wheel is shown in Fig.7 and is amounted
to be 33325 minimum. Contours of Von-Mises stress in rail
joint is shown in Fig.8, the von-Mises stress is amounted to be
214.27 MPa. Whereas contours of Equivalent von-Mises stress
in rail joint bars with wheel is shown in Fig.9. Equivalent von-
Mises stress in rail joint bars is shown in Fig.10.
Fatigue Damage is a contour plot of the fatigue damage at a
given design life. Fatigue damage is defined as the design life
divided by the available life. The default design life may be
set through the Control Panel. For Fatigue Damage, values
greater than 1 indicate failure before the design life is reached.
Fatigue Damage is shown in Fig.11.
Fatigue material properties are based on uniaxial stresses but
real world stress states are usually multiaxial. This result gives
the user some idea of the stress state over the model and how
to interpret the results. Biaxiality indication is defined as the
principal stress smaller in magnitude divided by the larger
principal stress with the principal stress nearest zero ignored.
A biaxiality of zero corresponds to uniaxial stress, a value of –
1 corresponds to pure shear, and a value of 1 corresponds to a
pure biaxial state. Biaxiality indication is shown in Fig.12,the
majority of this model is under a pure uniaxial stress, with
parts exhibiting both pure shear and nearly pure biaxiality.
In a Stress Life fatigue analysis, one always needs to query an
SN curve to relate the fatigue life to the stress state. Thus in a
fatigue analysis, the equivalent alternating stress can be
thought of as the last calculated quantity before determining
the fatigue life. The usefulness of this result is that in general
it contains all of the fatigue related calculations independent of
any fatigue material properties.
The main function of track is to guide the train. Another
function of the track is to carry the load of the train and to
distribute the load over an area of the sub grade that is as large
as possible. The sleepers, supported by the ballast, transmit the
load via the sleeper base area to the ballast, and the ballast
disperses the load over a larger area of the sub ballast and sub
grade. The rail was placed upon an elastic foundation with
stiffness 0.05039N/mm2. Since this elastic foundation acts
over an area, the units of stiffness are force/deflection/area.
The stiffness value was divided by the area of the rail section.
Hence, the elastic support is being considered between ballast
and sleepers in the present work and value is taken with
reference to Broad Gauge is 8.632*10-4 N/mm³.
The vertical load is assumed to be the maximum design load
which is taken with reference to Technical Data of Coaching
Stock of Indian Railways. Because of maximum availability of
load using AC-3 Tier Sleeper load.

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Fig.5 Safety Factor in Rail joint bars with wheel
Fig.6 Safety Factor from the lateral direction with wheel
Fig. 7 Life in rail wheel joint bars with wheel
Fig.8 Contours of von-Mises stress with wheel
Fig.9 Equivalent von-Mises stress in rail joint bars with wheel
Fig.10 Equivalent von-Mises stress in rail joint bars

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Fig. 11 Contour Plot of Fatigue Damage over the whole model
Fig.12 Contour Plot of Biaxiality Indication over the whole
model
a. Tare weight = 515143.3245 N
b. Carrying Capacity = 50210.048 N
c. Gross load = 565353.3725 N
d. Maximum Axle load = 159358.0625 N
Vertically downward load is sum of Gross load and Maximum
axle load. Normally wagons are comprised of eight wheels. A
wheel set comprises two wheels rigidly connected by a
common axle. Load is proportional on each wheel. Hence,
gross load is divided by number of wheels in the wagon.
Similarly, axle load is also divided by number of wheels on
axle. Hence, distributing load proportionally in each wheel.
Load is applied at the center of wheel on downward direction.
Hence taking load proportionally with respect to wheels.
Rotational velocity is taken as 15.3 rad/s for the wheel. After
defining material properties and boundary conditions, results
are being evaluated. The safety factor is being evaluated in
fatigue.
CONCLUSIONS
The prescribed method in this research may be used to
estimate the fatigue life of bolted rail joints in a variety of
conditions. The finite element model for reverse bending
calculates joint bar bending stresses that are comparable to the
engineering estimates based on beam on elastic foundation
theory. The engineering estimates are, therefore, an efficient
method to estimate the tensile reverse bending stress at the top
outer fiber of the joint bar, which is important for fatigue
crack growth calculations. However, the finite element model
for the wheel over the joint calculates stresses that are higher
than the engineering approach. These results suggest that the
engineering approach provides reasonable estimates for
vertical bending only. Moreover, the finite element analysis
captures the combined effect of vertical and lateral bending;
i.e., two-axis bending; which is not included in the beam
theory approximations.
REFERENCES
[1]. Brandon T., David Y.J. and Jeff G., Estimation of The
Fatigue Life of Railroad Joint Bars, 2007 ASME/IEEE, USA,
Joint Rail Conference and Internal Combustion Engine Spring
Technical Conference (JRCICE – 2007), held at Pueblo,
Colorado, USA, during March 13-16, 2007.
[2]. Chandrupatia, Tirupati R. & Ashok D. Belegundu,
Introduction To The Finite Elements In Engineering, Prentice-
hall of India Pvt. Ltd., New Delhi.
[3]. ANSYS, “ANSYS.12 manuals,” Swanson analysis system
limited.
[4]. ANSYS, “ANSYS.12help Gui’s”.
[5]. HanbiaoNong, Jianhui Lin, Study on Rail Load
Measurement Base on Finite Element Analysis, The Ninth
International Conference on Electronic Measurement &
Instruments, ICEMI’2009
[6]. M.M. Agrawal, Indian Railway Track, Prabha and
Cooperation, A-68, N.D.S.E. Pt II, New Delhi-110049 India.
[7]. Li Ping Sun, Jian Zhang, Jun Zhang, Analyses On Wheel-
Rail Contact Using Finite Element Method During Passing
Through Curved Track, International Conference on
Measuring Technology and Mechatronics Automation, China,
2009
[8]. Mohammad HosseinAbolbashari, Reza Ahrari,A
Simplified Finite Element Model For The Insulated Rail Joint
Bar Stress Analysis,17th. Annual (International) Conference
on Mechanical Engineering-ISME, held at University of
Tehran, Iran, May, 2009
[9]. P HosseiniTehrani, M Saket, Fatigue Crack Initiation Life
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(2009) 012038
[10]. Simon Iwnicki, Handbook Of Railway Vehicle
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[11]. Yongjun Liu, XiaofangLiu,CombiningMbs With Fem
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