• • Applying different wheel velocities •

•     
Fracture Mechanics

•     
Adhesion Theories

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•     
NDT methods for track and wheel sets

•     
Rolling contact defects

•     
Rail Inspection methods

Stage 2: Static Analysis

•     
Wheel and profiles:

•     
Creating 3D models of the wheel and track using geometrical
dimensions from published data.

•     
Short track and a section of the wheel “reduce
simulation time”

•     
FEA – Using Ansys software

•     
Determine area formed by contact bodies (contact
patch)

•     
Determine stresses: (Normal, compressive)

•     
Analytical approach – Hertz Method

•     
Validation of FEA
results using published data and analytical method

•     
Fatigue analysis
using FEA and Fracture mechanics assuming a defect has been detected by NDT
methods

Stage 3: Dynamic Analysis

•     
Create a 3D model of the track and wheel

•     
100m long straight track and a complete wheel

•     
Consider effects of changing:

•     
Applying different wheel velocities

•     
Track curvature

Stage 4: Discussions and Conclusions

•     
Discussion of Static and dynamic models

•     
Fatigue life analysis and maintenance recommendations

•     
Recommendations for future work

•     
Conclusions

Evaluation and Testing
Methods

The procedure
for evaluating FEA will be undertaken using grid dependency testing techniques.
This involves producing an initial set of results with a course mesh then
proceeding to refine the mesh until there is little or no change between
stresses achieved from one iteration to another. While refining the mesh at the
beginning of each study, a mesh quality metrics will be evaluated before
proceeding with the FEA simulation. Validation of the FEA model will be done
using published data and also compared with Hertz analytical methods for
contact stress and fracture mechanics for fatigue cycles to failure.

Economic, legal, social,
ethical and environmental considerations

Economic

The rail
industry is a very lucrative sector not only because of the numbers of people
that use the trains for transport but also long haulage and mass movement of
heavy loads. To keep the wheels of the economy moving on the rail it is vitally
important that the infrastructure is available almost all the time and that service
work between peak times is kept at a minimum as much as possible to avoid any
disruptions to the network. The types of tracks, wheels and locomotives used on
a given section of line should be chosen with a clear understanding of the
geography in that area. This helps to prolong track life and reduce financial
penalties incurred due to regular maintenance. Furthermore, regular maintenance
calls for more operatives and this can impact on company profits etc.

Legal

To prevent
endangering people’s lives and damage to reputation of organisations control
standards have been put in place to make sure that suppliers of rail equipment
such as tracks and wheel all conform to the guiding procedures. The procedures
gives limits on material requirements, profile designs and tolerances, load
limits, wear limits and maintenance requirements just to name a few.

Wheel profile designs

In the United Kingdom, wheel
profile design shall be done in line with Railway Group Standard GM/RT2466
Section 2.3 of Part 2 which states that:

New wheelset
designs shall use monobloc design wheels. The width of the wheel rim (the
distance between the flange back and the outside face of the rim) shall be
within the range 127 to 150 mm and the Tread profile limits are shown in Appendix
K. For monobloc wheels only, it is permissible to reduce the rim thickness at
the final re-profiling such that the fatigue life of the wheel rim becomes
finite. The predicted fatigue life of the wheel after the final re-profiling
shall be not less than three times the remaining service life. New wheel
designs shall make provision for balancing without the need for holes in the
wheel. Maintenance requirements for wheels should be in keeping with Part 4
which states when what action is required when wheel flats reach a certain
length as shown in Appendix J. (Railway Group Standard, 2009)

Track profile designs

Guidance for design track systems is highlighted in the Railway
Group Standard GC/RT5021 which covers many aspects of track design which
include but not limited to:

Track geometry
requirements – which in itself
includes things like circular curves, transition curves, track gauge, normal
limit design values, general horizontal alignments requirements, rail
inclinations etc. Track systems and component requirements – gives guidance on performance specification for
track systems, requirements for rails, rail, gaps and fastening requirements. Appendix
A of GC/RT5021 gives guidance for the geometrical requirements for a 60E2 rail
profile recommended for high speed infrastructure and it is also shown in this
report in Appendix M. Requirements for other rail profile systems including
that of UIC60 which is being investigated in this project are shown in Appendix
G.

Social and ethical

Working with
rail infrastructure such as tracks and train accessories such as train wheels
either from a design, maintenance or management stand point in my opinion
carries the same responsibility as a doctor would to their patients. The
conditions under which the rail and the track operate are very arduous to say
the least and this naturally places them in in the same bracket as other risk
adverse structures such as bridges, aeroplanes cars e.tc. People’s lives are at
stake and the safety of passengers who commute by rail on daily basis depends
on the competency and professionalism of the people who are committed to
applying best practice in designing and maintenance of our rail network. It is
therefore, important to understand the implications of designing track and
wheel profiles in a certain way, not only on the aspect of safety but also interaction
phenomenon between the track and wheel for passenger comfort and reducing
premature wear of these structures.

Environmental

There is a
massive drive nowadays by governments of leading nations to reduce pollution
either at manufacturing and consumption level. Environmental agencies have been
set-up to take a leadership role in setting the standards to which many
companies are subscribed including rail operators and those that look after the
rail network such as Network Rail in the UK. That said, it is imperative from a
design stand point to have a clear understanding of track defects which are
influenced by the types of wheels used on given track locations so that best
conditions are created for sustained usage and reduced wear rates. Track life
can be extended by applying good design practice, this translates to reduced
replacements which intern reduces consumption of row materials at
manufacturing. Furthermore, extended maintenance operations can cause air
pollution through moving earth and transport of raw materials on site.

Stage 2 Attainments

Static Analysis

The
static analysis model was created using the profile of a UIC60 rail and a mono
block wheel published in the article by (J.
P. Srivastava, 2014) . The results from this paper were used to validate our FEA
model. 3D
CAD models of wheel and the rail which were created using an external 3D CAD
packaged then imported into Ansys for FEA analysis. The dimensions of the wheel
and rail are shown in Figure 13. To enable a like for like comparison with the
results obtained in the publication the rail and the wheel were assumed to
linear elastic. The material properties used in the static analysis were
assumed to be as follows:- Elastic Modulus, E = 210GPa for both the wheel and
the rail and the Passions ratio was  and Density 7850kg/m3.The
coefficient of friction between the rail and the wheel were considered to be
0.3.

FEA
simulation set-up assumes a fixed support at the base of the rail to prevent
rigid body motion. To reduce the complexity of the FEA model only a section of
the wheel was modelled. A compressive load of 10 tonnes (98100N) was applied on
the bearing surface of the wheel where the axle is mounted. A mesh dependency
study was conducted starting a default course mesh then refining it until it
was observed that the results obtained one iteration to another remained unchanged
or virtually the same.  Analytical
methods have been employed using Hertz theory the details of which will be
covered in the body of the main report. However, for the purposes of
submission, Appendix N shows
a screen shot of the excel file used to compute the analytical Max contact stress
listed in Table 1.

Results

The
results for each iteration leading to the final converged set, mesh convergence
plot, contact analysis are shown in Appendix H. Convergence was reached when
there was 1.42% change between simulation number 7 and 8. The highest stresses
can be seen on the rail head towards the gauge corner where the contact
analysis plot indicates sliding behaviour between the rail and the wheel. The
Von-Mises stress at this point is 480.6MPa. This is considered to be the
critical location for fatigue crack initiation. The Contact Pressure is
1031.8MPa, again this is shown in Appendix H. A like for like comparison has
been done between FEA results and published in form of contour plots to see the
distribution of stresses around the contact point. Max values are shown in
Table 1 to further validate the FEA model.

Table 1.
Table of results to validate FEA model.

Static Analysis

Contact Stress (MPa)

Von-Mises Stress (MPa)

FEA

Published data

Analytical

FEA

Published data

Analytical

1031.8

1226.8

1205.387

480.6

350.59

In progress

Project Management

Project planning
and execution shall be done as shown in Appendix I starting with identification
of project and drafting a proposal leading up to submissions which already been
accomplished in Milestone 1. Milestone 2 which where I am herded will culminate
in the submission of a Preliminary Report which is due on the 15th
of Jan 2018. Extracts of what been achieved so far has been highlighted in the background,
literature review and Stage 2 attainments. Time scales leading up to the
Interim Presentation, Viva Voice and Final submission including sub-steps in
between have also been presented in the Gantt chart.

Conclusion

Notable headway
has been made in directing this project on a path that pursues in the best
possible way the list of objectives which have been commitment to at the
proposal stage. Comprehensive literature on different accidents which have
occurred in the past have been reviewed from which the ones discussed in this
submission have emerged. It quite intriguing to learn how crucial the contact
point between the rail and the track from both a safety and design point of
view and also what can happen when things go wrong. Common track defects have
been highlighted and will be embellished on later as the report progresses.
What has been observed thus far is that fatigue accounts for some of the most
disastrous accidents which have occurs on the railway all over the world and
continues to be a major issue even in recent years. FEA analysis of UIC60 rail
and mono block wheel with a tread diameter of 1000mm has been undertaken under
static loading conditions. The results obtained have been validated using
published data and analytical methods to show a good correlation between all
three. Although the FEA model predicts the lowest contact pressure the
difference to the published results is 16% and 14.4% lower than the analytical
results. Factors which influence these observations shall be look into at a
later stage with a fine tooth comb. The bulk of work intended to reach
Milestone 2 as shown in Appendix I has been met to a level that warrants submission.
It is on this strength that I believe the project to be on track and I can now
take aim at Milestone 3.