Additive manufacture for railway track component life extension with premium laser-clad coatings
Lead Research Organisation:
University of Sheffield
Department Name: Mechanical Engineering
Abstract
This is an exciting PhD research opportunity combining research at University of Sheffield with experience at Network Rail. It focuses on the mechanics and materials of the rail-wheel contact, at which high train loads routinely take rail materials to extreme stress levels. The research will develop understanding of how a large-scale additive manufacturing method using laser-clad coatings on basic steel track components can extend their life. Success in this area will mean fewer line closures for maintenance and reduced cost, thereby having a big impact on how the rail network runs.
Project detail
Additive approaches to creating graduated change in materials and mechanical properties through a component are novel in rail track manufacture (rail, insulated block joints, switches & crossings). Research challenges include understanding tolerable material imperfections through contact stress and fracture mechanics assessment, and ensuring wear, friction and plasticity of the developed surfaces meet the demands placed on them. Research will focus particularly on modelling (e.g. finite or boundary element techniques), combining this with experimental work at small and full-scale.
The research lies in the areas of contact mechanics, fracture mechanics and tribology. Alongside this the PhD includes the opportunity to spend periods with Network Rail getting a real understanding of the opportunities for improvement to the rail-wheel system, and to see how your research can be applied
Project detail
Additive approaches to creating graduated change in materials and mechanical properties through a component are novel in rail track manufacture (rail, insulated block joints, switches & crossings). Research challenges include understanding tolerable material imperfections through contact stress and fracture mechanics assessment, and ensuring wear, friction and plasticity of the developed surfaces meet the demands placed on them. Research will focus particularly on modelling (e.g. finite or boundary element techniques), combining this with experimental work at small and full-scale.
The research lies in the areas of contact mechanics, fracture mechanics and tribology. Alongside this the PhD includes the opportunity to spend periods with Network Rail getting a real understanding of the opportunities for improvement to the rail-wheel system, and to see how your research can be applied
Publications
Tomlinson K
(2021)
Measuring material plastic response to cyclic loading in modern rail steels from a minimal number of twin-disc tests
in Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/R512175/1 | 30/09/2017 | 01/01/2024 | |||
| 1949426 | Studentship | EP/R512175/1 | 30/09/2017 | 24/12/2021 | Katherine Tomlinson |
| Description | In conclusion laser clad coating is considered to be a viable enhancement process for railway track component life extension using Martensitic Stainless Steel (MSS) alloy with 14.64% chromium. The laser process parameters and the depth of laser clad coating must be carefully controlled to achieve the desired quality, if the coating is too thin and the peak contact stress occurs below it, plastic shear strain accumulates within the substrate. The low levels of plastic shear strain observed in this work indicates that the wear and RCF performance would be improved compared to conventional rail steels. There is potential to reduce rail replacement frequency if applied to areas in track prone to damage. It is shown in the repair tests that this can cause the coating to become elongated and creep along the surface. There is further potential to utilise the laser clad coating method for in-situ repairs. A series of twin-disc tests were designed to test the integrity, wear and RCF of laser clad repairs using three candidate materials. A repair with a homogeneous material to the parent rail provided the most effective repair as the comparable ratcheting rate prevented material flow of the parent rail over the repair site, reducing crack initiation points. The geometry of the repair must be carefully controlled to avoid a thin coating at the surface interface as it is shown in the repair tests that this can cause the coating to become elongated and creep along the surface |
| Exploitation Route | The method is to be used to investigate the rate of strain accumulation rather than its steady state is required, in which additional tests of intermediate length will still be required. The results of the investigation will be presented to Network Rail and will have the ability to inform material selection in track across the rail network. There is the expectation that the developed method itself can be used within the rail industry, as rail samples taken from within track can be characterised in this way. As the material response is independent of the loading history, in this case the twin disc testing would be eliminated from the analysis method. |
| Sectors | Transport |
| Description | The current findings from this award have been presented to RSSB Vehicle-Track, Track Advisory Group meeting. The benefits of the newly developed material response measurement method were well received by Network Rail and RSSB. Following this presentation a further reserach project has been granted funding to apply the method to a greater range of new materials. |
| First Year Of Impact | 2019 |
| Sector | Transport |
| Impact Types | Societal,Economic |
| Description | Collaboration Poster at Adhesion Research Group Seminar |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Poster session at the Adhesion Research Group seminar |
| Year(s) Of Engagement Activity | 2018 |
| Description | Poster at Engineering Research Group Sheffield |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Postgraduate students |
| Results and Impact | Poster presentation at University Engineering Research Group event |
| Year(s) Of Engagement Activity | 2019 |
| Description | Poster presentation UKRRIN |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Poster presentation at UKRRIN conference London |
| Year(s) Of Engagement Activity | 2018 |
| Description | Poster presentation University of Sheffield Department of Mechanical Engineering |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Postgraduate students |
| Results and Impact | Second place awarded for poster presentation at the Department of Mechanical Engineering 18 month PhD poster competition |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presenation of research at RSSB London |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Presentation of measurment method developed in this PhD award entitled "Measuring rail material response to repeated wheel loading." From this presentation further funding has been secured to extend the work to other rail materials. |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation at Mission of Tribology research at the IMechE London. |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | I gave a presention entitled "Rail-wheel contact stress and plasticity of a bi-material rail system" at the Mission of Tribology research at the IMechE London. |
| Year(s) Of Engagement Activity | 2018 |
| Description | Presentation at TriboUK at the Universiity of Leeds |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | Presentation at TriboUK conferencehosted by the University of Leeds |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation at the European Conference on Tribology in Vienna |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Presentation given entitled "Quantifying plasticity in laser clad coatings on rail steels" at the European Conference on Tribology in Vienna. |
| Year(s) Of Engagement Activity | 2019 |
| Description | Presentation of research at Network Rail |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Presentation of first year research summary and plans, to a board meeting of around 15 including head of track at Network Rails Technical Board meeting. |
| Year(s) Of Engagement Activity | 2018 |