Dr David Fletcher

BEng, PhD

Dr David Fletcher

Senior Lecturer in Mechanical Engineering

Department of Mechanical Engineering
Sir Frederick Mappin Building
Mappin Street
Sheffield
S1 3JD
UK

Telephone: +44(0)114 22 27760
Fax: +44(0)114 2227890

email : d.i.fletcher@sheffield.ac.uk


Profile

Dr David Fletcher is a graduate of Leeds University where he studied Mechanical Engineering and worked with his sponsoring company CarnaudMetalbox Packaging. He was awarded a PhD in Mechanical Engineering from the University of Sheffield, and went on to conduct research in a range of areas including railway engineering, forming tool design and development of assistive tools for cataract surgery. From 2004 to 2009 he conducted research with Newcastle University focusing particularly on full scale railway engineering testing, before returning to Sheffield. He has been awarded several prizes for research in the railway area, including the prize for best paper addressing system interaction issues at the World Congress on Railway Research, Korea 2008, the Institution of Mechanical Engineers Railway Division, TA Steward-Dyer / F H Trevithick Prize, 2005, and the Institution of Mechanical Engineers Tribology Trust, Tribology Bronze Medal, 2000.

Areas of Research

Dr Fletcher's research interests are in engineering design and in performance of materials. The majority of his work has application in the railway sector, and combines experimental and modelling approaches. Major themes include:

Railway rail-wheel interface

The rail-wheel interface subjects the rail and wheel to extreme loading, often leading to high maintenance requirements. Dr Fletcher's research has developed new understanding of the interaction between rolling contact fatigue, surface crack initiation, crack growth and wear, linking these to the metallurgy of the steels involved. The research has combined experimental approaches including small and full scale trials to investigate crack growth, with modelling based on both fracture mechanics and contact energy, to understand and find solutions to the damage mechanisms involved.

Recent work has focused on adhesion at the rail-wheel contact, and development of new understanding of the creep-adhesion relationship. This is linked to earlier work on chemical approaches to prevention of low adhesion, and research into the performance of a range of lubricants and friction modifiers.

In 2009 Dr Fletcher revisited the Japanese Railway Technical Research Institute (RTRI), Tokyo, to continue a collaboration begun in 2006 on modelling crack growth in rail steel. This was originally supported through a short fellowship undertaken at RTRI funded by the Japan Society for the Promotion of Science.

Tribology

Research on the rail-wheel interface and its contact mechanics is a specialist area of tribology, and Dr Fletcher also applies tribological understanding to a range of wider industrial problems. Most recent work has looked at the railway overhead line to pantograph contact that can suffer extreme heating and wear problems due to the high sliding speeds, electric current and variable forces involved. The investigation was conducted by developing a wear testing machine capable of up to 200kph sliding speed, replicating in the laboratory the wear of copper overhead line and pantograph contact strips to better understand their performance.

Rail system design for safety and security

Over recent years European rail systems have been subject to terrorist attack, and their crowded and open nature makes them difficult to protect. Dr Fletcher is conducting research through UK and EU projects aiming to design resilience into stations and vehicles, thereby lowering the risk and impact of attack, and making recovery faster. Knowledge of rail system design and understanding of performance of materials under extreme loading links this area of work with the more conventional engineering aspects of Dr Fletcher's research. An essential aspect of this work is the acceptability to travellers and operators of any change in the design of stations or rail vehicles, and linking design decisions to risk assessment.

Professional Activity

  • Dr Fletcher has conducted research on ESPRC, EU and industrially funded projects with partners including Network Rail, Tata, DeltaRail, London Underground, the Rail Safety and Standards Board, Korean Railroad Research Institute, Japanese Rail Technical research Institute, and the UK Health and Safety Executive.
  • Deputy Director Rail Innovation & Technology Centre, University of Sheffield/Network Rail (2011-)
  • International Committee member for Conference on Contact Mechanics and Wear of Rail/Wheel Systems, CM2012.
  • Executive Committee member of Rail Research UK Association (RRUK-A, 2010-2012)
  • Guest editor for IMechE Journal of Rail and Rapid Transit special issue "Engineering a Secure Railway" (2011)

Major Research Grants and Projects

  • EU Framework 7 project 'SUSTRAIL: The sustainable freight railway - Designing the freight vehicle-track system for higher delivered tonnage with improved availability at reduced cost', 2011-2015
  • EU Framework 7 project: 'SecureStation: Passenger station and terminal design for safety, security and resilience to terrorist attack', 2011-2014
  • EPSRC grant EP/H024743/1 'Factor 20: reducing CO2 emissions from imland transport by a major modal shift to rail', Feasibility account grant 'Freight 2035', 2010-2011
  • EPSRC grant EP/F008635/1 'Resilient design (re-design) for counter-terrorism: Decision support for designing effective and acceptable resilient places', 2007-2010

PhD Students:

  • Smith, L - Rolling Contact Fatigue in Wheel-Rail Contact (2007)
  • Anthistle, T - Modelling blast loading in rail vehicles (2010-)

PhD research opportunities are available in any of my research areas - please contact me for discussion.

Prizes

  • World Congress on Railway Research, Korea, Prize for Best Paper Addressing System Interaction Issues, for paper Three-Dimensional Microstructural Modelling Of Wear, Crack Initiation and Growth in Rail Steel, 2008
  • The Institution of Mechanical Engineers Railway Division, TA Steward-Dyer / F H Trevithick Prize, 2005
  • The Institution of Mechanical Engineers Tribology Trust, Tribology Bronze Medal, 2000
  • The Institution of Mechanical Engineers Railway Division, William Alexander Agnew Meritorious Award / Clarence Noel Goodall Award, 2000
  • The University of Sheffield Herbert Walker Swift Bursary, 2000
  • The Institution of Mechanical Engineers Frederic Barnes Walden Prize, 1994
  • The University of Leeds Foundation Prize in Mechanical Engineering, 1994
  • ICI Prize, University of Leeds, 1993
  • Cameron Iron Works Prize, University of Leeds, 1992

Teaching

Dr Fletcher is module leader for the first year module Mechanical Engineering Design Skills (MEC131). He also teaches Mechanical Engineering in Railways to fourth year MEng and MSc students and is part of the team organising the 3rd year BEng/MEng group design project (MEC307).

Selected publications

 Selected refereed journal papers:

  • Studs: A squat-type defect in rails,
    Grassie, S. L., Fletcher, D. I., Gallardo Hernandez E. A. & Summers, P. (2011),
    Journal Proceedings of the IMechE, Part F: Journal of Rail and Rapid Transit.

  • Developing an effective and acceptable engineering response to terrorist attacks on railway systems,
    Powell, J. P. & Fletcher, D. I. (2011),
    Proceedings of the IMechE, Part F: Journal of Rail and Rapid Transit, 225(4), pp. 359-371.

  • Planning rail grinding using crack growth predictions,
    Hyde, P. & Fletcher, D. I. (2010)
    Japan Society of Mechanical Engineers, Journal of Mechanical Systems for Transportation and Logistics, 3, pp. 216-225.

  • Rail rolling contact fatigue dependance on friction, predicted using fracture mechanics with a three-dimensional boundary element model,
    Fletcher, D. I., Smith, L. & Kapoor, A. (2009),
    Engineering Fracture Mechanics, 76, pp. 2612-2625.

  • Resilient design for community safety and terror-resistant cities,
    Coaffee, J., Moore, C., Fletcher, D. I., and Bosher, L. (2008),
    Journal of the Proceedings of the Institution of Civil Engineers: Municipal Engineers, 161 (2), pp. 103-110.
    Online (open access)

  • Three-dimensional microstructural modelling of wear, crack initiation and growth in rail steel,
    Fletcher, D. I., Franklin, F. J., Garnham, J. E., Muyupa, E., Papaelias, M., Davis, C. L., Kapoor, A., Widyarta, M.and Vasic, G. (2008),
    Korean International Journal of Railway, 1 (3), pp. 106-112,
    Online (open access)

  • Modelling and full scale trials to investigate fluid pressurisation of rolling contact fatigue cracks,
    Fletcher, D. I., Hyde, P., and Kapoor, A. (2008),
    Wear, 265 (9-10), pp. 1317-1324,
    Online (journal subscription required)

  • A rapid method of stress intensity factor calculation for semi-elliptical surface-breaking cracks under three dimensional contact loading,
    Fletcher, D. I., and Kapoor, A. (2006),
    Journal Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 220 (3), pp. 219-234,
    Online (open access)

  • Computer simulation of strain accumulation and hardening for pearlitic rail steel undergoing repeated contact,
    Kapoor, A., Beynon, J. H., Fletcher, D. I., and Loo-Morrey, M. (2004),
    Journal of Strain Analysis for Engineering Design, 39 (4), pp. 383-396,
    Online (open access)

  • Image analysis to reveal crack development using a computer simulation of wear and rolling contact fatigue,
    Fletcher, D. I., Franklin, F. J., and Kapoor, A. (2003),
    Fatigue and Fracture of Engineering Materials and Structures, 26 (10), pp. 957-967,
    Online (journal subscription required)

  • Experimental assessment of materials for indirect surface texturing,
    Fletcher, D. I., Al-Battashi, S. A., and Kapoor, A. (2002),
    ASTM Journal of Testing and Evaluation, 30 (6), pp. 501-507,
    Online (journal subscription required)

  • Development of a machine for closely controlled rolling contact fatigue and wear testing under high stress conditions,
    Fletcher, D. I., and Beynon, J. H. (2000),
    ASTM Journal of Testing and Evaluation, 28 (4), pp. 267-275,
    Online (journal subscription required)

  • A simple method of stress intensity factor calculation for inclined surface-breaking cracks with crack face fracture under contact loading,
    Fletcher, D. I., and Beynon, J. H. (1999),
    Journal Proceedings of the Institution of Mechanical Engineers, Part J: Engineering Tribology, 213 (6), pp. 481-486,
    Online (open access)

  • A simple method of stress intensity factor calculation for inclined fluid-filled surface-breaking cracks under contact loading,
    Fletcher, D. I., and Beynon, J. H. (1999),
    Journal Proceedings of the Institution of Mechanical Engineers, Part J: Engineering Tribology, 213 (4), pp. 299-304,
    Online (open access)

Selected refereed conference papers:

  • Three-dimensional modelling of rail steel microstructure and crack growth,
    Franklin, F. J., Gahlot, A., Fletcher, D. I., Garnham, J. E., and Davis, C.
    8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems - Firenze, Italy, September 15-18, 2009

  • The acceptability of counter-terrorism measures on urban mass transit in the UK,
    Kappia, J. G., Fletcher, D. I., Bosher, L., and Powell, J. P.
    15th International Conference on Urban Transport - Bolgana, Italy, June 22-24, 2009

  • Effect of traffic on crack initiation in rails,
    Vasic, G., Franklin, F. J., Fletcher, D. I., and Kapoor, A.
    International Symposium on Speed-up, Safety and Service Technology for Railway and Maglev Systems - Japan, June 16-19, 2009

  • Planning rail grinding using crack growth predictions,
    Hyde, P., and Fletcher, D. I.
    International Symposium on Speed-up, Safety and Service Technology for Railway and Maglev Systems - Japan, June 16-19, 2009