Manicka Dhanasekar & Nannan Zong (QUT) Acknowledgements: Robert Taylor (ARTC)/ Ian Marks (QR)/ Chris West (Thermit)/ David Wexler (UoW)/ Paul Boyd (CQU)/ Vladimir Luzin (ANSTO)/ Dr Thusyanthan (Cambridge, UK)/ Andy Take (Queens University, Canada)/ Thaminda Bandula Heva (PhD student)/ Chandu Rathod (PhD Student) & Hossein Askarinejad (PhD Student)
Manicka Dhanasekar & Nannan Zong, QUT delivered the presentation at the RISSB’s 2013 Rail Turnouts Workshop.
The RISSB’s National Rail Turnouts Workshop 2013 gives all those involved an in-depth forum to consolidate and share the latest technical information for rail turnouts. Drawing on industry expertise, the workshop features technical and practical presentations that address key turnout functions in an every-day operational context.
For more information about the event, please visit: http://www.informa.com.au/railturnoutsworkshop13
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Manicka Dhanasekar & Nannan Zong (QUT)
Acknowledgements: Robert Taylor (ARTC)/ Ian Marks (QR)/ Chris West (Thermit)/ David Wexler (UoW)/ Paul Boyd (CQU)/ Vladimir Luzin (ANSTO)/ Dr Thusyanthan (Cambridge, UK)/
Andy Take (Queens University, Canada)/ Thaminda Bandula Heva (PhD student)/ Chandu Rathod (PhD Student) & Hossein
Askarinejad (PhD Student)
THE CONTEXT IRJ is a gapped rail joint – the gap of which must be maintained over
its life: Similar to the Point Blades/ Switch IRJs are source of Impact: Similar to the Crossings in Turnouts IRJs suffer from Ratchetting: Similar to the Tips of Blades & Crossings High Yield Materials Trialed in Turnouts & IRJs; fundamental studies
are limited. THIS PRESENTATION WILL BRIDGE THIS GAP IN KNOWLEDGE
When damage is excessive, or joint bars break, new IRJs welded; No guideline to positioning of the gap: Suspended between sleepers? Or supported onto the sleeper?
Ballast depth?
Frequency of ballast tamping?
Rail Grinding near gap?
IRJs are positioned randomly when replaced
The ROOT CAUSE is the passage of loaded wheels: Let‟s re-visit the theory of wheel-rail contact
Field Practices: IRJ
Wheels Passing Gaps Produce Impact and Railhead
Ratchetting
Is Impact Load itself THE Problem?
Is the Wheel-Railhead Contact at the Un-Supported Gapped Edge THE Problem?
Is the rail yield strength THE problem?
Fundamental Research Questions
Dr Zong will uncover the answer…………
6 IRJs monitored Gap narrowing
Joint dipping
Time Based Observation: Over 19 Months
Gap Narrowed
Joint Dipped
Time Based Observation: Over 19 Months
Shakedown Theory
Assumes elliptic Hertzian Pressure: Not Applicable for IRJs
Lattice Spacing Narrowed at Top in Severely Trafficked Railhead
0 5 10 15 20 25 30 35 40 45 50 55 60
-60
-55
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
Experiments: Field Instrumented IRJ in the field
General view of data recording setup
Modelling
Rapid Variation of Strain in the Plastic zone => Very Fine
Mesh
Is Impact @ Gap THE problem?
10mm
5mm
174KN 163KN
Gap size was 8.5mm in 2003 – now it is 5mm
~9% impact load cannot cause 65% life reduction
Contact impact from field test Contact impact force from FEA
Is low yield railhead steel THE problem?
Martensitic Stainless Steel (~1200MPa)
Maraging Steel (~2000MPa)
VAS (~1600MPa) – through hardened railhead?
INTERFACE with rail steel seems a problem
Idea???
IF the stress concentration moves away from the corner into the railhead, with reduced magnitude, THEN the rail end should behave like a continuous rail (in theory).
Is vertical cut of the rail THE problem?
Both 90° / 75° cuts are Just Vertical – leaving the top of railhead vulnerable