Wear transition in the wheel-rail contact

Background

An observation that can be made about wear is that an increase of the severity of loading at some stage leads to a sudden change in the wear rate. Wear transitions are identified using wear maps and are defined in terms of sliding velocity and contact pressure. Wear regimes are related to expected wheel-rail contact conditions and contact points (tread/flange).

Such wear assessments are becoming more significant as train speeds are increasing and new specifications are being imposed relating to safety and reliability. It can also help in determining more efficient maintenance schedules on particular routes; where different track profiles may be needed to reduce the severity of the wheel-ail contact and where application of lubrication or change of material may be necessary to reduce wear problems.

The transitions between the different wear mechanisms are studied with special emphasis on the transition between mild and severe wear. The test equipment to be used is a seizure tribometer developed at KTH, Machine Design. The way contact pressure and relative sliding velocity are related to the transition from mild wear to severe wear/seizure can be studied in this test equipment.

Purpose

The overall goal is to construct wear and seizure maps that include the contact between rail gauge and wheel flange. The transfer from mild wear to severe wear seizure is studied in detail. Further on the goal is to study how the transfers from mild wear to severe wear depend on the type of lubricant, surface coating and topography.

Publications

J. Sundh and U. Skytte af Sätra, Influence of surface topography and surface modifications on seizure initiation in lean lubricated sliding contacts, Wear, 2007, vol 262, pp. 986-995.

J. Sundh and U. Olofsson, Seizure mechanisms of wheel–rail contacts under lubricated conditions using a transient ball-on-disc test method, Tribology International, In press, Available online 28 March 2008

J. Sundh, U. Olofsson, and K. Sundvall, Seizure and wear rate testing of wheel-rail contacts under lubricated conditions using pin-on-disc methodology, Wear, 2008, In press, corrected proof.

J. Sundh, An experimental study on wear transitions in the wheel-rail contact, Licentiate thesis, TRITA-MMK 2007:02, Stockholm, 2007.

J. Sundh, U. Olofsson, L. Olander, and A. Jansson, Wear rate testing in relation with airborne particles generated in a wheel-rail contact, To be presented at Nordtrib 2008, June 10-13, Tampere, Finland.

Contact

Jon Sundh, e-mail: sundh@md.kth.se, phone: +46 8 7909549
Ulf Olofsson, e-mail: ulfo@md.kth.se, phone: +46 8 7906304