The present project aims at building a model for fatigue life prediction of fatigue damage concerning rails submitted to severe loading in order to give orientations for improved steel grades and optimised track maintenance. Modelling is actually the best way to understand the pertinent mechanical and metallurgical parameters which lead to better use of the rails for heavy haul, and allows for minimising the expensive real tests. After a presentation of the general frame of heavy haul transportation, selected profiles of rails and wheels, track conditions and mechanical behaviours useful for the calculations, the study itself is presented. It concerned two kinds of works, essential to the subject of fatigue damaging of rails: (1) characterisations, consisting in monotonous and cyclic tensile tests, Wöhler curves, crack propagation rates and wear behaviour tests on samples machined on four chosen grades; (2) fatigue calculations which use these data to foresee the starting fatigue which is involved in two particular zones of the rail head: at the surface, submitted to elasto-plastic behaviour with a high plasticity level up to 5 % (shakedown and ratchetting behaviours) and, under the surface, in the Hertz zone where the Dang Van criterion estimates the risk of elastic starting. An important item is then proposed: the interaction between damage starting and wear loss that inhibits it in relation to the notion of critical size defect ('magic wear rate'). This behaviour can lead to a controlled damage avoiding propagation. The experimental checking for the modelling consists of full scale tests on an RCF (rolling contact fatigue) machine, the results of which are commented.
Contact fatigue of rails under severe conditions
Kontaktermüdung von Schienen unter starker Beanspruchung
2004
367 Seiten, Bilder, Tabellen, 23 Quellen
Report
Englisch
Contact fatigue of rails under severe conditions : final report
TIBKAT | 2004
|Contact fatigue damage of wheels and rails
Tema Archiv | 2002
|Track - Harder rails prove their worth - New rails are cutting rolling contact fatigue
Online Contents | 2008
Engineering Index Backfile | 1914
|Rolling Contact Fatigue of Rails: Characteristics, Causes and Treatments
British Library Conference Proceedings | 1997
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