Maximize Rail Life

Samenvatting

Rolling contact fatigue (RCF) frequently occurs in railway rails. Grinding is the most common way to influence the loading conditions and to remove the cracks to elongate service life and to prevent dangerous fracture. Under a given loading condition the performance of a material against RCF is mainly determined by its microstructure. As railway loading determined by traffic and track structure varies greatly, proper material and grinding parameters have to be selected for different locations to achieve an economic service life. White etching layer (WEL) is a structurally changed surface layer; it has frequently been associated with RCF and is suspected that it can cause RCF initiation. WEL can be caused by rolling contact and by grinding. The influence of microstructure and loading, including WEL and grinding, on RCF initiation and growth has not been well understood. The selection of rail grade and grinding parameters has been made by trial and error. This has led to high maintenance costs and dangerous RCF cracking.

The most important research aims and expected results of the project are:
• Understand the role of microstructure and loading, including WEL and grinding, on RCF initiation and growth.
• Develop models that link macroscopic performance of rail to microstructure and loading
• Determine quantitative relationships between crack initiation and growth rate and loading, rail grades.
• Develop a frame work for the optimization of rail grinding.

To this end, RCF will be reproduced in controlled laboratory tests for a range of rail materials on the vehicle-track interaction test rig at the Railway Engineering group. Special effort will be made to observe and analyse the complete evolution process of the cracks from micro- to macro-scope. So far, such observations are missing. The damages and the associated microstructural changes will be linked to the loading by multiscale modelling. For these the CT-scan technique and thermal-mechanical modelling methods developed in the previous ProRail/STW-project, PRIME, will be employed. The project will, like the previous project PRIME, be performed in close collaboration with a parallel project proposed by the Materials Science and Engineering group of Delft University of Technology, in which detailed microscopic analyses will be performed with advanced characterization techniques; thermo-mechanical experiments and mechanical testing devices for fatigue testing and standardized determination of mechanical properties will be used.

Kenmerken

Projectnummer

15796

Hoofdaanvrager

Dr. ir. Z. Li

Verbonden aan

Technische Universiteit Delft, Faculteit Civiele Techniek en Geowetenschappen, Afdeling Bouw & Infra

Looptijd

01/07/2017 tot 30/06/2021

Budget

€ 746.312