Micromechanical modeling of railway steels under impact fatigue present at crossing nose

January 11, 2016 in

PhD Research by Omid Hajizad


Advisor(s)
Zhiwei Qian, Zili Li

Period
02/01/2014 - ongoing

Theme(s)


Keywords
crystal plasticity (CP), damage mechanisms, microstructure modelling, rolling contact fatigue (RCF),

Partners
ProRail, M2i

Funding
ProRail, M2i, TU Delft

Link or Download
Not available

Summary

Frogs or also called common crossings are subjected to severe impact when wheel rolls from the wing rail to the crossings nose or in the opposite direction. This leads to various defects like irregular wear, plastic deformation, squats, lipping, head checks and etc. finally leading to failure of the crossings which causes safety concerns and financial issues due to replacement.

The main steels used to build common crossings rolled pearlitic steels or casted austenitic Mn-steels. Due to constant increase in vehicle speed and axle load ProRail in seeking new materials which are more resistant to damage under such working condition. Apart from operational disruptions in the network, high and unnecessary monitoring and replacement costs result from this situation.

 The focus of this research will be mostly on the development of fundamental insights in the relations between mechanical loading, damage development, and microstructural features of the rail steels. This will be done by developing a computational model of steel microstructure under fatigue damage condition. 

Meso and Micromechanical models of steel using crystal plasticity material models will be created in order to study their mechanical behavior under impact fatigue load which is present at railway crossings. Different steel microstrucures include Hafield austenitic, pearlitic and most importantly bainitic steels.

His research is part of a M2i (Material Innovation Institute) project which uses an interdisciplinary approach with three main disciplines, material science, tribology and numerical modelling and his task is to create the numerical models.