09:30

Opening

M.J. Santofimia

09:40

Railway rails and rail maintenance

B. Schotsman

Railway rails need maintenance to maintain the profile shape and to remove damage initiations. In the presentation recent research results are shown on the interrelations between material removal (grinding depth), the MESH of the grinding wheels, and the introduction of preferential sites for damage initiation.

10:20

Damage and Microstructure of In–Field Loaded Rails from Macro- to Nano-scale

R.H. Petrov

Structural changes on the surface of R260Mn-grade railway steel, developed during wheel–rail contact, were investigated using optical microscopy, electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD) in a scanning electron microscope (SEM), atom probe tomography (APT), and transmission electron microscopy (TEM). The microstructures of the heavily deformed and phase-transformed surface layer—known as the white etching layer (WEL)—and the underlying deformed layer were characterized across multiple length scales. Ferrite grain fragmentation and alignment in the normal direction (perpendicular to the traffic direction) were analyzed using the aforementioned techniques. Substructures with misorientations below 5° were identified through local misorientation (kernel average misorientation, KAM) analysis. Retained austenite was detected in the WEL using X-ray diffraction (XRD), EBSD, and TKD. The presence of retained austenite, the development of a characteristic “shear” body-centered cubic (BCC) texture at the surface, and the formation of ultrafine grains indicate a mixed mechanism for WEL formation involving both martensitic transformation and severe plastic deformation. The hypothesis that the WEL originates primarily from martensitic transformation was further supported by physical experiments and phase-field modelling.

11:00

RCF caused by static and dynamic loads.

Z. Li

In the presentation, we will show that head checks are caused by static load, and squats by dynamic loads. We show these with field observations and with numerical analyses

Break

12:10

Modelling of rolling contact fatigue in a rolling contact under traction

M.B. de Rooij

Rolling Contact Fatigue (RCF) is a primary failure mechanism in rolling elements across critical engineering applications such as rail-wheel systems, bearings, steel rolls, and gears. With increasing demands for higher load-bearing capacities, accurate failure prediction and optimized maintenance strategies are essential. The presentation will give an overview of recent research performed in the group involving both modelling and experimental validation, with a focus on the effects of interacting effects of hardness and roughness of the contacting surfaces.

12:50

Recent developments in modelling plastic strain failure in rail steels with GPU accelerated computing

D.I. Fletcher

Rail failures through plastic strain accumulation develop over many thousands of wheel passes. Models of the process based solely on strain accumulation show good prediction capabilities for steady state wear, but have some difficulties in predicting wear in the first few thousand contact cycles. A new method will be described for representing microstructures for plastic strain accumulation modelling, including a novel representation of material failure inspired by Peridynamics. The modelling is underpinned by extensive nano-indentation data collection, enabling prediction of rail steel strain accumulation and surface roughness development. The research uses the FLAME GPU (Graphics Processing Unit) computing framework for the first time in contact mechanics modelling, demonstrating the computational acceleration possible by a move to massively parallel processing.

13:30

Wrap-up and closure

M.J. Santofimia/ D. Leonetti