Lecture of Docent – Arezou Baba Ahmadi

Railway wheel and rail only make contact in a small area about the size of a small coin. While this small contact area between hard steel surfaces is the reason for the low rolling resistance of railway wheels leading to the high energy efficiency of the railway system, the interaction of wheel and rail in this area is also the origin of several undesired phenomena. The small contact area results in high stresses and contact forces, entailing rolling contact fatigue and wear. These damage mechanisms cause surface irregularities that further increase contact forces and lead to the excitation of vibrations and noise. This lecture gives an introduction to high-frequency wheel/rail interaction responsible for wheel and rail vibration and radiated rolling, impact, and squeal noise. Some selected research results demonstrate how numerical modelling can be used to increase the understanding of the phenomena and to develop mitigation methods. While vibrations and noise are, per se, unwanted, they can also be used to extract information about irregularities and damages on the running surfaces of wheels and rails. This acoustic monitoring enabling condition-based maintenance is an upcoming field that will be the main focus of future research.