Fatigue crack growth in wheelset axles under bending and torsional loading

In the past, unexpected failures in wheelset axles lead to catastrophic consequences. To avoid those failures inspection intervals must be defined. The definition of the inspection intervals is based on fracture mechanical approaches. In the present work, the railway axle steel 34CrNiMo6 is investigated. For this material fatigue crack growth data have been experimentally determined for a range of different negative and positive stress ratios. Furthermore, the FORMAN/METTU parameters for different probabilities of survival are identified. In wheelset axles different geometry factors influence the crack growth behaviour. Therefore, different shouldered solid shafts with transition radii and a press fit seat are designed and tested under rotating bending. Moreover, the load situation also has an influence on the crack growth. The main bending load is overlapped with torsional loading at special wheel-rail-situations. With the developed mixed mode test rig, the influence of different load situations on wheelset axles are examined.