On the fatigue performance and residual life of intercity railway axles with inside axle boxes

Railway axles with inside axle boxes have a great potential in modern urban railway system due to good dynamic performance on small-radius track. However, because of entirely different loading nature from widely-used one, a challenging problem of the fatigue performance and damage endurance arises in the case of defects from various external sources. In this paper, a stepwise fatigue assessment framework composed of safe life as the first level and damage tolerance as the second level was tentatively proposed for the wheelset with inside axle boxes. An assumed load spectrum was employed to estimate the remaining life for a damaged axle made of the EA4T steel. Calculated results show that the critical safety region has been transferred to the axle center in contrast to classical axles, where a 1.0 mm-depth crack as the inspection limit has less probability to propagate. Besides, the wheelset with inside axle boxes shows the smaller stress value. The analysis from well-known Kitagawa-Takahashi diagram indicates a security risk while only using nominal stress approach.