Assessing fatigue crack growth in railway axles

Railway axles are safety critical components. Designing in failsafe mechanisms is very difficult and the safety of the component is determined though a good understanding of the structural integrity and through effective management policies. This paper first reviews from a historical viewpoint the development of the design and management of railway axles, and then outlines state of the art methodologies to be employed in the successful management of railway axles. Advancements in fatigue fracture mechanics have permitted the development of statistical techniques which enhance the understanding of axle failures which occur relatively infrequently. Because of the extremely low number of in-service failures, there exists a possibility to increase the NDT inspection interval, and to even abandon certain inspection procedures, such as far-end ultrasonic scans, completely. There is some evidence to suggest that inspection procedures which involve a degree of disassembly of the axle actually introduce a risk which offsets the benefit associated with crack detection.