Prevention of Railroad Wheel Fracture

Railroad wheel brittle fractures normally occur from the tips of thermal cracks originating in the tread or flange. Tensile stress that contributes to the fracture is produced by abnormal brake heating. In the US, there used to be a comparable number of derailments due to such brittle wheel fractures. In Japan, brake conditions have not been so severe, and maintenance has been moderate. Therefore, such fractures have not been a major concern in wheel damage. However, conditions such as load and speed of railroad vehicles have become more severe in recent years. Therefore, more precise evaluation of wheel strength and safety is necessary. On the other hand, recent developments in fracture mechanics and elastic-plastic finite element analysis enables us to understand the causes and processes of mechanical failure such as brittle fracture. This paper reports on the research on strength estimation and safety improvements, which are required to prevent the railroad wheel fractures.