Strain measurements at railway wheels

The development of the radial strain component in railway wheels was investigated by neutron diffraction. In the as manufactured state four railway wheels were investigated. In all four wheels no significant strains were found. After 18,400 km usage first strain gradients close to the outer surface of the wheels were detected. In axial middle ranges the changes in strain are weak. After an usage of 61,000 km the gradients becomes strong at the axial outer position between about +700 μɛ close below the tread and −500 μɛ in a depth of 12.5 mm below the tread. At axial middle positions also strain gradients are formed. The end of live state (510,000 km) differs only slightly from the state measured after a usage of 61,000 km.