Fatigue property and design criterion of cast steel for railway bogie frames

Abstract

The fatigue design criterion for members of cast steel is not specified in the design standard of railway bogie frames in Japan. The objectives of the present study involve clarifying the fatigue property of cast steel used in railway bogie frames and proposing a fatigue design criterion for members of cast steel. Fatigue tests are conducted on test specimens with casting or machined surfaces under axial loading or plane bending. The results indicate that the fatigue strength of specimens with casting surfaces exceeds that of specimens with machined surfaces. The fatigue strength under plane bending significantly exceeds that under axial loading. The results are attributed to differences in the locations and geometries of cast defects where cracks originate. A fatigue design criterion for members of cast steel is proposed by the statistical evaluation of fatigue data. Furthermore, the validity of the proposed criterion is demonstrated via a full-scale fatigue test of bogie frames with members of cast steel.