2018 Volume 67 Issue 12 Pages 1065-1072
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 paper are to clarify the fatigue property of cast steel used in railway bogie frames and to propose 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. It is clarified that the fatigue strength of specimens with casting surfaces is higher than that of specimens with machined surfaces; the fatigue strength under plane bending is extremely higher than that under axial loading. These results are attributed to differences of locations and geometries of cast defects where cracks originate. A fatigue design criterion for members of cast steel is proposed by statistical evaluation of the fatigue data. Moreover the validity of the proposed criterion is demonstrated by the full-scale fatigue test of bogie frames with members of cast steel.
