Evaluation of fatigue crack growth behavior of bogie frames under operating load

The bogie frame of a railway vehicle is a welded structure that supports passengers and cargo. The bogie frame is subjected to regular non-destructive testing to inspect cracks. In this study, the crack growth characteristics of the bogie frame were evaluated while considering the dynamic stress. A finite element analysis for evaluating the critical areas and the stress intensity factor and crack growth analysis was conducted while taking into consideration the dynamic stress. Under the maximum vertical load condition, the critical crack length was 234 mm. When the shape function obtained from the bogie frame was applied, the crack growth life was evaluated to be longer than when the shape function of the specimen was applied. As the crack growth life from the initial crack length of 40 mm to the critical crack length requires 3.3 years, unstable crack growth can be detected in an inspection performed every 3 years.