Research on Welded Joints Stress Condition Assessment of Railway Freight Car Welded Frame with Considering Stress Concentration Effect

摘要

In recent years, fatigue problems of bogie welded frame have occur at welded joints with stress concentration, which reflects the current design method of welded joints needs to be improved. The structural stress method can effectively identify the stress concentration of welded joints. In this paper, the structural stress method in ASME standard is programmed, and combined with BS EN15085-3:2007 standard, the assessment route of stress condition of welded joints of freight car welding frame is put forward. Based on the fatigue load of EN13749:2011, the Master S-N curve with 98% reliability -2o is selected to predict the fatigue life of the weld, and the stress factor is calculated according to the equivalent structural stress of the weld. The analysis shows that the stress factor of the weld of the frame cross beam and brake hanger, cross beam and traction rod base is larger, the maximum value is 0.81, the stress state grade is "medium", and the stress condition of the other welds is "low". The stress condition assessment method proposed in this paper can identify the stress concentration of welded joints. In order to improve the rationality of design, it is necessary to study the stress condition of welded joints in the design stage for other complex structures.