The Reserch On Fatigue Strength Of Susprnsion Components Of Subway Vehicle Bogie

The operation of the metro is one of the effective means of relieving the traffic pressure in medium to large cities in China.As China’s metros continue to develop towards the goals of speed,high capacity and light weight,and as the operating environment for their bogies becomes increasingly hostile,the interaction between the metro structure and the lines leads to more and more bogie cracking.In view of the frequent cracking of the bogie frame and its components of a subway operation company in China in the operation process,and considering that the components with cracks are all suspension components on the frame,which are mainly affected by the inertial load,based on the finite element simulation analysis and field measurement data,the influence of the structure design of the bogie and the rail corrugation section on the life of the local area of the bogie(mainly the end area of the frame,the ATP antenna beam area and the train proximity sensor area)is studied in this paper.In order to analyze the fatigue strength of the bogie frame and its components more accurately,a finite element modal analysis of the bogie frame,the ATP antenna beam and the train proximity sensor should be carried out first to verify the accuracy of the finite element model and the rationality of the mesh division.Then,the above components are connected into a coupled model of the bogie and a constrained modal analysis is carried out.At the same time,the coupled modal frequency of the bogie is compared with the field test data based on hammer strikes and the reliability of the coupled model of the bogie is demonstrated.This provides the basis for a subsequent study of the causes of fatigue cracking.The initial structure of the bogie is evaluated for fatigue strength according to the standard UIC 615-4 OR Motive Power Units-Bogies and Running Gear-Bogie Frame Structure Strength Tests.The S-N curve was selected for each weld seam by selecting the corresponding weld joint class.The fatigue strength of the partial welds is assessed by means of a modified Goodman-Smith fatigue limit diagram corresponding to their fatigue limits.The fatigue strength of the ATP antenna beam and the train proximity sensor was evaluated for random vibration in accordance with the standard IEC 61373-2010 Railway Applications-Rolling Stock Equipment-Shock and Vibration Tests.The results of the evaluation showed that the initial structure of the bogie frame and its suspension components complied with the standard fatigue strength specifications.The time domain fatigue life of the relevant measurement points for random vibration was predicted based on test data from the field.The results found that a significant proportion of the measurement points in the end area of the frame,in the area of the ATP antenna beam and in the area of the train proximity sensor have a fatigue life less than their design life.This is mainly due to the harsh environment of the line and the resonance with the local structure of the bogie,which significantly amplifies the vibration amplitude in this region.Rail corrugation on line conditions was studied and the results found that rail corrugation at different wavelengths is the main cause of dynamic stresses and vibration transfer characteristics in the relevant fatigue regions.The frequent occurrence of 80 mm wavelengths on the line was found to be the main cause of fatigue cracks at the end of the frame.200 mm wavelengths were found to be the main cause of fatigue cracks in the ATP antenna beam.The31.5 mm wavelength is the main cause of fatigue cracks in the area of the train near the sensor and also has an effect on the fatigue cracks in the ATP antenna beam.