Research On Fatigue Resistance Of Welded Frame Of High Speed Train Bogie

The bogie is the running gear of the locomotive,the frame as the main load-bearing structure of the bogie,is the most important components of the locomotive.It bears and transmits static and dynamic loads in all directions.Studies have shown that the failure of the bogie frame is mainly the welding position,that is,the fatigue damage of the weld.Railway vehicles are developing in the direction of high speed and heavy load.With the increase of the speed of the railcar,the amplitude and frequency of the dynamic loads on the frame are also increasing,which puts new and higher requirements on the safe operation of the high-speed train bogie frame.This paper first describes the research status and related theories of the fatigue field of high-speed train welded frames at home and abroad,and then based on the nominal stress method,the Goodman curve method,the International Welding Association IIW standard and the British BS standard are used to calculate the fatigue resistance characteristics of the frame.Finally,the advantages and disadvantages and application scope of the three methods are compared and analyzed.The specific research contents are as follows:(1)The finite element model of the bogie frame was established with Hypermesh software.The bogie frame was loaded and constrained according to the UIC standard of the International Railway Union.The stress and strength of the frameunder 4 supernormal loads and 9 operating loads was calculated using Ansys software.(2)Based on the stress calculation results of 9 operating conditions,24 key position welds were selected.Based on the nominal stress,the Goodman fatigue curve of each weld was obtained,and the stress state and safety factor of each weld were obtained.The calculation results show that the fatigue life of each key weld meets the requirements;(3)According to the IIW standard of the International Welding Society and the British BS standard,the fatigue life of important welds of the bogie welding frame was calculated and evaluated.First determine the fatigue level and corresponding S-N curve of the weld to be evaluated,then calculate the damage value,fatigue life and cumulative damage value of the weld,and then calculate and evaluate the fatigue life of the weld of the frame.The calculation results show that the fatigue life meets the requirements;(4)Combining the above calculations,the results of the three methods of Goodman curve method,IIW standard and BS standard are compared and analyzed,then the advantages and disadvantages and application scope of these three evaluation methods are analyzed.The results show that the welded bogie frame meets the fatigue life design requirements,and the Goodman curve evaluation results based on the nominal stress method are more accurate and conservative.