Analysis On The Strength And Fatigue Of An EMU Bogie With Built-in Axle Box

Since the 21 st century,with the rapid development of high-speed railway,the related technology of high-speed bullet trains is becoming increasingly mature and the running speed is breaking through constantly.With the increasing speed of high-speed EMUs,more and more high requirements for train safety,the traditional static strength check has been unable to meet the needs of the high-speed era,the influence of frequent alternating dynamic load on vehicle life has tended to the main position,bogie as the main bearing parts of high-speed train,need to hang or install a large number of equipment,and Its key parts are subjected to complex loads.Therefore,it is very important to ensure that the high-speed train bogie has enough fatigue life for the safe operation of high-speed train.Against the above background,this paper takes the built-in axle box bogie of an EMU as the research object to carry out the following research:(1)According to the principle of finite element modeling,the finite element model of the frame is established using hexahedral solid elements and a few tetrahedral elements.According to UIC515-4 standard,a total of 22 static strength conditions of the welded frame were determined,and the static strength and modal analysis of the welded frame were carried out.The results show that the static strength of the welded frame meets the application requirements,and has good vibration characteristics and stiffness.(2)According to the operating load conditions determined above,fatigue analysis of key parts of the welded frame base metal was carried out based on Goodman curve.Then,four fatigue loading conditions were determined according to UIC515-4 standard,and three loading stages were carried out.The fatigue life of key welds of welded frames was calculated based on nominal stress method of IIW standard and BS 7608 standard respectively.The results of calculation of the two methods were compared,and the results showed that: The fatigue life of the frame meets the requirements of use,and the calculation of fatigue life of BS 7608 standard is more advantageous.(3)According to ASME standard,the equivalent structural stress method was used to evaluate the fatigue strength of the key weld of the frame,and the calculation results of the three methods were compared.The results showed that: The fatigue strength of the frame also meets the application requirements,but the location of the maximum damage weld is different.Compared with the nominal stress method,the equivalent structural stress method can identify the fatigue failure location of the welded structure more accurately,which is more practical.