The Anti-Fatigue Design For Welded Structures Of Railway Wagon With Large Axle Load

As the major trends in today’s world of rail freight transport, overloading of rail transportcould not only achieve the purpose to alleviate tension in rail capacity and improve thetransmission capacity of line, but also be able to reduce the cost of rail transport, especially inthe transport of bulk cargo, which shows the advantage of its transport characteristics of largecapacity. Therefore, heavy transport will be one of the important development directions ofChina railway in the future.Currently welding is the main connection in railway vehicles, and the weak links aremost likely to have fatigue failure, the vast majority of fatigue accidents have occurredbecause of the welded joints. Railway freight car body is basically welded with plates, whichcontains a variety of joint types, the more structures there are, the more complex the joint typeand the joint force are, as the increasing of the vehicle load the occurrence of fatigue failurewill be greater. Therefore, it is of great practical significance to study the fatigue resistance ofwelded structure of the railway freight vehicles.During the operation of the railway vehicle, the force the car body to withstand is acontinuous random process, the stress state of the welding parts is very complicated, the basicformula of Mechanics of Materials and Elasticity can not solve this problem, and currently,we cannot carry out a fatigue test of the whole vehicle because the car body of heavy freighttrain is of great bulk. Therefore, the use of Virtual Prototype Technology and advancedmethod of fatigue life analysis is particularly necessary to study the fatigue life of heavyfreight vehicles. The main contents of this article are as follows:First, based on the AAR loading standard, the car body of freight vehicle with a largeaxle load would be studied, static strength analysis of the vehicle body would be taken under12kinds of load conditions, the results show that the car body could meet the designrequirements of intensity. Select15test points on the car body under the vertical load andtensile load conditions according to the strength test data from the design factory, and thencompare the finite element static strength calculation results and experimental results.Then, use freight vehicles load spectrum in AAR maintenance standard based on thestatic strength calculation, and assess the main welding seam fatigue life of the heavy carbody using the latest welded structure fatigue life prediction techniques-Main S-N curvemethod, then improve the structure of the welding seam which could not meet the designedyears of fatigue life.The life of the changed welding seam has improved significantly.Finally, in order to verify the accuracy of fatigue life prediction which use finite elementmodel of mass shell of the car body, improving the structural elements to take a fine analysis with the application of sub-modeling techniques, and assess the fatigue life of the weldingseam in this part. Then compare the calculation results after fine analysis with the results ofthe assessment of the original model, which shows little difference between the twoassessment results of fatigue life. It is verified that insensitivity of grid of the main S-N curvemethod and the accuracy of using of the whole vehicle model for welding seam fatigue lifeassessment.