Investigation On The Welded Crack On Cross Beam Of C80E General Gondola Car

With the increase of freight car axle load, capacity, and the number of train marshaling, fatigue reliability of the structure becomes the main factor affecting heavy-load transportation safety and comprehensive economic benefit, so improving the structure fatigue reliability proves to be one of the key technologies of the heavy-load freight car. The carbody is the main bearing structure of the freight car, and the cross beam is one of the major bearing component of the car body, therefore the reasonable design of the structure, strength, position of the cross beam has a great influence on the bearing capacity of the carbody.Based on the research and test project on C80E general gondola car of CRRC Qiqihar Rolling Stock Co.,Ltd, after the car completes running evaluation mileage 200 000, cracks are found on the weld of the top cover plate of the cross beam and floor when the carbody is disassembling. With the analysis of the combination of FEA and dynamic stress test in the thesis,deep research is conducted on the cause of the crack and reinforcement scheme.FEA is conducted for the complete general gondolacar,and the relevant test results are summarized. It is confirmed that the strength of the complete car has met the requirements under the current operating condition.Based on the FEA, the FEA model of the local part of cross beam including weld details is built.The fatigue life of the weld on the cross beam is done with structure stress method and nominal stress method, and the improvement plan is proposed.The results of the fatigue life analysis show that the weld on top cover plate of the cross beam and floor cannot meet the requirements. Track dynamic stress test on the carbody structure for the original plan and the improved plan is carried out; the stress spectrum is drafted and the equivalent stress is calculated. Finally, the cause of the crack on the weld and the feasibility of the improved plan are confirmed.The analysis method of the cause of the weld crack on the cross beam and the FEA modeling method involved in the thesis will provide the beneficial reference for the future reliability research on key components of the heavy-load freight car.