Study On Load Spectrum Compiling Method Of C70Car Body Simulation Fatigue Test

Along with the railway freight volume increased significantly, the structure fatigue problem of wagon car body is more prominent. C70gondola car body have occurred fatigue fracture in many welding structure, which has brought huge losses to the railway transportation. Fatigue fracture problem of wagon car body has become one of the bottleneck restricting the technology development of wagon car body. An effective way to get wagon car body welded structures fatigue performance data is to process indoor simulated fatigue loading test. Domestic Qiqihar Railway Equipment Co., Ltd. has basically completed car body fatigue test rig. The test rig can be a good simulation of the car body bearing form and vibration form and can process the whole car body fatigue test. Compiling scientific and accurate load spectrum is the key to fatigue test, which is the main research content of this paper.The car body load data as well as the stress data of fatigue critical parts are obtained on the basis of C70gondola car general line load spectrum test. The method of utilizing the measured data for compiling fatigue test load spectrum is studied, and the way of using relationship of car body load and stress response for compiling fatigue test load spectrum is put forward. Large load which can cause car body structural fatigue damage is relatively small when the vehicle is in the actual operation of the line, and the small load which contribute little or no damage to the car body fatigue damage accounted for most of the time. Stress is the response of the load, which is the essential reason of the car body fatigue damage. This paper studies the impact of small stress cycle on the car body damage. According to the damage equivalent principle, the small stress cycle which has no contribution to car body damage is cut out, and stress time history is simplified and concentrated. By using synchronicity of load and stress test, load time history is concentrated as well. Combining with the cumulative damage theory, the car body fatigue damage before and after concentration is analyzed in comparison. The feasibility and accuracy of this method is verified.