Research And Application Of Longitudinal Load Spectrum Characteristics Of Railway Freight Car

The longitudinal load is the key factor that affects the performance of the railway freight car, and it is the main index to evaluate the strength of the vehicle structure. In order to ensure the safe operation of the railway freight car, a lot of longitudinal load spectrum tests have been carried out at home and abroad. However, the longitudinal load spectrum characteristics of different freight cars need further research. The influence of different factors on fatigue of vehicle can be obtained by exploring the relationship between the load spectrum and axle load and traction tonnage. The research has guiding significance to the vehicle structure fatigue design, strength evaluation and safety control.The characteristics of different load spectra were compared in terms of the two aspect of maximum load and fatigue damage based on coupler longitudinal load spectrum under general line, coupler longitudinal load spectrum under Da-Qin line, AAR 90.7t hopper car coupler longitudinal load spectrum and FMG ore gondola car coupler longitudinal load spectrum. Railway freight cars are different in axle load, traction tonnage, formation type and braking ability, etc. According to longitudinal dynamics simulation method, the influence of single factor on load spectrum characteristics was obtained. The main research contents and conclusions can be summarized as follows:(1) Based on the longitudinal load spectrum of different railway freight cars, the maximum longitudinal load value was obtained. By comparing different statistical inference values, we can found that the maximum longitudinal load of railway freight cars increase with axle-load and traction tonnage.(2) The longitudinal load spectrum characteristics were analyzed based on the fatigue damage. The equivalent stress amplitude of the key parts of the C80 aluminum alloy car body was estimated by using the longitudinal load spectrum of different freight cars. The results showed that the equivalent stress amplitude of the key parts of the car body increase with axle-load and traction tonnage.(3) The longitudinal dynamics of railway freight car was established by using the numerical simulation method. Taking the single ton train model as the research object, the influence of different factors (axle load, traction tonnage, formation type) on the longitudinal load of railway freight car were analyzed. The analysis showed that the longitudinal load increase with the axel load under the same formation type; the increase of the train tonnage will aggravate the longitudinal impulse of the train; the Locotrol skill can alleviate the longitudinal impulse of the train.(4) Based on the finite element method and the longitudinal dynamics simulation method, the dynamic stress and the equivalent stress amplitude of the vehicle body were obtained. The dynamic stress and equivalent stress amplitude of the key points increased with the axle load and the traction tonnage, the axle load and traction tonnage are the influence factors of fatigue damage of vehicle structure. The Locotrol technology can reduce the dynamic stress and equivalent stress amplitude of the critical points. Comprehensive results can explain the traction tonnage; axle load and formation type can influence magnitude of load, fatigue damage caused by frequency and cycle.