Dynamic Stress Response and Fatigue Reliability of Gearbox Housing for G-Series High-Speed Train

The cast aluminum alloy gearbox for G-series high-speed train is subjected to complex load conditions and stochastic stresses during service. Taking a new-type gearbox for G-series high-speed train as the research object, the influence of train speed, motor output torque and track condition on the dynamic stress response and fatigue strength of gearbox was analyzed combined with line tests. By means of stress-strength interference theory, an equivalent stress and fatigue strength interference reliability model for gearbox was established, and the relationship between the fatigue reliability of gearbox housing and service mileage was analyzed. Results show that, with the increase of train speed and motor output torque, the stress level at each measuring point on the gearbox housing increases in varying degrees, and the stress change at the seat of end hanger rod is the most obvious. When the train speed increases from 200 to 400 km•h-1, the maximum dynamic stress amplitude increases about 120%, while it increases about 150% when the motor output torque changes from 0 to 1 400 N•m. The track condition also has a significant influence on the equivalent stress of the housing. With the increase of the service mileage of the train, the fatigue reliability of the housing decreases continuously. Under the certain reliability, with the improvement of the quality grade of cast aluminum alloy housing, the service life of the gearbox housing can be prolonged, for example, the service mileage can be increased by a factor of 3.8 when the casting pore size changes from 0.9 to 0.5 mm in diameter. © 2018, Editorial Department of China Railway Science. All right reserved.