Progresses on the fatigue reliability research of China railway vehicles in recent decade

Main progresses are reviewed and prospected from four elements on the fatigue reliability analysis research of China railway vehicles during recent decade. First, material fatigue database has been moderately developed and an emphasis was placed on the systemized fatigue properties. Second, a great of on-line inspections have been performed on the wheel-track contact forces and service stresses of key structures. A reliable vehicle dynamics simulation technique has been developed for simulating the contact forces and a multi-variable quadratic regression approach has been proposed to calculate the service stresses for recuing imperfect inspections. Third, systemized fatigue reliability researches have been made on improved fatigue limit measurement, probabilistic S-N curves, scale-deduced fatigue behavior, design Goodman-Smith diagram, and reliability analysis approach to address on the real super-long life of railway vehicle's structures. Fourth, a critical safety state theory is established to address the time-dependent off-round wheel wear and the interactive fatigue damage between components. Fatigue cracking threshold measurement is improved. And a fatigue crack growth modeling is developed to cover entire physical process from the threshold to the fracture. The axle critical safety sizes are determined under considering the off-round wheel and the wheel critical safety wear sizes are measured to ensure the axle expected safety life. All researches are valuable to be further studied.