Abstract: Aiming at the problem that the actual line test load of bogie frame of high-speed EMU can not be directly used in frame structure design, the load expansion method of load spectrum establishment of high-speed train frame is studied. A method of load spectrum extension of frame based on fatigue limit is proposed. Firstly, the stress region of the frame is divided by clustering algorithm according to the characteristics of stress damage. The load sensitivity and damage distribution characteristics of measuring points in different stress regions are analyzed to determine the dominant load and key points of stress propagation in different stress regions. Based on the fatigue limit, the load expansion model of each stress region is established and the load of the frame is extended. The results show that the framework can be divided into seven different stress regions according to the stress conditions, and the dominant loads are different in each stress region. The general trend of stress damage distribution in different stress regions is similar, and the stability of maximum stress measurement point is the basis of load expansion. Except for torsion load, transverse load and braking load, the design load obtained by the extension of the rest of the load is close to the design load specified in EN13749 standard. The research work provides a new idea for load spectrum extension, and lays a foundation for providing design load based on actual line test load for frame structure design.

Key words: high speed EMU, frame load, load extension, fatigue limit