Abstract: The stress-time test of high-speed train axles is done along the rebuilt railway line and Jingjin intercity railway line. The stress spectrum sample under bending load is got on the basis of stress-time data of hollow axles using the rain-flow cyclic counter method. The equivalent stress of the stress spectrum is researched when there are notches on axles. It is shown that the equivalent stresses of smooth and notched axles are different for the same stress spectrum. Under different speeds the dynamic stress of heavy vehicle axle is bigger than empty one. The equivalent stresses under different speeds change slightly for a kind of rail. On the contrary, for different kinds of rails the equivalent stressed change largely, that is to say, the equivalent stress amplitude along the rebuilt railway is higher obviously than Jingjin intercity railway. The S-N curve parameters with different notches and the corresponding fatigue limits were calculated. If there is no notches on the axle the equivalent stress is lower the fatigue limit of smooth axle material. But the equivalent stress of notched axles trends to exceed the relevant fatigue limit. So in view of damage tolerance design the train’s running environment and axles’ surface status should be considered in the axles fatigue strength design.

Key words: axle, damage tolerance, equivalent stress, load spectrum