Research on the fatigue test of full-scale wheelsets for high-speed trains

Abstract

Traditional axle design employs an infinite-life design based on nominal stress methods. This cannot meet practical requirements due to initial defects in the axle caused by processing environments or impact from flying stones, leading to crack initiation, propagation, and axle failure. Based on the vertical force on the axle neck and wheel-rail force extracted from the coupled rigid-flexible dynamic model, as well as the load-stress transformation relationship at the critical section of the axle, the force load time history and the stress time history in the crucial section of the axle are converted. The stress time history after conversion is subjected to load spectrum compression based on time correlation methods to reduce test time. The compressed stress time history is then subjected to rainflow counting and mean stress correction. Under the principle of equivalent crack growth length, it is converted into the equivalent load cycles corresponding to the stress at the critical section of the axle obtained from the calibration of the wheelset fatigue test bench under full axle load. A test scheme for initiating axle cracks is proposed. In the crack initiation test conducted on the test axle with a prefabricated semi-elliptical flaw using a wheelset fatigue test bench, no crack initiation was observed after 5.5 million load cycles. Based on full-scale axle crack propagation tests, the remaining service life of the axle was determined to be 83,476 km.