Research on the damage mechanism of the rolling contact fatigue of a wheel–rail contact system under the influences of surface defects

Abstract

Severe wheel–rail rolling contact fatigue (RCF) can be affected by the surface defects, which threaten the operational safety of rail vehicles. To explore the RCF damage mechanisms of the wheel–rail under the influences of surface defects, an indentation device was used to prepare surface defects. Twin-disc RCF and wear tests and finite element analyses (FEAs) were conducted. The influence of surface defects on wheel–rail RCF damage were explored by observing the surfaces and cross-sections of defects. The results show that as the number of cycles increases, an RCF crack is generated in the maximum stress concentration area of the defect, i.e., the region near the middle edge, and it expands in the form of a “C” shape. The leading edge of the defect spalls first due to the large number of laminar cracks. As the cracks continue to propagate, large spalls can be seen. The FEA results show that the residual stress distributed on the shoulder around the defect is the largest. The maximum residual tensile stress is located on the lower surface of the defect and the largest stress concentration is located on both sides of the middle edge of the defect when the wheel–rail rolls.