A novel rolling contact fatigue testing method based on dry-wet alternation and damage mechanism of rails

Rolling contact fatigue (RCF) damage is the critical damage form faced by rails, especially under rainy and humidity conditions. In order to deeply explore the mechanisms of RCF damage under such conditions, a novel wet-dry alternation testing method (D/W-A test) was proposed, and rail RCF damage evolution tests were conducted in this study. Detailed comparisons between the novel testing method and three widely used rail RCF methods were analyzed. The results show that under wet-dry alternating conditions, the crack growth rate and wear rate were initially low, with cracks predominantly located in the region near the rail surface. Thus, there was a significant competitive relationship between crack propagation and wear in this period. Then, with the increase in cycling number, RCF damage was gradually dominated by crack propagation, which extended deeper into the material along its deformation orientation. Meanwhile, the severe material spalling led to a rapid increase in wear rate. Through comparative analysis of the accuracy, repeatability, evaluability, rationality, and practicability of the four testing methods, it was found that the novel method proposed in this study had significant advantages in rationality and accuracy compared with traditional RCF testing methods, providing a more effective tool for systematic studies on RCF performance of rail materials.