Study on fatigue damage tolerance of rail steel materials using peridynamics

With railways transitioning into the maintenance era, this study proposes a method to ensure structural safety and control maintenance costs. We develop a Peridynamics (PD) fatigue crack growth prediction model to determine the safe crack threshold for rail steel material under cyclic loading, known as the fatigue damage tolerance size. By conducting fatigue tests, we obtain the PD parameters for the rail steel and rigorously validate the model's reliability. Using both the compact tensile (CT) specimen model and a transient wheel-rail contact model, we analyze factors influencing crack propagation and fatigue damage tolerance. The results reveal that higher cyclic loads and smaller stress ratios result in shorter fatigue life and smaller damage tolerance sizes. Additionally, larger initial crack angles, faster train speeds, and heavier axle loads reduce fatigue crack propagation life and damage tolerance sizes. Ultimately, based on damage tolerance analysis, it is recommended to limit crack propagation in U71Mn rail steel within a 3.8-millimeter safety range for reliable operation.