Investigation on fatigue crack propagation behaviour of U71Mn and U75V rails using peridynamics

Fatigue crack propagation in rails is an important factor that increases the cost of railway maintenance and threatens operating safety. Research into fatigue crack propagation rules for different rail materials helps to provide scientific guidance for rail selection and maintenance plans. Based on the results of fatigue crack propagation tests on U71Mn and U75V rails, the bond fatigue fracture criterion was established for the two materials, and their accuracy was verified. Using ordinary state-based peridynamic theory, a model was established to analyse the process of crack propagation in the two types of rails. The behaviour of U71Mn and U75V rails was then simulated with different wheel loads and wheel-rail friction coefficients, and the characteristics and rules for fatigue crack propagation in the two types of rails were analysed in a comparative manner. The results showed that the material type exerted little impact on the crack propagation path within the rails and that the U71Mn rail, which showed a lower crack propagation rate than the U75V rail, is more suitable for high-speed railways. The rate of crack propagation increased with both wheel load and wheel-rail friction coefficient. Certain measures, such as track regu-larity improvement, could be employed to reduce dynamic wheel-rail impact, while others, such as lubrication, could be adopted to decrease wheel-rail friction coefficients to prolong rail service life.