Assessment of stability and crack growth trajectories in rails under cyclic loading conditions

Abstract

This article examines methods for analyzing and predicting the development of subsurface cracks in the railhead. Particular attention is given to longitudinal-transverse and transverse cracks, as well as the factors influencing their growth and trajectory changes. The objective of the research is to develop and refine analytical and numerical methods for predicting the growth trajectory of subsurface cracks in rails under cyclic loading. The focus is on assessing the potential for longitudinal cracks to transition into transverse cracks and determining the conditions under which this phenomenon occurs. Research methods include the application of fracture mechanics, analytical calculation models, and numerical simulations using the finite element method. Equations describing the stress-strain state of the rail and crack growth stability criteria are employed. The calculations account for contact load parameters that influence crack growth and trajectory changes, such as friction force, contact patch size, and the relative position of the crack. Results show that longitudinal-transverse cracks in rails develop significantly faster than transverse cracks, substantially increasing the risk of rail failure. It is established that under certain conditions, the crack growth trajectory may deviate, leading to its transition into a normal separation crack. Numerical experiments identified critical load parameters and crack geometry affecting the likelihood of unstable crack growth. Practical significance: The study's findings can be used to improve the prediction and prevention of rail failures under operational conditions, thereby enhancing railway transport safety. The assessment models and methods can be integrated into rail track diagnostics and monitoring systems, enabling timely detection and elimination of hazardous defects.