Criticality of Cracks in Rails Using Photoelasticity and Finite Elements

Welded rails are widely used in the railway industry nowadays for better performance over jointed rails. Cracks initiate in these rails during service increasing its vulnerability to failure in adverse thermal gradients. It is desirable to study the adverse cases using simplified models to get meaningful insights for prototype analysis. Toward this, photoelastic experiments are carried out on simplified planar models for certain crack configurations in tension and compression zones under contact loading. The stress intensity factors (SIFs) are evaluated using over-deterministic nonlinear least squares method. The same cases are numerically simulated using Abaqus® and compared with experimental results for validation. Configurations are identified for their criticality based on the evaluated SIFs. A symmetrically loaded bottom crack configuration is taken first to gauge the difference in numerical and experimental SIFs. Next, for two different configurations with same load, it is noted that crack in the compression zone shows higher SIF compared to that in tension zone. It is shown that the numerical results match with experiments for crack in compression zone when it is remodelled as a crack with a finite root radius. This study finds application in rail-fracture analysis considering multiple crack interactions.