Numerical analysis of stress field modification in rails to evaluate the minimum specimen dimensions for FBW process’s residual stress measurements

ABSTRACT This study aimed to determine the optimal specimen size using a finite element model, minimizing dimensions for better logistical efficiency while maintaining the stress field’s integrity. The methodology consisted of simulating a cutting process on a specimen, where the only mechanical load applied was the residual stress resulting from the flash butt welding (FBW) process, which is the most commonly used method for joining rail segments. Consequently, any variation observed in the residual stresses was attributed to a redistribution caused by material removal. The cutting process was simulated by sequentially removing elements with the element death feature, replicating vertical cutting conditions. Cutting distances ranged from 200 mm to 25 mm from the weld interface to identify the optimal distance preserving stress field setup. The results showed that stress variation increased as the cut approached the weld interface. A cut at 25 mm caused significant changes in the stress field, with an average difference of 89%, while a 125 mm cut resulted in a smaller 3% variation at measured points. These findings highlight the importance of selecting appropriate specimen sizes to ensure accurate mechanical testing and residual stress analysis in railway applications.