Combining welding-induced residual stress with thermal and mechanical stress in continuous welded rail

Abstract

Continuously welded rail (CWR) with flash-butt welded joints has become standard practice for railway construction around the world. The welding process during rail installation or repair forms a residual stress field in the weldment altering locally the distribution and amplitude of the total stress that develops when the rail is in service. This paper presents a computer simulation approach to study the combined residual, thermal, and mechanical stress caused by the fastener system that develops in rail during the in-track welding and installation. The proposed approach simulates within a Finite Element Analysis framework the rail welding and installation sequence using detailed thermal and mechanical models of the weldment formation, and in-track installation. The model is validated with experimental measurements reported in the literature. It is implemented in a study that demonstrates the combined effects of such stresses with stress that develops in the rail during a daily solar-induced thermal cycle. A non-trivial stress gradient is observed where the mean tensile stress in the weldment is elevated relative to the rail at large. The higher mean stress warrants further investigations in view of fatigue performance under wheel loading. The proposed computer simulation approach is a tool that will enable future investigations focusing on more detailed examinations of weldment behavior, particularly concerning fatigue failures and track configurations, as well as in optimizing welding parameters to control the development of residual stresses.

Keywords

• Flash-butt welding
• Residual stress
• Thermal expansion
• Numerical simulation
• Combination loading