A comparative study between FEA,trepanning and neutron strain diffraction on residual stresses in flash-butt welded rails

Abstract

This paper compares three independent methods for deriving the residual stresses distribution in AS60 normal cooled flash-butt welded rail. A numerical technique utilised a sequentially coupled thermo-mechanical analysis with representative temperature dependent and phase transformation properties of the rail steel. The numerical model also incorporated an element removal regime to assess the effect of stress relaxation when slicing a plate section from a welded rail section for neutron stress mapping. Two experimental techniques were used to quantify the magnitude of residual stresses in the weld; these were strain gauging and trepanning, and neutron diffraction (ND). The results showed satisfactory correlation between the residual stress distribution obtained from the numerical analysis and the strain gauge/trepanning data and ND stress mapping,respectively. The ND and numerical analysis both confirmed that the tensile residual stresses in both vertical and longitudinal directions are concentrated in the web region, despite a significant relaxation as a result of the sectioning method used to obtain the plate section for neutron stress mapping.