Experimental characterization and modelling of triaxial residual stresses in straightened railway rails

摘要

Residual stresses in railway rails have a significant influence on the rail functional properties and reliability in service life. Already during the production, the roller straightening as the final production step removing the rail curvature causes the formation of complex stress fields. In this work, a complementary experimental characterization of longitudinal, transversal and normal residual stresses in an uncut straightened rail with a length of 0.5 m is performed using neutron diffraction and contour method. Additionally, the residual stresses are predicted numerically by means of an extensive three-dimensional finite element simulation taking into account the cyclic elastic-plastic material behaviour of the rail including combined kinematic-isotropic hardening. The very good agreement between the experimental and numerical data provides a basis for the understanding and predicting how the straightening procedure, that is, the positioning of the individual rollers and forces applied by the rollers, influences the triaxial stress fields at the rail cross-section.