Fatigue behaviour of rail steel—a comparison between strain and stress controlled loading

Strain and stress-controlled fatigue testing of rail material UIC grade 900A has been performed. The tests were carried out in uniaxial, constant amplitude push–pull loading on polished test bars. Strain-controlled experiments were performed at 0.4, 0.6 and 1.0% total strain amplitude. Two identical tests at each strain level were made and the results show very little spread: <1.5% difference in stress amplitude during the fatigue life and <5% difference in number of cycles to failure. The stress-controlled tests were selected to match the strain-controlled experiments in terms of stabilised stress levels. The number of cycles to failure in the two types of tests is very similar, indicating little influence of initial overloads experienced in strain control.