Effect of Proportional/ Non-Proportional Axial-Torsion Cyclic Loading on Fatigue Life of Notched Specimens of C-Mn Steel

The present study aims to present experimental results on notched tubes of C-Mn steel under proportional and non-proportional axial-torsion cyclic loading conditions. Tubes with two different sizes of through-thickness circular holes in the gauge region of tube specimens were used for fatigue experiments. These tubes with circular holes have been subjected to remote in-phase (proportional) and out-of-phase (non-proportional) axial-torsion strain-controlled conditions. During the test, localized strain fields ahead of the hole have been measured using digital image correlation technique. The test fatigue lives under proportional and non-proportional loading conditions have been compared for the same set of remotely controlled axial and torsion strain amplitudes. The experimental fatigue life under non-proportional conditions comes out to be higher than that of corresponding proportional loading conditions for such tubes with holes and same remote loading conditions.