Tension–torsion high-cycle fatigue failure analysis of 2A12-T4 aluminum alloy with different stress ratios

Fatigue experiments with solid cylindrical bar specimens are carried out to investigate effects of axial stress ratio and mean shear stress on the tension–torsion high-cycle fatigue failure of 2A12-T4 aluminum alloy under proportional (φ = 0°) and non-proportional loading (φ = 90°). Experiment results about effects of axial stress ratio show that fatigue life reduces gradually with the increase of axial stress ratio. The reduction is more significant under non-proportional loading than that proportional loading. Experiment results about effects of mean shear stress show that there are no remarkable effects on fatigue life under proportional loading. However, the existence of mean shear stress makes a significant reduction of fatigue life under non-proportional loading. Macro-analysis and micro-analysis of specimen fracture appearance is conducted in order to obtain the fracture characteristics with different stress ratios under tension–torsion loading.