High cycle fatigue and fracture mode analysis of 2A12–T4 aluminum alloy under out-of-phase axial–torsion constant amplitude loading

Fatigue experiments with solid cylindrical bar specimens are carried out to investigate the effects of stress amplitude ratios and phase angles on the axial–torsion high-cycle fatigue failure of 2A12–T4 aluminum alloy. Macro- and micro-analysis of the specimen fracture appearance is conducted in order to obtain the fracture characteristics under combined axial–torsion loading with different stress amplitude ratios and different phase angles. The soft factor of fatigue loading is introduced to estimate the failure mode under the combined axial–torsion loading. The result indicates that the estimation about the soft factor of fatigue loading is consistent with the macro- and micro-analysis.