The Effects of Mean Stress and Stress Concentration on Fatigue Under Combined Bending and Twisting

The Gough test data on fatigue under combined bending and twisting with superimposed mean bending and torsion stresses with and without stress raisers has been re‐investigated in terms of the stresses acting on the plane of maximum range of shear stress. It has been shown that the allowable amplitude of shear stress on this plane can be predicted from an equation of the form τa= [t ‐ c1 (Kt×σa)1.5−c2σ2m]/Kt where σa and σm are the normal stress amplitude and mean normal stress respectively on the plane of maximum range of shear stress, c1 and c2 are defined material constants and Kt is the theoretical stress concentration factor.