Shape of the Cyclic Stress-Strain Loop in the Low-Cycle Fatigue Tests

Abstract

The stress-strain relations for nickel-chrome steel, aluminum, and low-carbon steel were investigated under various cyclic loading conditions, such as constant strain cycling, constant load cycling with and without mean stress. The following approximate formula to represent the shape of cyclic stress-strain loop was obtained for the whole range of life excluding the initial and final periods, [numerical formula] where σ and ε denote the changes of stress and strain in each half cycle measured from the tip of each loop, σ_max is the maximum tensile stress in each half cycle and K, m, and p are material constants. Cyclic stress-strain curve proposed by Morrow can be deduced from the above formula in a special case.