An Estimation of Mean Stress in Circumferentially Notched Components of Annealed Copper Subjected to Cyclic Loading

Circumferentially notched components of annealed copper were low-cycle fatigued under load-controlled condition being accompanied with mean load. In addition, their cyclic stress-strain responses were calculated under the corresponding loading conditions by means of elastic-plastic finite element method, where the constitutive equation proposed by the authors in their earlier paper was employed. The calculated nominal stress-diametral strain response at the minimum cross-section was in quite good agreement with the experiment, showing the validity of the present computation. The compressive mean stress generated at first one cycle at the notch-apex shakes down to be attenuated during the following cyclic loading under the condition of the load ratio Rp = -1.0, while this changes very slightly in the same direction during the further cyclic loadings at the Rp = -1/3 and 0. The stress ratio at the notch root Rσ is generally smaller than Rp, and the difference between them is much greater at Rp = -1/3 and 0 than at Rp = -1.0, in the sharper notch than in the duller notch, and under smaller applied cyclic loading than under the greater one. Incidentally, the tensile mean stress was yielded in the center region at the minimum cross-section of the notched components.