切欠き材の疲労強度に関する一考察

抄録

For designing various machinery components or structures, it is important to clarify the condition of crack initiation in notched specimens. Now, the local stress state of any place of the parts, from which a crack may initiate, can be calculated comparatively easily by the elasto-plastic analysis with an electronic computer, so that the fatigue life prediction of the components or structures is achieved more accurately.
In this study, fatigue tests have been carried out on both the smooth and notched specimens of annealed S 35 C steel in order to obtain the crack initiation life, and the elasto-plastic calculation has been performed by FEM to find the stress and strain at the notch root. These data were used to discuss the relationship between the stress or strain at the notch root and the crack initiation life.
The results show that, except the fatigue limit, the crack initiation life can be predicted from the stress or strain at the notch root, and that an equation
K_t-1/K_σ-1-1=2(K_ε-1/K_t-1-1)
is convenient to estimate the fatigue strength of the notched specimen from both S-N curve and σ-ε curve of the material.