等方性炭素鋼平滑材の回転曲げとねじり疲労における疲労限度と微小き裂伝ぱ則

概要

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Rotating bending and torsional fatigue tests were carried out on plain specimens and small-hole specimens of annealed cast carbon steel. The specimens are regarded as isotropic. The fatigue limit ratio between rotating bending and torsional fatigue (τ_w/σ_w) in the isotropic carbon steel is different from that in a rolled round bar of carbon steel. We should use isotropic materials in fatigue tests under combined stresses. In torsional fatigue, crack propagation on plain specimens is of the shear type in the initial stage and tension type in the latter stage. Cracks of the shear type were generated in both the circumferential and the axial directions. The crack growth laws in bending and torsion are expressed by dl/dN= C_1τ^n_al. The dependency of 1/N_f on the stress amplitude τ_a in the torsional fatigue is nearly the same as the dependency of the crack growth rate on τ_a.
一般社団法人日本機械学会の論文
1993-02-25