モードI・モードII組合せ応力負荷の下での疲労き裂進展挙動とき裂発生・破断寿命

概要

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The mixed mode fatigue testing was carried out by applying the same phase and arbitrary ratio of torsional loading to tensile loading. The threshold stress intensity factor and fatigue fracture toughness decreased with an increase of ΔK_<II0> foe initial crack. On the other hand, the stable fatigue crack growth region was found to be devided into II_a region of low growth rate and II_b region of accerated fatigue crack growth rate. Both regions were influenced by mixed mode loading. The crack initiation life N_i and propagation life N_f had similar characteristic in terms of (1+Δτ/Δσ)/√<ΔK_<I0>^2+3ΔK_<II0>^2>=(1+ΔK_<II0>/ΔK_<I0>)/√<ΔK_<I0>^2+3ΔK_<II0>^2>, where ΔK_<I0> and ΔK_<II0> are the stress intensity factor amplitude od initial crack. The value of N_i/N_f was found to be about 0.12.
社団法人日本材料学会の論文
1986-08-15